Thermal treatment of a material comprising a mineral

Abstract

The present disclosure relates to a method of treating a material comprising a mineral, which comprises subjecting the material to radiant heating, for example a high flux and rapid radiant heating. In a particular form, the mineral is a hydrous mineral.

Description

THERMAL TREATMENT OF A MATERIAL COMPRISING A MINERALTECHNICAL FIELD

[0001] The present disclosure relates generally to a method for treating a material comprising a mineral and uses thereof. In a specific form, the present disclosure relates to a method of treating a material comprising a hydrous mineral and uses thereof.BACKGROUND

[0002] Reserves of high-grade (Fe > 60 wt%, minor impurities) iron ores are limited and those of grade sufficiently high for processing via the Direct-Reduced-Iron (DRI) to Electric Arc Furnace (EAF), typically classified as DR-Grade (Fe>68%), are even more limited. Lower-grade (for example, Fe < 55 wt% or significant impurities) iron ores are relatively plentiful, although they are presently not utilised effectively due to the cost of processing. One reason for this is that raw high gangue (i.e., impurities such as SiOz and AI2O3) ores are not compatible with current refinement processes, with the cost of processing increasing significantly with increasing gangue content [1]. Therefore, they must be beneficiated through pre-treatments before processing. New and improved technologies are required to treat available low- grade ore while making efficient use of energy and water as well as generating low carbon emissions. One potential method of improving the quality of iron ore is to heat it to >300 °C.

[0003] Typically, industrial scale ore thermal treatment utilises furnaces, kilns, or fluidised beds for the purpose of heating.

[0004] Furnaces and kilns are well established technologies that can handle a wide range of input ore sizes. However, they are typically energy intensive systems with limited capacity, long roasting times, relatively low throughput, and are prone to sticking or ring formation [2] . Comparatively, suspensionbased devices including fluidised bed and flash for pre-treatment are flexible in design, with a suspension roasting furnace being capable of providing a high capacity at low to moderate temperatures (e.g., 450 °C to 800 °C) with a relatively low energy consumption and absence of moving parts. These systems can provide rapid heating in the range of 100 °C / s to 1000 °C / s, depending on initial particle size. However, the effect of this change in heating rate on the material beneficiation has not been previously assessed. The primary drawbacks of these systems are that they require a dedicated large plant and for the feed to be pre-ground to <1 mm (typically in the range 10 pm to 200 pm for flash, and up to 500 pm for fluidised bed), which is an energy intensive process. Additionally, fluidised bed reactors have relatively poor control of the particle residence time, heating rate, or the temperature profile during heating [2], often resulting in undercooking / overcooking of the processed ore, while flash systems are at a much earlier stage of development for processing of iron ore.

[0005] Another alternative heat treatment to provide relatively high heating rates of 10 °C / s to 100 °C / s (greater than for typical furnaces) is to use microwaves. The advantages of microwave heating are that it is non-intrusive, material selective (leading to thermal stresses from different expansions), and under certain conditions can heat the material volumetrically instead of just the surface as for typical heat transfer processes

[0024] . The microwave absorption of the phases within a material typically differs, leading to differences in the heating rates and therefore also thermal expansion. For example, goethite and hematite strongly absorb microwaves while quartz does not. This leads to cracks forming on grain boundaries

[0025] , which allows greater liberation of iron during later processing. Additionally, the energy required to reach the same material temperature is much lower than that of a typical furnace, as shown in pilot-scale applications

[0026] . Extended heating periods have also been shown to heat the material in excess of 900 °C, and the process can be completed within reducing environments to promote the transition to magnetite

[0027] . However, micro wave equipment at the scale required for the pre-treatment of a mineral or an ore comprising a mineral requires highly specialised equipment that is still at an early stage of development. Parameters that still need to be addressed before these processes can be made commercial include how to address the variations in local microwave density and particle composition, together with limitations in the scale of the microwave technology and cost. Hence other methods of high flux heating are still needed.

[0006] Mineral carbonation is an alternative and emerging approach for storing CO2, either from concentrated streams (e.g., flue gas) or from atmospheric air, and may provide an alternative to the better- known form of storage in stable geological reservoirs [3] . Mineral carbonation is a process whereby CO2 is sequestered in magnesium (Mg)- or calcium (Ca)-rich minerals [4], which are abundant in the Earth’s crust and commonly found in waste streams from industrial processes including as mine tailings, slags, incinerator ash, and cement kiln dust [5-7]. An example of a typical reaction for mineral carbonation, in this case forsterite carbonation, is:Mg2SiC>4 (S) + 2 CO2 (g)—” 2 MgCOs <S) + S i O2 <S)

[0007] The resulting carbonate is chemically stable with no potential for CO2 leakage back to the atmosphere [6]. The carbonate and silicate materials can also both be recovered as useful, value-adding products [8].

[0008] The carbonation process occurs naturally, although over geological time scales. Previous research has shown that the reaction can be greatly accelerated by controlling the temperature, pressure, composition, and pH in a reactor [6, 9, 10], termed ex-situ carbonation. Aqueous mineral carbonation typically requires two reaction steps, namely: 1) dissolving the mineral in an aqueous solution to liberate the metal ions, and 2) reacting with CO2 to precipitate the carbonate. In a single stage carbonation system, both of these processes occur simultaneously in the same reactor (direct carbonation), while for a two-stage system they occur sequentially in separate reactors (indirect carbonation) [5]. The indirect carbonation process has several potential advantages over the direct route, including: 1) greater control of the individual reaction steps, for example improving Mg dissolution by controlling the solution pH; 2) the separate dissolution reactor can operate at lower temperatures and pressures than a single stage carbonation reactor; and 3) easier separation of the precipitated solid products in the second stage from the feed added in the first [6, 9], with the potential for other value-adding minerals to also be separated

[0011] . Generally, the indirect approach to dissolution process is understood to produce greater conversion rates of Mg and Ca to solid carbonates, and with a higher purity than the direct process

[0010] . Nevertheless, the rate of all these processes depends on the micro-structure of the material to be carbonated, which can potentially be increased by heat activation of hydrous ores to generate microfractures.

[0009] Lizardite (idealised formula being Mg3Si2Os(OH)4 with planar structure

[0012] ) is a common mineral of serpentine subgroup that has previously been identified as a promising candidate feedstock for the industrial mineralisation of CO2, providing relatively high Mg extraction for aqueous mineral carbonation. Heat activation of the raw lizardite is typically performed prior to the dissolution / carbonation reactions, to destabilise and remove the chemically bound hydroxyl groups. Most of the previous research into the heat treatment of lizardite utilised heating from a kiln or furnace, with the material heated for a period ranging from 15 minutes to several hours at relatively slow heating rates (estimated to be on the order of 0.05 to 1 °C / s) [13, 14, 15]. Heating of lizardite powder in a flash calciner, achieving a temperature of approximately 880 °C for 2 seconds residence time, has also been proposed

[0016] . However, the high temperatures from this process were found to lead to forsterite being the predominant mineral phase, which has relatively poor magnesium extractability compared to the heat- treated material with an amorphous structure. Despite the range of heat treatment experiments carried out previously, the activation of lizardite is yet to be enhanced for industrial applications.

[0010] There is a need for a new or improved method that can be used to thermally treat a mineral, which may alleviate or overcome one or more existing problem or may produce one or more advantage over known methods. The problems or advantages include, but are not limited to, conducting in an effective manner (in terms of time, cost and / or equipment), obtaining a desirable property (chemical and / or physical properties), and enabling downstream processing to be efficient. Alternatively, there is a need for an alternative to known methods that can be used to thermally treat a mineral with similar or comparable effects being achieved.SUMMARY

[0011] According to a first aspect, there is provided a method of treating a material comprising a mineral, which comprises subjecting the material to radiant heating.

[0012] In some embodiments of the first aspect, the mineral is a hydrous mineral and the material is a material comprising a hydrous mineral.

[0013] In some embodiments of the first aspect, the material comprising a mineral is one or more selected from the group consisting of the mineral, ores comprising the mineral, rocks comprising the mineral, and soils comprising the mineral.

[0014] In some embodiments of the first aspect, the radiant heating is a pre-treatment prior to a downstream process. In some embodiments, the downstream process is selected from the group consisting of a comminution circuit, a dissolution process, and a carbonation process.

[0015] In some embodiments of the first aspect, the radiant heating is conducted under conditions so that a physical change and / or a chemical change occurs to the material comprising a mineral compared to the one that is not subjected to the radiant heating. In some embodiments, the radiant heating is conducted under conditions so that a structural change and / or a compositional change occurs to the material comprising a mineral compared to the one without being subjected to the radiant heating. In some further embodiments, the material subjected to the radiant heating has a mineral (for example, a hydrous mineral) in a crystalline state and the mineral in a crystalline state turns into amorphous state after the radiant heating.

[0016] In some embodiments of the first aspect, the radiant heating is conducted so that the activation energy (for example, for decomposition) of the mineral (for example, a hydrous mineral) is lowered. In some embodiments, the radiant heating is conducted so that the specific surface area of the material is increased. In some embodiments, the radiant heating is conducted so that chemically bound hydroxy groups or water molecules comprised by the mineral (for example, a hydrous mineral) are destabilised and removed. In some embodiments, the radiant heating is conducted so that the specific grinding energy required for a subsequent particle size reduction of the material (for example, comminution circuits) is reduced. In some embodiments, the radiant heating is conducted so that different minerals contained by the material are expanded at different rates when being rapidly heated and are separated afterwards. In some embodiments, the radiant heating is conducted so that the particle distribution of the material after the radiant heating is adjusted and / or optimised. In some embodiments, the radiant heating is conducted so that the material comprising a mineral is upgraded (for example, with an increased content of an element). In some embodiments, the radiant heating is conducted so that the mineral (such as a hydrous mineral) is activated (for example, activated serpentine). In some embodiments, the radiant heating is conducted so that a calcined product (for example, metakaolin) or a beneficiated product is produced from the material comprising a mineral.

[0017] In some embodiments of the first aspect, the radiant heating is a radiant heating with a high flux intensity. In some embodiments, the radiant heating is a rapid radiant heating (for example, from a burner). In some embodiments, the radiant heating is a uniform radiant heating (such as can be provided from a radiant porous matrix burner or from an electrical radiator). In some further embodiments, the radiant heating is a rapid and uniform radiant heating with a high flux intensity.

[0018] In some embodiments of the first aspect, the radiant heating is conducted within a flameless environment. In some embodiments, the radiant heating has a uniform heating flux at the point source in the range of about 0.3 MW / m2to about 3 MW / m2. In even further embodiments, the radiant heating has a mean radiation intensity of about 0.5 MW / m2.

[0019] In some embodiments of the first aspect, the radiant heating is carried out by means of 1) a combustion radiant heating source; 2) an electric radiant heating source; and / or 3) concentrated solar thermal energy. In some further embodiments, the combustion radiant heating source is selected from the group consisting of an infrared burner, a premixed or partially premix radiant burner (for example with ceramic or metallic meshes to establish a surface combustion), a self-recuperative radiant tube, and a moderate or intense low-oxygen dilution (MILD) / flameless combustion process. In some further embodiments, the electric radiant heating source is an electric resistance heater, for example an electrical radiant tube heater and an electrical radiator. In some further embodiments, the radiant heating is carried out by means of a burner, for example a flat burner, such as a flat porous burner.

[0020] In some embodiments of the first aspect, the material is radiantly heated to a temperature in the range of about 300 °C to about 1200 °C. In some further embodiments, the material is radiantly heated to a temperature in the range of about 500 °C to about 700 °C, for example about 530 °C to about 630 °C. In some embodiments where the material comprising a hydrous mineral is a kaolinite containing material (such as a kaolinite containing ore), it is radiantly heated to a temperature in the range of about 600 °C to about 800 °C, for example about 700 °C to about 800 °C. In some embodiments where the material comprising a mineral is a magnetite containing material (such as a magnetite containing ore), it is radiantly heated to a temperature in the range of about 500 °C to about 900 °C, for example about 600 °C to about 900 °C. In some embodiments where the material comprising a mineral is selected from a goethite and / or hematite containing material (such as a goethite and / or hematite containing ore) and a pisolitic iron containing material (such as a pisolitic iron ore), it is radiantly heated to a temperature in the range of about 300 °C to about 800 °C, for example in the range of about 500 °C to about 600 °C. In some embodiments where the material comprising a mineral is a copper ore and / or a nickel ore, it is radiantly heated to a temperature in the range of about 400 °C to about 800 °C.

[0021] In some embodiments of the first aspect, the radiant heating is carried out at a heating rate of about 5 °C / s to about 1000 °C / s, for example about 10 °C / s to about 1000 °C / s. In some furtherembodiments, the radiant heating is carried out at a heating rate in the range of about 50 °C / s to about 1000 °C / s. In some further embodiments, for the material with an initial particle size of less than about 200 pm, the radiant heating is carried out at a heating rate in the range of about 300 °C / s to about 1000 °C / s. In some further embodiments, for the material with an initial particle size of about 300 pm to about 1000 pm, the radiant heating is carried out at a heating rate in the range of about 50 °C / s to about 300 °C / s. In some further embodiments, for the material (such as larger crushed ore) with an initial particle size of about 1000 pm to about 10,000 pm, the radiant heating is carried out to allow the surface layer of the material to be heated at about 10 °C / s to about 300 °C / s.

[0022] In some embodiments of the first aspect, the total exposure time for the material to be subjected to radiant heating is no more than about 30 minutes. In some further embodiments, the total exposure time for the material to be subjected to radiant heating is no more than about 10 minutes. In some further embodiments, the total exposure time for the material to be subjected to radiant heating is no more than about 5 minutes, such as about 100 seconds. In even further embodiments, the total exposure time for the material to be subjected to radiant heating is no more than about 1 minute, for example no more than about 10 seconds or no more than 1 second.

[0023] In some embodiments of the first aspect, the radiant heating is carried out at a distance between a radiant heating surface and the material to be heated that is between 5% and 25% of the width of a supporting surface (such as a conveying belt) .

[0024] In some embodiments of the first aspect, particles of the material are distributed over a supporting surface at a thickness of 1 to 10 times the diameter of the largest particles, for example, about 2 to 10 times, about 3 to 10 times, or about 5 to 10 times. In some embodiments, when the diameter of the largest particles is larger than about 2 mm, particles of the material are distributed over a supporting surface at a thickness of about 3 to 10 times, for example about 5 to 10 times the diameter of the largest particles. In some embodiments, particles of the material are distributed over a supporting surface at a thickness of about 1.5 mm to about 5 mm in order to conduct the radiant heating. In some further embodiments, when the material comprising a mineral is a lizardite containing material (such as a lizardite containing ore), particles of the material are distributed over a supporting surface at a thickness of about 1.5 mm to about 2.5 mm, for example, about 1.5 mm to about 2.0 mm, in order to conduct the radiant heating.

[0025] In some embodiments of the first aspect, the material subjected to the radiant heating comprises one or more hydrous mineral. In some embodiments, the material subjected to the radiant heating is rich in a hydrous mineral. In some embodiments, the material subjected to the radiant heating comprises the hydrous mineral in an amount of about 5 wt% to about 80 wt% based on the total weight of the material.

[0026] In some embodiments of the first aspect, the material subjected to the radiant heating comprises or consists of iron ore (for example, a low-grade iron ore), bauxite ore, copper ore, nickel ore, magnesium ore, calcium ore, aluminium ore, and / or lithium ore (for example, spodumene). In some embodiments, the material subjected to the radiant heating is in the form of raw ore and / or waste / tailings. In some embodiments, the hydrous mineral is the valuable part of the ore while the rest of the ore is impurity. In some further embodiments, the aluminium ore comprises or consists of bauxite ore. In some further embodiments, the magnesium ore comprises or consists of serpentinite ore. In even further embodiments, the magnesium ore comprises a silicate mineral (such as serpentine and olivine) and / or a carbonate mineral. In some further embodiments, the copper ore comprises malachite. In some further embodiments, the nickel ore comprises a serpentine group mineral. In some embodiments, the material subjected to the radiant heating is a goethite -rich ore or a hematite-rich ore. In some embodiments, the material subjected to the radiant heating is a hydrous magnesium silicate ore.

[0027] In some embodiments of the first aspect, the hydrous mineral is one or more selected from the group consisting of goethite (FeO(OH)); (hydrous) hematite (for example, having a formula of 2Fe2O3-H2O); (hydrous) forsterite (for example, having a formula of Mg2-xSiO4H2x); antigorite (an idealised formula thereof: Mg3Si2Os(OH)4); lizardite (an idealised formula thereof: Mg3Si2Os(OH)4); chrysotile (an idealised formula thereof: Mg3Si2Os(OH)4); muscovite (KA12(AlSi30io)(OH)2); biotite (K(Mg,Fe)3AlSi3Ow(OH)2); bischofite (MgCF- FfcO); epsomite (MgSCh-TFLO); gypsum (CaSO4-2H2O); brucite (Mg(OH)2); (hydrous) aragonite; (hydrous) spodumene (for example, having a formula of 2[LiAlSi2C>62H2O]); (hydrous) magnesite (for example, having a formula of 3MgCOs- Mg(OH)2- 3H2O or MgCOs- SFfcO); gibbsite (A1(OH)3); boehmite (AIO(OH)); diaspore (AIO(OH)); bay erite (A1(OH)3); doyleite (A1(OH)3); nordstrandite (A1(OH)3); kaolinite (A12Si2C>5(OH)4); epidote (Ca2(Fe,Al)3(SiO4)3(OH)); and malachite (Cu2CO3(OH)2).

