Apparatus and process

Abstract

Disclosed is a container for producing a metal or element from a metal or elemental ore or concentrate. The container is configured to receive the metal or elemental ore or concentrate, and a carbon source and to form a part of or be removably placed within a high temperature furnace. The high temperature furnace is configured to maintain the metal or elemental ore or concentrate and the carbon source at a reaction temperature for an operational time to produce the metal or element. Preferably, the high-temperature furnace comprises a volume utilization factor of greater than 10%. In an example, the container is closed or substantially closed and configured to maintain a gaseous atmosphere surrounding the metal or elemental ore or concentrate and the carbon source.

Description

APPARATUS AND PROCESSTECHNICAL FIELD

[0001] The invention broadly relates to an apparatus and process for producing metals or elements from mining ores or concentrates, including the produced metals or elements. Example embodiments include, but are not limited to, the energy efficient production of iron in purified form, from mined iron ores. Example embodiments also relate to the production of renewable (‘green’) metals or elements from their mined metal ores or concentrates using renewable energy, including, but not limited to, the production of renewable iron from iron ores.BACKGROUND

[0002] Iron and steel production processes are energy intensive, requiring, on average, 19.76 GJ to convert mined iron ore to a tonne of steel. They are also carbon intensive, with an average of 1.83 tonnes of carbon dioxide (CO2) emitted per tonne of steel produced. Indeed, iron and steel production processes are estimated to be responsible for 5-11% of all global carbon emissions.

[0003] Much of the energy consumption and carbon emission are due to the reduction and smelting processes employed during ‘ironmaking’, which involves the conversion of mined iron ore into iron itself (that may thereafter be used to produce steel). Such processes have traditionally been carried out in ‘Blast Furnaces’ (BF). Blast furnaces are large industrial furnaces that utilise temperatures exceeding 1,500 °C to convert iron ore into molten iron. In a blast furnace, fuel (e.g. coke), iron ores, and flux (e.g. limestone) are supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment and coal / natural gas injection) is blown into the lower section of the furnace, causing chemical reactions to take place throughout the furnace as the materials move downward. The molten iron is collected at the bottom of the furnace in a form that, after solidification, is known as ‘pig iron’ (in solid form) or ‘hot metal’ (in liquid form). Pig iron may comprise 90-95% metallic iron (Fe) with high carbon content. Such pig iron may subsequently be processed, in molten form, into low-carbon steel, using a separate furnace known as a ‘Basic Oxygen Furnace’ (BOF).

[0004] The iron ore employed in a blast furnace typically comprises mostly of hematite (Fe2O3, which comprises 69.9% total Fe content), but may also include other minerals such as goethite (FeO(OH), 62.9% total Fe content), magnetite (Fe3O4, 72.4% total Fe content), limonite (FeO(OH).n(H2O), 55% total Fe content), wilstite (FeO; 77.7% total Fe content), or siderite (FeCO3, 48.2% total Fe content). The total iron content of a material refers to the mass of all of the Fe atoms, as a percentage of the total mass of the material. Before being passed into the blast furnace, the iron ore may typically be crushed and sieved into particles known as ‘lumps’. In one industry standard, lumps are agglomerations of iron ore in the size range 6.3 - 31.5 mm, while iron ore particles smaller than 6.3 mm are referred to as ‘fines’. These ‘sizes’ derive from the size of the openings in the sieves that are used to sort them.

[0005] A process for producing metallic iron from iron ores that avoids the need for a blast furnace is generally termed a ‘Direct Reduced Iron’ (DRI) production process. An example of a DRI production process is the MIDREX process, or related variants, which uses a gas, such as hydrogen gas or ‘syngas’ (a mixture of hydrogen and carbon monoxide (CO) gas), as a reductant.

[0006] In a typical DRI process, iron ore, preferably comprising mainly of magnetite (Fe3O4, 72.4% total Fe content), is finely crushed, sieved, and then combined with binders (e.g. bentonite) to form ‘pellets’. Pellets are balls or small structures that may typically be formed by rolling moist concentrates and finely crushed or powdered iron ores of different mineralogical and chemical composition with additives and binders, in a horizontal drum or in an inclined disc. After heating and sintering, such iron ore pellets may, illustratively, have a rounded profile with a relatively uniform size range (e.g. 9 - 13 mm width).

[0007] Following their production, such pellets may, in a typical DRI process like the MIDREX process or related variants, be dropped into a ‘Shaft Furnace’ (SF), which is a cylindrical or rectangular furnace that is heated by a counter current flow of hot combustion and reduction gases (e.g. hydrogen gas) moving up from the bottom of the furnace. Within the shaft furnace, the pellets may form a moving bed that becomes progressively more reduced down the height of the furnace. Pellets are typically needed (rather than ‘lumps’) to avoid the formation of blockages in the shaft furnace. The pellets collected from the bottom of the shaft furnace may typically be termed ‘sponge iron’ or ‘Hot DRI’ (HDRI), andcomprise 86-94% metallic iron (Fe), meaning that 86-94% of the product mass is iron metal. Sponge iron may also, ideally, be 90-96% ‘metallized’. This percentage indicates the extent to which iron oxides in the ore have been converted to metallic iron during the reduction process. The ‘metallization percentage’ of a material, is the percentage of the metal in the material that is in an oxidation state of zero (i.e. in metallic form) relative to all other oxidation states. Thus, for example, a sponge iron sample that is 90% metallized means that 90% of the iron atoms present in the sample are metallic iron (i.e. Fe(0)), with the remainder being in higher oxidation states of iron, like Fe(II) or Fe(III). Achieving such high metallization percentages typically requires large energy inputs, which include the energy needed to produce the pellets used as a feedstock in the process.

[0008] As sponge iron may typically be porous and therefore reactive, with a risk of uncontrolled, exothermic oxidation or auto-ignition during subsequent storage or transportation, it may be converted into ‘briquettes’ following its formation. Briquettes may typically be pillow-shaped and sized structures that are produced from hot DRI, without use of a binder. The product of a briquetting process may typically be termed ‘Hot-Briquetted Iron’ (HBI). HBI is the preferred product for the merchant metallics market as it is denser than cold DRI, which reduces the re-oxidation rate and enables HBI to be stored and shipped as a bulk cargo without special safety precautions. Provided that it contains a very high proportion of metallic iron, HBI may be used to make steel within an ‘Electric Arc Furnace’ (EAF), wherein the heat necessary for melting of the metal comes from an electric arc that is created by electrodes within the furnace.

[0009] The potential to reduce the energy consumption of (and thereby also the cost of) DRI ironmaking processes, as well as their carbon emissions, relative to blast furnaces, is a topic of notable interest in the industry. A publication in the journal Steel Research International (2023), Volume 94, article number 2200297, which is incorporated herein by reference, outlined typical material and energy consumptions of the various individual process steps that may be involved in cradle-to-grave steel production. Considering only the reduction processes involved in ironmaking (i.e. processes that, effectively, convert iron ore into pig iron or sponge iron), they found the following typical material consumptions and energy intensities, per tonne of pig iron or sponge iron produced:Blast Furnace:The production of 1 tonne of pig iron typically requires an energy consumption of 12.6 GJ (3,500 kWh), wherein 0.43 tonnes of coke is used to produce 11.59 GJ (3,220 kWh), while natural gas and electricity produce the remaining 1.01 GJ (280 kWh). Around 1.8-2.4 tonnes of CO2 is emitted per tonne of pig iron produced.(Section 2.1.1 and Table 2 in Steel Research International (2023), Volume 94, article number 2200297).• Gas-based DRI (example: the MIDREX process):The production of 1 tonne of sponge iron may typically require 12.59 GJ, comprising of:- 10.55 GJ (2,931 kWh) to carry out the chemical reduction process itself, via the use of 72 kg of hydrogen (8.62 GJ; 2,395 kWh equivalent), 36.56 kg of natural gas (1.28 GJ (355 kWh @35 MJ / kg, LHV of natural gas), and 0.65 GJ (180 kWh) of electricity; and- 2.04 GJ (566 kWh) to pelletize the iron ore prior to the DRI process, via the use of 46 kg of natural gas (1.61 GJ (447 kWh@35 MJ / kg, LHV of natural gas]) and 0.43 GJ (119 kWh) of electricity.Approximately 0.35 tonnes of CO2 may typically be emitted per tonne of sponge iron produced.(Figure 3 and associated text describing the use of 75% DRI and 25% scrap metal, natural gas case, in steelmaking in Steel Research International (2023), Volume 94, article number 2200297).

[0010] While gas-based DRI production processes like the MIDREX process therefore have notably lower CO2 emissions, blast furnaces are still generally considered to offer the lowest cost method of producing purified iron.

[0011] The above energy consumption / energy intensity and carbon emission data provide benchmarks for ironmaking. Many other industrial DRI processes require more energy and emit more CO2 than the above.

[0012] Examples in this respect may generally include DRI production processes that employ solid-state carbon as a reductant at high temperature, in a ‘carbothermic’ reaction. Illustrative examples include the FASTMET process developed by Kobe Steel and MidrexTechnologies, the Stelco-Lurgi / Republic Steel-National Lead (SL / RN) process, and the Hoganas process developed by the Swedish company Hoganas AB.

[0013] In the FASTMET process and related variants, finely particulated iron-bearing feed materials (e.g. iron ore or steel mill residues) may be mixed with finely powdered carbon source materials (e.g. non-coking coal) and pelletised. The resulting pellets may be layered within and heated to very high temperatures (e.g. 1,350 °C) in a ‘Rotary Hearth Furnace’ (RHF). A mixture of carbon monoxide (CO) and hydrogen (H2), known as ‘Synthesis’ gas (or ‘Syngas’) may be simultaneously passed through the furnace. The syngas may typically be separately produced by gasification of coal in a device known as a ‘Coal Gasifier’. A carbothermic solid-state reaction may thereby be facilitated within the furnace, in which the carbon reduces the iron ore into metallic iron (Fe) in the pellets. The pellets may typically require heating for only 6 - 12 minutes in the rotary hearth furnace. The Direct Reduced Iron (DRI) thus produced, may typically comprise 85-96% total Fe content.

[0014] Most of the coal -based DRI production in India involves the direct reduction of iron ore or pellets thereof, using solid carbon (coal) in a rotary kiln. The SL / RN process and related processes, provide examples in this respect. The rotary kiln may typically be provided with a refractory lining to protect its shell, and have a slope of 2.5% - 3.0% toward the discharge end. The raw materials, including the iron oxides (e.g. hematite that is rich in iron content, with 65% or more Fe) and non-coking coal may typically be fed into the kiln continuously from the feed end. As the charge moves down the kiln length, it may gradually pick up heat from hot gases flowing in the opposite direction of the charge within the kiln. The charge may typically pass through a pre-heating zone in the kiln, followed by a ‘reduction’ zone (maintained at 900-1,050 °C), in which oxygen atoms are removed from the hematite. The residence time of the iron ore inside the kiln may typically be 8 - 10 hours, to form metallic iron. Following cooling, the resulting sponge iron may typically be purified using magnetic separation.

[0015] In the Hoganas process and variants thereof, a reduction mixture (typically incorporating finely dispersed coke) may be combined with finely crushed magnetite ore within large, vertically arrayed, open-topped, cylindrical ceramic tubes. Each ceramic tube may typically comprise of four interconnecting, hollow tubular elements that are stacked on each other, imparting the ceramic tube with a total height of up to ~2.0 - 4.5 metres, and aninternal diameter of ~0.5 - 0.9 metres. Each ceramic tube, with its internal charge, may then be passed through a long tunnel kiln (e.g. 260 metres in length), moving sequentially through, first, a preheating zone, followed by a firing zone (typically maintained at 1,100 - 1,200 °C), and, finally, a cooling zone. The total time required in the kiln may typically fall in the range 1.5 - 4 days, of which 20 - 48 hours may be spent in the firing zone. To inhibit ingress of air, the magnetite / coke charge in each ceramic tube may typically be covered with a layer of excess carbon on top and around it. This has been found to better hinder air ingress than seeking to physically close and / or seal the ceramic tube, which can, in practice, only be successfully achieved at near ambient temperatures, prior to entering the tunnel kiln. Once the ceramic tube is heated to the elevated temperatures in the kiln, the volume of carbonbased gases produced inside it, are such that they will necessarily break or burst any physical closures or seals, including, potentially, in a catastrophic manner (e.g. by an explosion).

[0016] The carbon-based gases that are produced in carbothermic processes, derive from the direct or indirect reductions that occur. In processes where the metal oxides and the carbon reductants are in physical contact with each other (e.g. where they are physically mixed, in finely divided forms, in pellets of the type used in FASTMET), the direct reduction reactions (l)-(3) below may occur. In these reactions, solid-state iron oxide particles (e.g. Fe2O3, Fe3O4, FeO) react with physically abutting solid-state carbon particles (C), to produce carbon monoxide gas (CO).Direct reduction reactions, e.g.3 Fe2O3+ C 2 Fe3O4+ CO...(I)Fe3O4 + C 3 FeO + CO...(2)FeO + C → Fe + CO...(3)In such processes, the quantity of carbon used must be very carefully metered since any excess, unreacted carbon remaining after the process, may typically contaminate the product DRI pellets. This may create complications for their subsequent processing into steel. A carbothermic DRI process that avoids or, at least, better controls such contamination may be desirable.

[0017] CO gas, from the above reactions or from externally supplied syngas, may also reduce iron oxides (e.g. Fe2O3, Fe3O4, FeO), producing carbon dioxide gas (CO2) by indirectreduction reactions of the types shown in (4)-(6) below. These reactions avoid the need for physical contact between the metal oxides and the carbon reductants:Indirect reduction reactions, e.g.3 Fe2O3+ CO → 2 Fe3O4+ CO2...(4)2 Fe3O4+ 2 CO — ► 6 FeO + 2 CO2...(5)6 FeO + 6 CO 6 Fe + 6 CO2...(6)Overall: 3 Fe2O3+ 9 CO 6 Fe + 9 CO2...(7)[Additional note: The gaseous hydrogen (H2) in externally supplied syngas may also act as a reductant, giving the overall indirect reduction reaction:Overall: 3 Fe2O3+ 9 H2→ 6 Fe + 9 H2O...(8)]Processes relying solely on indirect reduction reactions of the above types eliminate the possibility of the product DRI being contaminated with carbon. Processes in which there is no or little physical contact between the metal oxides and the carbon reductants are termed ‘non-contact’ carbothermic processes.

[0018] The two carbon-based gases produced, CO and CO2, further exist in a chemical equilibrium with each other according to the ‘Boudouard’ reaction (9) below:2 CO ⇌ CO2+ C...(9)The molecular ratio of CO to CO2 present in the above equilibrium may typically depend on the temperature. Below -500 °C, CO2 may typically be overwhelmingly favoured over CO and may be the main carbon-based gas present in the equilibrium. Above -900 °C, however, CO may typically be strongly favoured over CO2 and may be the main carbon-based gas present in the equilibrium.

[0019] The large volumes of carbon-based gases produced in carbothermic processes are related to, and derive from, the often-high proportions of the oxygen atoms (e.g. in the ironoxides Fe2O3, Fe3O4, FeO) and the carbon atoms (e.g. in the coal), that are removed from the solid-state reactants in the form of gaseous CO or CO2.

[0020] Carbothermic reaction processes may typically be more energy -intensive (and more costly) than other direct reduction methods. According to Table 18 in the publication entitled " Comparison of Different Coal Based Direct Reduction Processes' by M. Kekkonen and E. L. Holappa, published in August 2020 by the Helsinki University of Technology in Finland, which may be obtained at: https: / / www.researchgate.net / publication / 269107176_COMPARISON_OF_ DIFFERENT COAL BASED DIRECT REDUCTION PROCESSES, and which is hereby incorporated by reference, the production of 1 tonne of sponge iron using the FASTMET process may typically require 15.912 GJ of energy. Related processes, such as the Inmetco process, may typically require 14.261 GJ per tonne of sponge iron produced, according to the same publication. Both energy consumptions are notably higher than those described earlier.

[0021] The rotary kiln-based processes described above may typically have still higher energy intensities. Indeed, according to the publication by Ghosh, A. M., Vasudevan, N. and Kumar, S., entitled " Energy-efficient Technology Options for Direct Reduction of Iron Process (Sponge Iron Plants) ’, published in New Delhi in 2021 by the Sponge Iron Manufacturers Association (SIMA), and incorporated herein by reference, the many coalbased DRI plants in India, which is the largest manufacturer of DRI globally, typically display energy intensities of 17.2 - 22 GJ (4.10 - 5.26 gigacalories (Gcal)) per tonne of DRI produced. This is likely due, at least in part, to the long residence times of 8 - 10 hours needed to form metallic iron in rotary kilns.

[0022] The Hoganas process and related variants, utilizing tunnel kilns, likely consume still higher energy per tonne of iron produced given their long processing and firing times, although their more efficient variants have been said to require around 14.5 GJ per tonne of iron produced (according to S. S. Bedarker in a paper published by the Sponge Iron Manufacturers Association of India, SIMA, p.2-4, September 2009). This likely includes the beneficial effect of burning excess CO from the process in the tunnel kiln. The long processing and firing times of this process reduce the ‘throughput’, i.e. the production rate, per unit time, at which a tunnel kiln may produce DRI. The resulting low throughput may beconsidered to restrict such processes to low-volume, high-cost, niche production methods in the field of ironmaking.

[0023] Author L. D. Danny Harvey published a detailed analysis of the energy consumption of present-day ironmaking techniques in an article entitled ‘A bottom-up assessment of recent (2016- -20) energy use by the global iron and steel industry constrained to match a top-down (International Energy Agency) assessment) in the journal Energy (2024), Vol 293, article number 130675, which is incorporated herein by reference. That study concluded (in its Table 3) that the ‘best practice’ energy consumption for iron ore reduction via the techniques available today were, for a blast furnace: 12.9 GJ per tonne of pig iron produced, while that of gas-based DRI was: 9.5-10.5 GJ per tonne of sponge iron produced. The ‘practical minimum’ energy consumption for these processes, however, was 10.4 GJ and 9.4 GJ per tonne of pig iron and sponge iron produced, respectively. All these values exclude the energy consumption required for pelletizing (which may involve an additional 0.41-2.1 GJ per tonne) and sintering / briquetting (which may require an additional 0.7-2.7 GJ per tonne), as well as the energy needed for coking (where this is required).

[0024] In order to decrease their CO2 emissions, a key objective of DRI processes is to reduce the proportion of the energy consumption provided directly by the carbon or carbonaceous materials used in the process and increase the proportion that is supplied by external energy sources. As noted above:• In a typical blast furnace, -92% (11.59 GJ / tonne iron) of the energy consumed is provided by the coal used in the process, with another -2% provided by externally supplied natural gas and a further -6% by externally supplied electrical power (1.01 GJ / tonne iron cumulatively). It is this direct and extreme use of highly emissive coal that leads to most of the CO2 emissions. CO2 emissions are also produced by the less emissive, externally supplied natural gas and, potentially by the electrical power if it is produced using fossil fuels. As noted above, typical blast furnaces emit around 1.8-2.4 tonnes of CO2 per tonne of pig iron produced.• By contrast, in a typical carbothermic FASTMET DRI process, only -62% of the energy consumed is provided by the coal used, with -26% provided by externally supplied, less emissive natural gas and -12% provided by externally supplied electrical power. (See:the published document at https: / / www.kzbriquettemachine.com / news / technology-of- coal-based-direct-reduction-iron4fastmet-method?, which is hereby incorporated by reference). For this reason, the FASTMET process generally has lower CO2 emissions. It may produce around 1.6 tons of CO2 per tonne of iron produced.• Gas-based DRI processes that avoid the direct use of carbon, such as the MIDREX process may display the lowest proportional use of carbonaceous materials. Thus, when using hydrogen as the reductant, none of the energy consumption is provided by the carbonaceous materials in the process. Emissions are created however by the externally supplied, less emissive natural gas (1.28 GJ / tonne iron) and, potentially, by the externally supplied electrical power (6%; 0.65 GJ / tonne iron). The remaining energy consumed is provided by the non-emissive hydrogen (82%; 8.62 GJ / tonne iron). Only 0.35 tonnes of CO2 may typically be emitted. The lowest emitting ironmaking techniques may generate around 0.18 tonnes of CO2 per tonne of iron produced.

[0025] In summary, an urgent need continues to exist for new ironmaking techniques that produce purified iron at a lower cost, using less energy, and producing less CO2 emissions. This is particularly needed in respect of DRI processes, which, in gas-based form, offer the lowest CO2 emissions but are currently still materially more expensive than blast furnace production. A DRI process that avoids the need for and costs associated with pelletization and briquetting, may contribute to this aim, which would also be desirable.

[0026] A need also exists to develop solid-state or gas-based carbothermic ironmaking and metalmaking techniques that combine the benefits of such processes, avoid their drawbacks, and thereby achieve low costs of production, low energy consumption, and low CO2 emissions.

[0027] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.SUMMARY

[0028] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify all of the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0029] The invention is to be interpreted with reference to at least one of the technical problems described above or affiliated with the background art. The present specification aims to address or ameliorate at least one of the technical problems and this may result in one or more advantageous effects as defined by this specification and described in detail with reference to the preferred embodiments of the present invention.

[0030] The inventors have discovered surprisingly highly efficient carbothermic processes to produce purified metals or elements from lumps or fines of their respective metal ores or concentrates, or elemental ores or concentrates. In particular, the inventors have discovered (and developed means to facilitate) a ‘self-accelerating’ carbothermic chain reaction, which, without limitation, may be ‘autocatalytic’ in character. A ‘self-accelerating’ reaction is a chemical process in which the reaction rate increases as the reaction proceeds, leading to a positive feedback loop that may accelerate the reaction and lead to a shorter time for its completion. An ‘auto-catalytic’ reaction is a specific type of self-accelerating reaction wherein one of the products of the reaction is also a reactant in the reaction, causing the reaction rate to increase over time as more product forms (rather than slowing down like most reactions). Such a reaction may, effectively, be considered to catalyse itself, speeding up its own completion, which property may be characterised by distinctively sigmoidal reaction curves.

[0031] Such reactions may create a powerful driving force for converting the metal or elemental ore or concentrate, for example, an iron ore, into its corresponding metal or element, for example iron. Thus, in their utilisation of such reactions, the inventors have been able to realise significant benefits. For example, they have been able to produce purified metals or elements from lumps or fines of respective metal ores or concentrates, or elemental ores or concentrates, that contain surprisingly low proportions (low enrichment) of their metals or elements. Moreover, the reactions may proceed to higher levels of completion, in shorter times, including much shorter times and much higher levels of completion, than hasbeen common to date. Additionally, because metals or elements of higher purity may be produced in shorter times, the energy consumption per tonne of metal or element produced may be lower, including materially lower, than has been common to date (with accompanying cost benefits). Low or lower proportions of carbon reductants may potentially also be used, leading to low or lower CO2 emissions.

[0032] The level of completion of a reaction may be indicated by the ‘metallization percentage’ or ‘elemental percentage’, in combination with the ‘total metal content’ or ‘total element content’, of the purified metal or element produced from the respective metal ore or concentrate, or elemental ore or concentrate. The metallization percentage or elemental percentage refers to the percentage of the metal or element atoms in the material having an oxidation state of zero (i.e. a pure metal or element) relative to the metal or element atoms having all possible oxidation states. The total metal content or total element content refers to the cumulative mass of all of the atoms of the metal or the element in the produced purified metal or element, as a percentage of the total mass of the produced purified metal or element.

[0033] The inventors have developed a foundational apparatus and process (and variants thereof) to facilitate self-accelerating carbothermic processes of the above types. The apparatus and process may involve at least one container comprising an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a suitable lid, of the type described herein). A ‘charge’, comprising of lumps and / or fines of a metal ore or concentrate, or an elemental ore or concentrate, and a carbon source, may be placed within the container. In one example, the charge may comprise a physical mixture of the metal / elemental oxides and the carbon source. In another example, the charge may comprise separate layers of the metal / elemental oxides and the carbon source, configured for a ‘non-contact’ carbothermic process. The container may form a part of, or be removably placed within a high temperature furnace, which may be, but is not limited to, a tunnel kiln, for example a commercial tunnel kiln that may be used to manufacture sanitaryware, tiles, tableware and other ceramic products. (It should be noted that, by definition, no distinction is made herein between a ‘furnace’ and a ‘kiln’; they are treated as equivalent high temperature ovens). The high temperature furnace may typically maintain the container, with its charge inside, at a reaction temperature (which may typically be below the melting point of the relevant metal or element, e.g. 1,100 °C for iron) for an operational time (e.g. 35 - 90 minutes) to thereby produce the purified metal or element. Thecontainer may be configured to regulate the gaseous atmosphere of CO and CO2 that may be produced within it during the operational time at the reaction temperature (for example, via reactions like ( 1 )-(6) above). The container may do so by providing for safe release of excess CO and CO2 gas whilst simultaneously maintaining at least a preferred internal partial pressure of CO and CO₂. This may be achieved by, for example, using a crucible with a lid, wherein the lid is capable of transiently and reversibly opening to release excess gas pressure and maintain a preferred internal partial pressure of CO and CO₂ within the crucible. The weight of the lid may, for example, be calibrated to create the preferred internal gas pressure. In other examples, the lid or the crucible may incorporate a high-temperature pressure release valve. In still other examples, other means of releasing excess gas whilst maintaining at least a preferred internal partial pressure of CO and CO₂, may be employed. The term ‘preferred internal partial pressure of CO and CO₂’ refers to the preferred simple sum of the partial pressures of CO and CO2 in the container. A crucible and lid may be preferred, albeit not exclusively so, as they may be used repeatedly in high-throughput batch-type production, and may be quickly and easily cycled between batches, as would be needed in an industrial process. During the process, a high temperature solid state transformation of the metal or elemental ore or concentrate into its corresponding metal or element may typically, but not exclusively, occur, without the metal or element ever being smelted or becoming molten at any stage.

[0034] The carbon source may comprise any form of accessible carbon, including, but not limited to, lumps or fines of: charcoal, activated carbon, coal, carbonaceous material, coke, agricultural residues, rice husks / rice straw / , coconut shells / husks, sugar cane bagasse, biomass, any organic fibrous materials, plastics, tyres, biosolids from wastewater treatment plants, wood, sawdust, or timber items, as well as gaseous forms of carbon such as carbon dioxide (CO2) and carbon monoxide (CO). Calcium carbonate (CaCO3) (limestone) may be used as an alternative to using a carbon source.

[0035] Commercial tunnel kilns for manufacturing sanitaryware, tiles, tableware and other ceramic products, have been developed to a high level of sophistication in recent decades and may be capable of realising previously unachievably high energy efficiencies overall (including via their heat recovery systems). Additionally, suppliers of such kilns may be able to provide detailed and reliable information (within a margin of error) regarding the expected heat losses through the walls and interfaces of such kilns. This makes it possible to determinethe energy consumption within such kilns, of processes of the type described herein, in advance, and thereby optimise the kilns employed industrially.

[0036] The inventors have found that, upon initial heating of the container and its charge, the relatively small quantity of atmospheric oxygen (O2) present in the container may initially combust with some of the carbon present, producing a relatively small quantity of carbon dioxide (CO2) gas inside the container. Additionally, if the solid-state metal ore or concentrate, or elemental ore or concentrate, is in physical contact with the solid-state carbon particles (C) inside the container, CO gas may be produced via direct reduction reactions similar to reactions (1)-(3) above. [Of course, if the charge is set up for a ‘non-contact’ carbothermic process in which there is little or no physical contact between the metal / elemental oxide and the carbon source, then such reactions will not occur]. Thanks to the configuration of the container, such CO2 and CO may be largely or somewhat retained inside it.

[0037] Once the container and its charge is at more elevated temperatures during the heating process, above 500 °C, and particularly above 900 °C, the CO2 inside the container will be converted to CO gas via the Boudouard equilibrium shown in reaction (9), which strongly favours CO over CO2 at such high temperatures:CO2 + C → 2 CO...(9)

[0038] The CO gas inside the container may then induce indirect reduction reactions, for example of the type depicted in reactions (4)-(6), when iron ores are used as the metal ore:3 Fe2O3+ CO → 2 Fe3O4+ CO2...(4) Fe3O4+ CO → 3FeO + CO2...(5)FeO + CO → Fe + CO2...(6)

[0039] The indirect reduction reactions may be represented in the general case, as follows:A MxOy+ CO → B Mx±nOy-m+ CO2...(10)where:MxOyis a metal or elemental oxide within the metal or elemental ore or concentrate, Mx±nOy-mis a chemically reduced form of MxOy, whereinM = a metal or element, O = oxygen, CO = carbon monoxide, CO2 = carbon dioxide, x = an integer in the series 1,2, 3, 4,...00, y = an integer in the series 1,2, 3, 4...00, n = an integer in the series 0, 1,2, 3, 4,...00, m = an integer in the series 1,2, 3, 4,...00, andA = an integer in the series 1,2, 3, 4,...00, B = an integer in the series 1,2, 3, 4,...00, and wherein reaction (10) is chemically balanced (i.e. has as many M, O, and C atoms on the left of the equation as on the right of the equation).

[0040] It should be noted that each indirect reduction reaction, of the specific type (4)-(6), or the general type (10), consumes one CO reactant molecule and produces one CO2 product molecule. However, as noted above, each CO2 molecule present in the container, which is closed or substantially closed, is favoured to react with a carbon (C) atom to produce two CO molecules according to the Boudouard reaction (9) above. That is, for every CO molecule that initiates an indirect reduction reaction, two new CO molecules may be produced in a following step. Each of these new CO molecules may initiate new indirect reduction reactions, which may each again ultimately produce two new CO molecules.

[0041] Thus, a self-accelerating chain reaction may be created, in which a single starting CO molecule may initiate a sequence of reaction steps that produce two new CO molecules in total. The two new CO molecules may each initiate new sequences of reaction steps, producing four new CO molecules in total. This may repeat iteratively, leading to the production of 8, then 16, then 32 new CO molecules in total, and so forth, all from a single starting molecule of CO. That is, there may be a spontaneous (and potentially rapid) increase in the rate at which the metal or elemental oxides in the charge inside the container are reduced to purified metals or elements. Such a self-accelerating chain reaction may be referred to as a carbothermic self-accelerating reaction or a carbothermic self-accelerating chain reaction.

