DIRECT IRON REDUCTION PROCESS

Abstract

The invention relates to a method and apparatus for the treatment of hydrogen-reduced DRI containing phosphorus in an induction furnace. This method involves treating molten DRI by separating at least a portion of the phosphorus in the DRI into slag, with the molten DRI becoming a ferrous feedstock which is at least essentially alpha iron and has a lower phosphorus concentration, typically less than or equal to 0.03% by mass, which is suitable for use as a direct feedstock for steelmaking processes, such as in existing steelmaking equipment, such as an EAF.

Description

[0001] DIRECT REDUCED IRON PROCESSING

[0002] TECHNICAL FIELD

[0003] The invention relates to a method and an apparatus for processing hydrogen-reduced direct reduced iron (DRI) that contains phosphorous, for example in the form of phosphorus oxide(s), into a low phosphorus iron feedstock for steel production purposes.

[0004] The invention relates particularly, although by no means exclusively, to a method and an apparatus for processing, for example batch processing, hydrogen-reduced direct reduced iron that contains phosphorous, for example in the form of phosphorus oxide(s) (as a residual after the DRI metallisation process), using an induction melting furnace that enables the processing of such DRI to produce an iron feedstock suitable for use in an existing steelmaking apparatus.

[0005] Such an iron feedstock, for example while in a molten state, may be subsequently directly delivered to a steelmaking furnace or a metal refining station or other steelmaking apparatus as hot metal feed for conversion into steel of a desired grade, or alternatively cast into a solid iron feedstock for subsequent supply as a ‘cold’ iron feedstock to a separate or remote steelmaking apparatus.

[0006] The term “steelmaking apparatus” as used herein describes facilities having fumace(s) for the production of steel such as (without being limited thereto) the following furnaces. a) Furnaces in which a bath of molten iron-containing carbon, as described herein, is fed and refined to steel by bulk oxidation of molten iron to FeO by oxygen injection into the molten bath, with back reaction reduction of FeO back to Fe by the conversion of carbon in the molten bath, thereby producing CO and ultimately producing a desired steel having a specified carbon content. Such furnaces typically are a basic oxygen furnace (BOF), also known as a LD converter (named after the Austrian town of Linz and district of Donawitz). Such furnaces are able to take about 20-30% of the metallic iron input as cold iron feedstock. b) Furnaces in which a predominantly ‘cold’ metallic iron input is melted using an electric arc to form a bath of steel, with the carbon concentration of the steel being adjusted to a required concentration once the molten bath is fully created in the furnace. Such a furnace typically is an electric arc furnace (EAF). These furnaces are usually fed with a majority of solid steel scrap, with a purer metallic iron component added as necessary to dilute any undesirable tramp elements arising from the source of scrap, such as tin and copper that cannot be removed in the steel making process. Such furnaces can use iron feedstock as the prime metallic iron input as an alternative to steel scrap. EAFs are used in some situations with ladle refining furnaces that make it possible to divide the steel melting operations, carried out in the EAFs, from those of treatment and refining to a final steel composition. The liquid steel produced by the EAF is poured into a ladle, which serves as a reactor for metallurgical operations at the treatment stations.

[0007] The term “steel” is understood herein to mean an alloy of iron and carbon in which the amount of carbon is more than 0.008% and less than 2.06% by weight. While the term “steel” applies to alloys of iron and carbon in which the amount of carbon can be up to 2.06% by weight, normal grades of steel that are commercially produced rarely exceed 0.8% carbon. It is also to be noted that other alloying elements may be present, including by purposeful addition to produce steels for special purposes, e.g., like manganese spring steels.

[0008] The term “iron-containing carbon” is understood herein to mean an alloy of iron and carbon in which the amount of carbon is 2.06% or greater by weight and less than 4.3% by weight in total. Such iron may have significant amounts of other elements within it as a function of the reduction / smelting process that has led to the production of such iron.