[0028] In some embodiments of the first aspect, the material subjected to the radiant heating is in the form of particles. In some further embodiments, the particles have an average size of about 1 pm to about 50,000 pm, for example, 1 pm to about 10,000 pm. In some further embodiments, the particles have an average size of about 1 pm to 500 pm, for example 45 pm to about 500 pm. In some further embodiments, the particles have an average size of about 500 pm to about 1,000 pm. In some further embodiments, the particles have an average size of about 1,000 pm to about 10,000 pm, for example about 1,000 pm to about 8,000 pm. In some further embodiments, the particles have an average size of about 50 pm to about 5,000 pm. In some further embodiments, the particles have an average size of about 300 pm to about 10,000 pm (for example, 500 pm to about 10,000 pm, or 300 pm to 5,000 pm) for reducing specific grinding energy required for a subsequent reduction of particle size of the material comprising the mineral.

[0029] In some embodiments of the first aspect, the material subjected to the radiant heating is a lizardite (MgsSizOs OH)^ containing material (such as a lizardite (MgiSizOdOH^J containing ore). In some embodiments, the method is to produce activated feedstock for mineral carbonation processes. In some embodiments, particles of the material have a size of about 10 pm to about 150 pm. In some embodiments, the method comprises subjecting the material to radiant heating at a rate of at least about 10 °C / s to a temperature of no more than about 630 °C for a total exposure time of no more than 10 minutes. In some embodiments, the lizardite containing material is radiantly heated to a temperature between about 530 °C to about 630 °C. In some embodiments, the lizardite containing material is radiantly heated at a rate of about 10 °C / s to about 25 °C / s, for example about 10 °C / s to about 23 °C / s, or about 10 °C / s to about 15 °C / s. In some embodiments, the lizardite containing material is subjected to radiant heating for a total exposure time of no more than about 10 minutes, for example no more than about 8 minutes, or about 5 minutes to about 8 minutes. In some embodiments, the lizardite containing material is radiantly heated at a rate of about 10 °C / s to a temperature between about 530 °C to about 630 °C for an exposure time of about 480 seconds.

[0030] In some embodiments of the first aspect, the material subjected to the radiant heating is a goethite and / or hematite containing material (such as a goethite and / or hematite containing ore). In some embodiments, particles of the material have an average size of no more than about 5 mm, for example about 4 mm to about 5 mm. In some embodiments, the material comprises Fe in an amount of less than about 60 wt%. In some embodiments, the method comprises subjecting the material to radiant heating at a rate of about 10 °C / s to about 50 °C / s to a temperature of about 400 °C to about 800 °C for a total exposure time of no more than 20 minutes. In some embodiments, the goethite and / or hematite containing material is radiantly heated to a temperature between about 400 °C to about 800 °C, for example about 500 °C to about 800 °C. In some embodiments, the goethite and / or hematite containing material is radiantly heated at a rate of greater than about 10 °C / s to about 50 °C / s, for example about 10 °C / s to about 20 °C / s for about 5 minutes to 20 minutes. In some embodiments, the goethite and / or hematite containing material is subjected to radiant heating for a total exposure time of no more than about 20 minutes, for example no more than about 8 minutes, or about 3 minutes to about 8 minutes.

[0031] In some embodiments of the first aspect, the material subjected to the radiant heating is a magnesite containing material (such as a magnesite containing ore). In some embodiments, particles of the material have a size of no more than about 10 mm, for example from about 500 pm to about 1000 pm. In some embodiments, the magnesite containing material is radiantly heated at a rate of about 30 °C / s to about 100 °C / s to a temperature of less than 950 °C for no more than about 5 minutes.

[0032] According to a second aspect, there is provided a product that is obtained or obtainable by the method of the first aspect.

[0033] According to a third aspect, there is provided use of radiant heating in inducing a physical change and / or a chemical change to a material comprising a mineral compared to the one without being subjected to the radiant heating.

[0034] According to a fourth aspect, there is provided use of radiant heating in inducing a structural change and / or a compositional change to a material comprising a mineral compared to the one without being subjected to the radiant heating.

[0035] According to a fifth aspect, there is provided use of radiant heating in lowering the activation energy of calcination reaction of a mineral comprised by a material.

[0036] In some embodiments of the fifth aspect, the material comprising the mineral is a magnesite containing material (such as a magnesite containing ore). In some embodiments, the activation energy of magnesite calcination reaction is lowered when the heating rate of the radiant heating is increased. In some further embodiments, the activation energy of magnesite calcination reaction is lowered from 220.8 kJmol1to 166.6 kJmol1when the heating rate of the radiant heating is increased from 0.1 °C / s to 102.9 °C / s.

[0037] According to a sixth aspect, there is provided use of radiant heating in increasing the specific surface area of a mineral comprised by a material.

[0038] In some embodiments of the sixth aspect, the material comprising the mineral is a magnesite containing material (such as a magnesite containing ore). In some embodiments, the specific surface area of the material comprising the mineral is increased when the heating rate of the radiant heating is increased. In some embodiments, the magnesite containing material is radiantly heated at a rate of about 59.2 °C / s to a temperature of less than 950 °C.

[0039] According to a seventh aspect, there is provided use of radiant heating in destabilising and removing chemically bound hydroxy groups or molecules comprised by a mineral of a material.

[0040] According to an eighth aspect, there is provided use of radiant heating in reducing the specific grinding energy required for a subsequent reduction of particle size of a material comprising a mineral.

[0041] According to a ninth aspect, there is provided use of radiant heating in allowing different minerals comprised by a material to expand at different rates when being rapidly heated and to be readily separated afterwards.

[0042] According to a tenth aspect, there is provided use of radiant heating in adjusting and / or optimising the particle distribution of a material comprising a mineral after the radiant heating.

[0043] According to an eleventh aspect, there is provided use of radiant heating in upgrading a mineral containing material, for example a low-grade iron ore.

[0044] In some embodiments of the eleventh aspect, the upgrading lies in the content of Fe being increased, the magnetic susceptibility being increased, and / or gangue removal with a high Fe recovery (for example > 70 wt%) being enabled.

[0045] According to a twelfth aspect, there is provided use of radiant heating in producing a calcined product or a beneficiated product from a material comprising a mineral.

[0046] In some embodiments of any one of the second to twelfth aspects, the mineral is a hydrous mineral and the material is a material comprising a hydrous mineral.

[0047] In some embodiments of the first aspect, the material comprising a mineral is one or more selected from the group consisting of the mineral, ores comprising the mineral, rocks comprising the mineral, and soils comprising the mineral.

[0048] In some embodiments of any one of the second to twelfth aspects, the mineral or the hydrous mineral is the one described for the first aspect. In some embodiments, the radiant heating is conducted in the manner described for the first aspect.BRIEF DESCRIPTION OF FIGURES

[0049] Embodiments of the present disclosure will be discussed with reference to the accompanying figures.

[0050] Figure 1 shows a simplified diagram highlighting key features of the method disclosed herein.

[0051] Figure 2 shows the arrangement of a flat porous burner that is useful for the present disclosure.

[0052] Figure 3 shows a flowchart of the treatments of a lizardite containing ore and application of the product obtained thereby according to the present disclosure.

[0053] Figure 4 shows the particle size distribution of the lizardite ore powder before (raw) and after the radiant heating treatment wherein the sample was held at a temperature of 630 °C for 6 minutes.

[0054] Figure 5 shows the experimental arrangement for dissolution of heat activated samples.

[0055] Figure 6 shows steady-state surface temperature of the sample, together with the heating rate of the sample surface averaged over the time taken to reach 20%, 60%, and 95% of the steady state temperature, as a function of distance from the face of the radiant burner.

[0056] Figure 7 shows average surface temperature of the sample as a function of time under the burner for the series of distances from the burner used in the experiments for lizardite heat treatment described in Table 3, together with lines annotating the positions of Ts,as, £20, teo, andfor the case with x - 78 mm.

[0057] Figure 8 shows magnesium (Mg) extraction as a function of dissolution time for a) a series of heat treatment temperatures with a tnoid= 480 seconds, b) a series of holding times for 7as- 530 °C, and c) a series of heating rates with Trem - 530 °C and tnoid - 0 seconds. The dissolution of the sample heat treated in the kiln operated under vacuum (Ts,as - 630 °C, tnoid - 4 hours) is also shown as the reference case on each plot (VK).

[0058] Figure 9 gives a summary of the extraction percentage for each heat treatment investigated after dissolution for 120 minutes.

[0059] Figure 10 shows the correlation between Mg and Si extraction after dissolution for 120 minutes for the series of investigated heat treatment conditions. The symbols with lines connecting them have indicated cases with differing hold times for the same removal temperature.

[0060] Figure 11 shows the correlation between Mg extraction and the slurry pH after dissolution for 120 minutes for the series of investigated heat treatment conditions. The symbols with lines connecting them have indicated cases with differing hold times for the same removal temperature.

[0061] Figure 12 shows the average percentage loss of mass due to dehydroxylation of lizardite for the heat-treated samples, both from the radiant burner and reference kiln operated under vacuum, as a function of the hold time for each of the conditions investigated (A), and correlation between the Mg extraction following dissolution for 120 minutes and the mass loss during heat treatment (B).

[0062] Figure 13 shows the XRD patterns for the heat-treated material for the series of removal temperatures with tnoid - 480 s, together with that of the raw material. L: lizardite, M: magnetite, a: metaserpentine, F: forsterite.

[0063] Figure 14 shows representative cross-sectional SEM images and elemental compositions of (a) the raw lizardite containing ore sample; (b) the lizardite sample treated at 630 °C for 480 seconds and (c) the lizardite sample treated at 630 °C for 480 seconds, following dissolution in carbonic acid for 120minutes (Note: the raw SEM images were taken with a magnification of 5000x). The elemental compositions shown in the fourth column are the average values based on 30-50 sample points.

[0064] Figure 15 shows diameter at which 80% of the ground material passes a sieve screen (dso) of the untreated (line) and heat-treated (symbols) iron ore samples A, B, and C for both the muffle furnace and radiant burner heating as a function of heat treatment temperature.

[0065] Figure 16 shows (A) specific grinding energy for raw and heat-treated samples as a function of targeted plant dso, and (B) ore temperature. Calculations are made using Wi variation with and without heat treatment for sample A.

[0066] Figure 17 shows (A) comparison of the energy requirement for grinding and for heating under different scenarios, and (B) comparison of the total energy requirement (combined heating and grinding) for a scenario with heating being performed prior to grinding, and another scenario where the heating is carried out after grinding, for two target dso- Calculations are made using measured data from sample A.

[0067] Figure 18 shows loss on ignition (EOI) during heat treatment of the iron ore samples A, B, and C for both the muffle furnace and radiant burner heating as a function of heat treatment temperature.

[0068] Figure 19 shows iron wt% (A) and gangue wt% (B), measured using XRF, of the untreated (line) and heat-treated (symbols) iron ore samples A, B, and C for both the muffle furnace and radiant burner heating as a function of heat treatment temperature; (C) the ratio of iron wt% to gangue wt%.

[0069] Figure 20 shows XRD spectra of the untreated and heat-treated iron ore in relation to sample A.

[0070] Figure 21 shows surface area calculated using the BET theory of the untreated (line) and heat- treated (symbols) iron ore samples A, B, and C for both the muffle furnace and radiant burner heating as a function of heat treatment temperature.

[0071] Figure 22 shows average pore width of the untreated (line) and heat-treated (symbols) iron ore samples A, B, and C for both the muffle furnace and radiant burner heating as a function of heat treatment temperature.

[0072] Figure 23 shows reflected light photomicrographs of sample A being radiantly heated at 700 °C (A), (B) and sample B being radiantly heated at 500 °C (C), (D).

[0073] Figure 24 shows a comparison of one stage (IT, top) and two-stage (combined IT and 2T, bottom) WHIMS separation for <500 pm particles of the untreated material (UT), treated in the muffle furnace (MF) at -500 °C, and heated by the radiant burner (RB) at 523 °C for samples A, B, and C. Theleft plot presents the change in Fe wt% before and after WHIMS separation, the right plot presents the total Fe wt% recovered during the WHIMS procedure.

[0074] Figure 25 shows a flow diagram showing the beneficiation process and composition after each stage. The representative content fractions included are from sample A heated to 500 °C with the radiant burner.

[0075] Figure 26 shows schematics of the WHIMS test showing the first pass at IT and a second pass of the ITRoNon-Mag stream at 2T.

[0076] Figure 27 shows measured conversion fraction, X, of magnesite for a series of heating rates dT40( ). In (a) X is plotted as a function of the sample temperature, Ts, and in (b) X is plotted as a function of exposure time, tr. The error bars representing the experimental data are displayed within the markers.

[0077] Figure 28 shows measured conversion fraction, X, of magnesite samples that were calcined to a dT40 final temperature of 900 °C as a function of the heating rate, — . Here, r 900 °c is the duration requiredfor the sample temperature to reach 900 °C. The error bars are also shown, noting that they are displayed within the markers.

[0078] Figure 29 shows specific surface area of magnesite calcined at a series of heating rates to a dT40 given final temperature of 900 °C. Here, X is the conversion fraction and is the heating rate (°C / s)of the samples.

[0079] Figure 30 shows measured values of pore size, showing (a) and total pore volume (b) of magnesite calcined at different heating rates for a given final temperature of 900 °C. Here, X is the dT40 conversion fraction and is the heating rate (°C / s) of the samples.

[0080] Figure 31 shows specific surface area of magnesite calcined at a series of heating rates, for which the corresponding asymptotic temperatures values are shown in Table 7. The residence time was varied to achieve similar values of the conversion fraction (~ 0.83) for the high heating rate experiments dT40(59.2 ~ 179.9 °C Zs). Here, X is the conversion fraction and is the heating rate (°C / s) of the samples.DESCRIPTION OF EMBODIMENTS

[0081] The present disclosure arises from the finding that thermally pre-treating a mineral (for example, hydrous mineral) containing ore by means of radiant heating (for example, high-flux and uniform radiant heating) induced physical, chemical, structural and / or compositional changes incomparison with its state before the thermal treating. It has also been surprisingly found by the present inventors that radiant heating to a specified temperature profile and / or a specified final temperature allowed quality control of engineered mineral products, facilitated a specific mineral recovery, contributed to ore upgrading / beneficiation, produced activated feedstock for mineral carbonation processes for carbon capture, utilisation, and storage (CCUS), and / or prepared iron-containing feedstock for metallurgical processes. High-flux and uniform radiant heating allows to achieve a relatively higher heating rate than previously proposed convective heating methods and provides improved control on the heating rate and temperature of the ore in comparison with previously proposed rapid heating methods.

[0082] The term “ore” used herein refers to a natural rock or sediment that contains one or more mineral concentrated above background levels and can be mined for profit. Common rocks include bauxite ore. An ore used for the present purpose may comprise at least about 10 wt% of an object mineral. Taking a lizardite containing ore as an example, the ore may contain about 95 wt% lizardite.

[0083] The term “mineral” used herein refers to a naturally occurring homogeneous solid with a definite chemical composition and a highly ordered atomic arrangement. A mineral typically contains one or more metal. Common minerals include quartz and olivine.

[0084] The term “hydrous mineral” used herein refers to a host mineral that comprises a bound water molecule (H2O), a bound hydroxyl group (-OH), or a combination thereof, in various crystalline forms or aggregates. For example, the hydrous mineral may contain OH dipoles in a crystal lattice. In some cases, H2O molecules are not comprised in the crystal structure of a host hydrous mineral and the chemical formula of the mineral does not contain “H2O”, but H2O is released during decomposition. Hydrous minerals generally have lower densities and lower melting temperatures than anhydrous minerals.Methods that can be used to detect the water content of a hydrous mineral include, but are not limited to, infrared spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and Terahertz time-domain spectroscopy (THz-TDS).

[0085] The term “radiant heating” used herein refers to a mode of heat transfer in which heat is transferred from a warmer body to a colder one via radiation waves (infrared waves similar to solar waves). This method does not require heating air, and these waves convert into heat after they collide with the cold object, and warm up the cold object in this way.

[0086] It should be appreciated that there may be or may not be another step between the steps described herein. That is, in some circumstances, the sequential steps described herein may be conducted immediately after one another.

[0087] It should be understood that every maximum numerical limitation given throughout this disclosure is deemed to include each and every lower numerical limitation as an alternative, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this disclosure is deemed to include each and every higher numerical limitation as an alternative, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this disclosure is deemed to include each and every numerical range or number that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. By way of example, the phrase from about 2 to about 4 includes the whole number and / or integer ranges from about 2 to about 3, from about 3 to about 4; each possible range based on real (e.g., irrational and / or rational) numbers, such as from about 2.1 to about 4.9, from about 2.1 to about 3.4 and so on; and the individual real numbers such as 2, 2.5, 3, 3.5, and 4.