[0042] Moreover, it is apparent that CO is not only a product of the above sequence of steps, but also a reactant. CO may be both consumed as a reactant in an indirect reduction reaction (the first step of the reaction sequence) and generated as a product in the Boudouard reaction (the second step of the reaction sequence). Indeed, CO may, as a reaction product, be generated in double the quantities it may be consumed as a reactant in each reactionsequence. Such properties may typically be consistent with a self-accelerating reaction that is autocatalytic in nature. Autocatalytic reactions have only relatively recently become a topic of significant study in science. Autocatalytic reactions are believed to play a major role in evolution and the origin of life.

[0043] It is to be understood, of course, that such self-accelerating chain reactions depend on and can be created only to the extent that the produced CO and CO2 gases may be retained in the closed or substantially closed container used in the apparatus above. The inventors have found that, in practice, if they are capable of safely releasing excess internal CO and CO2 gas, closed or substantially closed refractory containers may be configured to regulate their internal gaseous atmosphere and maintain at least a preferred internal partial pressure of CO and CO₂ at typical reaction temperatures. In this way, the substantial benefits of utilising a self-accelerating reaction, as described in, for example, paragraph

[0031] above, may be realised. The inventors have also found that the higher the partial pressures of CO and CO2 that may be safely maintained within the closed or substantially closed container, the greater the reaction rate amplifications, compressions of the required operational time at the reaction temperature, and other benefits, such as those described in paragraph

[0031] , that may be achieved. The inventors have found that such higher partial pressures may be facilitated by various means described herein, and may be influenced by numerous factors, including but not limited to: the shape of container used, its volume, its arrangement with other, similar containers in the high-temperature furnace, its mode of releasing excess gas pressure at the operating temperature, its capacity to conduct heat, its lid, its seal with its lid, the size and weight of the lid, and other factors described elsewhere in this specification. The weight of the lid may, for example, be calibrated to create and maintain a desired, elevated gas partial pressure within the closed or substantially closed container.

[0044] Preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.8 atm. In other examples, preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.82 atm, more than or equal to 0.84 atm, more than or equal to 0.86 atm, more than or equal to 0.88 atm, more than or equal to 0.9 atm, more than or equal to 0.92 atm, more than or equal to 0.94 atm, more than or equal to 0.96 atm, more than or equal to0.98 atm, more than or equal to 1.0 atm, more than or equal to 1.1 atm, more than or equal to 1.2 atm, more than or equal to 1.3 atm, more than or equal to 1.4 atm, more than or equal to 1.5 atm, more than or equal to 1.6 atm, more than or equal to 1.7 atm, more than or equal to 1.8 atm, more than or equal to 1.9 atm, more than or equal to 2.0 atm, more than or equal to 2.0 atm, more than or equal to 2.5 atm, more than or equal to 3.0 atm, more than or equal to 4.0 atm, more than or equal to 5.0 atm, more than or equal to 6.0 atm, more than or equal to 8.0 atm, or more than or equal to 10.0 atm, in the enclosed or substantially enclosed volume, during the operational time at the reaction temperature. In still other examples, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.75 atm, of more than or equal to 0.7 atm, of more than or equal to 0.6 atm, of more than or equal to 0.5 atm, of more than or equal to 0.4 atm, more than or equal to 0.3 atm, more than or equal to 0.2 atm, or more than or equal to 0.1 atm, in the enclosed or substantially enclosed volume, during the operational time at the reaction temperature.

[0045] Preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 133 atm. In other examples, preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 10.0 atm, of below 8.0 atm, of below 6.0 atm, or of below 5.0 atm.

[0046] A ‘gauge’ partial pressure refers to the partial pressure above the ambient pressure that exists outside of the closed or substantially closed container. Preferably but not exclusively, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.01 atm. In other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.05 atm, of more than or equal to 0.1 atm, of more than or equal to 0.15 atm, of more than or equal to 0.2 atm, more than or equal to 0.3 atm, more than or equal to 0.4 atm, more than or equal to 0.5 atm, more than or equal to 0.6 atm, more than or equal to 0.7 atm, more than or equal to 0.8 atm, more than or equal to 0.9 atm, more than or equal to 1.0 atm, more than or equal to 1.1 atm, more than or equal to 1.2 atm, more than or equal to 1.3 atm, more than or equal to 1.4 atm, more than or equal to 1.5atm, more than or equal to 1.6 atm, more than or equal to 1.7 atm, more than or equal to 1.8 atm, more than or equal to 1.9 atm, more than or equal to 2.0 atm, more than or equal to 3.0 atm, more than or equal to 4.0 atm, more than or equal to 5.0 atm, more than or equal to 6.0 atm, more than or equal to 7.0 atm, more than or equal to 8.0 atm, more than or equal to 9.0 atm, more than or equal to 10.0 atm, more than or equal to 15.0 atm, or more than or equal to 20.0 atm. In still other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.09 atm, more than or equal to 0.08 atm, more than or equal to 0.07 atm, more than or equal to 0.06 atm, more than or equal to 0.05 atm, more than or equal to 0.04 atm, more than or equal to 0.03 atm, more than or equal to 0.02 atm, or more than or equal to 0.01 atm.

[0047] Preferably but not exclusively, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 132.0 atm. In other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 9.0 atm, of below 7.0 atm, of below 5.0 atm, or of below 4.0 atm.

[0048] The inventors have discovered several other surprising benefits deriving from the processes above. Included amongst these is the capacity to energy efficiently reduce both lumps and fines of metal / elemental ores or concentrates. Such a capacity is unusual given that, for example, lumps may typically comprise structures with highly variable densities, porosities, microstructures, and the like. It is precisely for this reason that, for example, iron ores are routinely pelletized prior to reducing them in most Direct Reduced Iron (DRI) production processes. The pelletization creates great uniformity in their structures, facilitating their seamless reduction to iron without the need for large energy input. A further unexpected benefit of using the above processes is therefore avoidance of a need to pelletize metal or elemental ores or concentrates prior to their reduction. Elimination of the need for a pelletization step may reduce energy consumption, decrease CO2 emissions, and lower economic costs.

[0049] The inventors have further discovered that, when purified metals or elements are produced in the closed or substantially closed containers, using the apparatus and processdescribed above, they may be induced to adopt a structure that is complementary to that of the internal volume of the container, or a portion thereof. That is, the purified metal or element may be produced directly in the form of a briquette, thereby avoiding the need for an additional briquetting step. The physical properties of such briquettes may, moreover, be beneficially adjusted by various means described herein. Amongst others, such briquettes may be induced to incorporate unique, desirable structural features deriving from changes that occur in the microstructures of the metal or elemental ore or concentrate during the process. For example, a metal that may be subject to uncontrolled exothermic oxidation or auto -ignition, may be directly produced in a dense briquette that is suitable for subsequent safe storage and transport. For example, an iron briquette produced from an iron ore, may be suitable for safe storage and transport. Elimination of the need for a separate briquetting step may reduce energy consumption, decrease CO2 emissions, and lower economic costs.

[0050] The capacity to avoid the need for and the costs of both pelletizing and briquetting imparts the processes developed by the inventors with a utility that is not available to other competing processes, for example to DRI processes in the case of reducing iron ore to iron. It also allows for the production of purified metals or elements, for example DRI, from their metal or elemental ores or concentrates, at a notably lower overall energy consumption than other processes, for example the conventional DRI processes described in the Background section.

[0051] The inventors have further discovered that the above processes may be configured to avoid or, at least, minimize the presence of carbon in the produced metal or elements. In one example process, the charge included in the closed container or substantially closed container, may be configured in the form of separate layers for the carbon source and for the metal or elemental ore or concentrate. Such a configuration may be consistent with a ‘noncontact’ carbothermic process, in which the carbon source is not in substantial physical contact with (i.e. is physically separate from) the metal or elemental ore or concentrate, and any the metal or element that may be formed therefrom. By this means, the produced metal or element may avoid the incorporation within it, of significant quantities of carbon, thereby potentially simplifying its subsequent processing into other products. For example, iron produced in this way may avoid the incorporation within it, of significant quantities of carbon, thereby simplifying its subsequent processing into steel. This approach may also avoid the formation and presence of a layer or layers or a deposit or deposits of carbon in themetal or element produced. The produced metal or element, for example produced iron, may also avoid the incorporation of carbonaceous or non-carbonaceous ash, including in the form of a layer or layers or a deposit or deposits of ash. That is, carbonaceous ash, including in the form of a layer or layers or a deposit or deposits of ash, may also be notably absent from the produced metal or element, for example the produced iron.

[0052] Another contributor to the low energy consumption of the processes developed by the inventors may derive from the fact that the gaseous CO and CO2 that may serve as both reactants in and the products of the reduction reaction sequences, are formed and utilised directly inside the closed or substantially closed container. This may be surprisingly advantageous in that it avoids the especially high energy losses associated with transporting very hot gases, from one location to another, for example from the site of their formation or origin to the site of their actual use, within pipes or within vessels. Such transportation of very hot gases, from one location to another, for example from the site of their formation or origin to the site of their actual use, within pipes or within vessels, is required in: (for the example case of iron) all blast furnaces, all gas-based DRI processes, and almost all solid-state carbothermic DRI processes (see the Background section). By contrast, the dynamic body of hot CO and CO2 gas that is formed and used inside the above-mentioned closed or substantially closed container, which regulates and maintains at least a preferred internal partial pressure of CO and CO₂, may be considered to experience no energy losses associated with the transport of hot gases from one location to another, for example from the site of their formation to the site of their actual use. In fact, the excess CO gas released by the container (along with the released excess CO2 gas) may potentially be burnt outside of the container, and inside the high temperature furnace, to generate additional heat that diminishes the need for externally supplied heat energy.

[0053] A gas body, such as the dynamic body of hot CO and CO₂ gas inside the closed or substantially closed container, may herein be said to be ‘stationary’ or ‘substantially stationary’ if it is formed and used in the same location, and thereby avoids energy losses associated with the transport of hot gases from one site to another, for example from the site of their formation or origin to the site of their actual use. Another terminology used herein may refer to such a gas body as being ‘confined’ within a volume, which is preferably an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a lid). It is to be understood that a gas bodythat is ‘stationary’ or ‘substantially stationary’, or a gas which is ‘confined’ or ‘substantially confined’, may nevertheless be released in part, from the site of its formation during and after its use, provided that a preferred pressure thereof is maintained in the site of its use (for example, in the enclosed volume or a substantially enclosed volume, or the closed or substantially closed container, such as a crucible covered with a lid). That is, such a gas remains a dynamic body and retains all characteristic gaseous properties, for example a capacity to diffuse. Beyond the potential to regulate the gaseous atmosphere inside a crucible, another key benefit of having a well-sealed lid covering the crucible, may be that it prevents unwanted external gases, such as atmospheric oxygen, from entering the crucible.

[0054] In the case where more than one, multiple, or many closed or substantially closed containers are used in the above-described process, the inventors have, additionally, found that the energy consumption per tonne of the metal or element produced, may be minimised by filling, as far as may be reasonable, each container with the charge, and by packing, as tightly as may be reasonable, the charge-filled containers into the high-temperature furnace, which may preferably be, but is not limited to, a tunnel kiln, for example a commercial tunnel kiln used to manufacture ceramic tableware, sanitaryware, building products, and the like. This is said herein, to ensure that the high-temperature furnace contains a high volume utilization factor during the operational time. The term ‘volume utilization factor’ used herein, refers to the proportion of the available internal volume of the high-temperature furnace that is, effectively, occupied by the metal or elemental ore or concentrate and the carbon source. A high volume utilization factor means that a high proportion of the internal volume of the high-temperature furnace is occupied by the metal or elemental ore or concentrate and the carbon source. The metal or elemental ore or concentrate and the carbon source may be located within the enclosed volumes or substantially enclosed volumes created by the containers, for the purposes of calculating the volume utilization factor.

[0055] The higher the volume utilization factor, the lower the energy consumption may be per tonne of metal or element produced, because a larger proportion of the heat provided by the furnace may be absorbed and utilised by the metal or elemental ore or concentrate and the carbon source, and less may be wasted on unnecessarily heating that portion of the furnace volume which does not contain the metal or elemental ore or concentrate and the carbon source. The heating provided to the portion of the furnace volume which does notcontain the metal or elemental ore or concentrate and the carbon source, may typically need to include all of the energy losses that occur out of that volume, which may be substantial.

[0056] A low volume utilization factor means that only a small proportion of the internal volume of the high-temperature furnace may be used to heat the metal or elemental ore or concentrate and the carbon source (within the containers). The heat needed to maintain the rest of the furnace volume at temperature, including all of the energy losses that occur out of that volume, which may be substantial, may therefore be wasted.

[0057] Accordingly, a high volume utilization factor may amplify the energy efficiency with which the heat of the furnace may be used to drive the herein described reaction process. Preferably the volume utilization factor of the high temperature furnace is greater than 10%. In other examples, the volume utilization factor is greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, greater than 40%, greater than 45%, greater than 50%, greater than 55%, greater than 60%, greater than 65%, or greater than 75%. In other examples, the volume utilization factor is greater than 5%.

[0058] In summary, the inventors have found that the effect of one or more, or a combination of the following, herein-described factors, may notably reduce the energy required to produce metals or elements from their corresponding metallic or elemental ores or concentrates:(a) The use of a ‘self-accelerating carbothermic chain reaction’, including but not limited to an ‘autocatalytic’ reaction, which is promoted and enabled by:(b) a closed or substantially closed container, or multiple such containers, each preferably configured to:a. maintain at least a preferred internal partial pressure of the CO and CO₂ that may be generated during heating by a high-temperature furnace, including at the reaction temperature for the operational time,b. whilst simultaneously providing safe release of excess CO and CO₂ gas to thereby avoid catastrophic pressure relief; wherein:(c) the closed or substantially closed container / s are maintained at the reaction temperature for the operational time, within a high-temperature furnace and preferably with a high volume utilization factor, such as but not limited to a tunnel kiln.In concert with:(d) avoidance of the need for additional pelleting or briquetting steps, and(e) the utilisation of a ‘stationary’ body of hot CO and CO₂ gas inside the closed or substantially closed container / s, thereby avoiding energy losses associated with the transport of hot gases from one site to another, for example from the site of their formation to the site of their actual use, as is used in many other processes.Factors (a)-(c) above may be considered to be, fundamentally, process intensification techniques that more efficiently use the input energy. Factors (d)-(e) may be considered to avoid commonly needed steps and processes that are wasteful of energy. The above factors, individually or in combination, may also create the other benefits referred above, such as, for example, those described in paragraph

[0031] above

[0059] Thus, the inventors have found that, using the above apparatus and process, the energy required, for example, to reduce iron ore with low iron content (e.g. 58% total Fe content) into purified iron, may be decreased to less than 8.0 GJ per tonne of iron produced. Less than 6.0 GJ per tonne of iron produced, may be achieved using a furnace specialised for efficient operation, that incorporates special engineering measures, for example a commercial tunnel kiln incorporating an efficient heat recovery system. If the excess CO released from the closed or substantially closed container during operation is combusted (outside the container but within the furnace) and the heat produced thereby is taken into account, the energy consumption for producing purified iron from iron ore may be less than 4 GJ per tonne of iron produced. (For the purposes of simplicity and clarity in this specification, all energy consumptions described herein exclude such CO combustion contributions, unless explicitly included). The notably high energy efficiencies that these low energy consumptions represent, substantially improve upon those of existing ironmaking processes (as described in the Background section).

[0060] The inventors have further found that the CO2 emissions from the processes described above may be substantially reduced, for example to near-zero, zero, or even less than zero. In one example embodiment, this may be achieved by using carbon sources with low or negative carbon emissions in the processes described herein, such as but not limited to non-anthropogenic carbon. Non-anthropogenic carbon refers to carbon that has cycled naturally through the Earth's systems (oceans, land, living things) via photosynthesis, respiration, decomposition, and geological processes, distinct from human-caused emissions from fossil fuels and deforestation, which disrupt this balance and increase atmospheric CO₂, driving climate change. Thus, for example, trees naturally extract CO₂ from the atmosphere during their growth. When trees die and decompose, the captured CO₂ is released back into the atmosphere by natural processes, not caused by human activity. Thus, the use of wood as the carbon source in a process described herein may produce CO₂ that was, in any case, already CO₂ that had been removed from the atmosphere and that would have been released to the atmosphere via natural decomposition if the wood had not been used. In such an example process, there may be no carbon emissions despite it being a carbothermic process.

[0061] The CO₂ emissions deriving from the energy consumption of the processes described herein may also be substantially reduced or minimised by using renewable energy sources to provide the required heat energy. In one example, the furnace, may be heated by burning renewable hydrogen (also termed ‘green’ hydrogen), to thereby avoid the production of CO₂ by burning of a fossil fuel. Renewable (‘green’) hydrogen is hydrogen produced from the electrolysis of water in an electrolyser powered by renewable electricity, such as solar- or wind-generated electricity. The renewable hydrogen may, for example, be produced using the energy efficient ‘capillary-fed’ water electrolysis cells described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606, WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671, which are incorporated herein by reference. In another example, the furnace may be heated using renewable electrical energy, for example.

[0062] Moreover, it should be noted that the proportion of the energy consumption required for the herein described processes, that may be provided by direct burning or combustion of carbon or carbonaceous materials to produce CO₂, may already be very low, indeed, surprisingly low. The only step in the herein described processes that produces heat by direct combustion of carbon to form CO₂, is the abovementioned step in which atmospheric oxygen (O2) within the enclosed or substantially enclosed container is converted to CO₂ during the initial heating (up to 500 °C). In the example process of producing purified iron from iron ore, the energy produced by this step is only -0.002 GJ per tonne of iron produced. Asdemonstrated in Table 1 below, the remainder of the energy consumption may be supplied externally by:electrical energy, if the high temperature furnace is heated using electrical power (for example, using renewable electricity, such as wind- or solar-generated electricity); and / orgas-based heat energy, if the high temperature furnace is heated by burning a renewable gaseous fuel (for example, renewable or ‘green’ hydrogen).Table 1. Scenarios for low CO2 energy consumption by the herein described processes, as applied to producing purified iron from low-grade (58% total Fe content) iron ore, with comparison to conventional ironmaking processes.Example Example Energy provided Energy provided Energy provided Proportion Process Overall by directly by externally by burning an of Energy burning a carbon supplied externally Energy Consumption source in the electricity supplied Supplied process gaseous fuel Externally (%) (%) (%) (%) | Energy source] | Energy source] | Energy source]Herein 6 GJ / tonne ~0.002 GJ / tonne ~5.988 GJ / tonne 99.96 described iron iron ironprocess (0.030%) (99.97%)[Combustion of carbon [solar / windelectricity]Herein 6 GJ / tonne ~0.002 GJ / tonne ~5.988 GJ / tonne 99.96 described iron iron ironprocess (0.030%) (99.97%)[Combustion of carbon [Green hydrogen]Blast 12.6 GJ / tonne ~11.59 GJ / tonne -0.75 GJ / tonne -0.25 GJ / tonne 8 Furnace iron iron iron iron(92%) (6%) (2%)[Combustion of [coal-fired [natural gas]coal] electrical power]FASTMET 15.91 GJ / tonne ~9.86 GJ / tonne -1.91 GJ / tonne -4.14 GJ / tonne 38 iron iron iron iron(62%) (12%) (26%)[Combustion [coal-fired [natural gas]of coal] electrical power]MIDREX 10.55 GJ / tonne -0.65 GJ / tonne -8.62 GJ / tonne 100 (hydrogen) iron iron iron(6%) (82%)[coal-fired [Green hydrogen or electrical power] fossil hydrogen]-1.28 GJ / tonneiron(12%)[Natural gas]

[0063] The inventors have further found that the overall CO₂ emissions from the processes described herein may be reduced by fitting the high-temperature furnace with metal plates, preferably cooled metal plates, which act as sites on which any CO that is released from the container may form soot or ash. Such soot or ash may mostly comprise solid carbon, allowing it to potentially be used again, as the carbon source in new carbothermic reactions.

[0064] The inventors have also found that the CO₂ emissions of the processes described above may be reduced or minimised by their capacity to employ an unusually low ratio of metal or elemental ore to carbon, when compared to conventional carbothermic reductions of metal or elemental ores or concentrates to their corresponding metals or elements. In examples, the weight ratio of metal / elemental ore / concentrate to carbon may lie close to that expected if all oxygen atoms associated with the metal or element in the metal or elemental ore or concentrate were removed as CO₂ gas. For example, in the case of the reduction of hematite-containing iron ore (63% total Fe content) into purified iron (98% total Fe content; 93% metallization) using the processes described herein, the weight ratio of iron ore to carbon may he between 1: 0.122 and 1: 0.124. In other examples, it may he between 1: 0.10 and 1: 0.30.

[0065] The inventors have further discovered that the above-described processes may be applied beyond the production of iron from iron ores to the production of other purified metals and elements from their metal and elemental ores, including, but not limited to, the production of: gold (Au), platinum (Pt), silver (Ag), mercury (Hg), rhodium (Rh), iridium (Ir), copper (Cu), palladium (Pd), bismuth (Bi), antimony (Sb), lead (Pb), tungsten (W), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), phosphorus (P), potassium (K), zinc (Zn), chromium (Cr), nobelium (No), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminium (Al), uranium (U), lithium (Li), magnesium (Mg), and calcium (Ca). Moreover, metal oxides of different chemical composition to that initially primarily present in the ore or concentrate or mineralogical or chemical composition employed, may be formed using the processes described herein. Metal ceramic materials, including but not limited to metal carbides, may, for example, also be formed.

[0066] In an example aspect, there is provided an apparatus for producing a metal or element from a metal ore or an elemental ore, the apparatus comprising: a high temperature furnace; and at least one container comprising an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore, or an elemental ore, and a carbon source; wherein the at least one container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the metal ore, or elemental ore, and the carbon source at a reaction temperature for an operational time to produce the metal or element; wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and wherein a reaction occurs at the reaction temperature to produce the metal or element and the reaction is a self-accelerating carbothermic chain reaction within the enclosed volume or substantially enclosed volume.

[0067] In an example aspect, there is provided a method for producing a metal or an element from a metal ore or elemental ore using a self-accelerating carbothermic chain reaction, the method comprising the steps of: placing lumps and / or fines of a metal ore or elemental ore and a carbon source within at least one container inside a high temperature furnace, maintaining the metal ore or elemental ore and the carbon source within the container at a reaction temperature for an operational time, to thereby induce the self-acceleratingcarbothermic chain reaction that produces the metal or element from the metal ore or elemental ore, wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and, cooling and retrieving the produced metal or element.

[0068] Preferably but not exclusively, the carbothermic reaction has a high driving force, for example, as may be created by a self-accelerating reaction process, such as but not limited to an autocatalytic process, so that reduction of the metal or elemental ore or concentrate, to its corresponding metal or element is rapid even when the carbon source is well separated from the metal or elemental ore or concentrate.

[0069] Preferably but not exclusively, the energy consumption required to produce the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 80% of the energy required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore or concentrate.

[0070] In other examples, preferably but not exclusively, the energy consumption required to produce the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, less than 50%, less than 45%, or less than 40% of the energy required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore.

[0071] In other examples, preferably but not exclusively, the energy provided by direct combustion (burning) of carbon in the production of the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 1% of the energy consumption. In other examples, the energy provided by direct combustion of carbon in the production of the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 0.9% of the energy consumption, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, less than 0.1%, less than 0.09%, less than 0.08%, less than 0.07%, less than 0.06%, less than 0.05%, or less than 0.04% of the energy consumption of the process.

[0072] Preferably but not exclusively, the metal or elemental ore or concentrate, is a metal ore or concentrate, the metal ore or concentrate is iron ore or concentrate, and the metal is iron. In some examples, the iron ore or concentrate comprises primarily of hematite (Fe2O3). In other examples, the iron ore or concentrate comprises primarily of magnetite (Fe₃O₄). In still other examples, the iron ore or concentrate comprises primarily of goethite (FeO(OH)), limonite (FeO(OH).n(H₂O)), orwüstite (FeO).

[0073] In an example aspect, there is provided an apparatus for producing iron from iron ore, the apparatus comprising: a high temperature furnace; and at least one container comprising an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of iron ore and a carbon source; wherein the at least one container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the iron ore and the carbon source at a reaction temperature for an operational time to produce the iron; wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the iron ore and the carbon source within the enclosed or substantially enclosed volume during the operational time.

[0074] In an example aspect, there is provided an apparatus for producing iron from iron ore, the apparatus comprising: a high temperature furnace; and at least one container comprising an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of iron ore and a carbon source; wherein the at least one container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the iron ore and the carbon source at a reaction temperature for an operational time to produce the iron; wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the iron ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and wherein a reaction occurs at the reaction temperature to produce the iron and the reaction is a selfaccelerating carbothermic chain reaction within the enclosed volume or substantially enclosed volume.

[0075] In an example aspect, there is provided a method for producing iron from iron ore, the method comprising the steps of: placing lumps and / or fines of an iron ore and a carbon source within at least one container inside a high temperature furnace, maintaining the iron ore and the carbon source within the container at a reaction temperature for an operationaltime, to thereby induce a reaction that produces the iron, wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the iron ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and, cooling and retrieving the produced iron.

[0076] In an example aspect, there is provided a method for producing iron from iron ore using a self-accelerating carbothermic chain reaction, the method comprising the steps of: placing lumps and / or fines of an iron ore and a carbon source within at least one container inside a high temperature furnace, maintaining the iron ore and the carbon source within the container at a reaction temperature for an operational time, to thereby induce the selfaccelerating carbothermic chain reaction that produces the iron, wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the iron ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and, cooling and retrieving the produced iron.

[0077] Preferably but not exclusively, the metal or elemental ore is a hematite iron ore or concentrate of 55-65% total iron content and the operational time at which the hematite iron ore or concentrate, and the carbon source, are maintained at the reaction temperature of 1, 170 °C to produce iron with a metallization of >90%, is equal to or less than 3.5 hours. In other examples, the operational time at which the hematite iron ore or concentrate of 55-65% total iron content, and the carbon source, are maintained at the reaction temperature of 1,170 °C to produce iron with a metallization of >90%, is equal to or less than 3 hours, equal to or less than 2.5 hours, equal to or less than 2 hours, equal to or less than 1.5 hours, equal to or less than 1 hour, equal to or less than 30 min, equal to or less than 20 min, equal to or less than 10 min, or equal to or less than 5 min. In still other examples, the operational time at which the hematite iron ore or concentrate, and the carbon source, are maintained at the reaction temperature of 1,170 °C to produce iron with a metallization of >90%, is equal to or less than 5 hours, equal to or less than 6 hours, equal to or less than 7 hours, equal to or less than 8 hours, equal to or less than 9 hours, equal to or less than 10 hours, equal to or less than 12 hours, equal to or less than 14 hours, equal to or less than 16 hours, equal to or less than 18 hours, equal to or less than 20 hours.

[0078] Preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.01700wt% / min at a reaction temperature of 1,170 °C. The rate of oxygen removal at a stated temperature is:Wt% loss in the ore at 90% metallisation due to oxygen removalRate of oxygen removal = Time required to achieve 90% metallization at the stated temperatureThe rate of oxygen removal at or above a particular temperature is expressed in units of wt% per °C (wt% / °C). The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fc^Cfi). and / or wüstite (FeO), or mixtures thereof.

[0079] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.03151 wt% / min at a reaction temperature of 1,170 °C. The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fe3C>4), and / or wüstite (FeO), or mixtures thereof.

[0080] In still other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.05169 wt% / min at a reaction temperature of 1,170 °C. The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fe3C>4), and / or wüstite (FeO), or mixtures thereof.

[0081] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is less than or equal to 50 wt% / min at a reaction temperature of 1,170 °C.

[0082] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is less than or equal to 20 wt% / min at a reaction temperature of 1,170 °C.

[0083] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, at a reaction temperature of 1,170 °C, is more than or equal to 0.03151 wt% / min, is more than or equal to 0.01933 wt% / min, more than or equal to 0.02229 wt% / min, more than or equal to 0.02617wt% / min, more than or equal to 0.03151 wt% / min, more than or equal to 0.03930 wt% / min, more than or equal to 0.05169 wt% / min, more than or equal to 0.07449 wt% / min, more than or equal to 0.13032 wt% / min, more than or equal to 0.47846 wt% / min, more than or equal to 1 wt% / min, more than or equal to 1.5 wt % / min, more than or equal to 2 wt% / min, more than or equal to 2.5 wt% / min, more than or equal to 3 wt % / min, or more than or equal to 5 wt% / min.

[0084] Preferably but not exclusively, the externally supplied energy consumption for the production of purified iron from iron ore or concentrate is less than 8 GJ per tonne of iron produced. That is, the iron is, preferably but not exclusively, produced with an externally supplied energy consumption of less than 8 GJ per tonne of purified iron. In other examples, the iron is produced with an externally supplied energy consumption per tonne of purified iron, of less than 7.5 GJ, less than 7.25 GJ, less than 7.0 GJ, less than 6.75 GJ, less than 6.5 GJ, or less than 6.25 GJ. In still further examples, the high temperature furnace is equipped with a heat recovery system and the externally supplied energy consumption for the production of purified iron from iron ore or concentrate is less than 6 GJ per tonne of iron produced. That is, the iron is produced with an externally supplied energy consumption of less than 6 GJ per tonne of purified iron produced. In further examples, the iron is produced with an externally supplied energy consumption per tonne of purified iron produced, of less than 5.9 GJ, less than 5.8 GJ, less than 5.7 GJ, less than 5.6 GJ, or less than 5.5 GJ. In still further examples, the externally supplied energy consumption of the production of purified iron from iron ore or concentrate is less than 4 GJ per tonne of iron produced, when the effect of combustion of the CO released from the enclosed or substantially enclosed volume during the process is taken into account.

[0085] Preferably but not exclusively, the energy provided by direct combustion (burning) of carbon in the production of the purified iron from the iron ore or concentrate, is less than 0.1 GJ / tonne of produced iron. In other examples, the energy provided by direct combustion (burning) of carbon in the production of the purified iron from the iron ore or concentrate, is less than 0.05 GJ / tonne of produced iron, less than 0.025 GJ / tonne of produced iron, less than 0.01 GJ / tonne of produced iron, less than 0.009 GJ / tonne of produced iron, less than 0.008 GJ / tonne of produced iron, less than 0.007 GJ / tonne of produced iron, less than 0.006 GJ / tonne of produced iron, or less than 0.005 GJ / tonne of produced iron.