[0009] The term ‘alpha’ iron is understood herein to mean iron having 0.008% or less carbon by weight at room temperature and comprising a solid solution of carbon in pure iron. Such iron may have other trace elements as a function of the reduction process that has led to the production of such iron.

[0010] The term “iron feedstock” is understood herein to mean ‘alpha’ iron as well as steel and in both cases is not limited by physical state, i.e., it may be liquid or solid. The term “hydrogen-reduced direct reduced iron” is understood herein to mean iron material produced from the reduction of iron ore by a hydrogen rich reducing agent(s) at temperatures below the bulk melting temperature of the solids having over 95% metallisation of iron within it.

[0011] The term “hydrogen rich reducing agent(s)” is understood herein to mean a gas in which the reducing agent(s) comprises 90% or more hydrogen as the element that combines with oxygen from iron oxides in the iron ore. Such hydrogen will usually be in a form of H2 but does not exclude the use of a synthetic gas formed for example from NH3 or a blend of H2 and other gases such as CO and CH4.

[0012] The term “metallisation” is understood herein to mean the extent of conversion of iron oxides into metallic iron during reduction of the iron oxides, as a percentage of the mass of metallic iron divided by the mass of total iron.

[0013] BACKGROUND

[0014] Iron and steel making are historically carbon intensive processes in which carbon, usually from carbonaceous geological materials, is used and the carbon is eventually discharged to the atmosphere as CO2. With global efforts to reduce overall atmospheric CO2 there is pressure on iron and steel makers to find means to make iron and steel without causing net emissions of greenhouse gases. In particular, there is pressure not to use such geological origin carbonaceous material, like coal or natural gas, collectively often referred to as ‘fossil fuels’, which are non-renewable and result in increased concentrations of atmospheric greenhouse gases.

[0015] The majority of iron produced globally for conversion to steel is currently undertaken through the blast furnace route, which is a technology that has existed since prior to the industrial revolution. Even with technology advances, the blast furnace still requires around 800kg of metallurgical coal for every tonne of iron produced and emits high levels of CO2, roughly 1.8- 2.2 t CO2 per tonne of hot metal. The use of fossil fuels, in particular the requirement for coal (in the form of coke), is an essential feed material for a blast furnace to operate, and it is not possible simply to use hydrogen therein as a complete substitute.

[0016] An alternative approach to blast furnaces for the production of iron is the reduction of iron ore in the solid state by carbon monoxide and / or hydrogen derived from natural gas or coal. While such plants are (outside of India) minor in number compared to blast furnaces there are many processes for the direct reduction of iron ore. In India coal based rotary kiln furnaces are used to produce DRI, also known as sponge iron (approaching 20% of world production of DRI), while elsewhere they tend to be gas-based shaft furnace processes (approaching 80% of world production of DRI).

[0017] The gas-based direct reduction plants are often part of integrated steel mini-mills, located adjacent to an electric arc furnace (EAF) steel plant, but some DRI is shipped from captive direct reduction plants (usually Midrex™ or HYL™ process based) to remote steel mills. Because such DRI is used directly in electric arc furnaces, there are strict requirements on the levels of certain impurities in the DRI, like phosphorous, given many impurities are difficult and expensive to remove using an EAF. Hence, the iron ores used to make DRI are often crushed and ground to micron particle sizes to enable removal of gangue minerals. Such finely ground material can have challenges in its handling (both transport and operationally wise). Therefore, the material is typically agglomerated using water and / or binder to produce closely sized ‘green’ balls which are, once dried, then fed into furnaces where they are fired into hard pellets (a process known as induration), before eventually being supplied to direct reduction plants as feed material (or sometimes to blast furnaces as a high quality iron ore feed material to help dilute the gangue of the lump or sinter iron ore that a blast furnace uses). The ‘green’ balls that form the pellets have a typical compressive strength of around 10 N when wet, and 50 N when dried. As pellets (after induration), they have a compressive strength of around 2000 N.