[0088] The present disclosure provides a method of treating a material comprising a mineral, which comprises subjecting the material to radiant heating. On this basis, a product obtained or obtainable by the method is also disclosed. There may be more than one mineral in the material, which include a hydrous mineral and a non-hydrous mineral. In some circumstances, the mineral is a hydrous mineral and the material is a material comprising a hydrous mineral. It would be appreciated that the material comprising a mineral can be the mineral, ores comprising the mineral, rocks comprising the mineral, and / or soils comprising the mineral.

[0089] The material subjected to the radiant heating may comprise one or more hydrous mineral. In some cases, the material subjected to the radiant heating is rich in a hydrous mineral, for example, a goethite-rich ore or a hematite -rich ore. The hydrous mineral may be comprised in the material at a content of about 5 wt% to about 80 wt%, or about 10 wt% to about 80 wt% based on the total weight of the material.

[0090] For the purpose of illustration, the metal comprised in the mineral to be treated may be selected from iron, copper, nickel, magnesium, calcium, aluminium potassium, and lithium. There is no specific limitation on the form of the material to be treated. For example, the material may be in the form of raw ore and / or waste / tailings. In some further embodiments, the aluminium ore comprises or consists of bauxite ore. In some further embodiments, the magnesium ore comprises or consists of serpentinite ore. In even further embodiments, the magnesium ore comprises a silicate mineral (such as serpentine and olivine) and / or a carbonate mineral. In some further embodiments, the copper ore comprises malachite. In some further embodiments, the nickel ore comprises a serpentine group mineral. The serpentine group minerals (part of the kaolinite-serpentine group in the category of phyllosilicates) are greenish, brownish, or spotted and are commonly found in serpentinite. They are used as a source of magnesium and asbestos, and as decorative stones. The main serpentine group minerals are antigorite (an idealised formula thereof: Mg3Si2Os(OH)4), lizardite (an idealised formula thereof: MgsSizC^OH)^, and chrysotile (an idealisedformula thereof: Mg3Si2Os(OH)4). In some embodiments, the material subjected to the radiant heating is a lizardite containing ore. In some embodiments, the material subjected to the radiant heating is a hydrous magnesium silicate ore.

[0091] In some embodiments, the hydrous mineral comprised in the material can be selected from goethite (FeO(OH)); (hydrous) hematite (for example, having a formula of 2Fe2O3-H2O); (hydrous) forsterite (for example, having a formula of Mg2xSiO4H2x); antigorite (an idealised formula thereof: Mg3Si2Os(OH)4); lizardite (an idealised formula thereof: Mg3Si2Os(OH)4); chrysotile (an idealised formula thereof: Mg3Si2Os(OH)4); muscovite (KA12(AlSi3Ow)(OH)2); biotite (K(Mg,Fe)3AlSi3Ow(OH)2); bischofite (MgCF-bFfcO); epsomite (MgSCh 7FLO); gypsum (CaSO4-2H2O); brucite (Mg(OH)2); (hydrous) aragonite; (hydrous) spodumene (for example, having a formula of 2[LiAlSi2C>62H2O]); (hydrous) magnesite (for example, having a formula of 3MgCOs- Mg(OH)2- 3H2O or MgCChAtFO); gibbsite (Al(0H)3); boehmite (A10(0H)); diaspore (AIO(OH)); bay erite (A1(OH)3); doyleite (A1(OH)3); nordstrandite (A1(OH)3); kaolinite (A12Si2C>5(OH)4); epidote (Ca2(Fe,Al)3(SiO4)3(OH)); and malachite (CU2CO3(OH)2).

[0092] The method disclosed therein is applicable to bulk rocks or ores. Alternatively, it is possible to reduce bulk rocks or ores to a certain size, for example by multi-stage crushing so that particles or powders (i.e. fine particles) are supplied to the radiant heating operation. For the present disclosure, the particle size of the material to be radiantly heated may vary. In some circumstances, for example the particle size ranges from about 1 pm to about 50,000 pm, or from 1pm to about 10,000 pm. In some further circumstances, the material with an average size of about 1 pm to about 500 pm is used for radiant heating. In some further circumstances, the material to be radiantly heated may have an average size in the range of about 500 pm to about 1,000 pm. It is also possible to use larger crushed materials, for example, having an average size of about 1 ,000 pm to about 20,000 pm, or about 1 ,000 pm to about 8,000 pm. A narrow size distribution might be favourable in achieving a stable and uniform heating effect. From an industrial perspective, it might sometimes be advantageous to have a wider range of particle size to fill the gaps between the particles. If desirable, the material to be radiantly heated may have an average size of about 300 pm to about 10,000 pm (for example about 500 pm to about 10,000 pm, or 300 pm to about 5,000 pm) for reducing specific grinding energy required for a subsequent reduction of particle size of the material comprising the mineral.

[0093] The method disclosed herein is applicable to both a material having a low moisture content and a material having a high moisture content. A pre-heating and a pre-drying can be done to reduce total energy consumption. Advantageously, the energy obtained from transferring energy from the cooling system used to cool the heated material can be used for the pre-heating and the pre-drying. For example, a pre-heating can be done by convection (or convective heat transfer) using recovery energy (e.g. from a cooling step following the radiant heating). Before subjecting the material (such as a hydrous mineralcontaining material) to radiant heating, it may be desirable to remove some or all of unbound moisture. For this purpose, it is possible to dry the ore at a suitable temperature above 100 °C, for example at about 105 °C, for a period of time, for example about 12 hours. In some circumstances, a residual moisture content of about 0.05% (kg / kg) to about 0.28% (kg / kg) is obtained.

[0094] It may also select a suitable size range and distribution for the material prior to the radiant heating. This is to avoid any substantial adverse impact that variations in particle size could possibly have on the radiant heating. Size selection can be performed through crushing, wet milling, sieving (such as electronic sieving), or a combination thereof.

[0095] When a suitable material is available, it will be subjected to radiant heating. The radiant heating is conducted under conditions so that a physical change and / or a chemical change occurs to the material comprising the mineral compared to the one without being subjected to the radiant heating, or that a structural change and / or a compositional change occurs to the material comprising the mineral compared to the one without being subjected to the radiant heating. For instance, the material subjected to the radiant heating has a hydrous mineral in crystalline state and the hydrous mineral in crystalline state turns into amorphous state after the radiant heating. Specifically, a radiant heating may cause full dehydroxylation of the lizardite and thus leads to the formation of an amorphous phase of lizardite within a lizardite containing material, which in turn produces a material that enables greater Mg extraction than the raw lizardite or crystalline forsterite.

[0096] In some circumstances, the radiant heating may be a radiant heating with a high flux intensity. It may be preferable that the radiant heating is rapid and / or uniform. If desirable, a rapid and uniform radiant heating with a high flux intensity is performed on the material comprising a mineral. For radiant heating from combustion sources and / or resistive heating, uniformity can be achieved by selection of appropriate combustion technologies, e.g. (flat burners, flat resistive heating equipment for surface combustion) and geometrical arrangement within a heating apparatus. For radiant heating from concentrated solar radiation, uniformity can be achieved by selection of the optical system (including heliostat field, primary and / or secondary concentrators etc.) to achieve a nearly uniform flux at the aperture. The radiant heating disclosed herein may be flameless, which can be achieved through flameless combustion of both fossil and alternative fuels (e.g. hydrogen) and / or non-combustion energy sources. For the purpose of illustration, the radiant heating may have a uniform heating flux at the point source in the range of about 0.3 MW / m2to about 3 MW / m2, for example, about 0.5 MW / m2.

[0097] High-flux and uniform radiant heating allows achieving a relatively higher heating rate than previously proposed convective heating methods, which in turn brings about a less amount of total exposure time. As a result, the radiant heating may significantly reduce equipment costs and fuel consumption for a given material throughput. It also provides improved control on the heating rate andtemperature of the material in comparison with previously proposed rapid heating methods. The absence of a conventional flame enables avoidance of a hot spot and a thermal gradient naturally occurring within a flame, the latter of which could lead to a risk of either underheating or overheating the ore.

[0098] The radiant heating can be carried out within a flameless environment. That is, a material comprising a mineral is heated without presence of a direct flame, but for example by using surface combustion technologies, MILD / flameless combustion technologies, and / or non-combustion energy sources. The material can be radiantly heated in a suitable manner or by means of a suitable apparatus. An apparatus known in the art can be adapted for the present disclosure. For the purpose of illustration, a combustion radiant heating source may be used. The combustion radiant heating source is selected from an infrared burner, a premixed or partially premixed radiant burner (for example with ceramic or metallic meshes to establish a surface combustion), and a self-recuperative radiant tube. The combustion radiant heating source may be operated under flameless conditions. Exemplified fuels therefor include hydrogen, hydrogen based and / or fossil fuels. Furthermore, an electric radiant heating source and / or concentrated solar thermal energy may be utilised to conduct the radiant heating. The electric radiant heating source may be in the form of an electric resistance heater, for example an electrical radiant tube heater. It would be appreciated that different radiant heating sources can be used individually or in combination to continuously supply a high-flux and uniform radiation to thermally treat a material.

[0099] The radiant heating may commence when the material comprising the mineral is at room temperature or partially pre-heated. Also, if the heated material needs to be ground, it is advisable to cool it down as a commercial grinding technology might only deal with cool materials. In conducting the radiant heating, the distance between a radiant heating surface and the material to be heated may be selected to achieve a high view factor and high heat fluxes. For the purpose of illustration, the distance may be between 5% and 25% of the width of a supporting surface (such as a conveying belt). The distance between a radiant heating surface and the material to be heated can be adjusted to control the temperature and heating rate of the material. The distance needs to be large enough for combustion exhaust gases to flow between the belt and the heating surface, for example to reach an extraction system. It may be desirable for the velocity of these gases to be below a few m / s to avoid the pick-up of too much dust. If the distance is too much, it is difficult to create a sufficient heating intensity or it is not energy effective. For this purpose, a thermal camera can be used to continually monitor the surface temperature of the ore being heated. In order for uniform radiant heating, it is advisable that particles of the material comprising a mineral are uniformly distributed over a supporting surface (for example in a layer) and the supporting surface is flat, which does not mean the size of the particles needs to be uniform. The thickness of the particles layer can be selected to achieve a desirable effect. If the layer is too thick, excessive temperature gradients will occur and the particles cannot be heated at the same rate. If the layer is too thin, it will be not cost effective in terms of industrial scale and the ore particles might be heated too fast or even overheated. In some circumstances, particles of the material comprising a mineral aredistributed over a supporting surface at a thickness of about 1 to 10 times the diameter of the largest particles, for example, about 2 to 10 times, about 3 to 10 times, or about 5 to 10 times. As to the diameter of the largest particles is larger than about 2 mm, it might be desirable for the particles to be distributed over a supporting surface at a thickness of about 3 to 10 times or even 5 to 10 times.

[0100] A flat burner may be used to conduct the radiant heating, wherein ore particles are disposed on a supporting surface in a layer to receive radiant heat. A particular form of the flat burner is a flat porous burner. For example, a flat porous burner may have a capacity of about 10 kWth (kilowatt thermal capacity) and a flat mesh face. If desirable, the porous burner may be designed with two-layer pores, wherein one layer has coarse pores and the other layer has fine pores. The porous burner provides noncontact heat. The temperature and the heating rate for a sample are controllable based on the distance between the burner and the sample. The burner can be run with commonly available fuels such as natural gas, with the potential for hydrogen to be also incorporated. Porous burners emit, due to the extremely high surface temperature, more infrared radiation than conventional radiation burners. As the heat transferred through thermal radiation is highly efficient, porous burners could provide fast and homogeneous heating. A flat porous burner that is useful for the present disclosure may be set up as shown in Figure 2. In use, the porous burner emits strong radiation from a flat mesh face that is located within the flame and is fed with a constant flow of natural gas or air. For each individual run, a certain amount of material particles are placed on a crucible in a layer, for example, in a 1.75 ± 0.25 mm thick layer. This crucible can then be placed on a refractory platform that is quickly slid under the burner to start heating and is moved away after a pre-determined time.

[0101] The material comprising a mineral may be rapidly heated through radiant heating to a specific final temperature, for example a temperature in the range of about 300 °C to about 1200 °C. In the present sense, the final temperature is related to an average temperature across the thickness of the layer of material particles. A thermal camera (for example an infrared thermal camera) can be used to continually monitor the surface temperature of the material being heated. A thermocouple embedded in a sample can be used to measure the temperature of a sample or be used to calibrate the temperature measured by a thermal camera. In some embodiments, the material is radiantly heated to a final temperature in the range of about 500 °C to about 700 °C, for example about 530 °C or about 630 °C. Once the final temperature is reached, the material can be immediately removed from the heating zone or be kept at that temperature for a period which may depend on a desirable property or the average particle size of the material. The time for keeping the material at the final temperature may typically be comparable with the time required for the temperature increasing process.

[0102] The radiant heating disclosed herein may be carried out at a heating rate of about 5 °C / s to about 1000 °C / s, for example about 10 °C / s to about 1000 °C / s. In some circumstances, a higher heating rate is recommended, for example in the range of about 50 °C / s to about 1000 °C / s. The heating rateproposed here is higher than previously proposed thermal methods via convective heating. Factors such as the particle size of the material to be heated and the material mineralogy may play a role in selecting a heating rate. Larger ores or rocks will require more intense high flux radiation than powders to achieve a relatively fast heating due to thermal gradients within the ores or rocks. For the purpose of illustration, for the material having an average particle size of less than about 300 pm, the heating rate may be in the range of about 300 °C / s to about 1000 °C / s, while for the material having an average particle size of about 300 pm to about 1000 pm (for example 500 pm to 1000 pm), the heating rate may be about 50 °C / s to about 300 °C / s. For a larger crushed material with an average particle size of more than about 1000 pm (for example, more than about 10,000 pm or about 20,000 pm), it is possible for the surface layer of the material to be heated at about 10 °C / s to 1000 °C / s, although the average temperature of the material may rise more slowly.

[0103] The time period for the material being exposed to radiant heating may vary, for example, in terms of initial particle size and heating conditions. For the heating conditions, consideration may be given to heat flux, final material temperature, and initial material temperature. Generally, it is recommended that the total exposure time for the material to be subjected to radiant heating is no more than about 30 minutes. In some circumstances, the total exposure time for the material to be subjected to radiant heating is no more than about 10 minutes, for example no more than about 5 minutes. If need be, the material may be subjected to radiant heating for a total exposure time of no more than about 100 seconds, for example, no more than about 1 minute or no more than about 10 seconds, or even no more than 1 second. In some circumstances, if the total exposure time is too long, it is likely to promote recrystallisation of a hydrous mineral containing ore and this might not be desirable for a downstream process.

[0104] The term “total exposure time” used herein refers to the time to reach a target temperature plus the time that the material comprising the mineral stays at this temperature under a radiant heating.

[0105] The term “exposure time” used in relation to the radiant heating refers to the time for the sample temperature to reach 95% of a given steady-state temperature (tgs). The total exposure time (teXp) for a situation where holding time is also investigated (tnoid) is calculated from: texp — £95 + llold- wherein tuoid is the time that the sample remains beneath the burner for which t >

[0106] The use of rapid heating eliminates the need to use water to cool the material (the thermal shock is achieved due to fast heating). It also reduces the time that the material needs to remain in the reactor, and hence the total energy requirements. Alternatively, or in addition, the material may be exposed toradiant heating no more than about 10 minutes, which is in sharp contrast to existing thermal pretreatment methods that require duration over about 30 minutes and even up to a few hours. Overall, the method disclosed herein effectively enables a thermal “shock” during the radiant heating and reduces the total energy consumption of the heating process. A simplified diagram highlighting key features of the method disclosed herein is illustrated in Figure 1.

[0107] Once heated to a desirable temperature or kept at a final temperature for a desirable period, the material may be cooled prior to a subsequent downstream process if necessary. Natural or forced convection using different heat transfer fluids (HTF) (for example, air and CO2) can be utilised for the cooling operation. In some circumstances, the heat recovered through cooling down the material can be used to pre-heat the material prior to the radiant heating, which would typically also save energy.

[0108] The material comprising a mineral may be a lizardite (MgsSizOs OH)^ containing material. In this situation, the method disclosed herein may be used to produce activated feedstock for mineral carbonation processes. In some circumstances, it is desirable to radiantly heat the lizardite containing material (i) to a temperature no more than about 630 °C, for example between about 530 °C to about 630 °C; (ii) at a heating rate of no less than about 10 °C / s, about 10 °C / s to about 25 °C / s, for example about 10 °C / s to about 23 °C / s, about 10 °C / s to about 20 °C / s, or about 10 °C / s to about 15 °C / s; and / or (iii) for a total exposure time of no more than about 10 minutes, for example no more than about 8 minutes, or about 5 minutes to about 8 minutes. Specifically, a lizardite containing material may be heated rapidly to a temperature between about 530 °C to about 630 °C for an exposure time of about 480 seconds, for example at about 10 °C / s to about 20 °C / s. More specifically, the method disclosed herein may comprise radiantly heating the material up to about 630 °C at a rate greater than 10 °C / s for no more than 10 minutes. If desirable, it is possible to reduce the particle size of the material, for example to a size of no more than 150 pm. As a result, significant dehydroxylation of the crystalline lizardite occurs as the atomic structure is rearranged into meta-serpentine and amorphous phases. The subsequent carbonation potential may be enhanced when the ore is used as a precursor to dissolution experiments for magnesium extraction. The yield of magnesium carbonate may be increased by up to about 60% following dissolution in a saturated carbonic acid solution at room temperature for about 2 hours (i.e., exposed to carbon dioxide, CO2, at a partial pressure of 1 atm) compared to the same ore that is treated by heating in a kiln (for example a rotary kiln) or a furnace (for example a muffle furnace). A total Mg extraction after 120 minutes in the dissolution reactor of 76% was measured for the case heated to Trem = 530 °C with an exposure time of 480 s, which represents a 60% increase relative to that achieved by a kiln treatment. This suggests an enhanced viability of mineral carbonation using a lizardite containing ore as the feedstock for long-term chemically stable storage of carbon. Given the relatively short heating time and the moderate temperature, this method also has the potential to significantly decrease the energy and cost of thermal activation required for an industrial scale process, which has been identified as one of the main barriers for the mineral carbonation technique.