[0086] Preferably but not exclusively, the iron product is in a purified form. Preferably but not exclusively, the iron product has a total Fe content equal to or more than 86%. In other examples, the metallization percentage or elemental percentage is equal to or more than 87%, equal to or more than 88%, equal to or more than 89%, equal to or more than 90%, equal to or more than 91%, equal to or more than 92%, equal to or more than 93%, equal to or more than 94%, equal to or more than 95%, equal to or more than 96%, equal to or more than 97%, equal to or more than 98%, or equal to or more than 99%.

[0087] Preferably but not exclusively, the iron product has a high metallization percentage. Preferably but not exclusively, the iron product has a metallization percentage of Fe equal to or more than 83%. In other examples, the metallization percentage or elemental percentage is equal to or more than 84%, equal to or more than 85%, equal to or more than 86%, equal to or more than 87%, equal to or more than 88%, equal to or more than 89%, equal to or more than 90%, equal to or more than 91%, equal to or more than 92%, equal to or more than 93%, equal to or more than 94%, equal to or more than 95%, equal to or more than 96%, equal to or more than 97%, equal to or more than 98%, or equal to or more than 99%.

[0088] The produced iron may be magnetically separated from the waste materials. Preferably but not essentially, the produced iron is later magnetically separated from any waste materials (‘gangue’) that were present in the iron ore or concentrate.

[0089] In another example embodiment, the ore is primarily hematite and the product produced by the abovementioned apparatus and / or method, is primarily magnetite.

[0090] In a further example embodiment, the ore is primarily hematite and the product produced by the abovementioned apparatus and / or method, is primarily wtistite.

[0091] In another example aspect, there is provided a tunnel kiln for producing iron from fines or lumps of hematite (Fe2O3), magnetite (Fc^Cfi). wüstite (FeO), or other iron ores or concentrates with a total Fe content higher than 55%, wherein the kiln is capable of an annual production of directly reduced iron, per square metre of the cross-sectional area of the tunnel kiln, of more than 15,000 tons. In other examples, there is provided a tunnel kiln for producing iron from fines or lumps of hematite (Fe2O3), magnetite (Fe3C>4), wüstite (FeO), or other iron ores or concentrates with a total Fe content higher than 55%, wherein the kilnis capable of an annual production of directly reduced iron, per square metre of the cross-sectional area of the tunnel kiln, of more than 16,000 tons, more than 17,000 tons, more than 18,000 tons, more than 19,000 tons, more than 20,000 tons, more than 21,000 tons, more than 22,000 tons, more than 25,000 tons, more than 30,000 tons, more than 40,000 tons, or more than 50,000 tons.

[0092] In an example aspect, there is provided a container for use in a method of producing iron from iron ore, the container comprising an enclosed volume or substantially enclosed volume for receiving lumps and / or fines of iron ore and a carbon source, wherein the container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the iron ore, and the carbon source at a reaction temperature for an operational time to produce the iron; wherein the container is configured to maintain a gaseous atmosphere surrounding the iron ore and the carbon source within the enclosed or substantially enclosed volume during the operational time.

[0093] In an example aspect, there is provided a container for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the container comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the container, including the metal ore or concentrate or elemental ore or concentrate, and the carbon source, is configured to be: maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, release excess internal gaseous pressure, and maintain an absolute internal partial pressure of CO and CO₂ gas, greater than or equal to 0.8 atm, during the operational time at the reaction temperature, to thereby produce the metal or element.

[0094] In an example aspect, there is provided a container for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the container comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the container, including the metal ore or concentrate or elemental ore or concentrate, and the carbon source, is configured to be: maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, release excess internal gaseous pressure, and maintainan gauge internal partial pressure of CO and CO₂ gas, greater than or equal to 0.01 atm, during the operational time at the reaction temperature, to thereby produce the metal or element.

[0095] In one aspect, the container is configured to regulate a gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source. Preferably, the gaseous atmosphere is ‘stationary’. In another non-limiting aspect, the container is a closed container that is capable of releasing excess internal gas and maintaining a preferred internal gas pressure. In another non-limiting aspect, the container is a substantially closed container capable of releasing excess internal gas and maintaining a preferred internal gas pressure. In another non-limiting aspect, the container is at least partially covered. In another nonlimiting aspect, the container is fully covered.

[0096] In another non-limiting aspect, the container is configured to ‘confine’ the metal or elemental ore or concentrate, the carbon source and the gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source. Preferably, the gaseous atmosphere is ‘confined’ (but, nevertheless, able to be released by the container to maintain a preferred internal gas pressure). In another non-limiting aspect, the container provides a ‘confined volume’ or a ‘substantially confined volume’. In another non-limiting aspect, the container is a closed container. In another non-limiting aspect, the container is a substantially closed container. In another non-limiting aspect, the container is at least partially covered. In another non-limiting aspect, the container is fully covered. In another aspect, the container provides a confined or substantially confined volume including a seal which is substantially gas tight wherein the seal prevents the gaseous atmosphere from escaping the enclosed volume of the container.

[0097] Preferably but not exclusively, the container providing an enclosed volume or substantially enclosed volume, is in the form of a crucible covered with a lid. Preferably but not exclusively, the lid is capable of transiently and reversibly opening to release excess gas and maintain a preferred internal partial pressure of CO and CO₂ within the enclosed volume or a substantially enclosed volume. Preferably but not exclusively, the lid is fabricated to form a tight seal with the crucible when it is closed, providing for the maintenance of the preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume. Preferably but not exclusively, the lid incorporates a lip, orlips, or has a design, for example an inverted top hat design, which allows for an improved seal that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 gas with the enclosed volume or substantially enclosed volume. Preferably but not exclusively, the lid surface is fabricated to match, for example, to conform to, or mate to the surface of the crucible, facilitating a mechanical seal, for example via low surface roughness, that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume. Preferably but not exclusively, an intermediary material, such as, but not limited to a ceramic cloth, ceramic paper, ceramic felt, or cord seal, is incorporated between the lid surface and the surface of the crucible, allowing for an improved seal that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0098] Preferably but not exclusively, the weight of the lid is calibrated to create and maintain a high or a preferred internal partial pressure of CO and CO₂ within the enclosed volume or substantially enclosed volume formed by the closed or substantially closed container, for example, a crucible covered with a lid.

[0099] Preferably but not exclusively, the ratio of the lid mass to the container contact area is greater than 10 kg / m2. In other examples, the ratio of the lid mass to the container contact area is greater than 25 kg / m2, greater than 50 kg / m2, greater than 100 kg / m2, greater than 150 kg / m2, greater than 200 kg / m2, greater than 250 kg / m2, greater than 300 kg / m2, greater than 400 kg / m2, greater than 500 kg / m2, greater than 750 kg / m2, greater than 1000 kg / m2, greater than 2000 kg / m2, greater than 5000 kg / m2, greater than 7500 kg / m2, greater than 10,000 kg / m2, greater than 15,000 kg / m2, greater than 20,000 kg / m2, greater than 35,000 kg / m2, greater than 50,000 kg / m2, or greater than 90,000 kg / m2. In still other examples, the ratio of the lid mass to the container contact area is greater than 1 kg / m2, greater than 2 kg / m2, greater than 4 kg / m2, greater than 5 kg / m2, greater than 6 kg / m2, greater than 7 kg / m2, greater than 8 kg / m2, or greater than 9 kg / m2.

[0100] Preferably but not exclusively, the ratio of the container volume to the perimeter length of the container contact area, for example the ratio of a crucible volume to the perimeter length of the crucible contact area, is less than 150 litres per meter. In other examples, the ratio of the container volume to the perimeter length of the container contact area, for example the ratio of a crucible volume to the perimeter length of the crucible contactarea, is less than 140 litres per meter, less than 130 litres per meter, less than 120 litres per meter, less than 110 litres per meter, less than 100 litres per meter, less than 90 litres per meter, less than 80 litres per meter, less than 70 litres per meter, less than 60 litres per meter, less than 50 litres per meter, less than 40 litres per meter, less than 30 litres per meter, less than 20 litres per meter, less than 10 litres per meter, less than 5 litres per meter, less than 4 litres per meter, less than 3 litres per meter, less than 2 litres per meter, less than 1 litre per meter, less than 0.8 litres per meter, less than 0.6 litres per meter, less than 0.4 litres per meter, or less than 0.1 litres per meter.

[0101] In another example aspect, preferably but not exclusively, there is provided multiple enclosed or substantially enclosed containers capable of releasing excess gas pressure and maintaining a preferred internal gas pressure, for example of CO and CO₂. Preferably but not exclusively, each container providing an enclosed volume or substantially enclosed volume, is in the form of a crucible covered with a lid. In examples, each such container, for example a crucible with a lid, may, effectively, act as dead weight pressure relief valve wherein the lid transiently and reversibly opens to release excess gas and maintain a preferred internal gas partial pressure of CO and CO₂ within the enclosed volume or a substantially enclosed volume.

[0102] In example embodiments, preferably but not exclusively, the closed or substantially closed container has a rectangular shape. In other examples, preferably but not exclusively, the closed or substantially closed container has a square shape. In still other examples, preferably but not exclusively, the closed or substantially closed container has the shape of a cylinder.

[0103] In other examples, the container, for example a crucible, has the shape of a long, flat receptacle, for example a trough, cube, box, tray, or channel, to thereby, when covered with its lid, provide for the maintenance of a high internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume. In other examples, the container and its lid, for example a crucible and lid, is stacked with other closed or substantially closed containers and their lids, for example crucibles and their lids, on top of each other, during heating and / or whilst being brought up to the reaction temperature or maintained at the reaction temperature for the operational time in the high temperature furnace, to thereby increase the weights on the lids at the bottom of each stack1and providefor the maintenance of a high internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0104] In example embodiments, multiple closed or substantially closed charged containers, for examples crucibles with lids, are stacked next to each other, and / or on top of each other in arrays. Preferably but not exclusively, such arrays are maintained at the reaction temperature for the operational time. Preferably but not exclusively, multiple charged containers closed or substantially closed with lids, for examples crucibles with lids, are stacked on top of each other to thereby increase the weight on the lids nearer the bottom of each stack1allowing for the maintenance of a higher partial pressure of the carbonaceous gases inside these containers. In other examples therefore, the crucible and lid is stacked with other closed or substantially closed containers and lids, on top of each other whilst being maintained at the reaction temperature for the operational time in the high temperature furnace, to thereby increase the weights on the lids at the bottom of each stack1and provide for the maintenance of a high internal partial pressure of the CO and CO2 within these enclosed volume or substantially enclosed volume.

[0105] In another non-limiting aspect, the container, for example a crucible, provides a confined or substantially confined volume including a seal which is substantially gas tight wherein the seal, for example a mechanical seal, prevents the gaseous atmosphere from escaping the enclosed volume of the container, for example a crucible. In respect of achieving an optimum mechanical seal, preferably but not exclusively, the lid surface is fabricated to match, for example, to conform to, or mate to the surface of the crucible, for example via low surface roughness, that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0106] In further example aspects, preferably but not exclusively, the lid or the mouth of the container incorporates a lip, or lips, or has a lid design or a container mouth design, for example an inverted top hat lid design, that allows for an improved seal, which provides for the maintenance of a preferred internal partial pressure of the CO and CO₂ gas within the enclosed volume or substantially enclosed volume. Such designs may also provide for and guide larger upward deflections or movements of the lid during the periods that theytransiently and reversibly release excess gas pressures, as well as guide the lid back down and ensure it seats properly on the crucible mouth after the excess gas has been released.

[0107] In another example aspect, there is provided an orifice, such as a tiny aperture, pinhole, opening, or slit, within the lid or within a wall of the container, wherein the orifice has been deliberately sized to maintain a preferred gaseous partial pressure of CO and CO₂ inside the enclosed or substantially enclosed container during heating up to and at the reaction temperature for the operational time. That is, there is provided an orifice designed to allow the release of excess gas pressure within the container whilst still maintaining a preferred gaseous partial pressure of CO and CO₂ inside the enclosed or substantially enclosed container during heating up to and at the reaction temperature for the operational time. The use of such an orifice may necessitate the use of an oxygen-free atmosphere outside of the container, inside of the tunnel kiln.

[0108] In another example aspect, the container and lid, for example a crucible and lid is, preferably but not exclusively, provided in the form of a pressure vessel that incorporates an externally venting, high-temperature-capable, pressure relief valve (PRV), which provides for the maintenance of a high, including a very high, internal partial pressure of the CO and CO₂ within the enclosed volume or substantially enclosed volume. A pressure relief valve (PRV) is a type of safety valve used to control and / or limit the pressure in a system. Valves of this type are routinely available commercially and may be used to maintain a preferred gas pressure, for example a preferred partial pressure of CO and CO₂, inside an enclosed or substantially enclosed container, for example a crucible and lid.

[0109] In another example aspect, there is provided a pressure vessel for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the pressure vessel comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the pressure vessel is configured to: seal hermetically, be maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, incorporate a pressure relief valve (PRV) capable of releasing excess internal gaseous pressure above a threshold pressure at the reaction temperature, and maintain a high absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature to thereby produce the metal or element.

[0110] Preferably but not exclusively, the pressure vessel and incorporated pressure relief valve, maintains an absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature, of more than or equal to 1.0 atm. In other examples, the pressure vessel and incorporated pressure relief valve, maintains an absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature, of more than or equal to 1.1 atm, of more than or equal to 1.2 atm, of more than or equal to 1.3 atm, of more than or equal to 1.4 atm of more than or equal to 1.5 atm, of more than or equal to 1.6 atm, of more than or equal to 1.7 atm, of more than or equal to 1.8 atm, of more than or equal to 1.9 atm, of more than or equal to 2 atm, of more than or equal to 2.5 atm, of more than or equal to 3 atm, of more than or equal to 3.5 atm, of more than or equal to 4 atm, of more than or equal to 4.5 atm, of more than or equal to 5 atm, of more than or equal to 6 atm, of more than or equal to 7 atm, of more than or equal to 8 atm, of more than or equal to 9 atm, of more than or equal to 10 atm, of more than or equal to 12 atm, of more than or equal to 15 atm, of more than or equal to 20 atm, or of more than or equal to 50 atm.

[0111] In another example aspect, there is provided a container fitted with an internal lid, for example a crucible with an internal lid. An internal lid is a lid that fits within the mouth of a container. The internal lid may rest upon the charge inside the container. The internal lid may may move up and down, within the mouth of the container, to thereby release excess internal gas pressure and maintain a preferred gas pressure, for example a preferred partial pressure of CO and CO₂, inside an enclosed or substantially enclosed container, for example a crucible and an internal lid. The gap between the container and the internal lid may be an aperture designed to release excess internal gas pressure and maintain a preferred gas pressure, for example a preferred partial pressure of CO and CO₂, inside an enclosed or substantially enclosed container, for example a crucible and an internal lid.

[0112] In other example aspects, preferably but not exclusively, an intermediary material, such as, but not limited to a ceramic cloth, ceramic paper, ceramic felt, or cord seal, may be incorporated between the lid surface and the surface of the container, for example a crucible, allowing for an improved seal that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0113] In other examples, the crucible and its lid, filled with its charge, is tightly, densely, compactly, or closely packed with other crucibles and their lids, filled with their charge, whilst being brought up to, or maintained at the reaction temperature for the operational time to thereby increase the quantity of metal or element produced in a single run.

[0114] In one example aspect, the crucible and lid are each composed of a refractory or a high melting point material. The refractory material may be selected from a ceramic material including but not limited to: porcelain, ceramic, alumina, zirconia, graphite, molybdenum, silicon carbide, clay-graphite, quartz, mullite, corderite, or a metal including but not limited to: tungsten, stainless steel, and / or high temperature alloys (e.g. Inconel, Hasteloy).

[0115] In other examples, the crucible is highly conductive to heat or has a low heat capacity, for example as may be achieved by a metal or metal alloy crucible. Such a high conductivity to heat or low heat capacity may allow for a decrease in the reaction time at the operational temperature in the high temperature furnace, or an unchanged reaction time at a decreased operational temperature.

[0116] In other examples, the crucible and its lid, filled with its charge, is tightly, densely, compactly, or closely packed with other crucibles and their lids, filled with their charge, whilst being maintained at the reaction temperature for the operational time to thereby increase the quantity of metal or element produced in a single run.

[0117] In another example embodiment, the container is integrally formed as part of the high temperature furnace.

[0118] In another example aspect, there is provided an apparatus for producing a metal or element from a metal or elemental ore or concentrate, the apparatus comprising: a high temperature furnace, wherein the high temperature furnace comprises an enclosed volume or a substantially enclosed volume surrounding a metal or elemental ore or concentrate, and a carbon source; the enclosed volume or a substantially enclosed volume being capable of releasing excess gas and maintaining a preferred internal partial pressure of CO and CO₂,allowing for regulation of the gaseous atmosphere surrounding the metal or elemental ore orconcentrate, and the carbon source; wherein the high temperature furnace is configured tomaintain the metal or elemental ore or concentrate, and the carbon source for an operationaltime at a reaction temperature. The metal or element is preferably, but not exclusively, produced from the metal or elemental ore or concentrate, by a carbothermic reaction. Preferably, but not exclusively, the metal or elemental ore or concentrate, is passed through the high temperature furnace on a moving belt. Preferably, but not exclusively, the furnace has a volume utilization factor greater than 10%. Preferably, but not exclusively, the high temperature furnace is a tunnel kiln.

[0119] In another example aspect, there is provided an apparatus for producing a metal or element from a metal or elemental ore or concentrate, the apparatus comprising: a high temperature furnace, wherein the high temperature furnace comprises an enclosed volume or a substantially enclosed volume surrounding a metal or elemental ore or concentrate, and a carbon source, wherein the carbon source is separate from the metal or elemental ore or concentrate; the enclosed volume or a substantially enclosed volume being capable of releasing excess gas and maintaining a preferred internal partial pressure of CO and CO₂,allowing for regulation of a gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source; wherein the high temperature furnace is configured to maintain the metal or elemental ore or concentrate, and the carbon source for an operational time at a reaction temperature. The metal or element is preferably, but not exclusively, produced from the metal or elemental ore or concentrate, by a carbothermic reaction. Preferably, but not exclusively, the metal or elemental ore or concentrate, is passed through the high temperature furnace on a moving belt. Preferably, but not exclusively, the furnace has a volume utilization factor greater than 10%. Preferably, but not exclusively, the high temperature furnace is a tunnel kiln.

[0120] In another example aspect, there is provided a method for producing a metal or element from a metal or elemental ore or concentrate, by a carbothermic reaction, the method comprising the steps of: placing the metal or elemental ore or concentrate, and a carbon source within an enclosed volume or a substantially enclosed volume inside a high temperature furnace, wherein the enclosed volume or substantially enclosed volume is capable of releasing excess gas and maintaining a preferred internal partial pressure of COand CO₂, to thereby maintain a regulated gaseous atmosphere surrounding the metal orelemental ore or concentrate, and the carbon source; maintaining the metal or elemental oreor concentrate, and the carbon source within the enclosed volume or substantially enclosedvolume for an operational time at a reaction temperature, to thereby induce a carbothermicreaction that produces the metal or element from the metal or elemental ore or concentrate; followed by cooling and retrieving the produced metal or element. Preferably, but not exclusively, the furnace has a volume utilization factor greater than 10%. Preferably, but not exclusively, the high temperature furnace is a tunnel kiln.

[0121] In another example aspect, there is provided a method for producing a metal or element from a metal or elemental ore or concentrate, by a carbothermic reaction, the method comprising the steps of: placing the metal or elemental ore or concentrate, and a carbon source within an enclosed volume or a substantially enclosed volume inside a high temperature furnace, wherein the carbon source is separate from the metal or elemental ore or concentrate, and wherein the enclosed volume or substantially enclosed volume is capable of releasing excess gas and maintaining a preferred internal partial pressure of COand CO₂, to thereby maintain a regulated gaseous atmosphere surrounding the metal orelemental ore or concentrate, and the carbon source; maintaining the metal or elemental oreor concentrate, and the carbon source within the enclosed volume or substantially enclosedvolume for an operational time at a reaction temperature, to thereby induce a carbothermic reaction that produces the metal or element from the metal or elemental ore or concentrate; followed by cooling and retrieving the produced metal or element. Preferably, but not exclusively, the furnace has a volume utilization factor greater than 10%. Preferably, but not exclusively, the high temperature furnace is a tunnel kiln.

[0122] In one example aspect, the carbon source is a solid-state material (such as but not limited to charcoal, activated carbon, coal, carbonaceous material, coke, agricultural residues, rice husks / rice straw / , coconut shells / husks, sugar cane bagasse, biomass, any organic fibrous materials, plastics, tyres, biosolids from wastewater treatment plants, wood, sawdust or timber items, or a carbon-replacement material like calcium carbonate (CaCO₃) (limestone)). In another example aspect, the carbon source is separated from the metal or elemental ore or concentrate, in the container (i.e. in the enclosed volume or substantially enclosed volume). In another example aspect, a reaction occurs at the reaction temperature to produce the metal or element, and the reaction is a ‘non-contact’ carbothermic reaction.

[0123] In another example aspect, the carbon source includes a gaseous carbon source, for example gas-phase carbon monoxide (CO) or carbon dioxide (CO₂), and the gaseous carbon source is separated from the metal or elemental ore or concentrate, in the container by a phasedifference. In one example aspect, the carbon source is a combination of a solid-state carbon source and a gaseous carbon source.

[0124] In another example aspect, the carbon source comprises completely or partially of non-anthropogenic carbon that has low or negative carbon emissions, to thereby diminish the carbon emissions of the process.

[0125] In an example aspect, there is an absence of a desulphurisation agent which is received by the at least one container of the apparatus, or in the method of producing a metal or element. Preferably but not exclusively, a desulphurisation agent is not required due to an absence of a high level of sulphur in the carbon source.

[0126] Preferably but not exclusively, the metal or elemental ore or concentrate is substantially free of water prior to its reduction to its purified metal or element.

[0127] In an example aspect, there is an absence of a binder (e.g. bentonite, dolomite, carboxymethyl cellulose, or a cement binder) which is received by the at least one container of the apparatus, or in the method of producing a metal or element. Preferably but not exclusively, a binder is not required due to the metal or elemental ore or concentrate being in a native form, or an essentially un-processed form.

[0128] Preferably but not exclusively, the metal or elemental ore or concentrate, is in a physical form that is not pelletized, briquetted, or artificially agglomerated, and / or does not contain a binder (e.g. bentonite, dolomite, carboxymethyl cellulose, or a cement binder), for example in the form of lumps or fines. Ore or concentrate lumps comprise larger ore or concentrate agglomerations than fines. In the iron ore industry for example, according to one industry standard, the size of iron ore lumps fall in the range 6.3 mm - 31.5 mm, while iron ore fines are less than 6.3 mm.

[0129] Preferably but not exclusively, the metal or element takes the structural form of the container in which it is produced or a portion thereof, for example as a briquette within a briquette-shaped crucible. In this example, the briquette-shaped crucible includes a volume in the shape of a briquette. Preferably but not exclusively, the metal or element is produced in a crucible and takes the structural form of the crucible or a portion thereof upon itsproduction. Preferably but not exclusively, the metal or element is produced in the form of a briquette, this being the form of the crucible in which it was produced. Preferably but not exclusively, the produced metal or element briquette is suitable for safe storage and transport.

[0130] Preferably but not exclusively, the produced metal or element is in a purified form. Preferably but not exclusively, the produced metal or element has a metallization percentage or an elemental percentage equal to or more than 80%. A metallization percentage or an elemental percentage is the percentage of the metal or element atoms in an oxidation state of zero (i.e. a pure metal or element) relative to the metal or element atoms having all oxidation states. In other examples, the metallization percentage or elemental percentage is equal to or more than 82%, equal to or more than 84%, equal to or more than 86%, equal to or more than 88%, equal to or more than 90%, equal to or more than 91%, equal to or more than 92%, equal to or more than 93%, equal to or more than 94%, equal to or more than 95%, or equal to or more than 96%. In still other examples, the metallization percentage or elemental percentage is equal to or more than 78%, equal to or more than 76%, equal to or more than 74%, equal to or more than 72%, equal to or more than 70%, equal to or more than 68%, equal to or more than 66%, equal to or more than 64%, equal to or more than 62%, equal to or more than 60%, or equal to or more than 50%.

[0131] Preferably but not exclusively, the produced metal or element is substantially free of contamination with carbon. Preferably, the produced metal or element contains less than 0.1% carbon. In other examples, the metal or element contains less than 0.9% carbon, less than 0.8% carbon, less than 0.7% carbon, less than 0.6% carbon, less than 0.5% carbon, less than 0.4% carbon, less than 0.3% carbon, less than 0.2% carbon, less than 0.15% carbon, less than 0.14% carbon, less than 0.13% carbon, or less than 0.12% carbon. In still further examples, the metal or element contains less than 1% carbon, less than 1.5% carbon, less than 2% carbon, less than 2.5% carbon, less than 3% carbon, less than 3.5% carbon, less than 4% carbon, less than 4.5% carbon, less than 5% carbon, less than 7% carbon, less than 10% carbon, or less than 20% carbon.

[0132] Preferably but not exclusively, a surface of the produced metal or element has no, or substantially none, or little, ash deposited on the surface by the carbothermic reaction. Preferably but not exclusively, any ash deposited on the surface of the produced metal or element is insufficient to block or substantially slow or substantially limit the rate of thecarbothermic reaction. In example embodiments, a surface of the produced metal or element has less than a 1 mm thickness of ash deposited on the surface by the carbothermic reaction. In other examples, the thickness of ash is deposited on the surface of the produced metal or element by the carbothermic reaction is less than 0.9 mm, less than 0.8 mm, less than 0.7 mm, less than 0.5 mm, less than 0.2 mm, less than 0.09 mm, less than 0.08 mm, less than 0.07 mm, less than 0.06 mm, less than 0.05 mm, less than 0.04 mm, less than 0.03 mm, less than 0.02 mm, less than 0.01 mm, or less than 0.001 mm.

[0133] In some example embodiments, the metal or elemental ore or concentrate, may be passed through the tunnel kiln, or similar high temperature furnace, on a moving belt, with its operational time at the abovementioned reaction temperature set by the speed at which it passes through the tunnel kiln, or similar high temperature furnace, or the abovementioned enclosed volume or substantially enclosed volume therein. Preferably, but not exclusively, the moving belt is a train of refractory carts of the type used to roll through large industrial tunnel kilns on, for example, railway lines. In other examples, the high temperature furnace may be, but is not limited to, a roller kiln or a belt kiln, for example a constant atmosphere belt kiln, that is capable of withstanding the high temperatures involved, and the moving belt is a roller belt or a conveyor belt therein.

[0134] Preferably but not exclusively, the high temperature furnace is a commercial tunnel kiln of the type used commercially to manufacture sanitaryware, tiles, tableware, or other ceramic commercial products. In other examples, roller-type kilns or induction-heating furnaces or belt kilns may be used.

[0135] Preferably but not exclusively, the high temperature furnace is equipped with a heat recovery system. Preferably but not exclusively, the heat recovery system increases the energy efficiency with which the metal or element is produced. In some examples, the heat recovery system may, effectively, comprise of a heat exchanger to recapture heat that would otherwise be emitted by the furnace. In other examples, the heat recovery system may oxidize or bum CO that is produced inside the furnace, to thereby produce heat that diminishes the need for heat energy to be externally supplied to the furnace.

[0136] Preferably but not exclusively, the high temperature furnace comprises one or more metal or ceramic plates within the furnace such that soot or ash form on the metal or ceramicplates, include but not limited to cooled metal or ceramic plates, thereby reducing CO₂ emissions from the furnace during the production of the metal or element from the metal or elemental ore or concentrate.

[0137] In some example embodiments, the high temperature furnace is heated by burning natural gas, which is a relatively lower emitter of CO₂ than, for example, coal. In other example embodiments, the high temperature furnace is heated using microwaves. Such microwaves may be absorbed by, for example, the use of containers or crucibles that absorb microwaves, such as carbon-containing containers or crucibles.

[0138] In other example embodiments, the high temperature furnace is heated electrically, using renewable electricity, such as wind- or solar-generated electricity. Preferably but not exclusively, the use of renewable electricity avoids or reduces the emission of CO₂ when producing the metal or element.

[0139] In another example aspect, the high temperature furnace, is equipped to combust (bum) CO released from the container / s into the atmosphere of the furnace, thereby producing heat that helps maintain the high temperature of the kiln. In such a case, the added energy deriving from oxidising or burning the CO may diminish the consumption of externally supplied energy in the process.

[0140] In still further example embodiments, the high temperature furnace is heated by burning renewable (‘green’) hydrogen. In a preferred but non-limiting embodiment, the hydrogen may be produced by a capillary-fed water electrolysis cell powered by renewable electricity. Preferably but not exclusively, the tunnel kiln, or similar high temperature furnace, is heated by burning renewable (‘green’) hydrogen, to thereby avoid the production of CO₂ by burning of a fossil fuel. In some examples, the renewable hydrogen is produced using water electrolysis cells of the type described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606, WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671.

[0141] Preferably but not exclusively, the reaction temperature at which the metal or elemental ore or concentrate, and carbon source are maintained for the operational time, isequal to or more than 500 °C. In other examples, the reaction temperature at which the metal or elemental ore and carbon source are maintained for the operational time is equal to or more than 500 °C, is equal to or more than 600 °C, is equal to or more than 700 °C, equal to or more than 800 °C, equal to or more than 900 °C, equal to or more than 1,000 °C, equal to or more than 1,100 °C, equal to or more than 1,200 °C, equal to or more than 1,300 °C, equal to or more than 1,400 °C, equal to or more than 1,500 °C, equal to or more than 1,600 °C, equal to or more than 1,700 °C, equal to or more than 1,800 °C, equal to or more than 1,900 °C, or equal to or more than 2,000 °C.

[0142] In another example aspect, the produced metal or element includes but is not limited to one of the following metals or elements, and the metal or element ore or concentrate, is a mineralogical or chemical composition thereof: gold (Au), platinum (Pt), silver (Ag), mercury (Hg), rhodium (Rh), iridium (Ir), copper (Cu), palladium (Pd), bismuth (Bi), antimony (Sb), lead (Pb), tungsten (W), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), phosphorus (P), potassium (K), zinc (Zn), chromium (Cr), nobelium (No), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminium (Al), uranium (U), lithium (Li), magnesium (Mg), and calcium (Ca).