[0018] The process of making sponge iron as practised in India is rudimentary and not energy efficient. The main raw materials are iron ore (between 5-18 mm in size), lump coal and dolomite (4-8 mm in size to prevent pick-up of sulphur from the coal by the sponge iron). Metallisation of the iron ore (Fe content 62-66% by weight) is typically lower that the gasbased direct reduction plants. Metallisation is estimated in the range of 75% up to a maximum of 90% but is not specified (grade wise) until the reduction process has been complete, the sponge iron cooled (using a rotary cooler connected to the kiln) and the iron thereafter magnetically separated from the bulk of non-magnetic materials such as ash or unreacted coal or ore. As the three grades for India, are specified as Grade 1 (82% + metallisation), Grade II (78-82% metallisation) and Grade III (76-78% metallisation) it can be seen when the lower grades are fed into an induction furnace to make steel it can be expected that there will overall be a larger slag make.

[0019] In metallurgical terminology for iron or steel making, reference is typically made to the process (or a particular step therein) as either having or forming an ‘acid slag’ or a ‘basic’ slag, where acid refers to the bulk oxides in the slag being oxides of a non-metal, such as SiO2and P2O5, and basic refers to the bulk oxides in the slag being oxides of metal, such as FeO and CaO (lime). Reactions of such acids with such bases lead to formation of compounds in the slag, for example:

[0020] The slag is immiscible with and lighter than the metal in the bath and therefore tends to float on top of the metal. The slag may be purposefully made to be acid, basic, or neutral, depending largely on the fluxes added. As the temperature of the molten bath does not typically exceed the melting point of the main components of a typical gangue, often being a mixture of oxides of aluminium and silicon, it is desirable to add a flux(es) to react with the gangue and reduce its melting point to a level where everything within the bath is essentially molten, and as such the slag sufficiently fluid to be able to handled readily. A flux can be of the acid, basic or neutral type. An example of a neutral flux is Fluorspar (CaF2). The basic fluxes most commonly used in iron and steel making are limestone, essentially calcium carbonate, and dolomite, a mixture of calcium carbonate and magnesium carbonate. When added these fluxes break down into the oxides of the metal, with the evolution of carbon dioxide. It should be noted that at the steelmaking phase it is more typical to use lime (CaO) i.e., limestone that has been calcified through an earlier heating process, as the flux, instead of limestone. One proposal currently put forward for utilising existing high gangue ores to make steel in a ‘green manner’ i.e., without the involvement of fossil fuels, is through the production of DRI using hydrogen as the reductant. This could, for example, be through using the indurated pellet approach or through the reduction of iron ore fines in a fluidized bed system, such as the Metso Outotec hydrogen-based Circored ™ process, followed typically (but not exclusively) by smelting in a special form of electric arc furnace called a submerged arc furnace (SAF) or an electric smelting furnace (ESF) to produce iron-containing carbon. For such routes to be as low carbon users / emitters as possible requires conversion of renewable (green) energy into hydrogen (produced through electrolysis), particularly in periods when wind / solar power cost is low, with subsequent production of DRI using the hydrogen, as well as the use of renewable green energy to power the electric arc furnace. However, the final smelting step by definition requires some limited amount of carbon. Only high grade DRI with very low gangue and other impurities can be supplied to a conventional EAF for steelmaking by mixing such DRI with steel scrap.

[0021] Another proposal to make steel in a ‘green manner’ i.e., without any involvement of fossil fuels, is through the production of DRI using biomass as the reductant. A Group company of the applicant is developing technology to produce a biomass-reduced DRI from iron ore. The biomass technology, which includes the Bioiron™ process, uses raw biomass instead of metallurgical coal as a reductant to convert iron ore to metallic iron for use in steelmaking processes. The patent portfolio for such technology includes, for example, International patent applications PCT / AU2017 / 051163 (WO2018 / 076048), PCT / AU2021 / 050526 (WO2021 / 237308), PCT / AU2021 / 051094 (WO2022 / 061398), and PCT / AU2021 / 051398 (WO2022 / 109663).