[0109] In the case that the material comprising a mineral is a goethite and / or hematite containing material (such as a goethite and / or hematite containing ore), it may be desirable to radiantly heat the material (i) to a temperature between about 400 °C to about 800 °C, for example about 500 °C to about 800 °C, or about 500 °C to about 700 °C; (ii) at a heating rate of no less than about 10 °C / s, for example about 10 °C / s to about 30 °C / s, about 10 °C / s to about 50 °C / s, or about 10 °C / s to about 100 °C / s; and / or (iii) for a total exposure time of no more than about 20 minutes, for example about 5 minute to about 20 minutes, or about 3 minutes to about 8 minutes. In some circumstances, the method may comprise radiantly heating the goethite and / or hematite containing material to a temperature of about 400 °C to about 800 °C at a rate of about 10 °C / s to about 50 °C / s for about 5 minutes to about 20 minutes. In some circumstances, the material is a goethite -rich ore. If desirable, it is possible reduce the particle size of the material, for example to a size of no more than about 5 mm, for example about 4 mm to about 5 mm. When the material is a low-grade iron ore, the material may comprise iron, gangue (e.g. alumina and silica) and detrimental impurities (e.g. phosphorous). In some circumstances, the material comprises Fe in an amount of less than about 60 wt%. The radiant heating process or the method disclosed herein may be used to upgrade the quality of a low-grade iron ore by increasing the content of Fe, increasing the magnetic susceptibility, and enabling gangue removal with a high Fe recovery, for example > 70 wt%. This can be achieved with relatively low costs, and with a carbon footprint that can vary from zero to a low-carbon intensity depending on the energy source and fuel selected for driving the heating. For a goethite-rich iron ore, the radiant heating process or the method disclosed herein may allow goethite to transform into hematite and the transformation might lead to a 12-timex increase in the surface area of ore particles. In some circumstances, a reducing agent (e.g., hydrogen) may be added to the heating environment, for example to preferentially transform the goethite / hematite into a magnetite -rich concentrate.

[0110] In the case that the material subjected to the radiant heating is a magnesite containing material (such as a magnesite containing ore), the method disclosed herein may comprise radiantly heating the material to a temperature less than about 950 °C. In some circumstances, the material may be radiantly heated at a rate of about 30 °C / s to about 100 °C / s (for example, about 59 °C / s to about 77 °C / s). The total exposure time may be selected according to various factors and, as an example, no more than about 5 minutes. Before radiant heating, the material may be dried at about 105 °C for about 12 hours to reduce unbound moisture, for example to a residual moisture content of 0.28% (kg / kg). A high heating rate may lower the activation energy of magnesite calcination reaction and / or may improve the specific surface area of the ore particles. A high heating rate may induce microcracks and fractures in the particles, causing some to fracture. The material subjected to the radiant heating may have a particle size of no more than about 10 mm, for example about 500 pm to about 1000 pm. For instance, increasing the heating rate from a low heating rate of 0.1 °C / s to a high heating rate of 102.9 °C / s results in a 24.5% reduction in activation energy, E, from 220.8 kJmol1to 166.6 kJmol '. Additionally, the time required formagnesite calcination to achieve a given level of conversion decreased by a typical factor of 8 upon increasing the heating rate by a factor of 3.

[0111] The material treated by the method disclosed herein may be supplied to a downstream process for various purposes. Examples of the downstream process include, but are not limited to a comminution circuit, a metallurgical process, and mineral carbonation. A comminution circuit may be composed of multiple unit operation, with the objective of reducing mined rock to a size where valuable minerals grains are liberated from gangue. A metallurgical process may include the refining of metals and the manufacturing of alloys of different metals. Mineral carbonation is a potential storage method that accelerates the geological process of rock weathering. It involves the formation of stable carbonates by the reaction of CO2 with naturally occurring oxides or silicates of magnesium, iron, and calcium.

[0112] It has been found by the present inventors that the method comprising subjecting a material comprising a mineral (for example, a hydrous mineral) to radiant heating disclosed herein may find use in one or more of the following applications:Lower the activation energy of calcination reaction of a mineral contained by the material (such as a magnesite containing ore);Increase the specific surface area of a mineral containing material (such as a magnesite and / or goethite containing ore);Destabilise and remove chemically bound hydroxy groups or water molecules (such as hydrated water molecules) comprised by the material, particularly those comprised by a hydrous mineral of the material;Reduce the specific grinding energy required for a subsequent reduction of particle size of the material (i.e., comminution circuits);Separate different minerals as they expand at different rates when being heated at a high rate, which in turn facilitates liberation / recovery of a mineral;Adjust and / or optimise the particle distribution of a material comprising a mineral after the radiant heating, which can be done by finely tuning operating conditions of a radiation source (e.g., exposure time, maximum temperature, heat flux, and heating rate and profile);Upgrade a material comprising a mineral (for example, a low-grade iron ore and a bauxite ore);In this regard, a feedstock (for example, an iron-containing feedstock) may be prepared and provided for metallurgical processes. The feedstock prepared has higher surface area compared to the one before subjecting to the radiant heating. The low-grade iron ore may contain for example goethite and / or hematite. In some embodiments, the low-grade iron ore may comprise less than 60 wt% Fe, for example 44 wt% to 60 wt% Fe, or 47 wt% to 57 wt% Fe.Activate a mineral comprised by a material, for example activated feedstock (e.g., activated serpentine) for CCUS via mineral carbonation being produced, and / or provide a low-cost engineered material (e.g., high-surface silica); andProduce a calcined product or a beneficiated product from a material comprising a mineral, for example, metakaolin, calcined goethite, calcined alumina, calcined magnesite, calcined spodumene, and beneficiated bauxite ore.

[0113] Accordingly, the present disclosure relates to use of radiant heating in reducing specific grinding energy of a material comprising a mineral, in adjusting and / or optimising the particle distribution of a material comprising a mineral after the radiant heating, and / or in separating different minerals comprised by a material . Specific grinding energy is a parameter that represents the relationship between input and output of the grinding process. The specific grinding energy (typically reported in kWeih / ton) is the energy required per unit mass of the ore to reduce the ore from an initial size to a specified size. The radiant heating may be conducted in the manner described herein above. In this way, the specific grinding energy required in a comminution circuit may be reduced by about 20 to about 50% in comparison with the material without being treated by the radiant heating disclosed herein. The reduction of the specific grinding energy may facilitate liberation of a mineral. Without being bound by any theory, it is believed that the reduction in grinding energy is due to softening of the ore compared to the material without being treated by the radiant heating disclosed herein (with a consequent reduction in the Bond Work Index) via different mechanisms (either standalone or in combination). The mechanisms include enhanced cracking associated with different thermal expansion of different minerals within the material during rapid radiant heating, dehydroxilation of specific minerals with consequent release of steam as well as increased porosity and surface area, and / or structure re-arrangement of the material (e.g., transition from crystalline state to amorphous state). The appearance of cracking at grain boundary level can be further enhanced for some material if fast cooling is applied. However, this is not a requirement for achieving grinding energy reduction in first instance as long as a fast heating rate is applied.

[0114] The final temperature (i.e. the targeted steady-state temperature upon radiant heating) of the material achieved by the radiant heating may be determined by the nature of the material. For instance, a grinding energy reduction can be achieved for copper ore and nickel ore in the range of about 400 °C to about 800 °C, for iron ore in the range of about 250 °C to about 800 °C.

[0115] Table 1 shows measured maximum reduction in ore particle size, d8o, and specific grinding energy for different ores when different heating rates (slow heating rate of 10 °C / min, and fast heating rate with the method disclosed herein, > 50 °C / s) are applied.

[0116] Table 1

[0117] The present disclosure also relates to use of radiant heating in preparing a feedstock for a metallurgical process, for example an iron containing feedstock with high-surface area. In particular, it is possible to use radiant heating to prepare an iron containing feedstock for a metallurgical process from a low-grade iron ore, such as a goethite and / or hematite containing ore and a pisolitic iron ore. Fe content of the low-grade iron ore may be less than about 60% w / w. The radiant heating may be conducted in the manner described herein above.

[0118] Under a non-reducing environment, the method disclosed herein or the radiant heating process described herein can be used to upgrade a goethite and / or hematite containing ore and / or a pisolitic iron ore to a hematite concentrate. This may be done by rapidly heating the ore(s) to a temperature in the range of about 300 °C to 800 °C, for example at a heating rate of about 10 °C / s to about 100 °C / s. In some embodiments, the ore is rapidly heated to 500 °C to 600 °C to convert a low-grade iron ore into a hematite -rich ore. In addition, the specific grinding energy consumption may be lowered, which is beneficial for grinding if it is required for a downstream process, such as for a fluidised bed or a flash reduction process. After cooling, the newly formed hematite -rich ore is more susceptible to magnetic separation, with a much higher surface area than the ore without being rapidly heating. A hematite concentrate can be obtained by exposing the hematite -rich ore to a magnetic field of about 1 to 2 Tesla. For an ore having a high content of phosphor (P > 0.1 wt%), a leaching operation can be performed after / before the magnetic separation step. The leaching operation may also serve as an alternative to the magnetic separation. In summary, a hematite concentrate with Fe wt% > 60 wt% can be obtained from astarting iron ore with Fe wt% < 55 wt%. Furthermore, a higher surface area that is about 3 to 12 times higher than that of the ore without being rapidly heated, and a good iron ore recovery that is greater than 70 wt% can be achieved. It is considered that the higher surface area is linked to transformation from goethite to hematite, enhanced fracturing, and / or higher degree of amorphous content in the ore structure.

[0119] Under a reducing environment, if hydrogen and / or other reductants are added into the radiant heating zone (e.g., by operating a hydrogen radiant burner under fuel-rich conditions), partial reduction of the ore can be achieved to increase the magnetite concentration by rapidly heating the ore to a temperature in the range of about 600 °C to about 900 °C, for example at a heating rate of about 10 °C / s to about 100 °C / s. In addition, the specific grinding energy consumption may be lowered if a grinding process is needed after the heat treatment. A low-intensity magnetic field (< 1 Tesla) may be applied to further concentrate the magnetite once the ore is cooled. This offers a way to remove phosphor (P) without the need for leaching or other downstream processes, where the phosphor is bound to the nonmagnetic concentrate.

[0120] The method disclosed herein or the radiant heating process described herein may also provide a means to recover chemically bound water from the low-grade ore, which can be re-used within the method / process and / or be utilised for hydrogen production via electrolysis. The method disclosed herein or the radiant heating process described herein may also reduce the overall volume of ore.

[0121] Table 2 shows the impacts of the radiant heating treatment disclosed herein on iron beneficiation performance under selected conditions.

[0122] Table 2

[0123] The present disclosure also relates to use of radiant heating in activating a mineral (such as a hydrous mineral) contained by a material (such as an ore). For example, a thermally activated feedstock (e.g., activated serpentine) for CCUS via mineral carbonation is provided. In the meantime, a valuable byproduct may be recovered, such as silica having high surface area. The radiant heating may be conducted in the manner described herein above. It is worth mentioning that an activation potential provided by the radiant heating process disclosed herein is about 1.5 to 3 times that of previously proposed thermal activation methods (and at lower temperatures). Without being bound by any theory, it is believed that the radiant heating disclosed herein allows maximisation of the amorphous content in the heated ore while avoiding re-formation of crystalline phases that would otherwise inhibit extraction of Mg and Ca. It has been found by the present inventors that serpentine group minerals (either in raw ore or in tailings, including nickel waste / tailings) are well suited for this thermal activation method. In this regard, Figure 9 shows measured Mg extraction % from lizardite powders during mineral carbonation experiments (wherein the lizardite powders have been activated via the radiant heating treatment disclosed herein) and the value measured and reported for the same material that has been thermally treated in a kiln under vacuum (slow heating, heating time: 4 hours) for the purpose of comparison.

[0124] Furthermore, the present disclosure relates to use of radiant heating in producing a calcined product or a beneficiated product from a hydrous mineral containing ore. The radiant heating may be conducted in the manner described herein above. Illustrative examples of the calcined or beneficiated product are metakaolin, lime, beneficiated bauxite ore, and calcined magnesite. In some circumstances, it is possible to produce metakaolin having a high dehydroxilation degree (for example > 90%), high surface area (for example > 900 m2 / kg) and / or a pozzolanic activity by using kaolinite clay as a feedstock. In addition, the specific grinding energy may be reduced, which is beneficial for grinding if it is requiredafter radiant heating. In some embodiments, the kaolinite clay (for example with a particle size of about 50 pm to about 5000 pm) is rapidly heated to a temperature in the range of about 700 °C to about 800 °C (for example at a heating rate of about 5 °C / s to 100 °C / s) to produce the metakaolin (amorphous). In some embodiments wherein the radiant heating treatment disclosed herein is applied to produce a calcined product such as alumina, magnesite, spodumene and lime, the product obtained may have a surface area higher than that of the calcined product obtained through a radiant heating with a slow heating rate. It is also worth mentioning that a decreased exposure time is required for the radiant heating treatment disclosed herein to achieve a maximum conversion fraction. In some embodiments, a starting bauxite ore (for example with a particle size of about 50 pm to about 5000 pm) is radiantly heated to a temperature in the range of about 250 °C to about 500 °C (for example at a heating rate of about 5 °C / s to 100 °C / s) to produce beneficiated bauxite according to the present disclosure. As a result, the total organic carbon (TOC) is removed, goethite is dehydroxylated, there is no loss of alumina recovery in the digestion operation, and / or grinding energy is reduced.EXAMPLES

[0125] Heating treatment of a lizardite containing ore by means of high flux radiation and use of the product

[0126] Methods

[0127] Lizardite containing raw ore was obtained from the Great Serpentine Belt in NSW, Australia. The ore was crushed, wet milled, and sieved to remove particles of diameter >150 pm. The resultant particle size distribution (PSD) of the feed lizardite powder was measured using a Malvern Mastersizer 2000 and was found to have a most probable diameter of 25 pm Also presented is the PSD measured after full dehydroxylation following the radiant burner treatment according to the present disclosure. It shows that the radiant heating does not significantly alter the PSD for the conditions investigated. The chemical composition of the ore powder, measured using semi-quantitative XRD, is 92% by weight lizardite (Mg3Si2O5(OH)4), 5% by weight magnetite (Fe3O4) and 3% by weight clinochlore ((Mg5Al)(AlSi3)O10(OH)8). The complete dehydroxylation of lizardite can be represented by the reaction shown in the following equation:The dehydroxylation process is endothermic with an enthalpy for complete dehydroxylation of A / z = 565 kJ / kg. The total energy required to reach the dehydroxylation temperature of 630 °C has been estimated to be Q - 1292 kJ / kg, which takes into account both sensible and latent heat.

[0128] Heat treatment conditions

[0129] Samples were heated beneath a 5 kWth porous burner, as shown in Figure 2. This burner emits strong radiation from a flat mesh face that is located within the flame, which was fed with a constant flow rate of 8 SLPM natural gas and 100 SLPM air for all tests. For each individual run, 1.25 g of the lizardite ore powder was placed on a stainless-steel crucible in a 1.75 ± 0.25 mm thick layer. This crucible was then placed on a refractory platform that was quickly slid under the burner to start the heating, and removed after a pre-determined time. Compared to conventional furnace heating, the primary advantage of using radiant heating is that the heating rate of a sample is greatly increased, which in turn leads to a shorter total exposure time. This has the potential to significantly reduce the required plant cost and fuel consumption for a given throughput.

[0130] The sample was weighed using an analytical balance before and immediately after the heat treatment to determine the mass loss due to dehydroxylation of the lizardite. The temperature and heating rate of the samples were controlled by altering the distance between a sample and burner. A thermal camera was used to continually monitor the surface temperature, Ts, of a sample. Both the thermal camera and a thermocouple embedded in the sample were used to measure the sample temperature. A calibration function in linking the sample temperature to the distance between the burner and a sample was performed. The results of the calibration are presented hereinafter. The samples were treated at a series of temperatures (where the sample was removed from under the burner once it reached the steady-state temperature), a series of heating rates (where the samples were removed before reaching the steady-state temperature), and a series of holding times at a given steady-state temperature. A summary of the key heating parameters investigated is given in Table 3.