[0143] In other example aspects, the technology described herein, as applied using a tunnel kiln, may have applications in, but not limited to: the direct reduction of chromite in the manufacture of cheaper ferrochromium (chromite may be reduced with the help of calcium chloride to produce ferrochrome alloy powders with high metal recovery); the direct production of stainless steel from highly reduced chromite; the direct reduction of manganese in the manufacture of cheaper ferromanganese; the production of crude ferrosilicon; the direct reduction of iron ore fines (especially hematite or magnetite fines) that could then be charged to a blast furnace; the direct reduction of in-plant waste oxide materials for recycling, adding to plant productivity; the nitriding of titanium bearing slags and minerals for the recovery of TiO₂: the reduction of sulphates (e.g. precipitated barium sulphate); the formation of Mn₇C₃; the oxidation of the FeO present in chrome spinel to Fe-sequioxide (Fe₂O₃); the reduction of FeO to Fc A’ (iron carbides) at low temperatures.

[0144] In other example aspects, the technology described herein, as applied using a tunnel kiln, may have advantages that include, but are not limited to: an ability to directly process fine particulates, allowing use of ore fines generated during mining; an ability to directlyprocess lump particulates, allowing use of ore lumps generated during mining; an ability to handle materials that soften and become sticky under high temperature processing; a capacity to use coal as the carbon source to thereby reduce or eliminate coke requirements; a prospective capacity to reduce the electricity requirement for smelting of charge chrome in ferrochromium production (below 3400 to 2400 kWh / t); be more economical than alternatives, especially when using low grade minerals such as UG2 discards from the platinum industry, where high metal recoveries are essential to produce a product of acceptable quality; reduce CO₂ emissions for ferrochromium by about 20% per ton of liquid metal; achieve higher metal recoveries than alternative technologies; to avoid the need for hot briquetting when reducing iron ore fines; avoid the need for pellets that have been preindurated at 1100 to 1 350°C to have sufficient strength for handling and processing during reduction (‘Induration’ means hardening; it requires additional energy and adds an cost to the production of directly reduced iron).

[0145] In another example embodiment, the ore or concentrate, is a metal or elemental oxide and the product produced by the abovementioned apparatus and / or method, is primarily a metal or elemental carbide, or metal or elemental oxide of different composition to that which was initially primarily present in the ore or concentrate or mineralogical or chemical composition employed. In other embodiments, metal or elemental ceramic materials of diverse formulations may also be formed.

[0146] In another example aspect, during or after completion of the processes described herein, the CO and CO₂ gas released from the at least one container in the high temperature furnace, is reduced back to carbon and oxygen, to thereby regenerate the carbon source and make its use free of CO₂ emissions. Preferably but not exclusively, the tunnel kiln, or similar high temperature furnace, is also heated using renewable electricity or renewable hydrogen, making the produced metal or element renewable (‘green’); i.e. entirely free of any CO₂ emissions whatsoever.

[0147] In other example embodiments, during or after completion of the processes described herein, the CO gas released from the at least one container in the high temperature furnace, is, combined with hydrogen (H₂) gas to form ‘syngas’. The syngas may be used to produce a range of different chemical products, including, but not limited to, synthetic aviation fuel, polymers, or similar products. In some example embodiments, the hydrogen in the syngas isrenewable (‘green’) hydrogen, produced from water using electrolysis powered by renewable energy, thereby making the entire process more ‘green’. In further example embodiments, the renewable hydrogen is produced using water electrolysis cells of the type described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606, WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671.BRIEF DESCRIPTION OF THE FIGURES

[0148] Illustrative embodiments will now be described solely by way of non-limiting examples and with reference to the accompanying figures. Various example embodiments will be apparent from the following description, given by way of example only, of at least one preferred but non-limiting embodiment, described in connection with the accompanying figures.

[0149] Figure 1 depicts an example apparatus for a ‘non-contact’ reduction of a metal or elemental ore or concentrate, to its corresponding metal or element by a solid-state carbothermic reaction, in which the carbon source is separate from the metal or elemental ore or concentrate. Figure 1 shows how at least one container, such as a crucible, may be charged with a carbon source and a metal or elemental ore or concentrate, without contact between the carbon source and the metal or elemental ore or concentrate.

[0150] Figure 2 depicts how an example of at least one closed container, provided by the lidded crucible of Figure 1, may be processed in a suitable apparatus, to produce the corresponding metal or element in the form of a briquette.

[0151] Figure 3 depicts a different example apparatus for a ‘non-contact’ reduction of a metal or elemental ore or concentrate, to its corresponding metal or element by a solid-state carbothermic reaction, in which the container is an integral part of the furnace, wherein the carbon source is physically separate from the metal ore or elemental ore or concentrate.

[0152] Figure 4 depicts the steps of an example method for a reduction of a metal or elemental ore or concentrate, to its corresponding metal or element by a carbothermicreaction, in which the carbon source is separated from the metal or elemental ore or concentrate.

[0153] Figure 5 depicts illustrative reaction curves for the increase in metallization during the reduction of iron ore into iron in a closed or substantially closed container at >900 °C using a process of the type described herein, wherein: (a) demonstrates the effect of a selfaccelerating reaction mechanism (within a hypothetical perfectly sealed and closed container that fully retains all of the CO and CO2 produced) versus the absence thereof (using an open container in which CO and CO2 leaves the atmosphere about the reaction site as they are formed); and (b) depicts how the partial pressure of the CO and CO2 within the hypothetically perfectly sealed and closed container that fully retains all of the CO and CO2 produced, may be expected to increase during the reduction reaction, and how it will change (using an open container in which CO and CO2 leaves the atmosphere about the reaction site as they are formed). (Pco is the partial pressure of CO, Pco2 is the partial pressure of CO2; Pco+Pco2 is the partial pressure of CO and CO₂).

[0154] Figure 6 depicts the change in the percent metallization of the iron produced from FINES of a standard hematite (Fe2O3) iron ore containing 61% total metal iron content, using: (a) an unlidded crucible, or (b) a crucible covered with a well-fitting, heavy lid. The individual data points were empirically determined as described in the text. The lines depict the best curve fits of the individual data points.

[0155] Figure 7 depicts the change in the percent metallization of the iron produced from LUMPS of a standard hematite (Fe2O3) iron ore containing 61% total metal iron content, using: (a) a crucible covered with a well-fitting, heavy lid. The data in Figure 6 is depicted in the background of Figure 7 for comparison purposes. The individual data points were empirically determined as described in the text. The line depicts the best curve fit of the individual data points.

[0156] Figure 8 depicts preferred container arrangements for processes of the herein described types.

[0157] Figure 9 schematically depicts: (a) a container (for example, a crucible) with a ‘top-hat’ lid; the left image shows the container when closed by the lid, while the right-handimagine shows the container and lid when venting excess internal gas pressure, (b) a container that is a pressure vessel, fitted with a pressure relief valve, (c) a container fitted with an internal lid.

[0158] Figure 10 depicts x-ray powder diffraction spectra for an example sample of iron ore (‘Before Firing’) and an example sample of purified iron produced (‘After Firing’), along with Rietveld refinement analysis of their compositions, showing the compounds present and their proportions. The sample is that reported as process 1 in Table 3.

[0159] Figure 11 illustrates the effect of the volume utilization factor on the energy efficiency of transforming iron ore into purified iron. Figure 11(a) shows that when a constant energy is applied in a 500 litre kiln during an example process, the proportion of the energy going into the iron ore within the kiln increases with its volume utilization factor. Figure 11(b) shows that the percentage of energy going into the iron ore within the kiln increases with its volume utilization factor. Figure 11(c) shows that the energy consumption per tonne of purified iron produced declines with the volume utilization factor.

[0160] Figure 12 depicts Ellingham diagrams of various metals and elements relative to carbon.DETAILED DESCRIPTION OF THE INVENTIONDefinitions

[0161] A ‘metal’ is defined herein as a metallic element in physical form, for example (but not limited to) iron (Fe).

[0162] An ‘element’ is defined herein as a non-metallic element in physical form, for example (but not limited to) phosphorus (P).

[0163] A ‘metal ore’ or ‘metallic ore’ or a ‘metal concentrate’ or a ‘metallic concentrate’ or a ‘metal ore or concentrate’ or a ‘metallic ore or concentrate’ is defined herein as an ore of a metal or a concentrate of a metal, for example comprising a mineralogical or a chemical composition (e.g. a compound) of the metal. A concentrate of a metal is herein defined as amaterial incorporating the metal, including all chemical compositions of the metal, regardless of their particular or relative concentration in the material, including as chemical compounds on their own or in combinations, for example mixtures, with other species, including mixtures with related (e.g. alloyed) or unrelated chemical species or mineralogical species. A concentrate of a metal includes but is not limited to a material containing mineralogical forms thereof. A concentrate of a metal explicitly also includes chemical compositions (e.g. compounds) of the metal that have been processed to the point that they may no longer be considered to be of mineralogical origin, for example fine or technical grade chemicals that may be used in industrial or commercial processes. A ‘metal ore’ or a ‘metal concentrate’ or a ‘metal ore or concentrate’ may be produced by a mining operation, or by a mining and ensuing processing operation or operations. Such ensuing processing operation or operations explicitly include operations for massing the metal in an ore into concentrates of the metal, as well as agglomerating ores or concentrates of the metal into forms such as pellets, sinter, or hot- or cold-bonded ores or concentrates, for example briquettes. A ‘metal ore’ or ‘metal concentrate’ or ‘metal ore or concentrate’ is explicitly not limited to mineralogical or chemical compositions comprising relatively high total metal contents. An example of a metal ore or concentrate is an ‘iron ore’ (as defined herein).

[0164] An ‘elemental ore’ or an ‘element ore’ or a ‘elemental concentrate’ or a ‘element concentrate’ or ‘elemental ore or concentrate’ or an ‘element ore or concentrate’ is defined herein as an ore or a concentrate of an element, for example comprising a mineralogical or chemical composition (e.g. a compound) of the element. A concentrate of an element is herein defined as a material incorporating the element, including all chemical compositions of the element, regardless of their particular or relative concentration in the material, including as chemical compounds on their own or in combinations, for example mixtures, with other species, including mixtures with related or unrelated chemical species or mineralogical species. A concentrate of an element includes but is not limited to a material containing mineralogical forms thereof. A concentrate of an element explicitly also includes chemical compositions (e.g. compounds) of the element that have been processed to the point that they may no longer be considered to be of mineralogical origin, for example fine or technical grade chemicals that may be used in industrial or commercial processes. An ‘elemental ore’ or an ‘element ore’ or a ‘elemental concentrate’ or a ‘element concentrate’ or ‘elemental ore or concentrate’ or an ‘element ore or concentrate’ may be produced by a mining operation, or by a mining and ensuing processing operation or operations. Suchensuing processing operation or operations explicitly include operations for massing the element in an ore into concentrates of the element, as well as agglomerating ores or concentrates of the element into forms such as, but not limited to, pellets, sinter, or hot- or cold-bonded ores or concentrates, for example briquettes. An ‘elemental ore’ or an ‘element ore’ or a ‘elemental concentrate’ or a ‘element concentrate’ or ‘elemental ore or concentrate’ or an ‘element ore or concentrate’ is explicitly not limited to mineralogical or chemical compositions comprising relatively high total element contents. An example of an elemental ore is an ore containing the element phosphorus (P).

[0165] An ‘iron ore’ or an ‘iron concentrate’ or an ‘iron ore or concentrate’ is defined herein as an ore or a concentrate of iron, for example comprising a mineralogical or a chemical composition (e.g. a compound) of iron. A concentrate of iron is herein defined as a material incorporating iron, including all chemical compositions of iron, regardless of their particular or relative concentration in the material, including as chemical compounds on their own or in combinations, for example mixtures, with other species, including mixtures with related (e.g. alloyed) or unrelated chemical species or mineralogical species. A concentrate of iron includes but is not limited to a mineralogical concentrate of iron, for example including hematite (Fe2O3), goethite (FeO(OH),), magnetite (Fe3O4, limonite (FeO(OH).n(H₂O)), wüstite (FeO), and / or siderite (FeCO3). and the like. A concentrate of iron also explicitly includes chemical compositions (e.g. compounds) of iron that have been processed to the point that they may no longer be considered to be of mineralogical origin, for example fine or technical grade chemicals containing iron that may be used in industrial or commercial processes. An ‘iron ore’ or an ‘iron concentrate’ or an ‘iron ore or concentrate’ may be produced by a mining operation, or by a mining and ensuing processing operation or operations. Such ensuing processing operation or operations explicitly include operations for concentrating the iron in an ore into concentrates of iron, as well as agglomerating ores or concentrates of iron into forms such as pellets, sinter, or hot- or cold-bonded ores or concentrates, for example briquettes. An ‘iron ore’ or an ‘iron concentrate’ or an ‘iron ore or concentrate’ explicitly not limited to mineralogical or chemical compositions comprising relatively high total iron contents. ‘Mined iron ore’ is defined herein as an ore of iron produced by a mining operation.

[0166] An ‘elemental oxide’ is defined herein as the oxide of a non-metallic element, for example (but not limited to) an oxide of phosphorus.

[0167] The term ‘ton’ designates herein a tonne (i.e. 1,000 kg).

[0168] A ‘self-accelerating’ reaction is herein defined as a chemical process in which the reaction rate increases as the reaction proceeds, leading to a positive feedback loop that accelerates the reaction and leads it to proceed more rapidly and / or complete in a shorter time.

[0169] An ‘auto-catalytic’ reaction is herein defined as a specific type of self-accelerating reaction wherein one of the products of the reaction is also a reactant in the reaction, causing the reaction rate to increase over time as more product forms (rather than slowing down like most reactions). Such a reaction may, effectively, be considered to catalyse itself, speeding up its own completion, which property may be characterised by distinctively sigmoidal reaction curves. It should be noted that, autocatalysis in the processes described herein, occurs without the formal involvement of a catalytic material, being purely an outcome of the reaction mechanism. That is, the autocatalytic character, in this case, is not associated with the involvement of a metal catalysts in the reaction, for example iron or nickel or another metal acting as a catalyst.

[0170] A ‘chain reaction’ is herein defined as a reaction wherein each individual molecular or atomic reaction sequence initiates one, two or more new molecular or atomic reaction sequences, each of which also initiates one, two or more new molecular or atomic reaction sequences, and so on. It is like a domino effect, where the fall of one domino triggers the fall of the next domino, and so on. A ‘self-accelerating chain reaction’ is a chain reaction wherein, specifically, two or more new molecular or atomic reaction sequences are initiated each time, causing the overall reaction to mushroom into many, many simultaneous molecular or atomic reaction sequences occurring in parallel. Chemical and nuclear explosions typically involve self-accelerating chain reactions that proliferate into innumerable simultaneous molecular or atomic reaction sequences occurring in parallel.

[0171] A ‘self-accelerating carbothermic chain reaction’ is herein defined as a selfaccelerating chain reaction wherein the individual reaction sequences involve the reduction of metal or elemental ores or concentrates by carbon monoxide (CO) according to the generalreduction reaction shown in reaction (10), followed by the conversion of the produced carbon dioxide (CO2) back to CO according to the Boudouard reaction shown in reaction (9):General Reduction Reaction:A MxOy+ CO → B Mx±nOy-m+ CO2...(10)where:MxOyis a metal or elemental oxide, andMx±nOy-mis a chemically reduced form of MxOy, whereinM = a metal or element, O = oxygen, CO = carbon monoxide, CO2 = carbon dioxide, x = an integer in the series 1,2, 3, 4,...00, y = an integer in the series 1,2, 3, 4...00, n = an integer in the series 0, 1,2, 3, 4,...00, m = an integer in the series 1,2, 3, 4,...00, andA = an integer in the series 1,2, 3, 4,...00, B = an integer in the series 1,2, 3, 4,...00, and wherein reaction (10) is chemically balanced (i.e. has as many M, O, and C atoms on the left of the equation as on the right of the equation).Boudouard Reaction:CO2+ C → 2 CO...(9)The Boudouard reaction is an equilibrium that is sensitive to temperature, with the CO2 and C species being more favoured and dominating at temperatures below 500 °C and the CO species becoming more favoured above 500 °C, and dominating at temperatures above 900 °C. The reaction shown above in (9) depicts the situation at high temperatures, which are most favourable for self-accelerating carbothermic chain reactions.In the example case of the reduction of iron oxides into iron, the reaction sequence of a selfaccelerating carbothermic may involve reactions (4)-(6) and (9):3 Fe2O3+ CO → 2 Fe3O4+ CO2...(4)Fe3O4+ CO → 3FeO + CO2...(5)FeO + CO → Fe + CO2...(6)CO2+ C → 2 CO...(9)The reaction sequence is the following:The consumption of a single CO molecule in an individual reaction (4)-(6) may produce a CO2 molecule. The CO2 molecule may thereafter react with a carbon (C) atom in the carbon source via reaction (9), to produce 2 new CO molecules. Each of the 2 new CO molecules may initiate a new reaction sequence, resulting in the production of 4 new CO molecules. Each of the 4 new CO molecules may initiate a new reaction sequence, resulting in the production of 8 new CO molecules. The reaction sequence may continue to repeat iteratively, producing 16 new CO molecules, then 32 new CO molecules, and so forth, all from the single CO molecule that initiated the first reaction sequence. In this way, the overall reaction selfaccelerates.The self-acceleration may be considered to be ‘auto -catalytic’ in character, i.e. the overall reaction may catalyse itself, because CO is both a reactant and a product in the above reaction sequence. This would normally cause the reaction rate to increase over time as more product forms (rather than slowing down like most reactions). This property may be characterised by distinctively sigmoidal kinetic reaction curves.The creation of such a self-accelerating chain reactions depends on and can only be created if the produced and consumed CO and CO2 gases are retained in close proximity to each other. It is for this reason that the reaction must be carried out in a closed or substantially closed container. Even so, the volumes of the CO and CO2 gases may be expected to quickly become too large to be held within such a container, which is why it needs to be configured to release excess gas and maintain at least a preferred internal partial pressure of CO and CO₂. The greater the internal partial pressure of CO and CO₂ inside the container, the more effectively the self-accelerating carbothermic chain reaction can be harnessed to accelerate the overall reaction.

[0172] The term ‘metallization’ as applied to a metal-containing material, is herein defined as the proportion of the metal atoms in the material having an oxidation state of zero, relative to the metal atoms having all possible oxidation states.

[0173] The ‘metallization percentage’ or ‘elemental percentage’ of a material is herein defined as the proportion, expressed as a percentage, of the metal or the element atoms in thematerial having an oxidation state of zero, relative to the metal or element atoms having all oxidation states.

[0174] The ‘total metal content’ or ‘total element content’ of a material refers to the cumulative mass of all of the atoms of the metal or the element in the material, as a percentage of the total mass of the material.

[0175] A metal or an element produced from a metal ore or concentrate, or an elemental ore or concentrate, is herein defined as being ‘purified’, ‘substantially purified’, or ‘substantially pure’ if it has a high or a relatively high metallization percentage or elemental percentage. In the example case of iron, ‘purified’, ‘substantially purified’ or ‘substantially pure’ iron produced from iron ore or concentrate may also be referred to as ‘Direct Reduced Iron’, or DRI’.

[0176] A ‘container’ is herein defined as a receptacle, a vessel, a holder, a hollow object, a housing, or the like, that is used to receive, contain, hold or house the carbon source and the metal orelemental ore or concentrate. A ‘closed container’ or ‘substantially closed’ container is herein defined as a closed receptacle, a closed vessel, a closed holder, a closed hollow object, or the like, that is fully closed or is substantially closed but is capable of temporarily and reversibly opening to release excess gas or excess gas pressure whilst maintaining a preferred internal partial pressure of CO and CO₂. The closed container provides an internal enclosed volume, or an internal substantially enclosed volume, which receives the metal or elemental ore or concentrate, and the carbon source, however it may temporarily and reversibly open to release excess gas or excess gas pressure whilst maintaining a preferred internal partial pressure of CO and CO₂. It should be noted that in some examples the carbon source and / or the metal or elemental ore or concentrate, can be received by the container and can move or transit within the container.

[0177] The term ‘partial pressure of CO and CO₂’ means the simple sum of the partial pressures of CO and CO2. For example, a ‘preferred internal partial pressure of CO and CO₂’ in a container, means a preferred simple sum of the partial pressures of CO and CO2 inside the container

[0178] A ‘crucible’ is herein defined as an example type of container, comprising of a refractory material used for heating a substance that requires a high degree of heat. A ‘crucible covered with a lid’ or a ‘lidded crucible’ is herein defined as a crucible that has been closed or substantially closed by placing a lid on it. Preferably but not exclusively, the lid may be capable of transiently and reversibly opening to release excess gas pressure and maintain a preferred internal partial pressure of CO and CO₂ within. Preferably but not exclusively, the lid forms a tight seal with the crucible when it is closed. Preferably but not exclusively, the weight of the lid is calibrated to create and maintain the preferred internal partial gas pressure. In other examples, the lid or the crucible may incorporate a high-temperature pressure release valve. In still other examples, other means of releasing excess gas or excess gas pressure whilst maintaining at least a preferred internal partial pressure of CO and CO₂, may be employed. It is to be understood that any and all such means, without limitation, fall within the scope of this specification. A crucible with a lid may be a preferred option, albeit not exclusively so, as it may typically be used repeatedly in, and it may be quickly and easily cycled in high-throughput batch-type production, and, as would be required in an economically competitive industrial process for producing a metal or element from its metal or elemental ore or concentrate.

[0179] The ‘rate of oxygen removal’ is defined herein as follows. During a carbothermic reduction of a metal or elemental ore or concentrate (e.g. iron ore), the weight of the ore or concentrate decreases overtime as oxygen atoms are removed in the form of CO or CO2 gas. The ‘rate of oxygen reduction’ is defined herein as the weight loss in the ore or concentrate (e.g. iron ore) at the point that the produced metal or element (e.g. purified iron) achieves 90% metallization, divided by the time required at or above a stated temperature, for example above 900 °C, above 1,000 °C, above 1,100 °C, or at 1,170 °C.Wt% loss in the ore at 90% metallisation due to oxygen removalRate of oxygen removal = Time required to achieve 90% metallization at a stated temperatureThe rate of oxygen removal at or above a particular temperature is expressed in units of wt% per °C (wt% / °C).

[0180] An ‘internal lid’ is defined herein as the lid of a container that fits within the mouth of the container. Figure 9(c) schematically depicts an example container 780 with an internal lid 790.

[0181] The term ‘lid mass’ is herein defined as the mass of a lid that may cover a container, for example a crucible, that has been closed or substantially closed by placing a lid on it. Such ‘lid mass’ is expressed herein in units of: kilograms (kg).

[0182] The terms ‘container contact area’ and, for example, ‘crucible contact area’, as relating specifically to a container, for example a crucible, that is closed or substantially closed with a lid, are herein defined as the cross-sectional area of the mouth of the container, for example the cross-sectional area of the mouth of a crucible, that is physically contacted by the lid, such that the lid closes or substantially closes the container, for example the lid closes or substantially closes the crucible. In embodiments described herein, such a lid may typically be seated on the mouth of the container (for example, a crucible), creating a seal between the container (for example, a crucible) and the lid, when the lid closes or substantially closes the container (for example, a crucible). If, however, the internal gas pressure within the container (for example a crucible) exceeds a threshold pressure, the lid may transiently and reversibly move or deflect upward to break the seal with the container (for example a crucible) and thereby release any excess internal gas pressure from the container (for example, a crucible). Thereafter, the lid may re-seat itself on the mouth of the container (for example, a crucible), re-creating the seal that had earlier existed between the container (for example, a crucible) and the lid. Such ‘container contact area’, for example, ‘crucible contact area’, is expressed herein in units of: square metres (m2).

[0183] The ‘ratio of the lid mass to the container contact area’, for example the ‘ratio of the lid mass to a crucible contact area’, is herein defined as the ‘lid mass’ expressed in kilograms (kg), divided by the ‘container contact area’, for example, a ‘crucible contact area’, expressed in square metres (m2). The units of the ‘ratio of the lid mass to the container contact area’, for example the ‘ratio of the lid mass to a crucible contact area’, is therefore herein expressed in: kilograms per square meter (kg / m2).

[0184] The ‘perimeter length of a container contact area’, for example the ‘perimeter length of a crucible contact area’, is herein defined as the length of the perimeter around thecontainer contact area, for example, the length of the perimeter around a crucible contact area. Such perimeter length is expressed herein in units of: metres (m).

[0185] The terms ‘container volume’ and, for example ‘crucible volume’, is herein defined as the volume of a container in its closed or substantially closed state, for example the volume of a crucible in its closed or substantially closed state, expressed in units of: litres (L).

[0186] The ‘ratio of a container volume to the perimeter length of the container contact area’, for example the ‘ratio of a crucible volume to the perimeter length of the crucible contact area’, is herein defined as the ‘container volume’, for example the ‘crucible volume’, expressed in litres (L), divided by the ‘perimeter length of the container contact area’, for example the ‘perimeter length of the crucible contact area’, expressed in metres (m). The units of a ‘ratio of a container volume to the perimeter length of the container contact area’, for example a ‘ratio of a crucible volume to the perimeter length of the crucible contact area’, is therefore herein expressed as: litres per meter (L / m).

[0187] A ‘charged container’ is herein defined to be a container that is filled or substantially filled with a charge, comprising a metal ore or concentrate, or or elemental ore or concentrate, and a carbon source material.

[0188] A ‘shape that complements the shape of a container’ is herein defined as the shape of the metal or element that is produced which is complementary to the shape of the interior, or a portion thereof, of the at least one container. Otherwise stated, the at least one container includes an enclosed volume or substantially enclosed volume whereby the shape of the metal or element takes the complementary form of at least part of the enclosed volume or substantially enclosed volume. In this way, the at least one container includes an enclosed volume or substantially enclosed volume which acts as a mould for the metal of element that is produced.

[0189] A ‘carbothermic reaction’ is herein defined as a reaction in which a substance, for example a metal oxide or an elemental oxide within, but not limited to, a metal or elemental ore or concentrate, is reduced using carbon as the reducing agent at elevated temperature. The term ‘carbothermic reaction’ specifically includes but is not limited to:(a) a ‘self-accelerating carbothermic chain reaction’, as separately defined below; and / or (b) a ‘non-contact carbothermic reaction’, as separately defined below.

[0190] The term ‘stationary’ or ‘substantially stationary’ in reference to a gaseous atmosphere in an engineering system, for example an apparatus for reducing a metal ore or concentrate, or elemental ore or concentrate, is herein defined as referring to a body of gas, for example a body of hot CO and CO₂ gas, that is formed and used in the same location, and thereby avoids energy losses associated with the transport of hot gases from one site to another, for example from a site of their formation or origin to a site of their actual use. It is to be understood that a ‘stationary’ or ‘substantially stationary’ gas may nevertheless be highly dynamic, for example in respect of its molecules diffusing within the site of its formation and use, and being released from the site of its formation and use. That is, a gas body that is ‘stationary’ or ‘substantially stationary’, may nevertheless be partially released, from the site of its formation during and after its use, provided that a preferred pressure thereof is maintained in the site of its use (for example, in the enclosed volume or a substantially enclosed volume, or the closed or substantially closed container, such as a crucible covered with a lid). A ‘stationary’ gas may also be referred to as a ‘static’ gas, or a ‘stagnant’ gas.

[0191] The term ‘confined or ‘substantially confined’ may be used herein in reference to a gaseous atmosphere within a volume, which is preferably an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a lid), in an apparatus for reducing a metal ore or concentrate, or elemental ore or concentrate to its metal or element. In such a case, the term ‘confined or ‘substantially confined’ is herein defined as referring to a body of gas, for example a body of hot CO and CO₂ gas, that is formed and maintained for use in the same location, to thereby avoid energy losses associated with the transport of hot gases from one site to another, for example from a site of their formation or origin to a site of their actual use. It is to be understood that a gas which is ‘confined’ or ‘substantially confined’, may nevertheless be partially released, from the site of its formation during and after its use, provided that a preferred pressure thereof is maintained in the site of its use (for example, in the enclosed volume or a substantially enclosed volume, or the closed or substantially closed container, such as a crucible covered with a lid). That is, such a gas remains a dynamic body and retains all characteristic gaseous properties, for example a capacity to diffuse.

[0192] ‘Lumps’ and ‘fines’ of metal ores or concentrates or elemental ores or concentrates, refer to particulates thereof having selected size ranges. Such metal ores or concentrates or elemental ores or concentrates may typically be crushed and sieved into particles of differing sizes. The smallest particles may typically be referred to as ‘fines’, while larger particles may typically be referred to as ‘lumps’. In one industry standard, lumps are ore or concentrate agglomerations in the size range 6.3 - 31.5 mm, while ore or concentrate particles smaller than 6.3 mm are ‘fines’. Lump and fines components are sold as separate products because they typically may have different compositions, with the lump usually being higher in the metal or element and lower in other minerals. It is to be understood that, in different industries or different localities or under different conventions or general understandings, the terms ‘lumps’ and ‘fines’ may be associated with different physical dimensions and shapes to those described herein. That is, a ‘lump’ or a ‘fine’ may be a smaller or a larger-sized structure than stated above. They may also be differently shaped. It is to be understood that the terms ‘lumps’ and ‘fines’ as used herein, may incorporate and include all such understandings and conventions, deriving from different industries, localities, understandings, and the like.

[0193] In this specification, ‘lumps’ and ‘fines’ of a carbon source refer to particles or agglomerations of the carbon source materials having different physical sizes. Carbon source materials that are finely divided, for example being in essentially a powder or granulated form, may be referred to herein as ‘fines’, while carbon sources of larger size, for example that are not finely divided or in powder or granulated form, may herein be referred to as ‘lumps’. For example, powdered synthetic graphite, or powdered or granulated activated carbon may be considered ‘fines’. By contrast, charcoal briquettes, coal masses, coke masses, and larger carbon structures, may be considered to be ‘lumps. It is to be understood that, in different industries or different localities or under different conventions or general understandings, the terms ‘lumps’ and ‘fines’ may be associated with different physical dimensions and shapes to those described herein. That is, a Tump’ or a ‘fine’ may be a smaller or a larger-sized structure than stated above. They may also be differently shaped. It is to be understood that the terms Tumps’ and ‘fines’ as used herein, may incorporate and include all such understandings and conventions, deriving from different industries, localities, understandings, and the like.