[0022] In the discussion that follows, references to specific types of oxide forms of iron ore are made, being magnetite, haematite and goethite. In fact, geological iron ores are much more varied, and use of such references should not be interpreted as limiting the forms of iron ore that may be processed into DRI and as such the invention applicable to. Further, as geological minerals, they can be found in the same structures; thus when the oxide forms magnetite, haematite and / or goethite are used herein they are simply implying that the bulk, as a majority, is that mineral type. For example, the ‘taconite’ iron ore referred to below, besides containing magnetite, also contains some haematite.

[0023] Regardless of the approach taken for the production of DRI, there can be challenges in the downstream processing of that DRI in today’s steelmaking apparatus.

[0024] For example, where DRI is to be produced from an iron ore mineral that at its core is a ‘magnetite’, i.e., a FesC composition, the problems may not to be too severe, because the impurities / gangue in the ore, generally go are often readily separated by comminution and sorting to recover the magnetite. As an example, in the USA a ‘taconite’ iron ore, being 2 / 3 by weight silica, has to be ground down to separate (by magnetic separation) the magnetite from the silica.

[0025] A large percentage of iron ore used in blast furnaces today around the world is based around using minerals that are predominately ‘hematite’ i.e., Fe2C>3 in composition, or ‘goethite’, i.e., FeO OH in composition. Besides having a gangue component, these ores tend to have some impurities more tightly bound within the oxide form, and as such grinding has little effect on their removal. Further, if goethite is used as a feed in the pellets to be processed into DRI they have a tendency to decrepitate during the pellet hardening process (called induration).

[0026] Thus, only low-gangue ore types (or those able to readily be upgraded to remove gangue) can naturally be applied to the DRI / EAF combination. The EAF process becoming less efficient with high gangue material, i.e., there is increased slag make and iron unit losses, rendering the use of DRI produced from high gangue ore essentially non-competitive.

[0027] Another key problem is that DRI production processes do not have an easy way, whether physical or chemically, to reduce the amount of the undesirable impurity phosphorus. Phosphorus is a major contaminant in steelmaking, and if present in the eventual steel has a strong effect (much stronger than carbon) on the transition temperature at which a steel will change its phase (source: Physical Metallurgy Principles, 1964, R E Reed-HilT) potentially leading to the steel becoming brittle during any mechanical working or heat treatment process. Thus, phosphorous is to be avoided as much as possible in iron ore feed materials. It should be noted that phosphorus can in fact be removed in BOF / EAF steelmaking by forming a strong oxidising slag (in particular one containing high levels of FeO), but it slows down production times significantly for each batch of steel, and there is a necessary loss of iron units to the slag, thus making the steel much more expensive to produce.

[0028] For Indian steelmakers using induction furnaces, the position is more challenging. In an induction furnace any phosphorous (P) in the steel cannot readily be removed by lancing oxygen into the bath due to excessive metal losses arising from small diameter to height ratio. Typically, to remove P it is considered that a high slag basicity is needed, as well as high oxygen potential in the molten bath. One recommended approach for such steelmakers is to create synthetic slags having high FeO and high CaO contents. This can be achieved by reuse of BOF / LD slags (as a purposeful addition) to get such contents1.

[0029] While miners of non ‘magnetite’ iron ore tend to mine as much as possible iron ore having low phosphorus levels, many such deposits (having been formed within seas or in wet conditions) have significant amounts of phosphorus, causing the miners either to sell such ore at a discount or to blend it with lower phosphorus ores to produce a consistent iron ore blend with an acceptable phosphorus level. Unfortunately, as earlier mined ore bodies are deleted, it is becoming more challenging to maintain the status quo.