[0131] The primary heat transfer processes affecting the temperature of the sample are radiative heating from the burner, radiative losses to the environment, and cooling by natural convection, with the resultant temperature profile over time being a monotonic non-linear increase towards the asymptotic steady-state temperature condition, 7as(where the overbar denotes an average over the crucible surface area facing the burner). The exposure time required to reach each steady-state temperature was defined as the time taken for the sample temperature to reach 95% of the steady state value. That is,where Tamb is the ambient temperature of 25 °C. The total exposure time for cases where holding time was also investigated was therefore calculated from:where tuoid is the time that the sample remains beneath the burner for which t > The characteristic heating rate listed was averaged over the time taken for the sample to increase in temperature by 60% from ambient (teo) to Ts,as, that is:

[0132] The heating rates averaged over the time taken to reach 20% and 95% of the steady-state temperature were also calculated using the same method as for the equation immediately above during the calibrati ■on, and i expressed i as dT20 and . d 95 respecti .vel .y. „ Because th I e dTistance I between th i e i burner and ithe sample is fixed for each run, the heating rate and the asymptotic temperature are coupled.

[0133] To compare the radiant heating method with previous published results, a reference sample was also prepared following the identical procedure to that reported previously

[0017] and was heat-treated in a rotary kiln operated under vacuum held at 630 °C for 4 hours at an average heating rate of approximately 0.5 °C / s. This heat treatment was previously shown to provide greater Mg extraction than typical kiln / furnace heat-treated samples for the same treatment temperature, and is denoted in the figures by VK.

[0134] Table 3

[0135] Magnesium extraction procedure

[0136] The effectiveness of different treatment methods and conditions for Mg extraction was performed using a simplified dissolution reactor. An open beaker containing saturated carbonic acid solution at atmospheric pressure and room temperature, as shown in Figure 5, was prepared by flowing gaseous CO2 at a constant flow rate of 1.1 L / min into a glass beaker filled with 230 mL of purified water through a 2 pm aperture stainless-steel diffuser. The solution was left for 15 minutes under CO2 flow to ensure saturation of CO2 (as gauged by the steady recorded pH) before the sample was added. A magnetic stirrer in the solution was operated at 400 rpm during the dissolution tests to ensure a well-mixed condition. For each sample, 0.2 g of the heat-treated sample was added to the saturated carbonic acid solution, giving a solid loading of 0.1 wt%, with a dissolution time of 120 minutes. The relatively low solid loading used for all experiments was adopted to ensure that the dissolution response was not kinetically limited by the rate of stirring or the rate of CO2 mass transfer to the solution. The pH and temperature of the solution were monitored at 1 Hz, with two dissolution runs performed concurrently for each heat-treated sample to ensure repeatability. A 2 mL sample of the slurry was collected respectively at 5, 15, 30, 60, and 120 minutes after the start of each run, then filtered using a 0.22 pm syringe filter before dilution with 2 mL of 2% nitric acid to prevent possible precipitation of solid phases before elemental analysis.

[0137] Within the slurry, and for a typical two-stage indirect carbonation process, the magnesium carbonate (as nesquehonite) was formed according to the reactions shown in the following equations (1)- (3). First, the hydration of CO2 to form carbonic acid that dissociates forming protons and bicarbonate ions:The heat-treated samples then react with the disassociated carbonic acid (in the form of protons and bicarbonate ions) when added to the solution. The overall dissolution reaction is shown in Equation 2. In this equation the heat-treated lizardite is represented in the equivalent chemical form to that of forsterite, in order to demonstrate the full dehydroxylation of the raw lizardite. Magnesium and bicarbonate ions are produced while silicon-rich species precipitate in the solution, leading to the formation of silica.The magnesium ions then react with bicarbonate ions to form hydrated magnesium carbonate (nesquehonite).

[0138] Treated material analysis

[0139] The crystalline phases of the powder samples before and after heat treatment were identified using qualitative X-ray diffraction (XRD), using a Rigaku MiniFlex 600 X-Ray Diffractometer with a scan range of 3°< 20 < 80° in a step of 0.02°. The elemental concentration of the slurry during and after dissolution was measured using Inductively-coupled plasma mass spectrometry (ICP-OES, Varian 715- ES). Scanning electron microscopy (SEM, FEI Quanta 450 FEG) of the samples with carbon coating, combined with energy dispersive X-ray (EDS) mapping, was used to analyse the cross-sectional morphology and chemical composition. A cross-section of the powder samples before and after heat treatment, as well as after dissolution, was exposed by embedding the sample in epoxy resin then polishing with diamond solutions (Struers TegraPol-11).

[0140] Results

[0141] Radiant burner calibration

[0142] The steady-state temperature of the sample 7asas a function of distance from the burner (x) is presented in Figure 6, together with the characteristic heating rates to 20, 60, and 95% of the sample steady-state temperature (dT / dt). The steady-state temperature can be accurately controlled in a range from 7as- 250 °C at x = 168 mm to 7as- 750 °C at x = 46 mm. The increase in 7aswith decreasing x is non-linear and does not conform to a simple function due to the multi-mode heat transfer, predominantly comprised of radiative heating of the sample by the burner, radiative cooling of the sample to the surroundings, and free convection from the heated sample. The heating rate of the sample was measured based on three characteristic temperatures, namely T20, Teo, and T95, each defined by the equation:The maximum values of the heating rates based on these values for the case of T^as- 750 °C was dT20 / dt = 92 °C / s, dT60 / dt = 23 °C / s, and dT95 / dt = 2.6 °C / s.

[0143] The temperature of the sample during the calibration for a steady-state temperature was measured continuously using both a thermocouple embedded in the sample and the infrared camera. The temperature of the thermocouple was used to calibrate the temperature measured with the infrared camera, owing both to uncertainties in the temperature-dependent emissivity of the material and to interference due to the reflection of radiation emitted from the burner. The resulting temperature profiles of the sample measured using the infrared camera as a function of time under the burner (t;r) for a series of distances between the sample and the burner used in the experiments are presented in Figure 7. Note that the time axis of the graph is presented as a logarithmic scale. Also presented are lines annotating the positions of Ts,as, £20,for the case with x - 78 mm. It can be seen from the temperature profiles that the sample is heated rapidly when initially placed under the burner, due to the strong radiative heat transfer between the burner and the sample while the temperature of the sample is low. As the sample temperature increases, the difference in temperature between the burner mesh and the sample decreases. This leads to a decrease in radiative heat transfer to the sample while there is a concurrent increase in radiative losses to the environment and free convection to the surroundings from the sample.

[0144] Lizardite dissolution results

[0145] Figure 8 presents the Mg extraction as a function of time during the 120 minute dissolution for: the series of sample steady-state temperatures (TSjaS) shown in Table 3 with a holding time of tnoid - 480 s (top); the series of tnoid with Tiem- 530 °C (middle); and for the series of heating rates with Tiem- 530 °C and tnoid- 0 s (bottom). The Mg extraction from the reference sample heat-treated in a kiln operated under vacuum is also presented for each plot. The Mg extraction can be seen to increase monotonically with dissolution time over the period examined, with the extraction expected to continue to increase towards an asymptotic value for longer dissolution runs. Despite the sample does not reach the final extraction condition, the time period presented here is sufficient to identify the trends in the rate of Mg extraction for the series of heat treatment conditions investigated.

[0146] For the samples treated using the radiant burner, the Mg extraction increases with increasing Tremfor Trem 530 °C then remains approximately the same for Trem - 630 °C. The Mg extraction also increases with increasing tnoid for tnoid480 s, i.e. over the range of holding times considered in the present experiments. Additionally, decreasing the total exposure time led to a decrease in the Mg extraction. Taken together, these results indicate that the kinetics (reaction rate) for both dehydroxylation and re-crystallisation of the samples during the heat treatment are implicit in producing a material that responds well to the dissolution. That is, when the samples are heated to a particular temperature the timeheld at that temperature must be sufficiently long for the lizardite structure to destabilise with hydroxyl groups being removed but not so long or at sufficiently high temperatures to promote re-crystallisation into forsterite.

[0147] Full dehydroxylation of the lizardite leads to the formation of an amorphous phase with low crystallinity, which results in a material that provides greater Mg extraction than the raw lizardite or crystalline forsterite. Additional analysis to support this conclusion is presented in Figures 12 to 14, wherein results from the dehydroxylation due to mass loss during heating is given in Figure 12, crystalline structure using XRD is given in Figure 13, and cross-sectional SEM imaging is shown in Figure 14.

[0148] Figure 9 presents the total Mg extraction after 120 minutes in the dissolution reactor as a function of the holding time tnoid for the series of combinations of removal temperatures and heating rates investigated. It can be seen that the Mg yields increase with tnoid for each Trem- This shows that the series of reactions for lizardite activation using radiant heating is kinetically controlling.

[0149] Figure 9 also shows that the heat treatments with the radiant burner of Trem530 °C and tnoid - 480 seconds yield a Mg extraction of up to 76%, which is significantly greater than that for the reference case of 45% from the material heated in the kiln. It should also be noted that the exposure time for the high heating rate cases of up to 600 seconds is some 24 times less than the 14,400 seconds (4 hours) of the reference case, providing strong potential for significant energy and cost savings in terms of fuel usage and plant size when scaling up the process.

[0150] The samples with short exposure times (i.e., tnoid - 0 s) for Trem530 °C show poor extraction. However, the sample with Trem= 630 °C and tnoid - 0 s has an extraction similar to the reference case from the kiln. This indicates that, while treatment at 530 °C provides good extraction after a long exposure time, the higher temperature of 630 °C may be preferable for a short exposure time to potentially decrease the overall energy / cost requirements. For the samples treated using different heating rates with Trem= 530 °C and tnoid - 0 s, the extraction for dTf dt - 15 °C / s was 33% while for dT / dt - 22 or 23 °C / s the extraction was 22%. These results provide further evidence of the importance that the kinetics of the dehydroxylation and recrystallisation processes, together with the thermal time -constants of the particles in the crucible, are limiting factors in the extent of Mg extraction during dissolution for the activation heating rates and temperatures investigated.

[0151] Figure 10 presents the correlation between the extraction of silicon (Si) and Mg after 120 minutes in the dissolution reactor for the series of heat-treated samples investigated. The trends for Si extraction closely match those for Mg, with greater extraction from the cases treated at Trem530 °C than at Trem= 450 °C. The extraction of Si from the reference sample heat treated in the kiln is higherrelative to the radiant burner treated samples than for the Mg. There is also a discrepancy in the radiant burner cases with Trem= 530 and 630 °C, which is in contrast to the Mg extraction over time being almost identical. It is important to note that the extraction figures presented relate to net extraction as the precipitation of Mg silicate and silica phases are possible within the reacting system. Consequently, these differences in relative Mg and Si extraction are attributed to the precipitation of a Si-rich layer on the outside of the particles during the dissolution, which can inhibit the Mg extraction from the particle core.

[0152] Figure 11 presents the correlation between the Mg extraction and pH of the slurry after 120 minutes in the dissolution reactor for the series of heat treatment conditions. The cases having relatively high Mg extraction also show the greatest increase in pH from the initial carbonic acid mixture. The pH of the slurry is theoretically a direct indicator of the Mg extraction during dissolution, because the carbonic acid in the solution is neutralised upon reaction with the heat-treated samples (see Equation 3). The proportion of extracted Mg is limited by the mineral structure. The presented results are consistent with the heat activated material having released hydroxyl groups, which open up the previously layered lizardite structure and expose a greater proportion of freely available alkaline brucite to the solution

[0013] . The slurry pH can also be continuously monitored during the test with simple, well-established equipment, making it a reliable indicator for monitoring the progress of Mg extraction during tests on all scales.

[0153] Material analysis

[0154] Figure 12 presents the mass loss of the material due to dehydroxylation of the lizardite during the heat treatment for each of the investigated cases (A), together with the correlation between Mg extraction and mass loss (B). During the heat treatment, mass is lost due to the combination of the evaporation of adsorbed water, which was measured to be 2.5% on average following heating to 105 °C for 4 hours, and dehydroxylation of lizardite structure. It is reasonable to assume that the mass loss due to evaporation of adsorbed water is constant and complete for each heat treatment due to the temperatures of 530 °C. The residual mass loss, which was measured immediately after the experiment, is therefore dominated by the dehydroxylation process only. The mass loss of 10% measured from the samples heated in the kiln operated under vacuum are also included, for which the sample was dried at 110 °C prior to the initial weighing

[0013] .

[0155] The mass loss increases with heat treatment temperature Tremfor constant tnoid up to 630 °C, with increasing tnoid for constant Trem, and decreases with increasing dTf,o / dt (i.e., also less exposure time) for constant Trem- These trends are expected to continue up to the temperature and / or exposure time at which full dehydroxylation occurs. The greatest mass loss from the material being heated by the radiant burner was 8.2%, which is below the values of between 12 to 14% for reported full dehydroxylation in literature [18, 19]. This is consistent with the measurements above showing that dehydroxylation iskinetically limited for the ranges of temperature and exposure time investigated here. A positive correlation between the mass loss and Mg extraction following dissolution can be seen for each series of parameters investigated. However, the highest Mg extraction was seen for a mass loss of only 4.4%, indicating that while complete dehydroxylation of lizardite appears to be beneficial for Mg extraction during dissolution, it is not the only controlling parameter. The comparison with the reference case is alsoinstructive, since the Mg extraction for the case with> 10 °C / s is greater than for ~~~ = 0.5 °C / s even though the mass loss is similar. This suggests that the combination of high heating rates and relatively short exposure times produce a material with a more reactive molecular structure, thereby enabling greater magnesium extraction.

[0156] Figure 13 presents the XRD spectra of the raw and heat-treated samples for a series of treatment temperatures with tnoid - 480 °C. The crystalline phases corresponding to the peaks were identified from references [12, 13] in conjunction with the RRUFF database

[0020] . The spectra of the raw sample show strong crystalline peaks corresponding to lizardite (L), with weaker peaks corresponding to magnetite (M). For the heat-treated samples, there is little change in the spectra for Trem= 450 °C, which is consistent with relatively low mass loss and poor Mg extraction. Samples heated to Trem= 530 °C retain weak crystalline peaks, with the emergence of a broad amorphous hump spanning 10 < 2 9 < 50° and a weak peak at 2 9 6°. At Trem= 630 °C, the crystalline peaks associated with lizardite have almost completely disappeared.

[0157] These results are consistent with literature for low heating rates for lizardite heat-treatment, with previous investigations reporting that an intermediate phase (termed the “a” meta-serpentine phase) progressively replaces the lizardite below 580 °C as the structure is rearranged resulting in a low-angle feature at 2 9 6° [21, 22]. An amorphous meta-serpentine phase, characterised by the broad hump centred at 2 9 ~ 28°, is also identified for Trem530 °C [21, 13] The results indicate that the lizardite has undergone near-complete dehydroxylation for Trem= 630 °C, which is in good agreement with the mass loss presented earlier (Figure 12). The radiant burner used herein to provide heating rates in the order of dT - 10 °C / s with exposure times of approximately 5 minutes to a temperature between 530 °C and 630 °C was found to improve Mg dissolution when compared to reference cases using heating rates of <1 °C / s with several hour long treatment times at the same temperature

[0013] or heating rates of >100 °C / s to temperatures of >800 °C

[0016] . It is considered that the rapid heating method to moderate temperatures (< 630 °C) may favour the formation of the initial a-phase compared to the other methods.

[0158] For Trem530 °C no clear peaks associated with forsterite (F) also appear, which would signify that the material is starting to recrystallise. The formation of crystalline forsterite has been shown to be detrimental for Mg dissolution, with the reordering of the mineral structure reducing the accessibility of Mg ions in the solution [16, 18]. Both the a-phase and the broad amorphous meta-serpentine hump still appear for Trem - 630 °C, although their presence is slightly reduced in comparison with the case for Trem - 530 °C.

[0159] Representative cross-sectional SEM images with EDS mapping for magnesium (Mg), oxygen (O), and silicon (Si) within the raw lizardite (a), the sample after heat treatment at 630 °C for 480 s (b), and the same sample after dissolution in carbonic acid for 120 minutes (c) are presented in Figure 14. Also shown in the rightmost column are the relative elemental compositions within the particles measured using the EDS, averaged over at least 30 particles for each sample

[0160] The mapping images show that initial distributions of Mg and Si are close to uniform throughout the raw particles (row a), except for iron -rich magnetite inclusions that are represented by the bright white regions within the particle. No significant change in Mg / Si ratio (~1:1) can be seen following heat treatment (row b). It is considered that evaporation of water and dehydroxylation of the lizardite are the primary changes expected to occur during the heating.

[0161] A significant decrease of Mg in the particle is observed for the particle that has undergone dissolution (row c), with the Mg / Si ratio decreasing to ~1:2 in some regions. The Mg appears to be extracted from edge of sample towards the core, with reactions towards the core of the particle being inhibited by the formation of silicon rich layer in the edge regions. The other heat-treated samples (not presented here) show similar trends, with those that have poor dissolution tending to have less penetration and fewer particles with the ‘darker’ edge regions indicative of low Mg concentration. Taken together, these results indicate that the amorphous phase produced following heat treatment at a temperature >530 °C, for an exposure time of 480 s, allows a greater proportion of Mg ions to be liberated before the dissolution is inhibited by the Si-rich crust.