[0194] A ‘pellet’ is herein defined as a relatively small, relatively rounded particle comprising of a metal or elemental ore or concentrate, for example an iron ore or concentrate, combined with one or more binders (e.g. bentonite, dolomite, carboxymethyl cellulose, or a cement binder). Pellets may be formed by rolling finely crushed or powdered, moist metal or elemental ore or concentrate, for example finely crushed or powdered iron ores or concentrates of different mineralogical and chemical composition, with the addition of additives, binders and other materials, in a horizontal drum or in an inclined disc. After heating and sintering, such pellets, for example iron ore pellets, may illustratively have a rounded profile with a relatively uniform size range (e.g. 9 - 13 mm). A ‘pelletizer’ or a ‘pelletizing machine’ may be needed to manufacture pellets. It is to be understood that, in different industries or different localities or under different conventions or general understandings, the term ‘pellet’ may be associated with different physical dimensions and shapes to those referred to herein. That is, a ‘pellet’ may be a smaller or a larger-sized structure than stated above. It may also be differently shaped. It is to be understood that the term ‘pellet’ as used herein, may incorporate and include all such understandings and conventions, deriving from different industries, localities, understandings, and the like.

[0195] ‘Briquettes’ are herein defined as typically pillow-shaped and sized structures of purified metals or elements that are produced without use of a binder. It is to be understood that, in different industries or different localities or under different conventions or general understandings, the term ‘briquette’ may be associated with, or indicate different physical dimensions and shapes to those above, as well as a variety of different physical characteristics and properties. For example, a ‘briquette may be a smaller or a larger-sized structure than pillow sized. It may also be differently shaped than pillow shaped. A ‘briquette’ may, for example, also be very dense, or it may have low density, for example being sponge-like. It is to be understood that the term ‘briquette’ may incorporate and include all such understandings and conventions, deriving from different industries, localities, understandings, and the like.

[0196] ‘Iron Briquettes’ are herein defined as typically pillow-shaped and sized structures comprising of purified iron, that are produced from hot DRI without use of a binder in a process that may yield ‘Hot-Briquetted Iron’ (HBI). HBI is a preferred product for the merchant metallics market as it may typically be denser than cold DRI, which reduces the re-oxidation rate and enables HBI to be stored and transported without special safetyprecautions for shipping bulk cargoes. HBI may be used to make steel within an ‘Electric Arc Furnace’ (EAF), wherein the heat necessary for melting of the metal comes from an electric arc that is created by electrodes within the furnace. It is to be understood that, in different industries or different localities or under different conventions or general understandings, the term ‘iron briquette’ may be associated with, or indicate, or be understood to indicate different physical dimensions and shapes to those above. That is, an ‘iron briquette may be smaller or larger-sized structures than ‘pillow’ sized. It may also be differently shaped than pillow shaped. An ‘iron briquette’ may, for example, also be very dense, or it may have low density, for example being sponge-like. It is to be understood that the term ‘iron briquette’ may incorporate and include all such understandings and conventions, deriving from different industries or localities, and the like.

[0197] The term ‘energy consumption’ is herein defined as the energy required to chemically reduce a metal ore or concentrate, or an elemental ore or concentrate, to a metal or an element. For example, in the example case of iron ore or concentrate being reduced to purified iron, the term ‘energy consumption’ refers to, and is limited to the energy required to reduce the iron ore or concentrate to purified iron.

[0198] A ‘non-contact carbothermic reaction’ is herein defined as a carbothermic reaction in which both the substance to be reduced and the reducing carbon source are solid-state materials, wherein there is no contact, substantially no contact, minimal contact, little contact, not very much contact, or contact largely limited to an interlayer or a surface boundary, between the substance to be reduced and the carbon source, such that these materials can be said to be separate, essentially separate, largely separate, separate to all intents and purposes, or separate in comparison to comparable combinations in the prior art. For example, the substance to be reduced and the carbon sources may be in separate layers, in substantially separate layers, in essentially separate layers, in largely separate layers, in layers that are separate to all extents and purposes, in layers that are separate in comparison to comparable combinations in the prior art, in separate locations, in substantially separate locations, in essentially separate locations, in largely separate locations, in separate locations to all extents and purposes, or in separate locations in comparison to comparable combinations in the prior art.

[0199] The term ‘furnace’ or ‘high temperature furnace’ is herein defined as any device capable of heating items to more than 500 °C. It is to be understood that the term ‘furnace’ or ‘high temperature furnace’ explicitly includes all ovens, heaters, ceramic heaters, heating elements, igniters, kilns, heat pipes, heat pumps, and the like, capable of heating items to more than 500 °C. It is further to be understood that no distinction is made herein between a ‘furnace’ and a ‘kiln’, both of which are considered to fall within the definition of the term ‘furnace’.

[0200] The ‘volume utilization factor’ of a furnace or high temperature furnace is defined herein as the ratio of the internal volume of the furnace that is occupied by a metal or elemental ore or concentrate, and the carbon source, for example within a container or containers, to the overall internal volume of the furnace. For example, if the metal or elemental ore or concentrate, and the carbon source (for example, within a container or a multiplicity of containers) in a furnace occupies 1 m3of a furnace whose overall internal volume is 2 m3, then the volume utilization factor is Vi = 0.5 or 50%. The higher the volume utilization factor, the more energy efficient the furnace is. This may be illustrated by considering that a low volume utilization factor occurs when only a small proportion of the furnace volume is used to heat the metal or elemental ore or concentrate (for example, within the container or containers). The heat needed to maintain the rest of the high temperature furnace volume at temperature will therefore be wasted. This will include the heat losses that occur out of that volume through the walls of the furnace, i.e. the heat radiated through the walls of that volume, and not utilized, which may be substantial.

[0201] The term ‘ironmaking’ is herein defined as and limited to the processes involved in converting iron ores or concentrates into metallic iron (that may thereafter typically be used to make steel).

[0202] ‘Direct Reduced Iron’ (DRI) is defined herein as iron (Fe) that is produced by directly reducing iron ores or concentrates into iron using a reductant such as hydrogen gas or carbon (e.g. in the form of a carbon-based gas like CO).

[0203] ‘A Direct Reduction of Iron process’ or a ‘DRI process’ is a process by which metallic iron is produced by directly reducing iron ores or concentrates using a reductant such as hydrogen gas or carbon (including in the form of a carbon-based gas like CO). Theterm ‘direct’ refers to the fact that such processes do not require a blast furnace. As described in the background section, numerous DRI processes exist, most of which are referred to by an acronym, such as the MIDREX process, the FASTMET process, the Inmetco process, the Inmetco / REDSMELT process, the HYL III process, the ITmk3 process, the SL / RN process, Circored process, and the like. Comprehensive descriptions of such processes may be found in publications such as ‘Comparison of Different Coal Based Direct Reduction Processes’ by M. Kekkonen and E. L. Holappa, published in August 2020 by the Helsinki University of Technology in Finland, which may be obtained at: https: / / www.researchgate.net / publication / 269107176_COMPARISON_OF_ DIFFERENT COAL BASED DIRECT REDUCTION PROCESSES, and other publications.

[0204] ‘Pig iron’ is the form of purified iron that is produced by a blast furnace.

[0205] ‘Sponge iron’ is a form of purified iron that may be produced by a DRI process. Sponge iron may may have low density and be relatively porous and therefore reactive, with a risk of uncontrolled exothermic oxidation during subsequent storage or transportation.

[0206] ‘Hot DRI’ (HDRI) are the hot pellets (i.e. the hot direct reduced iron pellets) collected from the bottom of a shaft furnace producing Direct Reduced Iron (DRI).

[0207] ‘Gangue’ is defined herein as the unwanted, waste minerals that may be present in metal or elemental ores or concentrates. In the example case of iron, gangue may include but is not limited to silica, feldspar, kaolin minerals, aluminosilicates, amphibole, biotite, muscovite, pyroxene, albite, chlorite, calcite, dolomite, mica, gypsum, and apatite.

[0208] The following furnaces used in ironmaking are referred to herein using the abbreviations shown below. Such furnaces are described in publications including but not limited to the chapter entitled ‘Ironmaking’ by Yongxiang Yanga, Kalevi Raipalab and Lauri Holappac, in Treatise on Process Metallurgy, Volume 3 (http: / / dx.doi.org / 10.1016 / B978-0-08-096988-6.00017-1):- Blast furnace (BF)- Basic Oxygen Furnace (BOF)Electric Arc Furnace (EAF)Shaft Furnace (SF)- Rotary Hearth Furnace (RHF)

[0209] The ‘Boudouard reaction’ or ‘Boudouard equilibrium’ is the reaction shown in equation (9) below, describing the chemical equilibrium between carbon monoxide (CO) and carbon dioxide (CO2):2 CO ⇌ CO2+ C...(9)In general, the equilibrium is sensitive to temperature, with species on the right-hand side of the equilibrium being favoured and dominating at temperatures below 500 °C and the species on the left-hand side of the equilibrium becoming favoured and dominating at temperatures above 500 °C, most especially above 900 °C.

[0210] An ‘Ellingham diagram’ is a diagram showing the temperature dependence of the stability of compounds. Ellingham diagrams are usually used to evaluate the ease of reduction of metal oxides and sulfides. In metallurgy, Ellingham diagrams are used to predict the equilibrium temperature between a metal, its oxide, and oxygen. The diagrams are useful in predicting the conditions under which a metal ore or concentrate will be reduced to its metal.

[0211] A ‘capillary-fed’ electrolysis cell is an electrochemical cell of the type described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606, WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671.

[0212] A ‘Coal Gasifier’ is a device for producing gas, typically syngas, from coal. A ‘Carbon gasifier’ is a device for gasifying carbon.Detailed Description

[0213] The following modes, features or aspects, given by way of example only, are described to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments.Preferred system arrangements

[0214] Referring to Figure 1 and Figure 2, there is illustrated an example apparatus or system 5 for producing a metal or element from a metal or elemental ore or concentrate. The apparatus or system 5 comprises a high temperature furnace 70 and a container 10 (or at least one container 10) to receive the metal or elemental ore or concentrate 40 and a carbon source 20. In Figure 1, the metal or elemental ore or concentrate 40 is separate from the carbon source 20 within the container 10. In other examples, not depicted in Figure 1, the metal or elemental ore or concentrate 40 is mixed with the carbon source 20 within the container 10. The container 10 forms part of, or is able to be placed within, the high temperature furnace 70 which is configured to maintain the metal or elemental ore or concentrate 40 and the carbon source 20 at a reaction temperature for an operational time to produce the metal or element. In this example, the container 10 receives and contains and confines the carbon source and the metal or elemental ore or concentrate. However, it should be noted that in other examples the carbon source and / or the metal or elemental ore or concentrate can be received by the container but not be contained and confined by it, for example the carbon source and / or the metal or elemental ore or concentrate could move or transit within the container.

[0215] An enclosed volume or a substantially enclosed volume is provided by container 10 when closed with lid 50. That is, a closed container 10, 50 is provided by container 10 (e.g. a crucible in this example) and lid 50. Separation between the carbon source 20 and the metal or elemental ore or concentrate 40 can be provided by a separator 30 positioned within container 10, which can be a ceramic separator. Alternatively, there may be no separator 30 present and the metal or elemental ore or concentrate 40 and the carbon source 20 may contact each other only at an interface between them, wherein that interface lies at the location shown by 30 in Figure 1. In other embodiments, a first container charged with the metal or elemental ore or concentrate 40 is placed inside a second, larger container filled with the carbon source 20; that is, the first container sits on the bed of the carbon source, inside the second container, wherein the first container acts to separate the metal or elementalore or concentrate 40 and the carbon source 20. In other embodiments, the metal or elemental ore or concentrate 40 and the carbon source 20 are substantially separate, for example being in separate layers about an interface in the location shown by 30 in Figure 1. The enclosed volume or the substantially enclosed volume provided by the closed container 10, 50 allows for regulation of a gaseous atmosphere surrounding the metal or elemental ore or concentrate 40 and the carbon source 20. Preferably but not exclusively, the lid 50 may be capable of transiently and reversibly opening to release excess gas pressure and maintain a preferred internal gas pressure within the crucible 10 during heating to or at the reaction temperature. Preferably but not exclusively, the lid forms a tight seal with the crucible when it is closed. Preferably but not exclusively, the weight of the lid is calibrated to create and maintain a preferred elevated internal partial gas pressure. In other examples not depicted here, the lid or the crucible may incorporate a high-temperature pressure release valve or other means of releasing excess gas pressure whilst maintaining a preferred internal gas pressure within crucible 10. Preferably, the gaseous atmosphere surrounding the metal or elemental ore or concentrate 40 and the carbon source 20, and the metal or elemental ore or concentrate 40 and the carbon source 20 are ‘confined’ or ‘substantially confined’ by the container 10 (but, nevertheless, be partially released periodically to avoid a build-up of excess gas pressure and maintain a preferred internal gas pressure within the crucible 10 during heating to or at the reaction temperature). Preferably, the metal or element is produced from the metal or elemental ore or concentrate 40 by a carbothermic reaction. Preferably, the metal or element is produced from the metal or elemental ore or concentrate by a ‘self-accelerating reaction’, which may be or incorporate features of a ‘chain reaction’, a ‘self-accelerating carbothermic chain reaction’, and / or an ‘autocatalytic’ reaction (within the container 10). A ‘selfaccelerating reaction’, a ‘chain reaction’, a ‘self-accelerating carbothermic chain reaction’, and an ‘autocatalytic’ reaction are described and defined elsewhere in this specification. The metal or elemental ore or concentrate 40 is passed through the high temperature furnace 70 on a moving belt which is schematically depicted as 90 in Figure 2. Preferably, the high temperature furnace 70 is a tunnel kiln and the moving belt 90 is a train of connected refractory carts, such as those that may typically roll through industrial tunnel kilns on a railway line.

[0216] In a different example apparatus, depicted schematically in Figure 3 and described in Example 2 below, the container may be formed as an integral part of the high temperature furnace.

[0217] Referring to Figure 4, there is illustrated an example method 400 for producing a metal or element from a metal or elemental ore or concentrate 40 thereof, by a carbothermic reaction, including but not limited to: a self-accelerating carbothermic chain reaction and / or a non-contact self-accelerating carbothermic chain reaction. A self-accelerating carbothermic chain reaction is described and defined elsewhere in this specification. The method 400 includes step 410 of placing lumps or fines of the metal or elemental ore or concentrate, and a carbon source within a container (e.g. providing an enclosed volume or a substantially enclosed volume) inside a high temperature furnace. The container can be provided by a crucible and lid, to provide a closed container, that is placed within the high temperature furnace. The carbon source may be separate from the metal or elemental ore or concentrate, for example being separated by a separator, by contacting only at an interface between them, or by occupying separate layers. The enclosed volume or substantially enclosed volume provided by the container maintains a regulated gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source. The enclosed volume or substantially enclosed volume provided by the container may be capable of transiently and reversibly opening to thereby maintain a preferred internal pressure of gas within the volume. The enclosed volume or substantially enclosed volume provided by the container confines or substantially confines the gaseous atmosphere as well as the metal or elemental ore or concentrate, and the carbon source within the container. Step 420 involves maintaining the metal or elemental ore or concentrate, and the carbon source within the container at a reaction temperature for an operational time, during which a preferred internal partial pressure of CO and CO₂ gas is maintained within the container, to thereby induce a carbothermic reaction that produces the metal or element from the metal or elemental ore or concentrate. The carbothermic reaction may be a self-accelerating carbothermic chain reaction. The term ‘preferred internal partial pressure of CO and CO₂’ refers to the preferred simple sum of the partial pressures of CO and CO2 in the container. Step 430 involves cooling and retrieving the produced metal or element. The produced metal or element may take the form of the container or a portion thereof. For example, the metal or element may be produced in a structure that complements the structure of the container or a portion thereof.

[0218] In another example, the container 10 with lid 50 is configured to regulate a gaseous atmosphere surrounding the metal or elemental ore or concentrate 40 and the carbon source 20. In another example, the container 10 with lid 50 is configured to confine or substantiallyconfine a surrounding gaseous atmosphere and the metal or elemental ore or concentrate 40 and the carbon source 20. In another example, the container 10 with lid 50 provides an enclosed volume or a substantially enclosed volume. In another example, the container 10 with lid 50 is a closed container 10, 50. In another example, the container 10 with lid 50 is a substantially closed container. In another example, the container 10 is at least partially covered with lid 50. In another example, the container 10 is fully covered with lid 50. In another example, the lid 50 may transiently and reversibly open to release excess internal gas pressure to thereby maintain a preferred gas pressure within the container 10. In another example, the lid 50 forms a tight seal with the crucible 10 when it is closed. In another example, the weight of the lid 50 is calibrated to create and maintain a preferred, elevated gas pressure within the container 10.

[0219] In one example, the carbon source 20 is a solid-state carbon-based material such as, but not limited to, lumps or fines of: charcoal, activated carbon, coal, carbonaceous material, coke, agricultural residues, rice husks / rice straw / , coconut shells / husks, sugar cane bagasse, plastics, biomass, any organic fibrous materials, tyres, biosolids from wastewater treatment plants, wood, sawdust, or timber items. Calcium carbonate (CaCO₃) (limestone) may be used as an alternative to using a carbon source. The carbon source 20 is separate, for example by separator 30 or an interface at the location 30 shown in Figure 1, from the metal or elemental ore or concentrate 40 in the container 10. The reaction may be in the form of a ‘non-contact self-accelerating carbothermic chain reaction. In another example, the carbon source 20 is gas-phase carbon monoxide (CO) or gas-phase carbon dioxide (CO₂), and the gaseous carbon source is separated from the metal or elemental ore or concentrate 40 in the container 10 by a phase difference.

[0220] Preferably, the metal or element is produced in a purified form. For example, the produced metal or element has a metallization percentage or an elemental percentage equal to or more than 80%. In other examples, the metallization percentage or elemental percentage is equal to or more than 82%, equal to or more than 84%, equal to or more than 86%, equal to or more than 88%, equal to or more than 90%, equal to or more than 91%, equal to or more than 92%, equal to or more than 93%, equal to or more than 94%, equal to or more than 95%, or equal to or more than 96%. In still other examples, the metallization percentage or elemental percentage is equal to or more than 78%, equal to or more than 76%, equal to or more than 74%, equal to or more than 72%, equal to or more than 70%, equal to or morethan 68%, equal to or more than 66%, equal to or more than 64%, equal to or more than 62%, equal to or more than 60%, or equal to or more than 50%.

[0221] Preferably but not exclusively, there is an absence of a binder (e.g. bentonite, dolomite, carboxymethyl cellulose, or a cement binder) which is received by the at least one container of the apparatus, or in the method of producing a metal or element. Preferably but not exclusively, a binder is not required due to the metal or elemental ore or concentrate being in a native form, or an essentially un-processed form.

[0222] Preferably but not exclusively, the metal or elemental ore or concentrate, is in a physical form that is not pelletized, briquetted, or artificially agglomerated, and / or does not contain a binder (e.g. bentonite, dolomite, carboxymethyl cellulose, or a cement binder), for example in the form of lumps or fines. Ore or concentrate lumps comprise larger ore or concentrate agglomerations than fines. In the iron ore industry for example, according to one industry standard, the size of iron ore lumps fall in the range 6.3 mm - 31.5 mm, while iron ore fines are less than 6.3 mm.

[0223] In the example illustrated, an enclosed volume or substantially enclosed volume is provided by a closed container 10, 50, being in this example a crucible covered with lid 50, wherein the lid 50 is capable of transiently and reversibly opening to release excess gas pressure and maintain a preferred internal gas pressure within the crucible 10. In another example, the container is formed as part of the high temperature furnace 70 itself.

[0224] In another example, the container 10 provides a confined volume including a seal which is substantially gas tight when the volume is enclosed or substantially enclosed, wherein the seal prevents the gaseous atmosphere from escaping the enclosed volume of the container 10, except to maintain a preferred internal partial gas pressure of CO and CO2

[0225] In another example, the container 10 provides a confined volume including a lid 50 that is substantially gas tight wherein the weight of the lid 50 is calibrated to prevent the gaseous atmosphere from escaping the enclosed volume of the container 10 up to a preferred, elevated internal partial gas pressure of CO and CO₂. The preferred internal gas pressure is then maintained by the lid 50 transiently and reversibly opening to release excess gas when the preferred internal gas pressure within the crucible 10 is exceeded. Preferably, the weightof the lid is such as to provide and maintain an elevated gas pressure within the crucible 10 during the operational time at the reaction temperature.

[0226] In the example illustrated, the crucible 10 and lid 50 are each composed of a refractory material or a high melting point material. The refractory material may be selected from a ceramic material, including but not limited to: porcelain, ceramic, alumina, zirconia, graphite, molybdenum, silicon carbide, clay-graphite, tungsten, quartz, mullite, or corderite, or a metal, including but not limited to: stainless steel, and / or high temperature alloys (e.g. Inconel, Hasteloy).

[0227] Preferably, the metal or elemental ore or concentrate 40 is in a mined form or a mined and subsequently processed form, for example in the form of lumps or fines. Ore or concentrate lumps comprise larger ore agglomerations than fines. In the iron ore industry for example, according to one industry standard, the size of iron ore lumps lie in the range 6.3 mm - 31.5 mm, while iron ore fines are less than 6.3 mm.

[0228] Preferably, the produced metal or element takes the structural form of the container 10 in which it is produced. For example, the metal or element is produced as a briquette 99 when produced within a briquette-shaped container 10. In an example, the metal or element is produced in a crucible and takes the structural form of the crucible upon its production. In an example, the produced metal or element briquette 99 is suitable for safe storage and transport. In another example, the structure or micro-structure of the metal or element takes the structural or micro-structural form of the metal or elemental ore or concentrate from which it was produced.

[0229] In another example, the produced metal or element is substantially free of carbon, in the form of a layer or layers or a deposit or deposits of carbon, thereby simplifying its subsequent processing into other products, for example, in the case of produced iron, simplifying its later conversion to steel. Preferably, the produced metal or element contains less than 0.1% carbon. In other examples, the metal or element contains less than 0.09% carbon, less than 0.08% carbon, less than 0.07% carbon, less than 0.06% carbon, less than 0.05% carbon, less than 0.04% carbon, less than 0.03% carbon, less than 0.02% carbon, or less than 0.01% carbon. In still further examples, the metal or element contains less than 0.15% carbon, less than 0.2% carbon, less than 0.25% carbon, less than 0.3% carbon, lessthan 0.35% carbon, less than 0.4% carbon, less than 0.45% carbon, less than 0.5% carbon, less than 0.7% carbon, less than 1% carbon, or less than 2% carbon.

[0230] In another example, the produced metal or element has no, substantially none, or little, ash deposited in it or on its surface by the carbothermic reaction, including in the form of a layer or layers or a deposit or deposits of ash. Preferably, any ash deposited on the surface of the produced metal or element is insufficient to block or substantially slow or substantially limit the rate of the carbothermic reaction. In example embodiments, less than a 1 mm thickness of ash is deposited on the surface of the produced metal or element by the carbothermic reaction. In other examples, the thickness of ash deposited on the surface of the metal or element by the carbothermic reaction is less than 0.9 mm, less than 0.8 mm, less than 0.7 mm, less than 0.5 mm, less than 0.2 mm, less than 0.09 mm, less than 0.08 mm, less than 0.07 mm, less than 0.06 mm, less than 0.05 mm, less than 0.04 mm, less than 0.03 mm, less than 0.02 mm, less than 0.01 mm, or less than 0.001 mm.

[0231] In an example, the metal or elemental ore or concentrate 40 is passed through the high temperature furnace 70 which is a tunnel kiln, or similar high temperature furnace, on a moving belt 90, with an operational time at a reaction temperature set by the speed at which the metal or elemental ore or concentrate 40 passes through the tunnel kiln, or similar high temperature furnace, or the container therein. In an example, the high temperature furnace 70 is a commercial tunnel kiln of the type used commercially to manufacture sanitaryware, tiles, tableware, or other ceramic commercial products. In another example, the high temperature furnace 70 is equipped with a heat recovery system. Preferably, the heat recovery system increases the energy efficiency with which the metal or element is produced. In some examples, the high temperature furnace 70 is heated by burning natural gas. In other examples, the high temperature furnace 70 is heated using renewable electricity, such as wind- or solar-generated electricity. Preferably, the use of renewable electricity avoids or reduces the emission of CO₂ when producing the metal or element.

[0232] In another example, the high-temperature furnace 60 has a high volume utilization factor, meaning that the available internal volume of the furnace is significantly filled by the metal or elemental ore or concentrate 40 and the carbon source 20 (inside the container or containers 60b). The volume utilization factor provides the ratio of the proportion of the internal volume of the furnace that is occupied by the metal or elemental ore or concentrate40 and the carbon 20 (inside the container or containers 60b) to be heated. The higher the volume utilization factor, the more energy efficient the furnace. A low volume utilization factor means that only a small proportion of the furnace volume is used to heat the metal or elemental ore or concentrate 40 (inside the container or containers, for example the crucible or crucibles 60b). The heat needed to maintain the rest of the high temperature furnace volume at temperature, including all of the energy losses that occur out of that volume, which may be substantial, is therefore wasted. Preferably the volume utilization factor of the high temperature furnace is greater than 10%. In other examples, the volume utilization factor is greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, greater than 40%, greater than 45%, greater than 50%, greater than 55%, greater than 60%, greater than 65%, or greater than 75%. In other examples, the volume utilization factor is greater than 5%.

[0233] In examples, the high volume utilization factor may couple with the presence of a self-accelerating carbothermic chain reaction in the enclosed volume or substantially enclosed volume, and the avoidance of the need to expend energy to pelletise or briquette, as well as the use of confined, stationary gases, thereby avoiding energy losses from moving hot gases around, to produce a purified metal or element from its corresponding metal or elemental ore or concentrate, with an energy consumption that is less than 80% that required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore or concentrate. In other examples the energy consumption required to produce the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, less than 50%, less than 45%, or less than 40% of that required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore or concentrate.

[0234] In still further examples, the high temperature furnace 70 is heated using renewable (‘green’) hydrogen. The hydrogen may be produced by a capillary-fed water electrolysis cell powered by renewable electricity. Preferably, the high temperature furnace 70 is heated by burning renewable (‘green’) hydrogen, to thereby avoid the production of CO₂ by burning of a fossil fuel. In some examples, the renewable hydrogen is produced using water electrolysis cells of the type described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606,WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671.

[0235] In other examples, the high temperature furnace is equipped with suitable metal plates within the furnace upon which CO released from the container during 10 the process may form soot or ash, including but not limited to cooled metal plates, to thereby reduce the CO2 emissions.

[0236] Preferably but not exclusively, the carbon source 20 comprises of a non-anthropogenic carbon with a with low or negative carbon emissions.

[0237] Preferably but not exclusively, the CO₂ emissions of the process is reduced or minimised by employing a low ratio of metal or elemental ore to carbon (when compared to conventional carbothermic reductions of metal or elemental ores or concentrates to their corresponding metals or elements). In examples, the weight ratio of metal / elemental ore / concentrate to carbon may he close to that expected if all oxygen atoms associated with the metal or element in the metal or elemental ore or concentrate were removed as CO₂ gas. For example, in the case of the reduction of hematite-containing iron ore (63% total Fe content) into purified iron (98% total Fe content; 93% metallization) using the processes described herein, the weight ratio of iron ore to carbon may he between 1: 0.122 and 1: 0.124. In other examples, it may he between 1: 0.10 and 1: 0.30.

[0238] Preferably, the reaction temperature at which the metal or elemental ore or concentrate 40 and carbon source 20 are maintained for an operational time is less than the melting point of the produced metal or element. Preferably, the reaction temperature at which the metal or elemental ore or concentrate 40 and carbon source 20 are maintained for an operational time is equal to or more than 500 °C. In other examples, the reaction temperature at which the metal or elemental ore or concentrate 40 and carbon source 20 are maintained for the operational time is equal to or more than 600 °C, equal to or more than 700 °C, equal to or more than 800 °C, equal to or more than 900 °C, equal to or more than 1,000 °C, equal to or more than 1,100 °C, equal to or more than 1,200 °C, equal to or more than 1,300 °C, equal to or more than 1,400 °C, equal to or more than 1,500 °C, equal to or more than 1,600 °C, equal to or more than 1,700 °C, equal to or more than 1,800 °C, equal to or more than 1,900 °C, or equal to or more than 2,000 °C.

[0239] Preferably, the carbothermic reaction has a high driving force, so that reduction of the metal or elemental ore or concentrate 40 to its corresponding metal or element is rapid even when the carbon source 20 is separate from the metal or elemental ore or concentrate 40. The carbothermic reaction may be a self-accelerating carbothermic chain reaction that creates a high driving force. A self-accelerating carbothermic chain reaction is described and defined elsewhere in this specification. Preferably, the operational time at which the metal or elemental ore or concentrate 40 and carbon source 20 are maintained at the reaction temperature is equal to or less than 4 hours. In other examples, the operational time at which the metal or elemental ore or concentrate 40 and carbon source 20 are maintained at the reaction temperature is equal to or less than 3.5 hours, equal to or less than 3 hours, equal to or less than 2.5 hours, equal to or less than 2 hours, equal to or less than 1.5 hours, equal to or less than 1 hour, equal to or less than 30 min, equal to or less than 20 min, equal to or less than 10 min, or equal to or less than 5 min. In still other examples, the operational time at which the metal or elemental ore or concentrate and carbon source are maintained at the reaction temperature is equal to or less than 5 hours, equal to or less than 6 hours, equal to or less than 7 hours, equal to or less than 8 hours, equal to or less than 9 hours, equal to or less than 10 hours, equal to or less than 12 hours, equal to or less than 14 hours, equal to or less than 16 hours, equal to or less than 18 hours, equal to or less than 20 hours, or equal to or less than 50 hours.