[0030] A blast furnace, because of its melting approach, takes most of the gangue and some of the undesirable impurities out as part of the slag, e.g., typically Si (89%), titanium (77%), sulphur 80% and potassium 73%; (source: Modern Blast Furnace Ironmaking third edition, 2015, Maarten Geerdes et a ). However, due to the strong reducing nature of reactions in blast furnaces, undesirable elements like phosphorus are reduced (from their oxide forms) and captured in the metal as part of the ironmaking process. For a blast furnace, the acceptable level of phosphorus in the molten iron-containing carbon is controlled by blending different iron ores as the feed material, usually some with a higher or lower iron content than the bulk ore feed, but little phosphorus contamination. For higher iron content ore there is a price premium (due to limited availability), and when using lower iron content iron ores there is a penalty in energy minimisation (and CO2 admissions where fossil fuels are used) per tonne of metallised iron. Thus, the challenge is to establish a method and an apparatus that can turn DRI that contains significant amounts of phosphorous, for example in the form of phosphorus oxide(s), into a desirable iron feedstock without transferring phosphorus as an impurity thereto. If the DRI is, as part of that process, smelted (i.e., where melting and reduction reactions occur simultaneously under high temperature, highly reducing conditions) then it is likely that the phosphorus will be transferred to the iron feedstock.

[0031] It is understood that the above description is not to be taken as an admission of the common general knowledge in Australia or elsewhere.

[0032] SUMMARY OF THE DISCLOSURE

[0033] The invention is based on a realisation that a furnace that uses an electric arc (in whatever form) and other types of steelmaking apparatus may not be the best approach for the preparation of an iron feedstock for making steel using a hydrogen-reduced DRI, where the feedstock has as its origin iron ore that has a phosphorus content of greater than 0.07% phosphorus by weight.

[0034] The invention is based on a realization that a better approach in at least some situations is to treat a hydrogen-reduced direct reduced iron (DRI) that contains phosphorous using an induction furnace that reduces the phosphorous concentration to an extent that the treated DRI has a phosphorous concentration suitable for directly processing to produce steel, such as in a steelmaking apparatus, such as an EAF. Typically, this means reducing the phosphorous concentration to be 0.03% or less by weight.

[0035] The term “induction furnace” is understood herein to mean an electrical furnace in which the heat is applied by induction heating of metal. Induction furnace capacities range from less than 1kg to 100 or more tonnes. An induction furnace generates a rapidly alternating magnetic field that penetrates an electrically conductive material to be heated, generating eddy currents that lead to joule heating of the material.

[0036] In broad terms, the invention is a method and an apparatus for treating a hydrogen-reduced DRI that contains phosphorous, for example in the form of phosphorus oxide(s) (as a residual after a DRI metallisation process), in an induction furnace that includes treating molten DRI by at least partially partitioning phosphorus in the DRI into a slag, with the molten DRI becoming an iron feedstock which is at least substantially alpha iron and has a lower phosphorus concentration that is suitable for use as a direct feed material for making steel, such as in an existing steelmaking apparatus, such as an EAF.

[0037] In broad terms, the invention provides a method for producing an iron feedstock suitable for directly forming steel in a steelmaking apparatus having a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight, from a hydrogen-reduced DRI having a higher phosphorous concentration using an electric induction furnace that comprises:

[0038] (a) melting a hydrogen-reduced DRI in a chamber in an induction furnace via a magnetic field induced in the chamber and forming a molten DRI-containing bath;

[0039] (b) forming a basic slag in the chamber that at least partially partitions phosphorus in molten DRI to the slag, with the molten DRI becoming a molten iron feedstock which is at least substantially alpha iron with a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight, from the molten DRI; and

[0040] (c) removing, for example by tapping, at least a part of the iron feedstock from the furnace.