[0162] Heating treatment of a goethite / hematite containing ore by means of high flux radiation and use of the product

[0163] Table 4 provides composition of the 4 to 4.7 mm particles that were taken from each sample for testing.Table 4

[0164] Thermal treatment

[0165] Heat treatment of the iron ore particles was performed using two methods with vastly different heating rates:- The radiant burner (RB), mainly featuring radiant heating, to provide heating rates of 6 °C / s to 25 °C / s;- The muffle furnace (MF), simulating convective heating, to provide relatively slow heating rates of about 0.5 to 1 °C / s.Both methods were used to heat up the ore samples in the range of about 400 °C to about 800 °C, with the particles removed from heating immediately after reaching the target temperature.

[0166] Radiant burner arrangement

[0167] The arrangement used for the radiant burner heat treatment of the iron ore particles is presented in Figure 2. A 5 kW* porous burner was operated with constant gas flow rates of air at 100 SLPM and natural gas at 8 SLPM. The particles to be heated were evenly spaced on a stainless-steel crucible, which was placed on a refractory brick. The entire particle system was mounted on a sliding platform to control insertion and removal from under the burner. Both the steady-state temperature of the particles and heating rate are strongly dependent on the distance between the particles and the burner. This is because radiation is the primary heat transfer mechanism during initial particle heating stage, which results in a highly non-linear relationship of temperature with heating time. Using a mechanical traverse, the distance between the burner and crucible can be controlled to within 0.5 mm. However, there are still slight variations in the distance between individual particles and the burner due to the variety of particle shapes that were retained. Additionally, particle shape variation leads to a difference in the ratio of the surface area that is radiatively heated to the particle volume. This can lead to significant variations in the steadystate temperature and heating rate between individual particles.

[0168] An infra-red (IR) camera (FLIR T540) was used to continually measure the surface temperature of the particles during the heat treatment. The temperature images were recorded at 30 Hz, with an emissivity value assumed to be 0.9 for each sample (Fluke Process Instruments 2023). The IR camera had a sensor size of 464 x 348 pixels, with a resulting spatial resolution of 2.7 px / mm in one direction and 1.1 in the other due to angled camera view. The temperature range of the sensor was required to be changed during experiments, with the 0-650 °C range used initially to determine heating rate then switched to the 300-1500 °C range for cases where the peak temperature was in excess

[0169] Muffle furnace

[0170] A Muffle furnace (Ward kilns) was used to heat the iron ore particles with a relatively low heating rate of about 0.5 to 1 °C / s. A thermocouple was inserted into a particle with a hole drilled halfway through it, in order to monitor the internal particle temperature during heating for the radiant burner calibration. The furnace heating elements were switched off immediately after the internal particle temperature reached the target temperature to prevent the temperature overshooting the target value. The furnace was left to cool to ambient temperature between runs to ensure consistent initial temperatures and heating rates.

[0171] Experimental matrix

[0172] The experimental matrix of cases investigated for sample A is presented in Table 5. Target particle temperatures were set to be in the range of 500 < 7as< 800 °C. Similar temperatures were used for the other samples, although the distance from the burner (x), heating rate (dTeo / dt), and total exposure time (texp) differed between the samples. It can be seen that the particle heating rate from the radiant burner was approximately one order of magnitude greater than that in the muffle furnace, and that the total exposure time required using the radiant burner is typically less than half than that of the muffle furnace.

[0173] Table 5: Experimental matrix detailing heat treatment parameters for each heating case, with representative heating rate and exposure time taken for sample A. Note RB = radiant burner, MF = muffle furnace.

[0174] Thermal camera image processing

[0175] The particle temperature profile over time was extracted from the IR camera images. For each case, a best guess for the locations of the particle centres was manually selected from the images. Thetemperature of each particle was then calculated from the average from a 5x5 -pixel region around each selected particle centre point, for each image. It should be noted that the temperature measured using the IR camera is representative only of the particle surface, not the average of the entire particle. As such the actual average particle temperature is likely to be slightly lower than the presented value, due to internal particle heat transfer and external losses from particle surfaces for which the temperature was not measured.

[0176] The temperature and heating rate of the particles was measured for a series of distances from the burner to determine the distance x required to reach the target conditions. This calibration was performed separately for each sample, using the same particle size range as in the experiments. A type K thermocouple with a 1 mm probe was inserted into a series of ~6 mm diameter particles with a 1.1 mm diameter hole drilled approximately halfway through them to monitor the internal particle temperature during the calibration.

[0177] Mineral analysis

[0178] The untreated and heat-treated samples were analysed using a series of different techniques to provide insight into the effect of heat treatment on iron ore. These techniques were:- X-ray diffraction (XRD), using a Rigaku MiniFlex 600 X-Ray Diffractometer with a scan region of 3-80°, step size 0.2°, and scan rate 107min, used to identify the mineral phases present within each sample. The XRD testing was performed on the samples after grinding to < 500 pm. Quantitative XRD was also performed for specific samples to allow the specific fractions of each phase to be measured.- Adsorption measurements were performed to determine the BET surface area of the samples, as well as the pore size distribution. A Micromeritics 3Flex adsorption analyser with N2 adsorption was used. The samples were held at 150 °C for 2 hours prior to the adsorption measurements for degassing.- X-ray fluorescence (XRF) of the samples was used to measure the mass fraction of iron, alumina, silica and other impurities.- The mass loss / loss on ignition (LOI) of the iron ore particles after the heat treatment was obtained from the LOI data to 1000 °C with XRF analysis (i.e., LOI heated sample = XRF LOI of untreated material - XRF LOI of treated material)- Reflected light photomicrographs and backscatter electron image technique from polished samples to assess impact of heating on mineralogy.

[0179] As an additional downstream beneficiation stage, Wet High-Intensity Magnetic Separation (WHIMS) of the thermally treated samples following grinding was performed in a two-stage process: first with a magnetic intensity of IT, then using a magnetic intensity of 2T on the material that was collected from the non-magnetic stream of the first stage.

[0180] Grinding energy calculation

[0181] Particle grindability is typically characterised by the diameter at which 80% of the ground material passes a sieve screen (dso). This was assessed for the present samples by grinding the 4-4.7 mm particles (untreated and following heat treatment) for a set time. The sample grinding was performed using a Retsch MM40 ball mill operating at a frequency of 20 cycles / second with a 16 mm stainless steel ball. A grinding time of 37, 45, and 60 seconds used for samples A, B, and C, respectively. The grinding time was varied for different samples because of the differences in material hardness, with the time selected following analysis of the grinding curve of dso against grinding time for the untreated material. After the grinding of the material was complete, the material was passed through a sieve stack containing 100, 500, 250, 125, 75, 63, and 45 pm screens. The mass of material retained in each stack was measured, and the results used to calculate dso- The total grinding energy and the net energy savings were calculated following a procedure developed by the University of Adelaide, and adapted from previous works in copper and nickel. From the knowledge of the Bond Work Index, Wi, for the raw ore, and the variation in dso with and without heat treatment, the Wi of the treated ore can be estimated as:where Wi,ris the Work Index (kWh / ton) of the raw ore, Wi,tis the Work Index of the treated ore, while Pr and Frrefer to the measured 80% passing size of the raw ore product and feed streams, respectively. Likewise, Ptand Ftrefer to the measured 80% passing size of the treated ore product and test ore feed streams, respectively. The electric power consumption of the grinding circuit was calculated as follows:where P was fixed at 6.3 mm and F was varied in the range of 25-150 microns. The energy consumed for grinding with and without heat treatment was obtained by difference, using the WI values with andwithout heat treatment. The overall heat requirement for the heating step was obtained from process modelling calculations using ASPEN Plus as illustrated in the subsequent section.

[0182] Results

[0183] Figure 15 presents dsofor the untreated (UT) ore, the muffle furnace (MF) heated ore, and the radiant burner (RB) heated ore for each sample as a function of heat treatment temperature. It can be seen that heat treatment within the temperature range investigated leads to a decrease in the dso, which is considered to be caused by the formation of cracks and the transformation from goethite to a softer, amorphous, non-crystalline hematite during heating. For sample A, dso slightly increases with increasing heat treatment temperature above 500 °C, potentially due to the formation of crystalline hematite and sintering. Conversely, dsofor sample C decreases with increasing temperature up to 800 °C, with little change from the untreated material observed for Ts,as600 °C. The measured dso for the ore treated using the radiant burner and muffle furnace is typically similar at comparable temperatures. This indicates that heating rate is less important than the ore temperature with regards to grinding energy reduction, for the range of temperature and heating rate assessed here.

[0184] Using the measured variation in dso, the specific grinding energy and its relative variation with and without heat treatment was calculated. Figure 16 presents the specific grinding energy for different targeted dso of the plant as a function of both heating rate and ore temperature. It can be seen that the specific grinding energy of the ore can reduce of up to 30% due to the heat treatment, with the effect being slightly augmented by performing the heating step under fast heating rates. Also, for the sample considered here (A), a targeted temperature value of 500 °C is optimal to minimise grinding energy requirements.

[0185] A basic energy assessment of the whole process was also performed. Figure 17 presents a comparison of the heat and grinding energy requirements for the process (in MW*), and also a comparison of the total energy requirements for scenarios where the heating is performed prior to grinding, and another in which the grinding step is followed by heating. Overall, it can be seen that a complete off-set (i.e., a net energy expenditure = 0) is not possible when comparing the amount of energy required for heating and the energy savings from grinding due to the thermal pre-treatment. Nevertheless, if heating is required, to both increase the Fe%, for instance via goethite dehydroxilation and / or to improve magnetic susceptibility, a fairer comparison is to compare the total energy requirement for heating followed by grinding in opposite to grinding following by heating. The analysis highlights that heating performed prior to grinding brings several benefits, with up to 30% net energy reduction in comparison with the scenario where the grinding is carried out upstream.

[0186] Mass loss

[0187] Figure 18 presents the mass loss on ignition (LOI%) of the material during heat treatment as a function of particle temperature, for each sample heat-treated using the muffle furnace and radiant burner. The loss of mass during heating occurs because of the evaporation of adsorbed water and dehydroxylation reaction during goethite to hematite conversion. The measured LOI% increases with increasing temperature due to the continuous nature of these reactions and temperature gradients within the particles, as the entirety of the particles are heated. For the temperature range investigated, LOI% from the radiant burner heating is significantly greater than that from the muffle furnace at similar temperatures for sample A (e.g., 6.0% compared to 3.1% at approximately 500 °C). Conversely, for sample B the values were similar, with a LOI of 4.7% for the muffle furnace and 5.3% for the radiant burner at approximately 500 °C. Potential reasons for the different LOI between the two heating methods are:- The rapid heating of the particles initiates crack formation and pore growth, allowing internal gases to more easily escape.- The rate of the dehydroxylation reaction increasing with increasing heating rate.- The spread of individual particle temperatures when heated using the radiant burner is significantly greater than that for muffle furnace, sometimes by up to 100 °C. However, this doesn’t account for the magnitude of the difference in LOI measured.- These samples were removed immediately after reaching the target temperature. A longer exposure time at the target temperature may lead to more complete evaporation / dehydroxylation in the muffle furnace.

[0188] Elemental analysis - XRF

[0189] Figure 19 presents the weight percentage of iron (Fe wt%, top) and gangue (AI2O3 + SiO2Wt%, middle) as well as the ratio of iron to gangue (bottom) as a function of heat treatment temperature for samples A and B heated using the muffle furnace and radiant burner, together with the reference Fe wt% of the untreated material (lines). For sample A, the Fe wt% increased from 54.1% to 57.0% and 58.3% following heating to -500 °C using the muffle furnace and radiant burner, respectively. The cases treated using the radiant burner having a greater Fe wt% than those treated in the muffle furnace is consistent with the assumption that the change in composition is primarily due to the loss of water mass, as presented in Figure 18. Sample C exhibits a smaller change in Fe wt% than sample A, increasing from 57.2% to 58.4% following heating to 515 °C using the radiant burner, consistent with the fact that this ore features a much lower goethite presence in comparison with samples A and B. The results for Sample Bare significantly different from those of the other samples, with an increase in Fe wt% and decrease in AI2O3 + SiOz wt% following heating. This is possibly due to the heat treatment causing sample B particles to explode, leading to a difference in the compositions of particles that remain to be collected for analysis.

[0190] Mineral composition - XRD

[0191] Figure 20 presents the qualitative XRD spectra of sample A before and after heat treatment for select cases. The letters G and H that are overlaid on the plot correspond to peaks related to goethite and hematite, respectively

[0023] . The strong goethite peaks that can be seen in the spectrum for the untreated material are not present in heat treated sample, indicating complete transformation of goethite to hematite by 500 °C. This is supported by quantitative XRD results, which show complete transformation of the initial goethite to hematite (or into an amorphous phase) following heat treatment to 500 °C for each case except for sample A heated in the muffle furnace. The transformation to hematite is a typical step required for the processing of goethite and is also beneficial for magnetic separation of the iron bearing material. No significant further changes in the XRD spectra can be seen with increasing temperature from 500 °C to 663 °C. Similar considerations were found for samples B and C.

[0192] Surface area and pore volume

[0193] Figure 21 presents the specific surface area of the untreated and heat-treated iron ore as a function of temperature, for samples A and B. The samples were ground to < 250 pm particles prior to the measurement. The specific surface area of heat-treated material is significantly greater than that of the untreated for each heat treatment case for samples A and B. For sample A treated at -500 °C, the surface area increases from 12.5 m2 / g to 54.4 and 70.5 m2 / g for the muffle furnace and radiant burner, respectively. Conversely, for sample C there is no significant change in the surface area with heat treatment in the range of 500 to 800 °C. For sample A, the surface area decreases with increasing temperature for T,.as> 500 °C, down to 44 m2 / g at T,.as- 794 °C. This is attributed to increased crystallisation and sintering of the hematite with increasing temperature. The increased surface area of the heat-treated material is mainly attributed to the formation of pores during the phase transformation of goethite. The minor change in SSA for sample C is again consistent with the relative low amount of goethite in this sample in comparison with samples A and B.

[0194] Figure 22 presents the incremental pore volume as a function of pore width for the untreated and heat-treated samples. It can be seen that heat treatment increases the total pore volume, with the maximum volume increasing with increasing temperature for sample A. The peak pore width also grows with increasing temperature, from 2.5 nm at 523 °C to 3.2 nm at 663 °C. The volume of pores with a width of less than 4 nm is significantly greater for radiant burner than muffle furnace heat treatment forsample A, while for sample B the pore width distribution remains similar although with a greater volume for the muffle furnace treated material. Sample C exhibits little change in the pore distribution with heat treatment, consistent with the surface area results.

[0195] Photomicrograph and SEM-EDS analysis

[0196] Examination in reflected light and scanning electron microscopy has shown no substantial differences in the mineralogy of samples before and after heat treatment. There has been no transformation of any phase into another and there is no obvious evidence for mineral recrystallization.

[0197] Upon heating, vitreous goethite undergoes a marked fracturing linked to partial dehydration, rendering it more brittle and more readily milled. Radial fractures are, however, largely confined to distinct compositional domains rather than pervasive, an observation probably related to different degrees of crystallinity in discrete compositional zones, or alternatively to differential rates of healing during cooling depending on impurity content.

[0198] Although investigation has focused on samples tested at the highest temperatures, there is no visibly different response to the range of temperatures used. All heated samples display the same fracturing, whereas untreated samples do not.

[0199] Both samples are highly heterogeneous in terms of textures. In sample A, phosphorus occurs within vitreous goethite and as disseminated fine grains of fluorapatite. Lesser amounts of fluorapatite are seen in Sample B. There is no change in P speciation in response to heat treatment. Phosphorus cannot be lost from the sample as a result of heat treatment as the minerals containing it are not modified, only fractured. Silica and aluminium are present as quartz and kaolinite but can also reach concentrations of several wt.% in goethite.

[0200] Figure 23 presents reflected light photomicrographs of sample A being radiantly heated at 700 °C (A), (B) and sample B being radiantly heated at 500 °C (C), (D). Pervasive fracturing of vitreous goethite is visible and fracturing is most pronounced in coarser, compositionally heterogeneous vitreous goethite, particular in the larger orbicular grains. Fracture networks can be confined to discrete compositional domains but can also crosscut compositional boundaries (e.g., B).

[0201] Magnetic separation

[0202] Figure 24 presents the Fe wt %, gangue wt% (AI2O3 + S i O2J and Fe recovery % of the magnetic material recovered from each stage of the WHIMS process, for the untreated material and that heated to 500 °C in the muffle furnace and radiant burner. The results from both the first stage separation (top) and combined first and second stages (bottom) are presented (a schematic of the WHIMS test is shown inFigure 26). It can be seen that the Fe wt% of the untreated samples increases following WHIMS, most significantly for sample B. Combining the heat treatment at 500 °C using the radiant burner with the two- stage WHIMS process leads to an increase in Fe wt% for sample A from 54.1% to 60% (58.3% after heat treatment alone) with a total iron recovery of 85.7%. A similar increase in the iron content of the collected material can be seen for samples B and C. Importantly, the gangue fraction for each case also decreases following WHIMS, with a larger relative decrease in gangue for the heat-treated samples than untreated. To note that the dwo prior to WHIMS was set at 500pm for all cases, with the majority of the grinded product being in the range 125~300pm.