[0240] In one example the metal or elemental ore or concentrate is a metal ore or concentrate, the metal ore or concentrate is iron ore or concentrate, and the metal is iron. In some examples, the iron ore or concentrate comprises primarily of hematite (Fe2O3). In other examples, the iron ore or concentrate comprises primarily of magnetite (Fe₃O₄). In still other examples, the iron ore or concentrate comprises primarily of goethite (FeO(OH)), limonite (FeO(OH).n(H₂O)), or wüstite (FeO). Preferably, though not necessarily, the iron ore or concentrate is dry and does not contain or substantially contain water.

[0241] Preferably, though not necessarily, purified iron is produced from iron ore or concentrate, with an energy consumption of less than 8 GJ per tonne of purified iron. In other examples, the purified iron is produced with an energy consumption of less than 7.5 GJ (2,083 kWh), less than 7.25 GJ (2,014 kWh), less than 7.0 GJ (1,944 kWh), less than 6.75 GJ (1,875 kWh), less than 6.5 GJ (1,806 kWh), less than 6.25 GJ (1,736 kWh). In a furtherexample, the high temperature furnace 70 is equipped with a heat recovery system, and the iron is produced with an energy consumption of less than 6.0 GJ per tonne of purified iron. In further examples, the iron is produced with an energy consumption of less than 5.9 GJ, less than 5.8 GJ, less than 5.7 GJ, less than 5.6 GJ, or less than 5.5 GJ per tonne of purified iron. In a still further example, the high temperature furnace 70 is equipped with a heat recovery system, and is also equipped to combust (bum) CO that is released from the container 10, and the iron is produced with an energy consumption of less than 4.0 GJ per tonne of purified iron. In further examples, the iron is produced with an energy consumption of less than 3.9 GJ, less than 3.8 GJ, less than 3.7 GJ, less than 3.6 GJ, or less than 3.5 GJ per tonne of purified iron.

[0242] In one example, the produced iron may be magnetically separated from any waste materials. For example, the produced iron can be subsequently magnetically separated from any waste materials (‘gangue’) that were present in the iron ore or concentrate. In another example, the iron ore or concentrate is primarily hematite and the product produced by the apparatus and / or method is primarily magnetite. In another example, the magnetite is magnetically separated from any waste materials (‘gangue’) that were present in the magnetite or in the ore or concentrate that was used to produce the magnetite.

[0243] In other examples, the produced metal or element includes but is not limited to one of the following metals or elements, and the metal or element ore or concentrate is a mineralogical or chemical composition thereof: gold (Au), platinum (Pt), silver (Ag), mercury (Hg), rhodium (Rh), iridium (Ir), copper (Cu), palladium (Pd), bismuth (Bi), antimony (Sb), lead (Pb), tungsten (W), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), phosphorus (P), potassium (K), zinc (Zn), chromium (Cr), nobelium (No), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminium (Al), uranium (U), lithium (Li), magnesium (Mg), and calcium (Ca). In other examples, metal or elemental oxides of different chemical composition to that initially primarily present in the ore or concentrate or mineralogical or chemical composition employed, may be formed using the processes described herein. Metal or elemental ceramic materials, including but not limited to metal carbides, may, for example, also be formed.

[0244] In another example, during or after completion of the process, CO gas and / or CO2 gas released from the container 10 in the high temperature furnace is reduced back to carbonand oxygen (O2), to thereby regenerate the carbon source 20, and make its use free of CO₂ emissions. Preferably, the high temperature furnace 70 is heated using renewable electricity or renewable hydrogen, making the produced metal or element renewable (‘green’); i.e. entirely free of any CO₂ emissions whatsoever.

[0245] In other examples, during or after completion of the process, CO gas released from the container 10 in the high temperature furnace is combined with hydrogen (H₂) gas to form ‘syngas’. The syngas may be used to produce a range of different chemical products, including, but not limited to, synthetic aviation fuel, polymers, or similar products. In some examples, the hydrogen in the syngas is renewable (‘green’) hydrogen, produced from water using electrolysis powered by renewable energy. In further examples, the renewable hydrogen is produced using water electrolysis cells of the type described in the Applicant's prior International Patent Publication Nos. W02022056603, W02022056604, W02022056605, W02022056606, WO2023193055, WO2023193057, W02024082031, or International Patent Application No. PCT / AU2024 / 050671.

[0246] Competing processes typically use flowing hot gases that must be transported from their site of formation or origin to their site of actual use, for example hot gases may typically be produced by coal or carbon gasification in a separate process, located elsewhere. A surprising advantage of the process of the present invention is that carbon gasification or, when coal is the carbon source, coal gasification is, effectively, included as part of the process, further saving on energy expenditure, the need to transport hot gases (which is wasteful of energy), and the need for additional process apparatus and equipment.Self-Accelerating Carbothermic Chain Reaction

[0247] The inventors have discovered that the formation of and presence of a stationary gaseous atmosphere that is confined or substantially confined in the volume (for example within a container like a crucible), which is preferably an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a lid capable of releasing excess gas and maintaining a preferred gas pressure in the crucible), is surprisingly advantageous insofar as it may create a unique and powerful ‘self-accelerating carbothermic chain reaction’ that strongly drives the process. Thefollowing section provides a description of the ‘self-accelerating carbothermic chain reaction’ that has been discovered by the inventors.

[0248] The overall reaction process involves several reaction steps, the first of which involves the formation at low temperature (below 500 °C), during the initial heating-up process, of a relatively small quantity of carbon dioxide (CO2) gas by the reaction of the small amount of atmospheric oxygen (O2) gas initially present within the volume (for example, a container, like a crucible), preferably an enclosed or substantially enclosed volume (for example a closed or substantially closed container, such as a crucible covered with a lid), and a small proportion of the carbon source present therein. The carbon dioxide (CO2) gas thus produced, is confined or substantially confined within the volume (for example, a container, like a crucible), preferably an enclosed or substantially enclosed volume (for example a closed or substantially closed container, such as a crucible covered with a lid).

[0249] As the heating proceeds to more elevated temperatures (e.g. above 500 °C, and most especially above 900 °C), a second reaction step occurs in which the CO2 is converted by further reaction with carbon atoms in the carbon source, to carbon monoxide (CO) gas via the Boudouard reaction equilibrium in reaction (9):2 CO ⇌ CO2 + C ...(9)The Boudouard reaction equilibrium in (9) is dynamic and dependent on temperature. At temperatures below 500 °C, it favours the presence and dominance of the CO2 and C species (shown on the right-hand side above). Above 500 °C, the CO species (shown on the left-hand side above) starts being favouring. Above 900 °C, the CO species is dominant.

[0250] The carbon monoxide (CO) gas thus produced, may be confined or substantially confined within the volume (for example, a container, like a crucible), preferably an enclosed or substantially enclosed volume (for example a closed or substantially closed container, such as a crucible covered with a lid), within which it can diffuse into contact with the surface of the solid-state metal or elemental ore or concentrate, for example iron ore or concentrate. CO molecules may then undertake chemical reduction reactions of the type:A MxOy+ CO → B Mx±nOy-m+ CO2...(10)where:MxOyis a metal or elemental oxide within the metal or elemental ore or concentrate, Mx±nOy-m is a chemically reduced form of MxOy, whereinM = a metal or element, O = oxygen, CO = carbon monoxide, CO2 = carbon dioxide, x = an integer in the series 1,2, 3, 4,...00, y = an integer in the series 1,2, 3, 4...00, n = an integer in the series 0, 1,2, 3, 4,...00, m = an integer in the series 1,2, 3, 4,...00, andA = an integer in the series 1,2, 3, 4,...00, B = an integer in the series 1,2, 3, 4,...00, and wherein reaction ( 10) is chemically balanced (i.e. has as many M, O, and C atoms on the left of the equation as on the right of the equation).

[0251] For example, in the case of the transformation of iron ore or concentrate into iron or purified iron, the reduction reactions may be the indirect reactions (4)-(6):3 Fe2O3+ CO → 2 Fe3O4+ CO2...(4)Fe3O4+ CO → 3FeO + CO2...(5)FeO + CO → Fe + CO2...(6)

[0252] Due to the stationary gaseous atmosphere that is confined or substantially confined in the volume (for example, a container), which is preferably an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a lid capable of releasing excess gas and maintaining a preferred, elevated gas pressure in the crucible), the above reduction reactions initiate or set off a ‘selfaccelerating carbothermic chain reaction’, as follows:- In reactions of the type (10), including but not limited to, for example, each of the indirect reactions (4)-(6), each reaction consumes one molecule of CO and produces one molecule of CO2.- However, according to the Boudouard reaction (9), each molecule of CO2 is favoured (at above at least above 500 °C and most especially above 900 °C) to react with a further, solid-state carbon atom in the carbon source, to produce two molecules of CO.That is, at above 500 °C and most especially above 900 °C, a chain reaction may be created in which each CO molecule reacts with a metal or elemental oxide in the metal or elemental ore or concentrate, followed by the Boudouard reaction, to produce two new CO molecules (with accompanying consumption of a further carbon atom). Each of the two new CO molecules may thereafter also undertake the above reaction sequence, producing in total four new CO molecules. This process may repeat itself, leading to the production of eight new CO molecules in total, and so forth, all from a single starting CO molecule, spontaneously resulting in a dramatic and rapid increase in the quantity of CO molecules present in the volume (for example, a container, like a crucible), preferably an enclosed or substantially enclosed volume (for example a closed or substantially closed container, such as a crucible covered with a lid).This chain reaction may have the effect of accelerating and amplifying the rate at which the metal or elemental ore or concentrate, for example an iron ore or concentrate, is progressively reduced to its corresponding metal or element, for example to iron. Moreover, provided that the newly generated CO and CO2 molecules can be retained and become concentrated within the volume, this sequence may continue and ‘selfaccelerate’ until the metal or elemental ore or concentrate, for example an iron ore or concentrate, is largely or completely or fully converted to the corresponding metal or element, for example iron. By contrast, if the generated CO and CO2 molecules are free to leave the reaction site, for example if the container is not closed, thereby allowing the CO and CO2 molecules to diffuse away from the reaction site, then a chain reaction can not be established and there may be little or no acceleration in the rate at which the metal or elemental ore or concentrate is reduced to its metal or element.This may be demonstrated by applying the principles and procedures of classical kinetics to the iron reduction example above. At 1,200 °C, the reaction scheme will be the following:Fe2O3+ CO →k₁2 FeO + CO2...(4) & (5) combined2 FeO + 2 CO →k₂2 Fe + 2 CO2...(6)k13 CO2+ 3 C →k₃6 CO ...(9)Overall: Fe2O3+ 3 C 2 Fe + 3 COFrom the rate equations for this scheme, a graph may readily be obtained along the lines of that depicted in Figure 5(a)(‘with self-accelerating reaction’), which shows that, if the generated CO and CO2molecules can be fully retained inside the container, then the reaction rate (in the form of the metallization of the produced iron) is predicted to increase dramatically during the course of the reaction. This would greatly accelerate the reduction and compress the time needed for it to complete. By contrast, if the CO and CO2 molecules are free to leave the site of the reaction (Figure 5(a)( ‘without selfaccelerating reaction’)), and therefore do not become concentrated in the atmosphere about it, then no such increase occurs in the rate of the reaction, meaning that the reduction is not accelerated and the time required for the reaction to complete is not compressed.A constraint to practically realising a rate amplification like that in Figure 5(a)( ‘with self-accelerating reaction’) however, is that the self-accelerating reaction is also predicted to rapidly generate large quantities of CO and CO2, leading to very substantial increases in the partial pressures of CO and CO2 in the container (into many tens or even hundreds of atm potentially). This is depicted in Figure 5(b), wherein Pco in Figure 5(b) indicates the expected change in the partial pressure of CO and Pco2 in Figure 5(b) indicates the expected change in the partial pressure of CO2, both of which can be seen to increase dramatically. No such increase occurs if the container is open and the CO and CO2 gases leave the reaction site immediately after their formation (as shown in the curve for Pco+co2 in Figure 5(b)). The sigmoidal reaction curve depicted in Figure 5(a)(‘with self-accelerating reaction’) is distinctively characteristic of autocatalytic processes.While it is therefore not realistic to expect full retention of the produced CO and CO2 in a small container, the higher the cumulative partial pressures of CO and CO 2 that can be maintained in the container, the more accelerated the reduction is predicted to become.Accordingly, the higher the partial pressure of CO and CO₂ (PCO+CO2) that can be maintained in the container, which may be a closed or substantially closed container,the greater the benefit that may be obtained from the self-accelerating nature of the process.Thus, the above chain reaction creates a powerful driving force for accelerated and complete conversion of the metal or elemental ore or concentrate, for example, an iron ore or concentrate, into its corresponding metal or element, for example iron.During the above process, the carbon-based gas body within the volume (for example, a container, like a crucible), preferably an enclosed or substantially enclosed volume (for example a closed or substantially closed container, such as a crucible covered with a lid capable of releasing excess gas and maintaining a preferred gas pressure in the crucible), may be expected to change as follows (assuming the container is tightly sealed):o Prior to heating by the furnace:The initial partial pressure of carbon-based gas within the volume is around 427 parts per million of CO2 (which derives from the atmospheric concentration of CO2);o Below around 500 °C (during the heating -up phase):The partial pressure of CO2 increases due to the reaction of the atmospheric O2 with the carbon source in the volume. As O2 comprises around 20% of the atmosphere and one molecule of CO2 is produced for every 1 molecule of O2 present, CO2 comes to comprise around 20% of the gaseous atmosphere in the container;o Above 500 °C and most especially above around 900 °C:The CO2 that is present in the volume is increasingly converted to CO due to the shift in the equilibrium in reaction (9) above, that occurs at temperatures above 500 °C and most especially above 900 °C. This enables the abovementioned selfaccelerating carbothermic chain reaction to take place, wherein each CO molecule reacts to produce a CO2 molecule (via a reaction (10) (including but not limited to, for example, in the case of iron ore or concentrate, reactions (4)-(6)). This is followed by reaction (9), in which each CO2 molecule is converted to two new CO molecules, at temperatures above 500 °C and most especially above 900 °C. Thisleads to the creation of a partial pressure of CO and CO₂ inside the volume. The partial pressure of CO and CO₂ arises from the carbothermic nature of the reactions, which may be ‘self-accelerating’ if the CO and CO2 molecules become concentrated within the volume. The ‘self-accelerating carbothermic chain reaction’ and the high partial pressures of CO and CO2 it produces, may provide a remarkably and a surprisingly high driving force for the carbothermic reaction. The driving force may be amplified by the product metal or element having a low energy of formation. Provided that sufficient carbon is present in the carbon source, and the CO and CO2 molecules are concentrated within the volume, the CO and CO2 partial pressure continues increasing until the metal or elemental ore or concentrate, for example an iron ore or concentrate is largely or completely or fully converted to the corresponding metal or element, for example iron.Subsequent cooling to below 500 °C:During the subsequent cooling to 500 °C and below, any CO gas in the volume would be favoured to convert to CO2 and carbon (C) due to the shift of the equilibrium in reaction (9) that occurs below 500 °C. The inventors have found however, that such carbon tends to be deposited on the parts of the volume that cool the quickest, which are generally not in the body or on the surfaces of the produced metal or element, but rather exposed portions of the volume walls and the surface of any remaining, unreacted carbon. The quantity of deposited carbon is also typically only low, being dependent on the partial pressure of CO that was maintained at the more elevated temperature. The inventors have found, however, that it is critical for atmospheric oxygen to be as thoroughly excluded as possible from the volume during the cool-down phase. This may be needed to prevent reoxidation of the produced metal or element, which may be highly susceptible to oxidation in the presence of air oxygen at such temperatures. Beyond the potential to regulate the gaseous atmosphere inside a crucible during the process, another key benefit of having a well-sealed lid covering the crucible, may be that it prevents unwanted external gases, such as atmospheric oxygen, from entering the crucible during cool-down.

[0253] The involvement of the above-described ‘self-accelerating’ carbothermic chain reaction is a unique feature of the process discovered by the inventors to produce purified metals or elements from metal or elemental ore or concentrates.Proof of the presence of, and demonstration of the practical utility of a self-accelerating reaction. Conditions needed for a self-accelerating reaction

[0254] To prove the presence of, and demonstrate the practical utility of a self-accelerating carbothermic reaction, the inventors carried out a set of comparative experiments to prepare purified iron in a high temperature tube furnace, from a standard sample of iron ore fines containing hematite (Fe2O3). The sample was supplied by Independent Mineral Standards (16 Durham Road, Bayswater, Western Australia, 6053, Australia), and comprised the following, independently certified properties: a percent metallization (Fe) of 0%, a total Fe content of 61.03%, and an invariant composition. The experiments were carried out in a crucible fabricated of stainless steel 310, either without a lid, or fitted with a lid, which was heavy in weight. The crucible was charged with a single layer of 75 g of the independently certified iron ore fines, along with 18.5 g of a single batch of activated carbon, of which 12 g was placed in a layer below the iron ore and 1.89 g was placed in a separate layer above the iron ore. The crucible had dimensions of 20 cm length x 11 cm breadth x 6 cm height. The crucible lid had a lip around its perimeter that provided an excellent seal with a seat that was around the mouth of the crucible on which it was placed. This lip-and-seat arrangement also ensured that the lid remained on top of, and covering the crucible following transient and reversible releases of excess internal gas pressure from the crucible during high temperature heating. All experiments were repeated in multiple replicates to allow for a statistical analysis of the results.

[0255] During the experiments, the charged crucible was placed inside a high temperature tube furnace through which a flowing atmosphere of inert gas (argon) was continuously passed. The flow rate of argon through the tube furnace was such that the entire gas volume in the tube furnace was replaced with fresh argon every 15 minutes, continuously, throughout the experiment. The argon passing through the tube furnace ensured a complete absence of oxygen in the atmosphere about the crucible in the tube furnace. This replicated the largely oxygen-free conditions in the atmosphere about the crucibles inside large-scale tunnel kilns of the type used for ironmaking, as described in the Background section. The oxygen-freeconditions arise because of the combustion of natural gas, and / or emitted CO, that is needed to heat the tunnel kilns.

[0256] Each set of experiments involved heating the charged crucible, either with or without the well-fitting lid, in the tube furnace up to 900 °C at a ramp rate of 4.6 °C / min, whereafter the ramp rate was changed to a very slow 1.13 °C / min, up to the reaction temperature of 1,170 °C. The reaction temperature of 1,170 °C was thereafter maintained constant until the heating was turned off. The very slow ramp rate between 900 °C and 1,170 °C, which is far below ramp rates that may be achieved in industrial tunnel kilns, was chosen to get an idea of a likely maximum time required to achieve 90% metallisation in the different experimental arrangements (i.e. with and without a lid). The individual experiments that were carried out, differed in that the heating was turned off at different times after the tube furnace reached 900 °C, with the purified iron that was produced, then analysed, after it had cooled to room temperature, to determine its properties.

[0257] Figure 6 depicts the percent metallization data of the purified iron produced in these experiments as a function of the time at which the heating was turned off, when starting with the abovementioned, standard, mined, hematite (Fe2O3) ore fines with a total iron content of 61% iron. Figure 6(a) depicts the data using the unlidded crucible. Figure 6(b) depicts the data using the crucible with the well-fitting, heavy lid. As can be seen, the iron produced in the lidded crucible achieved 90% metallization far more rapidly during high-temperature heating, than the iron produced in the unlidded crucible.

[0258] Figure 6(a) demonstrates that the iron produced in the unlidded crucible was projected to require 714 minutes (11.9 hours) above 900 °C, including around 422 minutes (7 hours) at the reaction temperature to achieve 80% metallization. These times are comparable to, but somewhat shorter than those typical in modern-day, large-scale tunnel kiln ironmaking operations as described in the Background section, which may require 20 -48 hours to be spent in the firing zone, for example including but not limited to the Hoganas process. Such operations typically use coal as the carbon source, which is less active in the production of CO and CO2 at high temperature than the activated carbon used for the examples illustrated by Figure 6.

[0259] By contrast, Figure 6(b) shows that, despite the deliberately slow heating ramp rate between 900 °C and the reaction temperature of 1,170 °C, the iron produced in the lidded crucible achieved greater than 90% metallization within 255 minutes (4 hours 15 min) of the furnace reaching 900 °C, including less than 15 minutes at the reaction temperature of 1,170 °C.

[0260] The data in Figure 6(b) is all the more notable for the fact that it was achieved using standard, mined hematite (Fe2O3) ore fines with a total iron content of 61% iron. By contrast, modern-day large-scale tunnel kiln processes most typically utilise finely-ground magnetite (FesC concentrates with total iron content of -71.5%, or iron scale containing -74% total iron content. Magnetite (Fc^Cfi. 72.4% total Fe content) is, in effect, a partially pre-reduced iron oxide compared to hematite (Fe2C>3, 69.9% total Fe content), while iron scale, also called ‘mill scale’, typically comprises mostly of wtistite (FeO, 77.73% total Fe content), which is still more pre-reduced when compared to hematite. Moreover, the magnetite and iron scale concentrates used in tunnel kiln ironmaking today may often be pre-processed into pellets or similar aggregates with structures and porosities optimised for the fastest possible reaction. The wt% of oxygen that needs to be removed from these ores or concentrates to achieve 90% metallization is: 7.18 wt% for Hematite ore comprising 61%total iron content, 5.91 wt%for Magnetite concentrate comprising 71.5% total iron content, and 3.88 wt% for Wustite ore comprising 74% total iron content.

[0261] Thus, the reduction shown in Figure 6(b) had to remove notably more oxygen atoms to achieve 90% metallization than is normally required in present-day large-scale tunnel kiln processes.

[0262] Several important conclusions can be drawn from the data presented.

[0263] Firstly, as can be seen in Figure 6(a), the hematite iron ore in the unlidded crucible was reduced to purified iron following essentially a conventional kinetic profile. By contrast, as shown in Figure 6(b), the hematite iron ore in the lidded crucible followed a sinoidal profile in its formation of purified iron, which is distinctively characteristic of a selfaccelerating reaction, specifically an autocatalytic reaction.

[0264] To unambiguously prove the existence of a self-accelerating reaction when using the lidded crucible, a statistical analysis, in the form of quartile plots of all the replicate data summarised in Figure 6, was carried out for each of the lidded crucible and the unlidded crucible. The statistical software package JMP was used for the analysis (SAS Institute Inc., Cary, NC, USA). All data obtained for each of the lidded crucible and the unlidded crucible was found to fall within the 95% probability distribution that demonstrates statistical significance and reproducibility. Accordingly, the data in Figure 6, for each of the lidded crucible and the unlidded crucible, is statistically replicable. This statistical assessment across both sets of experiments confirmed that the observed percentage metallization values (and other measured properties) adhered to normal distribution behaviour with small standard deviations, validating the robustness and reproducibility of the measurement approach. The data in Figure 6 therefore proves, unequivocally, that a self-accelerating carbothermic reaction occurred within the lidded crucible.

[0265] Secondly, the data in Figure 6 provides clear evidence of the practical benefit and utility of a self-accelerating carbothermic reaction. A substantial rate acceleration was clearly realised using the crucible with the well-fitting, heavy lid, over the unlidded crucible.

[0266] Given the long firing time needed in Figure 6(a), that experiment may explain in large measure, the very long firing (and processing) times, and therefore also the very long tunnel kilns (e.g. 260 metres long), currently typical of large-scale tunnel kiln ironmaking. These long firing (and processing) times are the fundamental cause of their low throughputs - i.e. their low production rates per unit time. They create their high costs of production and their high energy consumptions per tonne of iron produced. As far as the authors are aware, the largest ironmaking tunnel kilns presently operating globally have maximum production rates of 70,000 - 100,000 tons of iron per annum. Considering the width and height of these kilns, their annual production may be up to around 10,000 tons per square metre of the cross-sectional area of the tunnel kiln. It is these low throughputs that limit tunnel kiln ironmaking to low-volume, high-cost, niche production.

[0267] Accelerating the processing and firing times by utilising a self-accelerating carbothermic reaction to achieve data of the type depicted in Figure 6(b), therefore stands to materially increase the throughputs of the tunnel kilns - i.e. increase their production rates per unit time - as well as decrease their length. This may be expected to significantly reducetheir high costs and high energy consumptions, making tunnel kiln ironmaking economically more competitive against other methods for producing direct reduced iron.

[0268] In further studies related to the experiments for Figure 6, the inventors examined the partial pressures of CO2 and CO maintained about the charge, with and without the lid on the crucible. They found that the cumulative partial pressures of CO2 and CO that were maintained about the charge inside the closed crucible (Figure 6(b)) during its firing time was around ~1.25 atm, and this was the reason it facilitated a self-accelerating (autocatalytic) carbothermic reaction. By contrast, a much lower partial pressure of CO2 and CO of around -0.60-0.75 atm was maintained about the charge in the unlidded crucible (Figure 6(b)), and this was the reason that it produced a conventional, near linear kinetic profile, absent of the sinoidal trait that demonstrates self-acceleration. That is, the CO2 and CO partial pressure that was maintained about the charge at the reaction temperature for the operational time, determined whether a self-accelerating (carbothermic) reaction occurred or not.

[0269] Studies also examined the effect of the partial pressures of CO2 and CO that were maintained about the charge, on their kinetic reduction profiles, as well as on the times needed to produce 90% metallization at the reaction temperature of 1, 170 °C. These studies demonstrated that a sinoidal kinetic profile was unambiguously evident only with CO2 and CO partial pressures of -1.1 atm. Potentially sinoidal kinetic profiles were observed with CO2 and CO partial pressures once these partial pressures were raised to the range -0.8 - 1.1 atm.

[0270] Accordingly, it can be concluded that the lowest partial pressure of CO2 and CO maintained around the charge, that may produce a sinoidal kinetic profile fell in the range 0.8 - 1.1 atm. That is, the self-acceleration (autocatalytic) carbothermic reaction commences when the partial pressure of CO2 and CO is in the range 0.8 - 1.1 atm, and becomes overwhelmingly dominant when the partial pressure of CO2 and CO exceeds 1.1 atm.

[0271] Modelling studies suggested that the local partial pressures within the iron ore itself inside the lidded crucible, may have been notably higher than the above values, in the order of several atmospheres higher. This suggested that the higher partial pressures maintained about the charge acted to slow the rate at which CO and CO2 from the carbon source diffusedthrough and / or out of the iron ore, and this was the fundamental source of the observed rate accelerations.

[0272] To assess the capacity of the crucible with well-fitted, heavy lid to reduce lumps (rather than fines), the standard, mined hematite (Fe2O3) ore fines used above, were also compressed using a hydraulic press into small ‘cubes’ of extremely high density. The high density ‘cubes’ then served as ‘lump proxies’, in studies to determine how lumps would reduce in the crucible with the well-fitted, heavy lid, under identical conditions to those used for Figure 6. The key difference between fines and lumps is that lumps generally have higher density and lower porosity, meaning that reducing gases cannot as easily reduce them.

[0273] Figure 7 depicts the data obtained when the high density ‘cube’, lump proxies were reduced in the crucible with the well-fitted, heavy lid, under identical conditions to those used for Figure 6. As can be seen in Figure 7(a), an unambiguous sinoidal kinetic profile was observed in these experiments too, albeit time shifted to around 100 minutes after the sinoidal profile of the fines in Figure 6(b).

[0274] Accordingly, the self-accelerating reaction may also be used to reduce hematite lumps containing 61% total iron content. Such, hematite (Fe2O3) ores in lump form, may also be directly obtained from mining operations. As far as the inventors are aware, lumps of iron ore have, to date, been too unviably slow to reduce in present-day large-scale, ironmaking tunnel kilns. However, they proved to be readily reduced by inducing a self-accelerating reaction using the crucible closed with well-fitted, heavy lid. That is, the self-accelerating reaction provides an additional utility and benefit; it may enable direct reduction of iron ores in lump form within ironmaking tunnel kilns, where this has not been possible to date.

[0275] Thus, in an example aspect, there is provided an apparatus for producing a metal or element from a metal ore or an elemental ore, the apparatus comprising: a high temperature furnace; and at least one container comprising an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore, or an elemental ore, and a carbon source; wherein the at least one container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the metal ore, or elemental ore, and the carbon source at or within a reaction temperature or range of reaction temperatures for an operational time to produce themetal or element; wherein the at least one container is configured to maintain a gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time; and wherein a reaction occurs at the reaction temperature to produce the metal or element and the reaction is a self-accelerating carbothermic chain reaction within the enclosed volume or substantially enclosed volume.

[0276] In examples, the metal ore is iron ore in the form of fines or lumps, for example hematite-based iron ore or magnetite-based iron ore.

[0277] Preferably but not exclusively, the at least one container maintains the gaseous atmosphere by maintaining a partial pressure of CO and CO₂ in the gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time.

[0278] Preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.8 atm.

[0279] In other examples, preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.82 atm, more than or equal to 0.84 atm, more than or equal to 0.86 atm, more than or equal to 0.88 atm, more than or equal to 0.9 atm, more than or equal to 0.92 atm, more than or equal to 0.94 atm, more than or equal to 0.96 atm, more than or equal to 0.98 atm, more than or equal to 1.0 atm, more than or equal to 1.1 atm, more than or equal to 1.2 atm, more than or equal to 1.3 atm, more than or equal to 1.4 atm, more than or equal to 1.5 atm, more than or equal to 1.6 atm, more than or equal to 1.7 atm, more than or equal to 1.8 atm, more than or equal to 1.9 atm, more than or equal to 2.0 atm, more than or equal to 2.0 atm, more than or equal to 2.5 atm, more than or equal to 3.0 atm, more than or equal to 4.0 atm, more than or equal to 5.0 atm, more than or equal to 6.0 atm, more than or equal to 8.0 atm, or more than or equal to 10.0 atm, in the enclosed or substantially enclosed volume, during the operational time at the reaction temperature. In still other examples, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during theoperational time, of more than or equal to 0.75 atm, of more than or equal to 0.7 atm, of more than or equal to 0.6 atm, of more than or equal to 0.5 atm, of more than or equal to 0.4 atm, more than or equal to 0.3 atm, more than or equal to 0.2 atm, or more than or equal to 0.1 atm, in the enclosed or substantially enclosed volume, during the operational time at the reaction temperature.

[0280] Preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 133 atm. In other examples, preferably but not exclusively, the at least one container maintains an absolute partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 10.0 atm, of below 8.0 atm, of below 6.0 atm, or of below 5.0 atm.