[0041] The invention provides a method for producing an iron feedstock suitable for directly forming steel in a steelmaking apparatus having a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically less than 0.03 % by weight, from a hydrogen reduced DRI having a higher phosphorous concentration using an electric induction furnace that comprises:

[0042] (a) feeding a hydrogen reduced feed DRI into a chamber in an induction furnace;

[0043] (b) operating the induction furnace and melting the DRI via a magnetic field induced in the chamber and forming a molten DRI-containing bath;

[0044] (c) forming a basic slag in the chamber that at least partially partitions phosphorus in molten DRI to the slag, with the molten DRI becoming a molten iron feedstock which is at least substantially alpha iron with a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight, from the molten DRI;

[0045] (d) removing, for example by tapping or raking, at least a part of the slag from the furnace; and

[0046] (e) removing, for example by tapping, at least a part of the iron feedstock from the furnace at the same time or other times as removing the slag from the furnace .

[0047] The hydrogen-reduced DRI may have a phosphorus concentration of greater than 0.07% by weight.

[0048] The method may include initially selecting and then controlling a slag composition during the method to be any suitable composition to facilitate partitioning phosphorus in the molten DRI to the slag.

[0049] The options to control the slag composition include the use of slag-forming additives to provide a required slag basicity and selection of operating temperatures in the induction furnace.

[0050] The method may include controlling slag basicity to be < 3, typically < 2, where slag basicity is defined as the ratio of basic oxides to acidic oxides in the molten slag, typically expressed as the (CaO% + MgO%) / SiO2% ratio of the molten slag.

[0051] The method may include controlling a slag composition during the method to have a FeO concentration in a range of 5-20% by weight.

[0052] The method may include controlling a slag composition during the method to have a FeO concentration below 10% of the slag by weight.

[0053] The method may include controlling a slag composition during the method to have a CaO to SiO2 ratio of < 2.0% by weight. The method may include controlling a slag composition during the method to have a CaO to SiCh ratio of < 1.5% by weight.

[0054] The method may include controlling a slag composition during the method to have a MgO to AI2O3 ratio of 0.4-0.6.

[0055] Typically, the method includes maintaining a slag composition that comprises 5% by weight FeO, a CaO to SiO2 ratio of 1.5, and a MgO to AI2O3 ratio of 0.5.

[0056] The method may include controlling a slag composition during the method by adding slagforming materials. It is noted that there may be slag-forming materials, such as CaO and MgO, in the DRI that will have an impact on the extent of the separate additions of these materials that may be required during the method.

[0057] The method may include maintaining the molten bath at a temperature of 1540°C.

[0058] The method may include forming the molten bath at a temperature up to 20°C above a liquidus temperature of the alpha iron.

[0059] The method may include forming the molten bath at a temperature up to 30°C above a liquidus temperature of the alpha iron.

[0060] The method may include forming the molten bath at a temperature up to 40°C above a liquidus temperature of the alpha iron.

[0061] The method may include forming the molten bath at a temperature up to 60°C above a liquidus temperature of the alpha iron.

[0062] The method may include forming the molten bath at a temperature no more than 90°C above a liquidus temperature of the alpha iron.

[0063] The method may include forming the molten bath at a temperature no more than 80°C above a liquidus temperature of the alpha iron.

[0064] The term “liquidus temperature of the alpha iron” is understood herein to mean the temperature at which all the reduced iron in the DRI is in a liquid form, including iron that might be bound to carbon or bond thereto during the melting process, i.e., Fe3C.

[0065] The method may include stirring or otherwise causing mixing of molten metal (as opposed to molten slag and molten metal) in the induction furnace.

[0066] The method may include controlling the method so that at least 2 / 3 of the phosphorous in the feed DRI partitions to the slag.

[0067] The method may include controlling the method so that at least 3 / 4 of the phosphorous in the feed DRI partitions to the slag.

[0068] The method may include supplying the feed DRI in a hot state (above room temperature) to the induction furnace.

[0069] The method may include supplying the feed DRI to the induction furnace at a temperature of at least at 400°C.

[0070] The method may include supplying the feed DRI to the induction furnace at a temperature of at least 600°C.

[0071] The method may include supplying the feed DRI to the induction furnace in an anoxic environment.

[0072] The term “anoxic” is understood herein to mean substantially or very deficient in oxygen.