[0203] The flow diagram for the beneficiation processes investigated is presented in Figure 25, with the representative mass retained and content fractions displayed from sample A. Overall, it can be seen that after heat treatment and one stage of WHIMS the iron content increased from 54.1 % for the raw ore to 60.0%, a combined AI2O3 plus SiO content of 10% (corresponding to some 20% reduction in gangue), and with 63.2% of the total initial mass remaining. For the first WHIMS step, the corresponding Fe recovery is 70%. This recovery can be significantly increased by including the second stage of WHIMS on the non-magnetic feed, achieving an overall Fe recovery of 86.5%, although with a slight decrease in the Fe wt% (59.7%).

[0204] In summary, some key outcomes from the experiments with iron ores are as follows:Thermally treated ores (under neutral roasting environment) feature an increase in Fe% via dehydroxilation of goethite to hematite. Other phases / minerals seem not to be significantly altered by the heating step for the conditions analysed to date. The heating step was also found to significantly improve the susceptibility and response of the selected ores to magnetic separation (WHIMS), in terms of Fe%, gangue removal and Fe recovery. A reduction of up 30% in Al and Si for thermally treated ores was measured, with over 85% Fe recovery and a maximum Fe% of some 60.5%, which correspond to about 6~10 Fe% increase in comparison with the initial Fe%.Moderate temperatures (for example, 500-700 °C) was found to be sufficient to drive the beneficiation process. Although higher temperatures were found to increase Fe% further, the majority of the assessments were carried out at 500 °C, as above this temperature the additional increase in Fe% from the heating step was found to be relatively small. A mass loss in the range 4-8% was measured for all samples after heat treatment, due to mainly goethite dehydroxilation and, in minor degree, to kaolin dehydroxilation.The heating rate can be selected to have a significant influence on the grindability of the ore, with XRF analysis also showing a slightly improvement in Fe% upgrading when the ores were subjected to radiative heating in comparison with slow heating conditions for the same operatingtemperature. In particular, heating was found to initiate cracking formation via both thermal stresses and goethite dehydroxilation (also leading to cracking via steam release), especially at higher heating rates. For goethite -rich samples (A, B), it was also found that the transformation from goethite into hematite leads to an 8 -fold increase in the surface area, for temperatures in the range 400-500 °C. Conversely, for sample C, both the specific surface area and pore size distribution of the treated and untreated ores were similar, indicating that the transformation of the samples is strongly dependent on the initial composition and mineralogy. Analysis of grinding data revealed that an up to 30% reduction in grinding energy is potentially achievable due to ore softening associated with the thermal treatment, which translates into some 20% net energy savings when comparing a scenario in which the heating is carried out prior to grinding, and another in which the heating is performed after the grinding step.

[0205] Heating treatment of a magnesite containing ore by means of high flux radiation and analysis of the product

[0206] Magnesite sample preparation

[0207] The magnesite ore used in this study is composed primarily of MgCO ? and had a broad particle size distribution ranging from sub 45 pm to 8 mm. The majority of the mass in the size distribution is within the 500-1000 pm size range. This size range was therefore chosen as the preferred particle size and selected, by electronic sieving, to avoid any possible influence of variations in particle size in the assessments. Table 6 provides the composition of magnesite ore, indicating that it is mainly composed of magnesium carbonate (MgCOs).

[0208] Table 6Note: LOI is a loss in ignition at 1000 °C.

[0209] Heating treatment

[0210] The magnesite containing ore samples were heat treated using a radiant energy of 50 kW / m2using the burner shown in Figure 2. The samples were placed in SS304 crucibles with dimensions of 75 mm (L) x 25 mm (W) x 3 mm (H) and positioned on a plate under a radiant burner fuelled by CNG, to expose the samples to the radiation energy.

[0211] The temporal history of the surface temperature of the samples was monitored using a thermal camera. The measurements of the thermal camera were validated against measurements with a K-type thermocouple (Testo) inserted into the bed. The samples were then exposed to the radiation energy for varying total exposure times (texp) ranging from 30 to 1920 s. To obtain different heating rates for a given final temperature, the samples were exposed to radiation energy until they reached the desired final temperature. The magnesite samples were heated to various temperatures, specifically 760 °C, 934 °C, 1037 °Cand 1079 °C, for each experiment.

[0212] A sample size of 1.5 g was used with a bed thickness of approximately 1 particle to minimize the resistance to heat and mass transfer across the bed. This was determined by evaluating the equivalent Biot number, Bi, which ranged from 0.007 to 0.04 (Bi << 0.1), which is sufficiently low to ensure that all of the material in the sample has a similar heating rate.

[0213] Table 7 also presents a series of heating rates, their corresponding ratios and characteristic times. It can be seen that the experiments can be classified into two distinct regimes, based on the ratio of T40 characteristic heating to reaction times, » which is analogous to the Damkholer number. The firstdT40 regime pertains to higher heating rate experiments (59 °C / s <dt< 180 °C / s), while the second regime dT40 corresponds to the low heating rate experiments conducted using TGA (— = 0.1 °C / s).

[0214] Table 7760 244.1 47.3 3,1 300 59,2 0.02934 271,5 60,7 4,9 90 76.8 0.051037 315.7 70.1 4.0 76 102.9 0.051079 350,7 78,0 2.4 65 179,9 0.04TGA 900 0.1 0,1 3944 6612 0.1 0.60

[0215] Magnesite calcination reaction

[0216] Figure 27 presents the measured conversion fraction, X, of magnesite as a function of the dT40 sample temperature, Ts(Figure 27 A), and exposure time, texp(Figure 27B), for a series of . It can beseen that the conversion fraction of magnesite samples increases with the surface temperature for a given dT40, as expected. For a heating rate of 179.9 °C / s, for instance, the conversion increases from 0.42 for Ts= 900 °C to 0.75 for Ts= 1022 °C. However, the conversion is higher for a lower °C with a giventemperature, which is clearly illustrated in Figure 28. These finding isolate the different effects of heating rate and temperature for magnesite both of which influence conversion.

[0217] Figure 28 presents the measured conversion fraction, X, of magnesite samples calcined to a dT40 final temperature of 900 °C, as a function of . The time required for the sample temperature to reachdT40900 °C for different values ofis denoted in the legend as T9OO °C- It can be seen that for a given temperature, the conversion is higher for a lower heating rate. For example, a 2.1 -fold reduction in X, dT40 from 0.89 to 0.42, was observed upon increasing the — by a factor of 2.3, from 76.8 °C / s to 179.9 °C / s.This illustrates the complex interplay between the heating rate and the residence time in the progress of calcination, represented by conversion.

[0218] Moreover, Figure 28 demonstrates that longer exposure times to reach 900 °C result in higher conversion fractions, highlighting the significance of both the heating rate and the exposure time above the onset temperature of calcination. The trend observed indicates that slower heating rates provide sufficient time for the reaction to proceed, leading to higher conversion levels. Conversely, faster heating rates result in a shorter residence time and limited reaction progress, resulting in lower conversion levels. These findings provide insight into the calcination behaviour of magnesite under heating rates that help optimizing the process for industrial calciners.

[0219] Specific surface area

[0220] Figure 29 presents the specific surface area (SSA) of magnesite samples calcined at different heating rates but to the same final temperature. It is clear that the SSA for samples calcined at high dT40 dT40 heating rates = 76.8 °C / s ~ 179.9 °C / s) is higher than that for the low heating rate case- dT400.1 °C / s). For example, upon increasing from the low (0.1 °C / s) to the high (76.8 °C / s) heating rate,the SSA increased by a factor of 6.2, from 14.1 m2 / g to 87.5 m2 / g. Notably, these two points have similar conversion fractions. The increase in SSA observed with the high heating rate compared with the low heating rate can be attributed to the microcracks developed within the magnesite particles. Figure 29 also shows that for samples calcined for a given final temperature, the SSA decreases upon increasing the heating rate from 76.8 °C / s to 102.9 °C / s and then to 179.9 °C / s. This decrease can be explained by the achieved conversion fraction at those heating rates for a 900 °C surface temperature.

[0221] Figure 30 presents the average pore size and total pore volume of magnesite calcined to a given final temperature of 900 °C, as a function of the heating rate. It is clear that both pore volume and pore size initially increase as the heating rate increases from low (0.1 °C / s) to high (76.8 °C / s), consistent withthe findings in Figure 29. Specifically, the total pore volume increased by a factor of 7.3, from 0.03 cm3 / g to 0.22 cm3 / g, and the average pore size increased by a factor of 1.1, from 9.0 nm to 10.1 nm, as the heating rate increased from a low (0.1°C / s) to a high (76.8 °C / s) heating rate. Figure 30 also shows that pore size and pore volume decrease as the heating rate is increased from 76.8 °C / s to 102.9 °C / s and then to 179.9 °C / s, which can be explained by the variation in conversion fraction, as discussed for Figure 29.

[0222] Figure 31 presents the measured specific surface area (SSA) of magnesite calcined at different heating rates and different corresponding asymptotic temperatures. The exposure time was varied to achieve similar values of the conversion fraction (~ 0.83) for the high heating rate experiments (59.2- 179.9 °C / s). The similar conversion fractions were obtained to ensure that the samples contained similar levels of MgO, allowing for a more accurate comparison of the effect of the heating rate on the SSA. It can be seen that the SSA of magnesite calcined at a high heating rate (59.2-179.9 °C / s) is higher than that of the low heating rate experiments (0.1 °C / s). For instance, the SSA increased by a factor of 8.7, from 14.1 m2 / g to 123.2 m2 / g, as the heating rate increased from a low (0.1°C / s) to a high (59.2 °C / s) heating rate. This can be attributed to the formation of microcracks in magnesite particles due to the higher heating rate, which in turn increases the SSA. Figure 31 also shows that the SSA decreases as the heating rate is increased from 59.2 °C / s to 76.8, 102.9, and 179.9 °C / s. This can be attributed to the sample temperatures exceeding 950 °C at these heating rates, which led to sintering occurring at varying levels. It can be concluded that the highest SSA is achieved at a heating rate of 59.2 °C / s because the sample temperature is below 950 °C, minimizing sintering, and the heating rate is high enough to induce microcracks in the particles.

[0223] The following are examples of application of methods, products and uses described herein.

[0224] Example 1 - A method of treating a material comprising a mineral, which comprises subjecting the material to radiant heating.

[0225] Example 2 - The method according to example 1 , wherein the mineral is a hydrous mineral and the material is a material comprising a hydrous mineral.

[0226] Example 3 - The method according to either example 1 or example 2, wherein the material comprising a mineral is one or more selected from the group consisting of the mineral, ores comprising the mineral, rocks comprising the mineral, and soils comprising the mineral.

[0227] Example 4 - The method according to any one of examples 1 to 3, wherein the radiant heating is a pre-treatment prior to a downstream process.

[0228] Example 5 - The method according to example 4, wherein the downstream process is selected from the group consisting of a comminution circuit, a dissolution process, and a carbonation process.

[0229] Example 6 - The method according to any one of examples 1 to 5, wherein the radiant heating is conducted under conditions so that a physical change and / or a chemical change occurs to the material comprising a mineral compared to the one without being subjected to the radiant heating.

[0230] Example 7 - The method according to any one of examples 1 to 6, wherein the radiant heating is conducted under conditions so that a structural change and / or a compositional change occurs to the material comprising a mineral compared to the one without being subjected to the radiant heating.

[0231] Example 8 - The method according to any one of examples 1 to 7, wherein the material subjected to the radiant heating has a mineral in crystalline state and the mineral in crystalline state turns into amorphous state after the radiant heating.

[0232] Example 9 - The method according to any one of examples 1 to 8, wherein the radiant heating is conducted so that the activation energy of a mineral contained by the material is lowered.

[0233] Example 10 - The method according to any one of examples 1 to 9, wherein the radiant heating is conducted so that the specific surface area of the material comprising a mineral is increased.

[0234] Example 11 - The method according to any one of examples 1 to 10, wherein the radiant heating is conducted so that chemically bound hydroxy groups or water molecules comprised by the material are destabilised and removed.

[0235] Example 12 - The method according to any one of examples 1 to 11, wherein the radiant heating is conducted so that the specific grinding energy required for a subsequent particle size reduction of the material is reduced.

[0236] Example 13 - The method according to any one of examples 1 to 12, wherein the radiant heating is conducted so that different minerals contained by the material are expanded at different rates when being rapidly heated and are separated afterwards.

[0237] Example 14 - The method according to any one of examples 1 to 13, wherein the radiant heating is conducted so that the particle distribution of the material after the radiant heating is adjusted and / or optimised.

[0238] Example 15 - The method according to any one of examples 1 to 14, wherein the radiant heating is conducted so that the material comprising a mineral is upgraded (for example, with an increased content of an element of interest).

[0239] Example 16 - The method according to any one of examples 1 to 15, wherein the radiant heating is conducted so that the mineral contained by the material is activated.

[0240] Example 17 - The method according to any one of examples 1 to 16, wherein the radiant heating is conducted so that a calcined product or a beneficiated product is produced from the material comprising a mineral.

[0241] Example 18 - The method according to any one of examples 1 to 17, wherein the radiant heating is a radiant heating with a high flux intensity.

[0242] Example 19 - The method according to any one of examples 1 to 18, wherein the radiant heating is a rapid radiant heating.

[0243] Example 20 - The method according to any one of examples 1 to 19, wherein the radiant heating is a uniform radiant heating.

[0244] Example 21 - The method according to any one of examples 1 to 20, wherein the radiant heating is conducted within a flameless environment.

[0245] Example 22 - The method according to any one of examples 1 to 21, wherein the radiant heating has a uniform heating flux at the point source in the range of about 0.3 MW / m2to about 3 MW / m2.

[0246] Example 23 - The method according to example 22, wherein the radiant heating has a mean radiation intensity of about 0.5 MW / m2.

[0247] Example 24 - The method according to any one of examples 1 to 23, wherein the radiant heating is carried out by means of 1) a combustion radiant heating source; 2) an electric radiant heating source and / or 3) concentrated solar thermal energy.

[0248] Example 25 - The method according to example 24, wherein the combustion radiant heating source is selected from the group consisting of an infrared burner, a premixed or partially premix radiant burner, and a self-recuperative radiant tube.

[0249] Example 26 - The method according to example 24, wherein the electric radiant heating source is an electric resistance heater, for example an electrical radiant tube heater.

[0250] Example 27 - The method according to any one of examples 1 to 24, wherein the radiant heating is carried out by means of a burner, for example a flat burner, such as a flat porous burner.

[0251] Example 28 - The method according to any one of examples 1 to 27, wherein the material is radiantly heated to a temperature in the range of about 300 °C to about 1200 °C.

[0252] Example 29 - The method according to any one of examples 1 to 28, wherein the material is radiantly heated to a temperature in the range of about 500 °C to about 700 °C, for example about 530 °C to about 630 °C.

[0253] Example 30 - The method according to any one of examples 1 to 28, wherein the material comprising a mineral is a kaolinite containing material, it is radiantly heated to a temperature in the range of about 600 °C to about 800 °C.

[0254] Example 31 - The method according to any one of examples 1 to 28, wherein the material comprising a mineral is a magnetite containing material, it is radiantly heated to a temperature in the range of about 500 °C to about 900 °C.

[0255] Example 32 - The method according to any one of examples 1 to 28, wherein the material comprising a mineral is a goethite and / or hematite containing material or a pisolitic iron containing material, it is radiantly heated to a temperature in the range of about 300 °C to about 800 °C, for example in the range of about 500 °C to about 600 °C.

[0256] Example 33 - The method according to any one of examples 1 to 28, wherein the material comprising a mineral is a copper ore and / or a nickel ore, it is radiantly heated to a temperature in the range of about 400 °C to about 800 °C.

[0257] Example 34 - The method according to any one of examples 1 to 33, wherein the radiant heating is carried out at a heating rate of about 5 °C / s to about 1000 °C / s, for example about 10 °C / s to about 1000 °C / s.

[0258] Example 35 - The method according to example 34, wherein the radiant heating is carried out at a heating rate in the range of about 50 °C / s to about 1000 °C / s.

[0259] Example 36 - The method according to example 34, wherein for the material with a particle size of less than about 300 pm, the radiant heating is carried out at a heating rate in the range of about 300 °C / s to about 1000 °C / s.

[0260] Example 37 - The method according to example 34, wherein for the material with a particle size of about 300 pm to about 1000 pm, the radiant heating is carried out at a heating rate in the range of about 50 °C / s to about 300 °C / s.

[0261] Example 38 - The method according to example 34, wherein for the material with a particle size of more than about 1000 pm (for example more than about 10,000 pm or more than about 20,000 pm), the radiant heating is carried out to allow the surface layer of the material to be heated at about 10 °C / s to about 1000 °C / s.

[0262] Example 39 - The method according to any one of examples 1 to 38, wherein the total exposure time for the material to be subjected to radiant heating is no more than about 30 minutes.

[0263] Example 40 - The method according to example 39, wherein the total exposure time for the material to be subjected to radiant heating is no more than about 10 minutes.