[0281] A ‘gauge’ partial pressure refers to the partial pressure above the ambient pressure that exists outside of the closed or substantially closed container. Preferably but not exclusively, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.01 atm. In other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.05 atm, of more than or equal to 0.1 atm, of more than or equal to 0.15 atm, of more than or equal to 0.2 atm, more than or equal to 0.3 atm, more than or equal to 0.4 atm, more than or equal to 0.5 atm, more than or equal to 0.6 atm, more than or equal to 0.7 atm, more than or equal to 0.8 atm, more than or equal to 0.9 atm, more than or equal to 1.0 atm, more than or equal to 1.1 atm, more than or equal to 1.2 atm, more than or equal to 1.3 atm, more than or equal to 1.4 atm, more than or equal to 1.5 atm, more than or equal to 1.6 atm, more than or equal to 1.7 atm, more than or equal to 1.8 atm, more than or equal to 1.9 atm, more than or equal to 2.0 atm, more than or equal to 3.0 atm, more than or equal to 4.0 atm, more than or equal to 5.0 atm, more than or equal to 6.0 atm, more than or equal to 7.0 atm, more than or equal to 8.0 atm, more than or equal to 9.0 atm, more than or equal to 10.0 atm, more than or equal to 15.0 atm, or more than or equal to 20.0 atm. In still other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of more than or equal to 0.09 atm, more than or equal to 0.08 atm, more than or equal to 0.07 atm, more than or equal to 0.06 atm, more than or equal to 0.05 atm,more than or equal to 0.04 atm, more than or equal to 0.03 atm, more than or equal to 0.02 atm, or more than or equal to 0.01 atm.

[0282] Preferably but not exclusively, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 132.0 atm. In other examples, the at least one container maintains a gauge partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume during the operational time, of below 9.0 atm, of below 7.0 atm, of below 5.0 atm, or of below 4.0 atm.TABLE 2. Expected time required to achieve 90% metallization in the iron product, at different reaction temperatures, for the reduction of different iron ore fines.Partial Rate of oxygen iiiiiiiiii xpected ti me requir ed to achi ex e 90" / < metalliza tion in th<; iron pr oduced 1 Tom:pressure of removalCO and Hem atitc (FeiO 3) iron orc fines etitc (FcjC >4) iron orc fines IIIIIO stitc(FcO) iron orc fi ncs CO2 i total Fe c ontent of 6 1% with total Fc ct ntent of 7 11111 1 total Fc c ontent of 7 4% t a temper ature abox e t a temper ature a box e t a temper atu re abox c maintainedabout the900 " C 1,000 " C 1,100 " C lillliii 900 °C 1,000 " C 1,100 »c llliili 900 " C 1,000 °C 1,100 " C 1,170 " C charge(min) (min) (min) (min) (min) (min) (min) (min) (min) (min) (min) (min) (Wt% / min)(atm)0.02814 above 900 °C 255 210 1381.25 0.03680 above 1,000 °C 195 161 1050.09569 above 1,100 °C 75 62 410.47846 at 1,170 °C 15 12 8 0.02432 above 900 °C 295 243 1591.20 0.03053 above 1,000 °C 235 194 1270.06237 above 1,100 °C 115 95 620.13032 at 1,170 °C 55 30 30 0.02134 above 900 °C 336 277 1821.15 0.02597 above 1,000 °C 276 228 1490.0459 above 1,100 °C 156 129 840.07449 at 1,170 °C 96 79 52 0.01894 above 900 °C 379 312 2051.10 0.02251 above 1,000 °C 319 263 1720.03609 above 1,100 °C 199 164 107 0.05169 at 1,170 °C 139 114 75 0.01698 above 900 °C 423 348 2281.05 0.01979 above 1,000 °C 363 299 1960.02958 above 1,100 °C 243 200 131 0.03930 at 1,170 °C 183 150 99 0.01534 above 900 °C 468 385 2531.00 0.01760 above 1,000 °C 408 336 2200.02494 above 1,100 °C 288 237 155 0.03151 at 1,170 °C 228 188 123 0.01396 above 900 °C 514 423 2780.95 0.01580 above 1,000 °C 454 374 2450.02148 above 1,100 °C 334 275 181 0.02617 at 1,170 °C 274 226 148 0.01277 above 900 °C 562 463 3040.90 0.01430 above 1,000 °C 502 413 2710.01879 above 1,100 °C 382 315 206 0.02229 at 1,170 °C 322 265 174 0.01174 above 900 °C 611 503 3300.85 0.01302 above 1,000 °C 551 454 2980.01664 above 1,100 °C 431 355 233 0.01933 at 1,170 °C 371 306 201 0.01084 above 900 °C 662 545 3580.80 0.01192 above 1,000 °C 602 496 3250.01489 above 1,100 °C 482 397 261 0.01700 at 1,170 °C 422 348 228

[0283] During a carbothermic reduction of a metal or elemental ore or concentrate (e.g. iron ore), the weight of the ore or concentrate decreases over time as oxygen atoms are removed in the form of CO or CO2 gas. The ‘rate of oxygen reduction’, as used herein, is the weight percent (wt%) loss in the ore or concentrate (e.g. iron ore) when the produced metal or element (e.g. purified iron) achieves 90% metallization, divided by the time required to achieve 90% metallization at or above a particular temperature, for example above 900 °C, above 1,000 °C, above 1,100 °C, or at 1,170 °C. That is, the rate ofoxygen removal at a stated temperature is:Wt% loss in the ore at 90% metallisation due to oxygen removalRate of oxygen removal = Time required to achieve 90% metallization at the stated temperatureThe rate of oxygen removal at or above a particular temperature is expressed in units of wt% per °C (wt% / °C).

[0284] The inventors have used the data in Figure 7(a) to correlate the partial pressure of CO and CO₂ maintained within the enclosed or substantially enclosed volume, about the charge, during the operational time, with other characteristics of the above system.

[0285] Thus, the second column from the left in Table 2 shows how the partial pressure of CO and CO₂ maintained within the enclosed or substantially enclosed volume, correlates with the average rate of oxygen removal at above 900 °C, above 1,000 °C, above 1,100 °C, and at a reaction temperature of 1,170 °C, in Figure 7(a).

[0286] The third to fourteenth columns from the left in Table 2 show how the partial pressure of CO and CO₂ maintained within the enclosed or substantially enclosed volume, correlates with the time required to achieve 90% metallization above 900 °C, above 1,000 °C, above 1,100 °C, and at the reaction temperature of 1,170 °C from:(third to sixth columns from the left): iron ore fines containing hematite (Fe2O3) with a total Fe content of 61.03% (determined using the standard sample supplied by Independent Mineral Standards and used in the experiments in Figure 6);(seventh to tenth columns from the left): iron ore fines containing magnetite (FC O4) with a total Fe content of 71.5% (Expected times, based on the rate of oxygen removal); and(eleventh to fourteenth columns from the left): iron ore fines containing wüstite (FeO) with a total Fe content of 74% (Expected times, based on the rate of oxygen removal).

[0287] Preferably but not exclusively, the metal or elemental ore is a hematite iron ore or concentrate of 55-60% total iron content, and the operational time at which the hematite iron ore or concentrate of 55-60% total iron content, and the carbon source, are maintained at a reaction temperature of 1,200 °C to produce iron with a metallization of >90%, is equal to or less than 3.5 hours. In other examples, the operational time at which the hematite iron ore or concentrate of 55-60% total iron content, and the carbon source, are maintained at the reaction temperature of 1,200 °C to produce iron with a metallization of >90%, is equal to or less than 3 hours, equal to or less than 2.5 hours, equal to or less than 2 hours, equal to or less than 1.5 hours, equal to or less than 1 hour, equal to or less than 30 min, equal to or less than 20 min, equal to or less than 10 min, or equal to or less than 5 min. In still other examples, the operational time at which the hematite iron ore or concentrate of 55-60% total iron content, and the carbon source, are maintained at the reaction temperature of 1.200 °C to produce iron with a metallization of >90%, is equal to or less than 4 hours, equal to or less than 4.5 hours, equal to or less than 5 hours, equal to or less than 6 hours, equal to or less than 7 hours, equal to or less than 8 hours, equal to or less than 9 hours, equal to or less than 10 hours, equal to or less than 12 hours, equal to or less than 14 hours, equal to or less than 16 hours, equal to or less than 18 hours, equal to or less than 20 hours.

[0288] Preferably but not exclusively, the metal or elemental ore is a hematite iron ore or concentrate of 61 -65 % total iron content, and the operational time at which the hematite iron ore or concentrate of 61-65% total iron content, and the carbon source, are maintained at a reaction temperature of 1,200 °C to produce iron with a metallization of >90%, is equal to or less than 2 hours. In other examples, the operational time at which the hematite iron ore or concentrate of 61-65% total iron content, and the carbon source, are maintained at the reaction temperature of 1,200 °C to produce iron with a metallization of >90%, is equal to or less than 1.9 hours, equal to or less than 1.8 hours, equal to or less than 1.75 hours, equal to or less than 1.5 hours, equal to or less than 1 hour, equal to or less than 30 min, equal to orless than 20 min, equal to or less than 10 min, or equal to or less than 5 min. In still other examples, the operational time at which the hematite iron ore or concentrate of 61-65% total iron content, and the carbon source, are maintained at the reaction temperature of 1,200 °C to produce iron with a metallization of >90%, is equal to or less than 2.5 hours, equal to or less than 3 hours, equal to or less than 3.5 hours, equal to or less than 4 hours, equal to or less than 4.5 hours, equal to or less than 5 hours, equal to or less than 6 hours, equal to or less than 7 hours, equal to or less than 8 hours, equal to or less than 9 hours, equal to or less than 10 hours, equal to or less than 12 hours, equal to or less than 14 hours, equal to or less than 16 hours, equal to or less than 18 hours, equal to or less than 20 hours.

[0289] In further examples, the metal or elemental ore is a magnetite iron ore or concentrate of 66-72% total iron content, and the operational time at which the magnetite iron ore or concentrate, and the carbon source, are maintained at a reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 1.5 hours. In other examples, the operational time at which the magnetite iron ore or concentrate of 66-72% total iron content, and the carbon source, are maintained at the reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 1.25 hours, equal to or less than 1 hour, equal to or less than 45 min, equal to or less than 30 min, equal to or less than 15 min, or equal to or less than 8 min. In still other examples, the operational time at which the magnetite iron ore or concentrate of 66-72% total iron content, and the carbon source, are maintained at the reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 2 hours, equal to or less than 2.5 hours, equal to or less than 3 hours, equal to or less than 3.5 hours, equal to or less than 4 hours, equal to or less than 4.5 hours, equal to or less than 5 hours, equal to or less than 6 hours, equal to or less than 7 hours, equal to or less than 8 hours, equal to or less than 9 hours, equal to or less than 10 hours, equal to or less than 12 hours, equal to or less than 14 hours, equal to or less than 16 hours, equal to or less than 18 hours, equal to or less than 20 hours.

[0290] In other examples, the metal or elemental ore is a wtistite iron ore or concentrate or a concentrate of mill scale or iron scale of 72-74% total iron content, and the operational time at which the wüstite iron ore or concentrate or the concentrate of mill scale or iron scale, and the carbon source, are maintained at a reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 25 minutes. In other examples, the operational time at which the wtistite iron ore or concentrate or the concentrate of mill scaleor iron scale of 72-76% total iron content, and the carbon source, are maintained at the reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 30 minutes, equal to or less than 35 minutes, equal to or less than 40 minutes, equal to or less than 45 minutes, equal to or less than 50 minutes, equal to or less than 55 minutes, equal to or less than 60 minutes, equal to or less than 70 minutes, equal to or less than 80 minutes, equal to or less than 90 minutes, equal to or less than 100 minutes, equal to or less than 110 minutes, equal to or less than 2 hours, equal to or less than 2.25 hours, equal to or less than 2.5 hours, equal to or less than 2.45 hours, equal to or less than 3 hours, equal to or less than 4 hours, or equal to or less than 5 hours. In still other examples, the operational time at which the wüstite iron ore or concentrate or the concentrate of mill scale or iron scale of 72-76% total iron content, and the carbon source, are maintained at the reaction temperature of 1,100 °C to produce iron with a metallization of >90%, is equal to or less than 24 minutes, equal to or less than 23 minutes, equal to or less than 22 minutes, equal to or less than 21 minutes, equal to or less than 20 minutes, equal to or less than 19 minutes, equal to or less than 18 minutes, equal to or less than 17 minutes, equal to or less than 16 minutes, equal to or less than 15 minutes, or equal to or less than 10 minutes.

[0291] Preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.01700 wt% / min at a reaction temperature of 1,170 °C. The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fc^Cfi). and / or wüstite (FeO), or mixtures thereof.

[0292] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.03151 wt% / min at a reaction temperature of 1,170 °C. The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fe3C>4), and / or wüstite (FeO), or mixtures thereof.

[0293] In still other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is more than or equal to 0.05169 wt% / min at a reaction temperature of 1,170 °C. The iron ore or concentrate fines may comprise of, for example, fines containing hematite (Fe2O3), magnetite (Fe3C>4), and / or wüstite (FeO), or mixtures thereof.

[0294] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is less than or equal to 50 wt% / min at a reaction temperature of 1,170 °C.

[0295] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, is less than or equal to 20 wt% / min at a reaction temperature of 1,170 °C.

[0296] In other examples, preferably but not exclusively, the average rate of oxygen removal from iron ore or concentrate fines with a total Fe content higher than 55%, at a reaction temperature of 1,170 °C, is more than or equal to 0.03151 wt% / min, is more than or equal to 0.01933 wt% / min, more than or equal to 0.02229 wt% / min, more than or equal to 0.02617 wt% / min, more than or equal to 0.03151 wt% / min, more than or equal to 0.03930 wt% / min, more than or equal to 0.05169 wt% / min, more than or equal to 0.07449 wt% / min, more than or equal to 0.13032 wt% / min, more than or equal to 0.47846 wt% / min, more than or equal to 1 wt% / min, more than or equal to 1.5 wt % / min, more than or equal to 2 wt% / min, more than or equal to 2.5 wt% / min, more than or equal to 3 wt % / min, or more than or equal to 5 wt% / min.

[0297] These examples provide for tunnel kilns with notable throughputs relative to those used in present day large-scale ironmaking. Accordingly, in an example aspect, there is provided a tunnel kiln for producing iron from fines or lumps of hematite (Fe2O3), magnetite (FesC, wüstite (FeO), or other iron ores or concentrates with a total Fe content higher than 55%, wherein the kiln is capable of an annual production of directly reduced iron, per square metre of the cross-sectional area of the tunnel kiln, of more than 15,000 tons.

[0298] In other examples, there is provided a tunnel kiln for producing iron from fines or lumps of hematite (Fe2O3), magnetite (Fe3C>4), wüstite (FeO), or other iron ores or concentrates with a total Fe content higher than 55%, wherein the kiln is capable of an annual production of directly reduced iron, per square metre of the cross-sectional area of the tunnel kiln, of more than 16,000 tons, more than 17,000 tons, more than 18,000 tons, more than 19,000 tons, more than 20,000 tons, more than 21,000 tons, more than 22,000 tons, more than 25,000 tons, more than 30,000 tons, more than 40,000 tons, or more than 50,000 tons.

[0299] In an example aspect, there is provided a method for producing a metal or an element from a metal ore or elemental ore using a carbothermic reaction, the method comprising the steps of: placing lumps and / or fines of a metal ore or elemental ore and a carbon source within at least one container inside a high temperature furnace, wherein the high temperature furnace comprises a volume utilization factor of greater than 10%; maintaining the metal ore or elemental ore and the carbon source within the container at a reaction temperature for an operational time, to thereby induce the carbothermic reaction that produces the metal or element from the metal ore or elemental ore; and cooling and retrieving the produced metal or element.

[0300] In another example aspect, there is provided an apparatus for producing a metal or element from a metal or elemental ore, the apparatus comprising: a high temperature furnace comprising, an enclosed volume or a substantially enclosed volume surrounding a metal or elemental ore and a carbon source; the enclosed volume or substantially enclosed volume allowing for regulation of a gaseous atmosphere surrounding the metal or elemental ore and the carbon source; wherein the high temperature furnace is configured to maintain the metal or elemental ore and the carbon source for an operational time at a reaction temperature.

[0301] In another example aspect, there is provided method for producing a metal or an element from a metal or elemental ore by a ‘non-contact’ carbothermic reaction, the method comprising the steps of: placing the metal or elemental ore and a carbon source within an enclosed volume or a substantially enclosed volume inside a high temperature furnace, wherein the enclosed volume or substantially enclosed volume maintains a regulated gaseous atmosphere surrounding the metal or elemental ore and the carbon source; maintaining the metal or elemental ore and the carbon source within the enclosed volume or substantially enclosed volume for an operational time at a reaction temperature, to thereby induce the carbothermic reaction that produces the metal or element from the metal or elemental ore; and cooling and retrieving the produced metal or element.

[0302] Preferably but not exclusively, the carbothermic reaction has a high driving force, for example, as may be created by a self-accelerating reaction process, such as but not limited to an autocatalytic process, so that reduction of the metal or elemental ore or concentrate, toits corresponding metal or element is rapid even when the carbon source is well separated from the metal or elemental ore or concentrate.

[0303] Preferably but not exclusively, the energy consumption required to produce the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 80% of the energy required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore or concentrate.

[0304] In other examples, preferably but not exclusively, the energy consumption required to produce the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, less than 50%, less than 45%, or less than 40% of the energy required in the equivalent present-day industrial process to produce the metal or element from its corresponding metal or elemental ore.

[0305] In other examples, preferably but not exclusively, the energy provided by direct combustion (burning) of carbon in the production of the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 1% of the energy consumption. In other examples, the energy provided by direct combustion of carbon in the production of the purified metal or element from its corresponding metal or elemental ore or concentrate, is less than 0.9% of the energy consumption, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, less than 0.1%, less than 0.09%, less than 0.08%, less than 0.07%, less than 0.06%, less than 0.05%, or less than 0.04% of the energy consumption of the process.Preferred containers, lids, shapes, arrangements, and ratios

[0306] In an example aspect, there is provided a container for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the container comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the container, including the metal ore or concentrate or elemental ore or concentrate, and the carbon source, is configured to be: maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, release excess internal gaseous pressure, and maintainan absolute internal partial pressure of CO and CO₂ gas, greater than or equal to 0.8 atm, during the operational time at the reaction temperature to thereby produce the metal or element.

[0307] In an example aspect, there is provided a container for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the container comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the container, including the metal ore or concentrate or elemental ore or concentrate, and the carbon source, is configured to be: maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, release excess internal gaseous pressure, and maintain a gauge internal partial pressure of CO and CO₂ gas, greater than or equal to 0.01 atm, during the operational time at the reaction temperature, to thereby produce the metal or element.

[0308] In one aspect, the container is configured to regulate a gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source, for example the gaseous atmosphere of CO and CO2 that may be produced within it during heating to the reaction temperature or maintaining the reaction temperature for the operational time. Preferably, the gaseous atmosphere is ‘stationary’ or ‘substantially stationary’. In another non-limiting aspect, the container is a closed container that is capable of releasing excess internal gas and maintaining a preferred internal gas pressure. In another non -limiting aspect, the container is a substantially closed container capable of releasing excess internal gas and maintaining a preferred internal gas pressure. In another non-limiting aspect, the container is at least partially covered. In another non-limiting aspect, the container is fully covered.

[0309] A gas body, such as the dynamic body of hot CO and CO₂ gas inside the closed or substantially closed container, may herein be said to be ‘stationary’ or ‘substantially stationary’ if it is formed and used in the same location, and thereby avoids energy losses associated with the transport of hot gases from one site to another, for example from the site of their formation or origin to the site of their actual use. Another terminology used herein may refer to such a gas body as being ‘confined’ within a volume, which is preferably an enclosed volume or a substantially enclosed volume (for example, a closed or substantially closed container, such as a crucible covered with a lid).

[0310] In another non-limiting aspect, the container is configured to ‘confine’ the metal or elemental ore or concentrate, the carbon source and the gaseous atmosphere surrounding the metal or elemental ore or concentrate, and the carbon source. Preferably, the gaseous atmosphere is ‘confined’ (but, nevertheless, able to be released by the container to maintain a preferred internal gas pressure, for example a preferred internal partial pressure of CO and CO₂, in the container). In another non-limiting aspect, the container provides a ‘confined volume’ or a ‘substantially confined volume’. In another non-limiting aspect, the container is a closed container. In another non-limiting aspect, the container is a substantially closed container. In another non-limiting aspect, the container is at least partially covered. In another non-limiting aspect, the container is fully covered. In another aspect, the container provides a confined or substantially confined volume including a seal which is substantially gas tight wherein a seal, for example a mechanical seal, prevents the gaseous atmosphere from escaping the enclosed volume of the container.

[0311] Preferably but not exclusively, the container providing an enclosed volume or substantially enclosed volume, is in the form of a crucible covered with a lid. Preferably but not exclusively, the lid is capable of transiently and reversibly opening to release excess gas and maintain a preferred internal partial pressure of CO and CO₂ within the enclosed volume or a substantially enclosed volume. Preferably but not exclusively, the lid is fabricated to form a tight seal with the crucible when it is closed, providing for the maintenance of the preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0312] Preferably but not exclusively, the lid has a high mass or weight to thereby provide an improved seal with the crucible and allow for the maintenance of a high partial pressure of the CO and CO2 gas within the enclosed volume or substantially enclosed volume.

[0313] The gaseous pressure that may be created and maintained inside a container by the mass or weight of a well-sealing lid upon that container, wherein the lid may transiently and reversibly move upwards to release excess internal gas, is essentially governed by the pneumatic force formula:P = F / A …(11)where P is the pressure (in units of: Pa) inside the container, F is the force created by the weight of the lid (in units of: N), and A is the area of the container that the lid covers (in units of: m2).

[0314] The force created by the mass and weight of a lid due to gravity is given by the formula for gravitational force:Fgrav = m X g •••(12)where Fgrav is the force due to gravity (in units of: N), m is the mass of the object (in units of: kg), and g is gravitational acceleration, which is around 9.8 m / s2, but varies depending on geographic location, and is taken herein as -9.82469 m / s2.

[0315] Accordingly, by combining equations (11) and (12), the gaseous pressure, P, that may be created and maintained inside a container by the weight of a well-sealing lid upon that container, wherein the lid may transiently and reversibly move upwards to release excess internal gas, is essentially:P = (9.82469 x m) / A...(13)

[0316] This formula is, effectively, that of a dead weight pressure relief valve. A dead weight pressure relief valve functions by balancing the internal pressure against a fixed external weight. The internal pressure, P, is the threshold pressure at which the valve opens. The valve remains closed, with the weight resting on and sealing its seat, as long as the upward pressure force is less than the downward gravity force. If the upward pressure force exceeds the downward gravity force, the valve opens to release the excess pressure. Once the excess pressure has been released, the weight moves back down onto its seat, closing the valve.

[0317] A simple analysis using the above formula reveals that the higher the mass of the lid and the smaller the area that is covered by the lid, the higher is the gas pressure that may be maintained inside the container. That is, the pressure that can be maintained in a container covered with a lid, for example, a crucible covered with a lid, wherein the lid may transiently and reversibly move or deflect upwards to release excess internal gas, depends on the ratio of the lid mass to the container contact area. The ‘container contact area’ is the area of the mouth of the container, which the lid covers and seals, expressed in square metres (m2). The lid mass is the mass of the lid, expressed in kilograms (kg). The container contact area is,effectively, equivalent to the area of the seat of a dead weight pressure relief valve. In the example wherein the container is a crucible covered with a lid, the container contact area may also be referred to as the ‘crucible contact area’. Preferably but not exclusively, the weight of the lid is calibrated to create and maintain a high or a preferred internal partial pressure of CO and CO₂ within the enclosed volume or substantially enclosed volume formed by the closed or substantially closed container, for example, a crucible covered with a lid.

[0318] Preferably but not exclusively, the ratio of the lid mass to the container contact area is greater than 10 kg / m2. In other examples, the ratio of the lid mass to the container contact area is greater than 25 kg / m2, greater than 50 kg / m2, greater than 100 kg / m2, greater than 150 kg / m2, greater than 200 kg / m2, greater than 250 kg / m2, greater than 300 kg / m2, greater than 400 kg / m2, greater than 500 kg / m2, greater than 750 kg / m2, greater than 1000 kg / m2, greater than 2000 kg / m2, greater than 5000 kg / m2, greater than 7500 kg / m2, greater than 10,000 kg / m2, greater than 15,000 kg / m2, greater than 20,000 kg / m2, greater than 35,000 kg / m2, greater than 50,000 kg / m2, or greater than 90,000 kg / m2. In still other examples, the ratio of the lid mass to the container contact area is greater than 1 kg / m2, greater than 2 kg / m2, greater than 4 kg / m2, greater than 5 kg / m2, greater than 6 kg / m2, greater than 7 kg / m2, greater than 8 kg / m2, or greater than 9 kg / m2.

[0319] Another important feature of a closed or substantially closed container, for example a crucible covered with a lid, is its internal volume. When such a container is fdled or substantially filled with charge (i.e. a ‘charged container’), it is this internal volume (occupied by the charge) that determines the quantity of gas that may be produced within it, for example CO and CO2 that may be produced during a carbothermic reaction. That is, the volume of excess gas produced within a closed or substantially closed container, for example a crucible covered with a lid, may generally be inherently dependent on the internal volume of a container that is filled with charge, for example the internal volume of a crucible covered with a lid.

[0320] Moreover, the extent to which the lid on a container, for example the lid on a crucible, moves upwards or deflects upwards to release excess internal gas pressure, may typically depend on the volume of excess gas produced within a charged container, for example within a crucible. The gap that may form, transiently and reversibly, between the lid and thecontainer, for example a crucible, during such a release of excess internal gas pressure, represents, in effect, an aperture through which the excess gas may flow out of the container, for example a crucible, during their release. The size of such aperture may typically be intrinsically dependent on the length of the perimeter of the container contact area with the lid, for example, the length of the perimeter of a crucible contact area with the lid. The longer such a perimeter length, the smaller the upward movement or deflection of the lid may need to be to release a particular volume of gas. The smallest possible upward movement or deflection by the lid during gas release, may generally be preferred in example embodiments.

[0321] Modelling the flow of gas through such an aperture, which may constitute a rectangular-type or an annulus-type aperture, may typically be exceedingly complex to perform accurately, and well beyond the scope of this specification. However, empirical considerations suggest a range of preferred ratios for the container volume to the perimeter length of the container contact area, for example preferred ratios of a crucible volume to the perimeter length of the crucible contact area.

[0322] In examples, preferably but not exclusively, the ratio of the container volume to the perimeter length of the container contact area, for example the ratio of a crucible volume to the perimeter length of the crucible contact area, is less than 150 litres per meter. In other examples, the ratio of the container volume to the perimeter length of the container contact area, for example the ratio of a crucible volume to the perimeter length of the crucible contact area, is less than 140 litres per meter, less than 130 litres per meter, less than 120 litres per meter, less than 110 litres per meter, less than 100 litres per meter, less than 90 litres per meter, less than 80 litres per meter, less than 70 litres per meter, less than 60 litres per meter, less than 50 litres per meter, less than 40 litres per meter, less than 30 litres per meter, less than 20 litres per meter, less than 10 litres per meter, less than 5 litres per meter, less than 4 litres per meter, less than 3 litres per meter, less than 2 litres per meter, less than 1 litre per meter, less than 0.8 litres per meter, less than 0.6 litres per meter, less than 0.4 litres per meter, or less than 0.1 litres per meter.

[0323] It can be seen that the combination of the above ratios, namely, the ratio of the lid mass to the container (e.g. crucible) contact area, and the ratio of the container (e.g. crucible) volume to the perimeter length of the container (e.g. crucible) contact area, favour smaller and narrower containers (e.g. crucibles), covered with heavy lids. That is, the combinationof the above ratios favour containers (e.g. crucibles) with smaller container (e.g. crucible) volumes, and smaller container (e.g. crucible) contact areas, covered with heavy lids. That is, higher internal gas pressures may be created and maintained inside containers (e.g. crucibles) with smaller volumes and smaller contact areas covered with heavier lids, than inside larger containers (e.g. crucibles) having larger container (e.g. crucible) volumes and larger container (e.g. crucible) contact areas, not covered by a lid. As noted above, such higher internal gas pressures, for example of CO and CO2 internal partial pressures, provide for more rapid and more complete conversion of a metal or elemental ore or concentrate into its corresponding metal or element when maintained at a recation temperature for an operational time. The greater the internal partial pressure of CO and CO₂ that can be maintained inside the container (e.g. crucible), the more effectively a self-accelerating carbothermic chain reaction may be harnessed to accelerate the overall reaction and provide higher metallisation or elemental percentages in a shorter time.

[0324] These findings stand in direct opposition to the very large container volumes and container contact areas, typically using very poorly sealed containers, without lids that are currently used in, for example, tunnel kiln ironmaking, as described in the Background section. Indeed, these findings explain that it is the use of such ill-sealed and poorly configured containers that create the long firing and processing times needed, and therefore also result in the need for excessively long tunnel kilns. The long firing and processing times are the fundamental cause of their low throughputs - i.e. their low production rates per unit time - that create their high costs and high energy consumptions, which limit such tunnel kiln ironmaking to low-volume, high-cost, niche production. The long firing and processing times can also be said to essentially limit large-scale tunnel kiln ironmaking of the type described in the Background section, to the use of partially pre-reduced reactants configured in elaborately optimised forms. For example, such large-scale tunnel kiln ironmaking is mostly limited to reduction of partially pre-reduced reactants like enriched mill scale, iron and steel plant wastes, or magnetite ores, rather than the more commonly available but less enriched hematite ores. Moreover, such partially pre-reduced reactants must typically also be configured in elaborately optimised forms, for example, in the form of highly engineered and processed pellets or agglomerations with carefully controlled porosities and gas permeation properties, to be reduced to a high degree in such large-scale tunnel kiln ironmaking. Hematite ores in lump form, as may be directly obtained from mining- Ill -operations, may generally be too poorly enriched, and too dense in its porosity and gas permeation properties, to be viably reduced to a high degree.

[0325] These findings teach that the containers used in, for example, the large-scale tunnel kiln ironmaking described in the Background section, should be configured to smaller and narrower sizes, that are far better sealed, and that are fitted with well sealing, heavier lids, to thereby provide for higher internal partial pressures of CO and CO₂. Such higher internal partial pressures of CO and CO₂ may allow for more rapid and more complete carbothermic reaction via a self-accelerated reaction mechanism. That is, more containers, each of smaller dimensions, are taught to be used, per unit production rate.