[0073] The method may include supplying the feed DRI to the induction furnace as at least 97% metallised DRI. The method may include supplying the feed DRI to the induction furnace as at least 99% metallised DRI.

[0074] The method may be operated on a batch basis, a continuous basis, or a semi -continuous basis.

[0075] The method may be operated on a batch basis, with successive batches of the molten iron feedstock being formed in the method in the induction furnace.

[0076] The batch method may include forming a heel of a molten iron feedstock or other suitable molten material in the furnace and then carrying out the above-described steps (a) to (e).

[0077] The method may include removing, for example by tapping, the molten slag and the molten iron feedstock periodically after forming a full melt in the furnace.

[0078] The term “full melt” is understood herein to mean a stage in the method when all the feed materials that can melt have melted.

[0079] The method may include removing, for example by tapping, the molten slag periodically before forming a full melt in the furnace to maintain the remaining slag in the furnace with desired properties and to ensure it remains fluid for tapping the slag.

[0080] The term “desired” properties is understood herein to mean properties that facilitate partitioning phosphorus in the DRI to the slag.

[0081] The method may include supplying the feed DRI is fed into the furnace in a gradual manner, along with any required slag forming materials, and melting the DRI at temperatures that are close to the liquidus of the DRI, thus avoiding bath temperatures well in excess of the liquidus temperature of alpha iron.

[0082] The Ca and / or Mg containing slag forming materials may be purposely added to the furnace on a needs basis or may largely be obtained through the introduction of the feed DRI to the induction furnace by having previously been added as a feed to the DRI forming process. The method may include forming the DRI from iron ore in a fluidised bed / beds process with hydrogen rich reducing agents. The fluidised bed / beds process may be any suitable process.

[0083] Typically, hydrogen is the only purposefully added reductant.

[0084] The iron ore used to form the hydrogen-reduced DRI forming may be in the form of iron ore fines.

[0085] The term “iron ore fines” is understood herein to mean any suitable size piece of iron ore as passed through an appropriately screen mesh of 4 mm spacing or below. In referring to such ore as iron ore fines it is not intended that the particles be so reduced in size by grinding or crushing that they could all also pass through a 1 mm screen. Preferably, the iron ore fines all pass through a 2 mm screen.

[0086] The method may include adding carbon to the molten bath to carburise the iron feedstock.

[0087] The method may include operating a plurality of the above-described induction furnace and producing the iron feedstock in the above-described method.

[0088] Typically, the method includes operating a plurality of induction furnaces so that one or more than one furnace can be undergoing maintenance / refractory reline while the other furnace(s) remain(s) operational.

[0089] The method may include casting the molten iron feedstock directly into ingots for subsequent downstream use as a ‘cold feed’ to a steelmaking apparatus.

[0090] The method may include, before removing (for example, by tapping) the molten iron feedstock from the induction furnace, but after removing (for example, by tapping) slag, heating the molten iron feedstock to ensure that the molten iron feedstock has enough superheat to enable it to be poured into a transport vessel, such as a ladle, and taken away for either remote casting activities or further downstream processing. The superheat may be at least 50°C over the liquidus of the molten iron feedstock.

[0091] The further downstream processing may include adding carbon and other additives at a ladle transfer station to make steel, followed by casting. Such casting may take all the traditional forms, such as a slab caster, billet caster or ingot casting.

[0092] Alternatively, the method may include, after removing (for example, by tapping) slag from the induction furnace, converting alpha iron of the molten iron feedstock into steel by adding carbon and other alloy additives into the melt and forming molten steel, followed by removing (for example, by tapping) the molten steel with enough superheat to enable it to be poured into a transport vessel, such as a ladle and taken away for remote casting activities or further downstream processing.

[0093] The superheat may at least 50°C over the liquidus of the particular grade of steel.

[0094] The term ‘superheat’ is understood herein to mean a temperature difference between the molten material and the temperature at which solidification of such material will commence.