[0264] Example 41 - The method according to example 40, wherein the total exposure time for the material to be subjected to radiant heating is no more than about 5 minutes, such as about 100 seconds.

[0265] Example 42 - The method according to example 41, wherein the total exposure time for the material to be subjected to radiant heating is no more than about 1 minute, for example no more than about 10 seconds or no more than 1 second.

[0266] Example 43 - The method according to any one of examples 1 to 42, wherein the radiant heating is carried out at a distance between a radiant heating surface and the material to be heated that is between 5% and 25% of the width of a supporting surface (such as a conveying belt).

[0267] Example 44 - The method according to any one of examples 1 to 43, wherein, in conducting the radiant heating, particles of the material comprising a mineral are distributed over a supporting surface at a thickness of about 1 to 10 times the largest particle size of the material to be treated, for example, about 2 to 10 times, about 3 to 10 times, or about 5 to 10 times.

[0268] Example 45 - The method according to any one of examples 1 to 44, wherein, in conducting the radiant heating, when the diameter of the largest particles is larger than about 2 mm, particles of the material are distributed over a supporting surface at a thickness of about 3 to 10 times, for example about 5 to 10 times the largest particle size of the material to be treated.

[0269] Example 46 - The method according to any one of examples 1 to 45, wherein, in conducting the radiant heating, when the diameter of the largest particles of the material is no more than about 1 mm, particles of the material comprising a mineral are distributed over a supporting surface at a thickness of about 0.5 mm to about 5 mm (for example, about 0.5 mm to about 3 mm), and when the diameter of the largest particles of the material is more than about 1 mm, particles of the material are distributed over a supporting surface at a thickness of about 1 to 10 times (for example, about 1 to 5 times, or about 5 to 10 times) of the largest particle size of the material to be treated.

[0270] Example 47 - The method according to any one of examples 1 to 46, wherein the material subjected to the radiant heating comprises one or more hydrous mineral.

[0271] Example 48 - The method according to any one of examples 1 to 47, wherein the material subjected to the radiant heating is rich in a hydrous mineral.

[0272] Example 49 - The method according to either example 47 or example 48, wherein the material subjected to the radiant heating comprises the hydrous mineral in an amount of about 5 wt% to about 80 wt% based on the total weight of the material.

[0273] Example 50 - The method according to any one of examples 1 to 49, wherein the material subjected to the radiant heating comprises or consists of iron ore (for example, a low-grade iron ore), bauxite ore, copper ore, nickel ore, magnesium ore, calcium ore, aluminium ore, and / or lithium ore.

[0274] Example 51 - The method according to any one of examples 1 to 50, wherein the material subjected to the radiant heating is in the form of raw ore and / or waste / tailings.

[0275] Example 52 - The method according to example 51, wherein the aluminium ore comprises or consists of bauxite ore.

[0276] Example 53 - The method according to example 51, wherein the magnesium ore comprises or consists of serpentinite ore.

[0277] Example 54 - The method according to example 51, wherein the magnesium ore comprises a silicate mineral (such as serpentine and olivine) and / or a carbonate mineral.

[0278] Example 55 - The method according to example 51, wherein the copper ore comprises malachite.

[0279] Example 56 - The method according to example 51, wherein the nickel ore comprises a serpentine group mineral.

[0280] Example 57 - The method according to example 51, wherein the material subjected to the radiant heating is a goethite-rich ore or a hematite -rich ore.

[0281] Example 58 - The method according to example 51, wherein the material subjected to the radiant heating is a hydrous magnesium silicate ore.

[0282] Example 59 - The method according to any one of examples 1 to 58, wherein the mineral is a hydrous mineral and the hydrous mineral is one or more selected from the group consisting of goethite (FeO(OH)); (hydrous) hematite (for example, having a formula of 2Fe2O3-H2O); (hydrous) forsterite (for example, having a formula of Mg2 xSiCEFfcx); antigorite (an idealised formula thereof: Mg3Si2Os(OH)4); lizardite (an idealised formula thereof: Mg3Si2Os(OH)4); chrysotile (an idealised formula thereof: Mg3Si2Os(OH)4); muscovite (KA12(AlSi3Ow)(OH)2); biotite (K(Mg,Fe)3AlSi3Ow(OH)2); bischofite (MgC12- 6H2O); epsomite (MgSCh-TFLO); gypsum (CaSO4-2H2O); brucite (Mg(0H)2); (hydrous) aragonite; (hydrous) spodumene (for example, having a formula of 2[LiAlSi2C>62H2O]); (hydrous) magnesite (for example, having a formula of 3MgCO3-Mg(OH)2-3H2O or MgCChAtEO); gibbsite (Al(0H)3); boehmite (A10(0H)); diaspore (A10(0H)); bayerite (Al(0H)3); doyleite (Al(0H)3); nordstrandite (Al(0H)3); kaolinite (A12Si2C>5(OH)4); epidote (Ca2(Fe,Al)3(SiO4)3(OH)); and malachite (CU2CO3(OH)2).

[0283] Example 60 - The method according to any one of examples 1 to 59, wherein the material subjected to the radiant heating is in the form of particle.

[0284] Example 61 - The method according to example 60, wherein the particles of the material have an average size of about 1 pm to about 50,000 pm, for example about 1 pm to about 20,000 pm, or about 1 pm to about 10,000 pm.

[0285] Example 62 - The method according to example 61, wherein the particles of the material have an average size of about 1 pm to 500 pm, for example 45 pm to about 500 pm.

[0286] Example 63 - The method according to example 61, wherein the particles of the material have an average size of about 500 pm to 1,000 pm.

[0287] Example 64 - The method according to example 61, wherein the particles of the material have an average size of about 1,000 pm to 20,000 pm, for example, greater than 1,000 pm and no more than 8,000 pm.

[0288] Example 65 - The method according to example 61, wherein the particles of the material have an average size of about 500 pm to 10,000 pm for reducing specific grinding energy required for a subsequent reduction of particle size of the material.

[0289] Example 66 - The method according to any one of examples 1 to 50 and examples 59 to 65, wherein the material subjected to the radiant heating is a lizardite (MgsSizOs OH)^ containing material.

[0290] Example 67 - The method according to example 66, wherein the particles of the lizardite containing material have a size of about 10 pm to about 150 pm.

[0291] Example 68 - The method according to either example 66 or example 67, wherein the lizardite containing material is radiantly heated to a temperature of no more than 630 °C, for example between about 530 °C to about 630 °C.

[0292] Example 69 - The method according to any one of examples 66 to 68, wherein the lizardite containing material is radiantly heated at a rate of about 10 °C / s to about 25 °C / s, for example about 10 °C / s to about 20 °C / s, or about 10 °C / s to about 15 °C / s.

[0293] Example 70 - The method according to any one of examples 66 to 69, wherein the lizardite containing material is subjected to radiant heating for a total exposure time of no more than about 10 minutes, for example no more than about 8 minutes, or about 5 minutes to about 8 minutes.

[0294] Example 71 - The method according to any one of examples 66 to 70, wherein the lizardite containing material is radiantly heated at a rate of about 10 °C / s to about 20 °C / s to a temperature between about 530 °C to about 630 °C for an exposure time of about 480 seconds.

[0295] Example 72 - The method according to any one of examples 1 to 50 and examples 59 to 65, wherein the material subjected to the radiant heating is a goethite and / or hematite containing material.

[0296] Example 73 - The method according to example 72, wherein particles of the material have an average size of no more than about 5 mm, for example about 4 mm to about 5 mm.

[0297] Example 74 - The method according to either example 72 or example 73, wherein the material comprises Fe in an amount of less than about 60 wt%.

[0298] Example 75 - The method according to any one of examples 72 to 74, wherein the goethite and / or hematite containing material is radiantly heated to a temperature between about 400 °C to about 800 °C, for example about 500 °C to about 800 °C.

[0299] Example 76 - The method according to any one of examples 72 to 75, wherein the goethite and / or hematite containing material is radiantly heated at a rate of about 10 °C / s to about 100 °C / s, for example about 10 °C / s to about 50 °C / s, or about 10 °C / s to about 20 °C / s.

[0300] Example 77 - The method according to any one of examples 72 to 76, wherein the goethite and / or hematite containing material is subjected to radiant heating for a total exposure time of no more than about 20 minutes, for example no more than about 10 minutes, or about 3 minutes to about 8 minutes.

[0301] Example 78 - The method according to any one of examples 72 to 77, wherein the goethite and / or hematite containing material is radiantly heated at a rate of about 10 °C / s to about 20 °C / s to a temperature between about 400 °C to about 800 °C for a total exposure time of about 5 minutes to about 20 minutes.

[0302] Example 79 - The method according to any one of examples 1 to 50 and examples 59 to 65, wherein the material subjected to the radiant heating is a magnesite containing material.

[0303] Example 80 - The method according to example 79, wherein the particles of the material have an average size of no more than about 10 mm, for example from about 500 pm to about 1000 pm.

[0304] Example 81 - The method according to either example 79 or example 80, wherein the magnesite containing material is radiantly heated at a rate of about 30 °C / s to about 100 °C / s.

[0305] Example 82 - The method according to either example 79 or example 81, wherein the magnesite containing material is radiantly heated to a temperature of less than about 950 °C.

[0306] Example 83 - The method according to either example 79 or example 82, wherein the magnesite containing material is radiantly heated for a total exposure time of no more than 5 minutes.

[0307] Example 84 - A product obtained or obtainable by the method of according to any one of the preceding examples.

[0308] Example 85 - Use of radiant heating in inducing a physical change and / or a chemical change to a material comprising a mineral compared to the one without being subjected to the radiant heating.

[0309] Example 86 - Use of radiant heating in inducing a structural change and / or a compositional change to a material comprising a mineral compared to the one without being subjected to the radiant heating.

[0310] Example 87 - Use of radiant heating in lowering the activation energy of calcination reaction of a mineral comprised by a material.

[0311] Example 88 - The use according to example 87, wherein the material comprising a mineral is a magnesite containing material.

[0312] Example 89 - The use according to example 88, wherein the activation energy of magnesite calcination reaction is lowered when the heating rate of the radiant heating is increased.

[0313] Example 90 - The use according to either example 88 or example 89, wherein the activation energy of magnesite calcination reaction is lowered from 220.8 kJmol1to 166.6 kJmol1when the heating rate of the radiant heating is increased from 0.1 °C / s to 102.9 °C / s.

[0314] Example 91 - Use of radiant heating in increasing the specific surface area of a mineral comprised by a material.

[0315] Example 92 - The use according to example 91, wherein the material comprising a mineral is a magnesite containing material.

[0316] Example 93 - The use according to either example 91 or example 92, wherein the specific surface area of the material comprising a mineral is increased when the heating rate of the radiant heating is increased.

[0317] Example 94 - The use according to either example 92 or example 93, wherein the magnesite containing material is radiantly heated at a rate of about 59.2 °C / s to a temperature of less than about 950 °C.

[0318] Example 95 - Use of radiant heating in destabilising and removing chemically bound hydroxy groups or water molecules comprised by a mineral of a material.

[0319] Example 96 - Use of radiant heating in reducing the specific grinding energy required for a subsequent reduction of particle size of a material comprising a mineral.

[0320] Example 97 - Use of radiant heating in allowing different minerals contained by a material to expand at different rates when being rapidly heated and to be readily separated afterwards.

[0321] Example 98 - Use of radiant heating in adjusting and / or optimising the particle distribution of a material comprising a mineral after the radiant heating.

[0322] Example 99 - Use of radiant heating in upgrading a material comprising a mineral, for example a low-grade iron ore.

[0323] Example 100 - The use according to example 99, wherein the upgrading lies in the content of Fe being increased, the magnetic susceptibility being increased, and / or gangue removal with a high Fe recovery (for example > 70 wt%) being enabled.

[0324] Example 101 - Use of radiant heating in producing a calcined product or a beneficiated product from a material comprising a mineral.

[0325] Example 102 - The use according to any one of examples 85 to 101, wherein the mineral is a hydrous mineral and the material is a material comprising the hydrous mineral.

[0326] Example 103 - The use according to any one of examples 85 to 102, wherein the material is one or more selected from the group consisting of the mineral, ores comprising the mineral, rocks comprising the mineral, and soils comprising the mineral.REFERENCES

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[0354] It will be understood that the terms “comprise” and “include” and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0355] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0356] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and / or features described or depicted herein.It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. A method of treating a material comprising a mineral, which comprises subjecting the material to radiant heating.

2. The method according to claim 1, wherein the mineral is a hydrous mineral and the material is a material comprising a hydrous mineral.

3. The method according to either claim 1 or claim 2, wherein the material comprising a mineral is one or more selected from the group consisting of the mineral, ores comprising the mineral, rocks comprising the mineral, and soils comprising the mineral.

4. The method according to any one of claims 1 to 3, wherein the radiant heating is a pre-treatment prior to a downstream process.

5. The method according to claim 4, wherein the downstream process is selected from the group consisting of a comminution circuit, a dissolution process, and a carbonation process.

6. The method according to any one of claims 1 to 5, wherein the radiant heating is a rapid and uniform radiant heating.

7. The method according to any one of claims 1 to 6, wherein the radiant heating is conducted within a flameless environment.

8. The method according to any one of claims 1 to 7, wherein the mineral is a hydrous mineral and the hydrous mineral is one or more selected from the group consisting of goethite (FeO(OH));(hydrous) hematite (for example, having a formula of 2Fe2O3-H2O); (hydrous) forsterite (for example, having a formula of Mg2xSiO4H2x); antigorite (an idealised formula thereof: Mg3Si2Os(OH)4); lizardite (an idealised formula thereof: Mg3Si2Os(OH)4); chrysotile (an idealised formula thereof: Mg3Si2Os(OH)4); muscovite (KA12(AlSi3Ow)(OH)2); biotite (K(Mg,Fe)3AlSi3Ow(OH)2); bischofite (MgCF-hJLO); epsomite (MgSCL^FLO); gypsum (CaSC>4-2H2O); brucite (Mg(0H)2); (hydrous) aragonite; (hydrous) spodumene (for example, having a formula of 2[LiAlSi2C>62H2O]); (hydrous) magnesite (for example, having a formula of 3MgC0s- Mg(0H)2- 3H2O or MgCChAtLO); gibbsite (Al(0H)3); boehmite (A10(0H)); diaspore (A10(0H)); bay erite (Al(0H)3); doyleite (Al(0H)3); nordstrandite (Al(0H)3); kaolinite (A12Si205(0H)4); epidote (Ca2(Fe,Al)3(SiO4)3(OH)); and malachite (Cu2CO3(OH)2).

9. The method according to any one of claims 1 to 8, wherein the radiant heating has a uniform heating flux at the point source in the range of about 0.3 MW / m2to about 3 MW / m2.

10. The method according to any one of claims 1 to 9, wherein the radiant heating is carried out by means of a burner, for example a flat burner, such as a flat porous burner.

11. The method according to any one of claims 1 to 10, wherein the material is radiantly heated to a temperature in the range of about 300 °C to about 1200 °C.

12. The method according to any one of claims 1 to 11, wherein the radiant heating is carried out at a heating rate of about 5 °C / s to about 1000 °C / s, for example about 10 °C / s to about 1000 °C / s.

13. The method according to any one of claims 1 to 12, wherein the total exposure time for the material to be subjected to radiant heating is no more than about 30 minutes.

14. The method according to any one of claims 1 to 13, wherein the radiant heating is carried out at a distance between a radiant heating surface and the material to be heated that is between 5% and 25% of the width of a supporting surface (such as a conveying belt).

15. The method according to any one of claims 1 to 14, wherein, in conducting the radiant heating, particles of the material comprising a mineral are distributed over a supporting surface at a thickness of about 1 to 10 times the largest particle size of the material to be treated, for example, about 2 to 10 times, about 3 to 10 times, or about 5 to 10 times the largest particle size of the material to be treated.

16. The method according to any one of claims 1 to 15, wherein the material subjected to the radiant heating is in the form of particles and the particles of the material have an average size of about 1 pm to about 50,000 pm, for example about 1 pm to about 20,000 pm, or about 1 pm to about 10,000 pm.

17. The method according to any one of claims 1 to 16, wherein the material is one or more selected from the group consisting of a lizardite containing material, a goethite containing material, a hematite containing material, and a magnesite containing material.

18. A product obtained or obtainable by the method of according to any one of the preceding claims.

19. Use of radiant heating in inducing a physical change and / or a chemical change to a material comprising a mineral compared to the one without being subjected to the radiant heating; and / or ininducing a structural change and / or a compositional change to a material comprising a mineral compared to the one without being subjected to the radiant heating20. Use of radiant heating in lowering the activation energy of calcination reaction of a mineral comprised by a material; increasing the specific surface area of a mineral comprised by a material; destabilising and removing chemically bound hydroxy groups or water molecules comprised by a mineral of a material; reducing the specific grinding energy required for a subsequent reduction of particle size of a material comprising a mineral; allowing different minerals contained by a material to expand at different rates when being rapidly heated and to be readily separated afterwards; adjusting and / or optimising the particle distribution of a material comprising a mineral after the radiant heating; upgrading a material comprising a mineral; and / or producing a calcined product or a beneficiated product from a material comprising a mineral.

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