[0326] Accordingly, preferably but not exclusively, there is provided multiple enclosed or substantially enclosed containers capable of releasing excess gas pressure and maintaining a preferred internal gas pressure, for example of CO and CO₂. Preferably but not exclusively, each container providing an enclosed volume or substantially enclosed volume, is in the form of a crucible covered with a lid. In examples, each such container, for example a crucible with a lid, may, effectively, act as dead weight pressure relief valve wherein the lid transiently and reversibly opens to release excess gas and maintain a preferred internal gas partial pressure of CO and CO₂ within the enclosed volume or a substantially enclosed volume.

[0327] In example embodiments, preferably but not exclusively, the closed or substantially closed container has a rectangular shape. In other examples, preferably but not exclusively, the closed or substantially closed container has a square shape. In still other examples, preferably but not exclusively, the closed or substantially closed container has the shape of a cylinder.

[0328] In other examples, the container, for example a crucible, has the shape of a long, flat receptacle, for example a trough, cube, box, tray, or channel, to thereby, when covered with its lid, provide for the maintenance of a high internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume. In other examples, the container and its lid, for example a crucible and lid, is stacked with other closed or substantially closed containers and their lids, for example crucibles and their lids, on top of each other, during heating and / or whilst being brought up to the reaction temperature ormaintained at the reaction temperature for the operational time in the high temperature furnace, to thereby increase the weights on the lids at the bottom of each stack1and provide for the maintenance of a high internal partial pressure of the CO and CO₂ within the enclosed volume or substantially enclosed volume.

[0329] In example embodiments, multiple closed or substantially closed charged containers, for examples crucibles with lids, are stacked next to each other, and / or on top of each other in arrays. Preferably but not exclusively, such arrays are maintained at the reaction temperature for the operational time. Preferably but not exclusively, multiple charged containers closed or substantially closed with lids, for examples crucibles with lids, are stacked on top of each other to thereby increase the weight on the lids nearer the bottom of each stack1allowing for the maintenance of a higher partial pressure of the carbonaceous gases inside.

[0330] Figure 8 depicts, on its left-hand side, an example 2-D array 600 of the type described above, wherein the array comprises of twelve crucibles 610 arranged in six rows of two crucibles 610 each. The array is held in place by a metal or ceramic lattice work 620, which guides the location of, and holds the crucibles 610 in place, but may not be affixed to any of the crucibles 610. Each crucible 610 may be affixed to a ceramic base 630, which may act as a lid for a similar array placed below it. The metal lattice work 620 may also not be affixed to the individual ceramic bases 630.

[0331] The right-hand side of Figure 8 depicts a 3-D array 640 of the type described above, wherein individual crucibles 610 and their lids 630 are stacked on top of each other to thereby increase the weight on the lids toward the bottom of each stack1and thereby allow for the maintenance of a higher partial pressure of the carbonaceous gases inside the crucibles toward the bottom of the stack. A set of extra heavy lids 650 (not shown in Figure 8) may be placed on the top of the crucibles 610 in the uppermost row of the 3-D stack 640, to thereby close them.

[0332] It is to be understood that the precise nature of preferred arrangements like those described above, may remain subject to the efficiency with which the individual containers (e.g. crucibles) may conduct the applied heat and transmit it to the charge within, to thereby heat the charge to, and maintain it at the reaction temperature for the operational time, in thespecific high temperature furnace used. The speed with which the charge in a closed or substantially closed container (e.g. a crucible covered with a lid) may be brought up to the operating temperature and maintained there, may supersede many of the other considerations when it comes to the minimising the overall energy consumption of the process.

[0333] That is, the precise arrangement of multiple crucibles enclosed with lids, including their volume, shape, and spatial arrangement with respect to each other, may depend on the specific crucible materials used and their capacity to conduct heat. Preferably but not exclusively, each crucible is highly conductive to heat or has a low heat capacity, for example as may be achieved by a metal or metal alloy crucible, or a ceramic crucible that is highly heat conducting. Such a high conductivity to heat or a low heat capacity in the crucible may allow for more rapid heating of the charge within, thereby, either: (i) decreasing the reaction time at the operational temperature, or (ii) allowing for an unchanged reaction time at a lower operational temperature, in the high temperature furnace. Such factors may materially influence the overall energy consumption of the process, and this may substantially influence the precise combination of the abovementioned ratios employed. That is, the precise combination of the ratio of the lid mass to the container (e.g. crucible) contact area, and the ratio of the container (e.g. crucible) volume to the perimeter length of the container (e.g. crucible) contact area, may be subject to, and materially dependent upon the capacity of the crucibles in a 2-D or 3-D array of crucibles (and lids) to efficiently take up and transmit the heat that is applied in the high temperature furnace, to the charge within each crucible.

[0334] In another example embodiment, the container is integrally formed as part of the high temperature furnace.

[0335] In another non-limiting aspect, the container, for example a crucible, provides a confined or substantially confined volume including a seal which is substantially gas tight wherein the seal, for example a mechanical seal, prevents the gaseous atmosphere from escaping the enclosed volume of the container, for example a crucible. In respect of achieving an optimum mechanical seal, preferably but not exclusively, the lid surface is fabricated to match, for example, to conform to, or mate to the surface of the crucible, for example via low surface roughness, that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0336] There is no single "plug-and-play" formula to calculate the internal pressure limit of a mechanical seal based on its surface roughness and spring force. In mechanical seal design, the pressure a seal can withstand may be determined by balancing the Closing Forces (trying to keep the seal shut) against the Opening Forces (trying to push the seal faces apart). This is known as the Force Balance method. Example 5 describes a step-by-step calculation framework used herein for such a determination. Such calculations may be used to design and fabricate efficient and reliable seals between lids and their containers, for example lids and their crucibles. All references in this specification to the pressure that can be maintained by a mechanical seal refer to the pressure as determined by the Force Balance method.

[0337] In further example aspects, preferably but not exclusively, the lid or the mouth of the container incorporates a lip, or lips, or has a lid design or a container mouth design, for example an inverted top hat lid design, that allows for an improved seal, which provides for the maintenance of a preferred internal partial pressure of the CO and CO₂ gas within the enclosed volume or substantially enclosed volume. Such designs may also provide for and guide larger upward deflections or movements of the lid during the periods that they transiently and reversibly release excess gas pressures, as well as guide the lid back down and ensure it seats properly on the crucible mouth after the excess gas has been released.

[0338] For example, Figure 9(a) schematically depicts, in cross-section, how a lid comprising an inverted top hat design may seal a container with a lip at its mouth, for example a crucible with a lip at its mouth. Figure 9(a) also illustrates how such an arrangement may provide for relatively large upward deflections or movements of the lid during the periods that it transiently and reversibly releases excess gas pressures, as well as guide the lid back down to correctly seat on the mouth of the crucible. As shown in the left-hand schematic in Figure 9(a), a lid-covered container 700 has a mouth 710 fitted with lips 711, that accommodate a lid 720 having the structure of an inverted top hat. The container 700 is filled with a gas 730 that is confined within the container 700 by the seal created at 712 between the lid 720 and the lips 711. Such a seal 712 may be a mechanical seal created by a structural match of the surface of the lid 720 that, for example, conformsto, or mates to, the surface of the crucible lip 711, for example via low surface roughness on each surface.

[0339] The right-hand schematic in Figure 9(a) shows how the lid 720 may act as a dead weight pressure relief valve that transiently and reversibly releases excess gas pressure if the pressure of the gas 730 in the container 700 comes to exceed a threshold pressure. If the pressure of gas 730 inside the container 700 exceeds the threshold pressure, it provides sufficient upward force to overcome the downward gravitational force created by the mass of the lid 720, thereby causing the lid 720 to move or deflect upwards as shown in the right-hand schematic in Figure 9(a). In so doing, an aperture 740 opens between the lid 720 and the lip 711 of the container 700. Gas 730 may then flow out of the aperture 740 as shown at 730a, thereby reducing the pressure of the gas 730 inside the container 700. The greater the initial internal pressure of the gas 730 inside the container 700, the higher the lid 720 may move, and the larger the aperture 740 may become, thereby releasing a larger the volume of gas through aperture 740. As a result of the gas release, the pressure of the gas 730 inside the container 700 may then decline, causing it to provide less upward force, thereby resulting in the lid 720 moving downwards, narrowing the aperture 740. This continues until the downward gravitational force created by the mass of the lid 720 overcomes the upward force of gas 730 inside the container, at which point the lid 720 re-seats itself on the lips 711, re-creating the seal 712 shown in the left-hand schematic in Figure 9(a), and confining the gas 730 inside the container 700. The pressure of the gas 730 inside the container may then be the threshold pressure or slightly less.

[0340] In another example aspect, there is provided an orifice, such as a tiny aperture, pinhole, opening, or slit, within the lid or within a wall of the container, wherein the orifice has been deliberately sized to maintain a preferred gaseous partial pressure of CO and CO₂ inside the enclosed or substantially enclosed container during heating up to and at the reaction temperature for the operational time. That is, such an orifice may allow the release of excess gas pressure within the container whilst still maintaining a preferred gaseous partial pressure of CO and CO₂ inside the enclosed or substantially enclosed container during heating up to and at the reaction temperature for the operational time. The use of such an orifice may necessitate the use of an oxygen-free atmosphere outside of the container, inside of the tunnel kiln.

[0341] That is, in another example aspect, the container and lid, for example a crucible and lid is, preferably but not exclusively, provided in the form of a pressure vessel that incorporates an externally venting, high-temperature-capable, pressure relief valve (PRV), which provides for the maintenance of a high, including a very high, internal partial pressure of the CO and CO₂ within the enclosed volume or substantially enclosed volume. A pressure relief valve (PRV) is a type of safety valve used to control and / or limit the pressure in a system. Valves of this type are routinely available commercially and may be used to maintain a preferred gas pressure, for example a preferred partial pressure of CO and CO₂, inside an enclosed or substantially enclosed container, for example a crucible and lid.

[0342] Figure 9(b) schematically depicts an example container and lid, for example a crucible with a lid, fitted with a commercially available or a custom-built pressure relief valve (PRV) capable of high temperature operation. The container 750 is a pressure vessel, being capable of safely holding an internal gas 751, up to a preferred gas pressure (e.g. 15 atm), at a preferred reaction temperature (e.g. 1,200 °C), if it is fully sealed. The container 750, which may be fabricated of a metal alloy that is dimensionally stable at the preferred reaction temperature (e.g. 1,200 °C), also contains a screw thread 751 around the outside of its mouth. There is further provided a pressure- and temperature-capable lid 760, fabricated of the same metal alloy, that can also safely accommodate up to the preferred gas pressure (e.g. 15 atm), at the preferred reaction temperature (e.g. 1,200 °C) if it is fully sealed. The lid 760 is designed to fit over the open mouth of the container 750, and incorporates a complementary screw thread 761 that allows it to be screwed onto the top of the container 750. The lid also incorporates an outlet to a commercially available pressure relief valve (PRV) 770 that is designed to open at the preferred gas pressure (e.g. 15 atm), at the preferred reaction temperature (e.g. 1,200 °C). When the lid 760 is screwed onto the container 750 as depicted in Figure 9(b), the combination of the container 750 and the closed lid 760, constitutes a pressure vessel that can safely accommodate the preferred internal gas pressure (e.g. 15 atm) at the preferred reaction temperature (e.g. 1,200 °C). If the container 750 is filled with a charge, with the lid 760 thereafter screwed onto the container 750 as shown in Figure 9(b), the enclosed volume may serve to confine CO and CO₂ that may be produced in a carbothermic self-accelerating reaction at the preferred reaction temperature. The pressure relief valve 770 may then release excess internal gas pressure and maintain the preferred partial pressures of CO and CO₂ (e.g. 15 atm) within the overall pressure vessel formed by the container 750 and the closed lid 760.

[0343] In this way, it may be possible to realise much higher cumulative partial pressures of CO and CO₂ within a container, during a self-accelerating carbothermic reaction, than can otherwise be achieved. As noted earlier, the higher the cumulative partial pressures of CO and CO₂ that can be maintained in the container, the more accelerated the reduction reaction will become, as it amplifies the feedback loop (i.e. the chain reaction) that occurs in a selfaccelerating process.

[0344] It is to be understood that the use of a screw connection as a means of assembling the pressure vessel in the above example, is purely illustrative and not limiting to the scope of any of the processes, apparatuses, or methods described herein. Any and all means of assembling containers into pressure vessels are explicitly incorporated and included in the processes, apparatuses, or methods described herein.

[0345] Accordingly, in another example aspect, there is provided a pressure vessel for producing a metal or element from a metal ore or concentrate or an elemental ore or concentrate, the pressure vessel comprising: an enclosed volume or a substantially enclosed volume configured to receive lumps and / or fines of a metal ore or concentrate or an elemental ore or concentrate, and a carbon source; wherein the pressure vessel is configured to: seal hermetically, be maintained at a reaction temperature in the range 500-2,000 °C, for an operational time, incorporate a pressure relief valve (PRV) capable of releasing excess internal gaseous pressure above a threshold pressure at the reaction temperature, and maintain a high absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature to thereby produce the metal or element.

[0346] Preferably but not exclusively, the pressure vessel and incorporated pressure relief valve, maintains an absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature, of more than or equal to 1.0 atm. In other examples, the pressure vessel and incorporated pressure relief valve, maintains an absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature, of more than or equal to 1.1 atm, of more than or equal to 1.2 atm, of more than or equal to 1.3 atm, of more than or equal to 1.4 atm of more than or equal to 1.5 atm, of more than or equal to 1.6 atm, of more than or equal to 1.7 atm, of more than or equal to 1.8 atm, of more than or equal to 1.9 atm, of more than or equal to 2 atm, of more than or equalto 2.5 atm, of more than or equal to 3 atm, of more than or equal to 3.5 atm, of more than or equal to 4 atm, of more than or equal to 4.5 atm, of more than or equal to 5 atm, of more than or equal to 6 atm, of more than or equal to 7 atm, of more than or equal to 8 atm, of more than or equal to 9 atm, of more than or equal to 10 atm, of more than or equal to 12 atm, of more than or equal to 15 atm, of more than or equal to 20 atm, or of more than or equal to 50 atm.

[0347] In another example embodiment, Figure 9(c) schematically depicts an example container 780 and lid 790, for example a crucible with a lid, wherein the container 780 is filled with a charge 781, and the lid 790 fits within the mouth of the container 780. A lid that fits within the mouth of a container is herein termed an ‘internal lid’. The internal lid 790 forms a seal 782 with the container 780. The internal lid 790 may rest upon the charge 781. The seal 782 may comprise a mechanical seal between the internal lid 790 and the mouth of the container 780. The internal lid 790 may move up and down, within the mouth of the container 780, whilst maintaining the seal 782. The seal 782 may comprise a tight tolerance between the internal lid 790 and the container 780; that is, the seal may comprise a very small gap between the container 780 and the internal lid 790. In other examples, the seal 782 may comprise of a physical aperture 780 between the container 780 and the internal lid 790. The size of the aperture 782 may be designed to maintain a preferred gaseous partial pressure of CO and CO₂ about the charge 781 inside the container 780.

[0348] In other example aspects, preferably but not exclusively, an intermediary material, such as, but not limited to a ceramic cloth, ceramic paper, ceramic felt, or cord seal, may be incorporated between the lid surface and the surface of the container, for example a crucible, allowing for an improved seal that provides for the maintenance of a preferred internal partial pressure of the CO and CO2 within the enclosed volume or substantially enclosed volume.

[0349] In other examples, the crucible and its lid, filled with its charge, is tightly, densely, compactly, or closely packed with other crucibles and their lids, filled with their charge, whilst being brought up to, or maintained at the reaction temperature for the operational time to thereby increase the quantity of metal or element produced in a single run.Other modes of operation and utility

[0350] In other example aspects, the technology described herein, as applied in atunnel kiln, may have applications in, but not limited to: the direct reduction of chromite in the manufacture of cheaper ferrochromium (chromite may be reduced with the help of calcium chloride to produce ferrochrome alloy powders with high metal recovery); the direct production of stainless steel from highly reduced chromite; the direct reduction of manganese in the manufacture of cheaper ferromanganese; the production of crude ferrosilicon; the direct reduction of iron ore fines (especially hematite or magnetite fines) that could then be charged to a blast furnace; the direct reduction of in-plant waste oxide materials for recycling, adding to plant productivity; the nitriding of titanium bearing slags and minerals for the recovery of TiO₂: the reduction of sulphates (e.g. precipitated barium sulphate); the formation of Mn₇C₃; the oxidation of the FeO present in chrome spinel to Fe-sequioxide (Fe₂O₃); the reduction of FeO to Fc? C (iron carbides) at low temperatures.

[0351] In other example aspects, the technology described herein, as applied in atunnel kiln, may have advantages that include, but are not limited to: an ability to directly process fine particulates, allowing use of ore fines generated during mining; an ability to directly process lump particulates, allowing use of ore lumps generated during mining; an ability to handle materials that soften and become sticky under high temperature processing; a capacity to use coal as the carbon source to thereby reduce or eliminate coke requirements; a prospective capacity to reduce the electricity requirement for smelting of charge chrome in ferrochromium production (below 3400 to 2400 kWh / t); be more economical than alternatives, especially when using low grade minerals such as UG2 discards from the platinum industry, where high metal recoveries are essential to produce a product of acceptable quality; to reduces CO₂ emissions for ferrochromium by about 20% per ton of liquid metal; achieve higher metal recoveries than alternative technologies; to avoid the need for hot briquetting when reducing iron ore fines; to avoid the need for pellets that have been pre-indurated at 1100 to 1 350°C to have sufficient strength for handling and processing during reduction (‘Induration’ means hardening; it requires additional energy and adds an cost to the production of directly reduced iron).FURTHER EXAMPLES

[0352] The following examples provide a more detailed description of particular embodiments. The examples are intended to be merely illustrative and not limiting to the scope of the present invention.Example 1: Example procedures to reduce a metal ore or concentrate, or an elemental ore or concentrate, to its corresponding metal or element, within at least one lidded crucibleExample la: Example procedure in which the carbon source is separate from the metal ore or concentrate (‘Non-contact’ procedure)

[0353] Referring again to Figure 1: container 10 is in the example form of a crucible, comprising a heat-resistant ceramic material, such as, but not limited to, an alumina crucible. Container 10 receives, by being loaded with, carbon source 20, such as, but not limited to, activated carbon to about one-third of its height. A ceramic separator 30 may optionally then be placed on top of the activated carbon or synthetic graphite. Thereafter, the upper volume of the container 10 receives, by being loaded with, lumps or fines of the metal or elemental ore or concentrate 40, in this example being iron ore or concentrate in the form of lumps or fines. The lumps and fines may comprise mostly of hematite (Fe2O3), for example 58% (total Fe content) hematite ore from the Pilbara region of Western Australia. The iron ore or concentrate 40 is not pelletized. In other variants, the carbon source 20 and the metal or elemental ore or concentrate 40 may be separate in the sense that they are layered one on the other, and thereby touch each other at an interface between them. In still other variants, the metal or elemental ore or concentrate 40 is completely separate from the carbon source 20 with no contact whatsoever between them. The filled container 10 then has the lid 50 placed upon it. The lid 50 forms a tight seal with the crucible 10 when it is closed. Preferably but not exclusively, the lid 50 may be designed and configured to be capable of transiently and reversibly opening to release excess internal gas pressure and maintain a preferred internal gas pressure within the crucible 10 during heating. For example, the weight ofthe lid 50 may be calibrated to provide and maintain an elevated gas pressure within the crucible 10. In other embodiments not depicted in Figure 1, the lid 50 or the crucible 10 may incorporate a high-temperature pressure release valve or other means of releasing excess gas pressure whilst maintaining a preferred elevated internal gas pressure within crucible 10. The filled container with lid 60 is then transported to the high temperature furnace 70, in this example being atunnel kiln, which is schematically depicted in cross-section in Figure 2. The tunnel kiln includes a train of connected refractory carts that roll through it on a railway line, to thereby, effectively, form a ‘moving belt’, which is depicted schematically as 90 in Figure 2. In another example, a plurality of containers can be provided as part of the high temperature furnace, for example being integrated with a moving section of the high temperature furnace. In some examples the tunnel kiln is an industrial tunnel kiln used commercially to produce ceramic sanitaryware, kitchenware, or other commercial products of this type. In one example, the tunnel kiln has a length of around 60 metres or more.

[0354] Referring again to Figure 2, the high temperature furnace 70, in this example being a tunnel kiln, is equipped with refractory walls 80 for keeping the heat inside the tunnel kiln, and the moving belt 90 capable of withstanding the high temperatures in the tunnel kiln. The tunnel kiln is further equipped with a loading (or ‘pre-heating’) zone 91, within which fdled containers 60a may be loaded onto the moving belt 90 prior to entering the tunnel kiln, a kiln heating (or ‘reaction’) zone 92, in which fdled containers 60b on the moving belt 90 are heated to 1,100 °C while passing through the kiln heating zone 92, and a cooling zone 93, in which the fdled containers 60c on the moving belt 90 are allowed to cool, prior to their removal from the tunnel kiln. The high-temperature furnace 70 has a volume utilization factor, for example greater than 10%; that is more than 10% of the furnace’s internal, heated volume is occupied by the metal or elemental ore or concentrate 40 and the carbon source 20 (inside the container or containers 60b). After removal from the tunnel kiln, the fdled containers 60d have their lids 50 removed, revealing the formation of a briquette of purified iron 99 (also referred to as ‘Direct Reduced Iron’, or ‘DRF, 99), which has taken the shape of the container 60d or a portion thereof, albeit somewhat shrunken away from perfect structural complementarity with the shape of the container 60d. The briquette 99 may be sufficiently dense that it is suitable for safe storage and transport. The speed of the moving belt 90 is set to ensure that the transit time of the filled containers 60b within the heating zone 92 match the operational time. The temperature of the heating zone is set to the reaction temperature.Example lb: Example procedure in which the carbon source is mixed with the metal ore or concentrate

[0355] In another example, the carbon source 20 and the metal or elemental ore 40 are physically mixed together. The crucible 10 is then filled with this mixture of the carbon source 20 and the metal or elemental ore 40, and the reduction is carried out in precisely the same way as described in Example la. That is, the identical procedure to that described in Example la is carried out except there is no separation of the carbon source 20 and the metal or elemental ore 40 within the crucible 10, as described in Example la or depicted in Figure 1.Example 2: Example ‘non-contact’ procedure to reduce a metal ore or concentrate, or an elemental ore or concentrate, to its corresponding metal or element, within an enclosed container inside the high temperature furnace

[0356] Referring to Figure 3: the high temperature furnace, in this example being a controlled atmosphere belt furnace or controlled atmosphere tunnel kiln 100, includes a container 120 (providing an enclosed...

Claims

CLAIMS1. A container for use in a method of producing a metal or element from a metal ore or an elemental ore, the container comprising an enclosed volume or substantially enclosed volume for receiving lumps and / or fines of a metal ore, or an elemental ore and a carbon source, wherein the container is configured to form a part of or be removably placed within the high temperature furnace, the high temperature furnace configured to maintain the metal ore, or elemental ore, and the carbon source at a reaction temperature for an operational time to produce the metal or element; wherein the container is configured to maintain a gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time.

2. The container of claim 1, wherein the container maintains the gaseous atmosphere by maintaining a partial pressure of CO and CO₂ in the gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume during the operational time.

3. The container of claim 1 or claim 2, wherein the container comprises an enclosed volume for receiving the metal ore or elemental ore and a carbon source and wherein the enclosed volume is defined by a container portion and a lid.

4. The container of claim 3, wherein the container is in the form of a pressure vessel.

5. The container of claim 3 or claim 4, wherein the container includes a seal between the lid and the container portion which is substantially gas tight wherein the seal prevents the gaseous atmosphere from escaping the enclosed volume during the operational time.

6. The container of claim 5, wherein the seal is a hermetic seal.

7. The container of any one of claims 3 to 6, wherein the container further includes a high temperature pressure relief valve in communication with the enclosed volume and the exterior of the container wherein the high-temperature pressure relief valve assists with maintaining the gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume.

8. The container of claim 7, wherein the high temperature pressure relief valve maintains an absolute internal partial pressure of CO and CO₂ gas, during the operational time at the reaction temperature, of more than or equal to 0.8 atm.

9. The container of claim 1 or 2, wherein the container maintains the gaseous atmosphere by maintaining a preferred gas pressure in the gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source within the enclosed or substantially enclosed volume whereby the container is configured to release excess internal gas during the operational time.

10. The container of claim 9, wherein the container is in the form of a crucible including a container portion covered with a lid.

11. The container of claim 10, wherein the weight of the lid of the crucible is configured to assist with maintaining the preferred gas pressure in the gaseous atmosphere.

12. The container of claim 10 or claim 11, wherein excess internal gas is released between the container portion and the lid to assist with maintaining the preferred gas pressure in the gaseous atmosphere surrounding the metal ore, or elemental ore and the carbon source.

13. The container of any one of claims 10 to 12, wherein the container portion includes a container contact area which makes a seal between the container portion and the lid.

14. The container of claim 13, wherein the ratio of a lid mass to the container contact area is greater than 1 kg / m2.

15. The container of claim 13, wherein the ratio of a lid mass to the container contact area is greater than 10 kg / m2.

16. The container of any one of claims 13 to 15, wherein the ratio of a volume of the container portion to a perimeter length of the container contact area is less than 150 litres per meter.

17. The container of any one of claims 13 to 15, wherein the ratio of a volume of the container portion to a perimeter length of the container contact area is less than 80 litres per meter.

18. The container of any one of claims 9 to 16, wherein the lid is in the form of a dead weight pressure relief valve whereby the lid transiently and reversibly opens to release excess gas and maintain a preferred gas pressure within the enclosed volume.

19. The container of any one of claims 9 to 18, wherein the container portion has a cross sectional shape selected from a square, rectangular or circle.

20. The container of any one of claims 9 to 18, wherein the container portion is in the shape of a trough, cube, box, tray or channel.

21. The container according to any one of claims 9 to 20, wherein one or more further containers may be stacked upon or at the side of the container to provide an array of containers.

22. The container according to claim 21, wherein the weight of a container stacked upon another container assists with maintaining a preferred gas pressure within the enclosed volume within the another container.

23. The container of any one of claims 9 to 22, wherein the shape of the lid is in the form of a disk or an inverted top hat.

24. The container of any one of claims 9 to 23, wherein is shaped to fit within a mouth of the container portion wherein the lid is internal to the container portion.

25. The container of any one of claims 9 to 24, wherein one or more lips is located on either the lid or the container portion which assists with making a seal between the lid and the container portion.

26. The container of claim 25 wherein the one or more lips located on either the lid of the container portion is associated with a structurally complementary seat on the other of thelid or the container portion wherein the seat assists with making the seal between the lid and the container portion.

27. The container of claim 26, wherein a low surface roughness is located on either or both of the lip and / or the seat which assists with making a seal between the lid and the container portion.

28. The container of any one of claims 9 to 27, wherein an intermediary material is located between the lid and the container portion which assists with making a seal between the lid and the container portion.

29. The container of claim 28 wherein the intermediary material is selected from ceramic cloth, ceramic paper, ceramic felt, and cord seal.

30. The container of claims 9 to 29, wherein the container portion and lid are each composed of a refractory material or a high melting point material.

31. The container of claim 30, wherein the refractory material or high melting point material is selected from a material including: porcelain, ceramic, alumina, zirconia, graphite, molybdenum, silicon carbide, clay-graphite, tungsten, quartz, mullite, corderite, stainless steel, and / or high temperature alloys (e.g. Inconel, Hasteloy).

32. The container of any one of claims 2 to 31, wherein the partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume is maintained above about 0.8 atm.

33. The container of any one of claims 2 to 31, wherein the partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume is maintained above about 1.0 atm.

34. The container of any one of claims 2 to 33, wherein the partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume is maintained below about 133.0 atm.

35. The container of any one of claims 2 to 33, wherein the partial pressure of CO and CO₂ within the enclosed or substantially enclosed volume is maintained below about 10.0 atm.

36. The container of any of the proceeding claims, wherein the at least one container is configured to confine the metal ore or elemental ore, the carbon source, and the gaseous atmosphere within the enclosed volume or substantially enclosed volume.

37. The container of any one of the preceding claims, wherein the metal or element is produced from lumps of the metal ore or elemental ore.

38. The container of any one of the preceding claims, wherein the metal ore or elemental ore is in a physical form that is not pelletized.

39. The container of any one of the preceding claims, wherein the metal ore or elemental ore is separate from the carbon source.

40. The container of any one of the preceding claims, wherein the carbon source is a solid- state material selected from the group consisting of: charcoal, activated carbon, coal, carbonaceous material, coke, agricultural residues, rice husks / rice straw / , coconut shells / husks, sugar cane bagasse, any organic fibrous materials, plastics, biomass, tyres, biosolids from wastewater treatment plants, wood, sawdust, or timber items.

41. The container of any one of the preceding claims, wherein the carbon source includes a gaseous carbon source present in the gaseous atmosphere including gas-phase carbon monoxide (CO) and / or gas-phase carbon dioxide (CO2).

42. The container of claim 41, wherein the gaseous carbon source is separated from the metal ore or elemental ore in the enclosed volume of the at least one container by a phase difference.

43. The container of any one of the preceding claims, wherein the produced metal or element is includes but is not limited to one of the following metals or elements, and the metal ore or elemental ore is a mineralogical or chemical composition thereof: iron (Fe), gold (Au), platinum (Pt), silver (Ag), mercury (Hg), rhodium (Rh), iridium (Ir), copper (Cu), palladium (Pd), bismuth (Bi), antimony (Sb), lead (Pb), tungsten (W), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), phosphorus (P), potassium (K), zinc (Zn),chromium (Cr), nobelium (No), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminium (Al), uranium (U), lithium (Li), magnesium (Mg), and calcium (Ca).

44. The container of any one of claims 1 to 43 wherein the metal ore or elemental ore is iron ore and the produced metal is iron.

45. The container of any one of the preceding claims wherein the metal ore or elemental ore is in the form of metal ore concentrate or elemental ore concentrate.

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