[0095] The invention also provides an apparatus for producing an iron feedstock suitable for directly forming steel in a steelmaking apparatus having a phosphorous concentration suitable for directly forming steel in a steelmaking apparatus, typically a phosphorous concentration of 0.03 % or less by weight, from a hydrogen-reduced DRI using an electric induction furnace that is configured to melt the DRI via a magnetic field induced in the induction furnace and form a bath of molten DRI and a molten basic slag, with the slag having a composition that can at least partially partition phosphorus in the molten DRI so that the molten DRI is treated in the furnace and forms a molten iron feedstock which is at least substantially alpha iron with a phosphorous concentration suitable for directly forming steel in a steelmaking apparatus, typically a phosphorous concentration of 0.03% or less by weight, with the induction furnace including a chamber for melting and treating the DRI, an inlet for supplying the DRI to the chamber, and an outlet for discharging slag from the chamber, and an outlet for discharging molten iron feedstock from the chamber.

[0096] The invention also provides a steelmaking method that includes making steel in a steelmaking apparatus as described herein from an iron feedstock having a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically a phosphorous concentration of 0.03% or less by weight, made by the above-described method for producing an iron feedstock from a hydrogen-reduced DRI.

[0097] The hydrogen-reduced DRI may contain phosphorus in a concentration greater than 0.07% by weight.

[0098] The invention also provides a steelmaking method that includes:

[0099] (a) producing a hydrogen-reduced DRI from an iron ore having a phosphorous concentration greater than 0.07% by weight in a DRI production apparatus;

[0100] (b) melting and treating the DRI in an induction furnace and reducing the phosphorus concentration of the DRI to a concentration suitable for directly forming steel in the steelmaking apparatus, typically a phosphorous concentration of 0.03% or less by weight, by partitioning phosphorus in the DRI into a slag in the induction furnace, typically including controlling the temperature in the furnace to be no more than 90°C above a liquidus temperature of the DRI, with the treated DRI becoming an iron feedstock that is at least substantially alpha iron; and

[0101] (c) making steel from the iron feedstock in a steelmaking apparatus.

[0102] The method may include maintaining the temperature in the furnace to be no more than 90°C above the liquidus temperature of the DRI, at least until a majority of slag is removed, for example, by being tapped or raked, from the furnace.

[0103] In one embodiment, the DRI production apparatus, the induction furnace, and the steelmaking apparatus may each be in quite separate and spaced-apart locations.

[0104] In such an event, the steelmaking method may include producing compressed briquettes of the hydrogen-reduced DRI produced in the DRI production apparatus, transporting the compressed briquettes while hot to the induction furnace, producing iron feedstock from the hydrogen-reduced DRI in the induction furnace, casting or granulating the iron feedstock, transporting the cast or granulated iron feedstock to the steelmaking apparatus, and making steel from the iron feedstock in the steelmaking apparatus. In another embodiment, the DRI production apparatus and the induction furnace may be in close proximity and the steelmaking apparatus may be in a quite separate and spaced-apart location to that of the DRI production apparatus and the induction furnace.

[0105] In that event, the steelmaking method may include producing the iron feedstock in the DRI production apparatus and the induction furnace, casting or granulating the iron feedstock, transporting the iron feedstock to the steelmaking apparatus, and making steel from the iron feedstock in the steelmaking apparatus.

[0106] In another embodiment, the DRI production apparatus may be in one location and the induction furnace and the steelmaking apparatus may be in a close proximity in a quite separate and spaced-apart location to that of the DRI production apparatus.

[0107] In that event, the steelmaking method may include producing compressed briquettes of the hydrogen-reduced DRI produced in the DRI production apparatus, transporting the briquettes while hot to the induction furnace, producing iron feedstock for the hydrogen-reduced DRI in the induction furnace, and making steel from the iron feedstock in the steelmaking apparatus.

[0108] In addition, the steelmaking method may include transferring the iron feedstock in a molten state directly from the induction furnace to the steelmaking apparatus.

[0109] The DRI production apparatus, the induction furnace, and the steelmaking apparatus may be a part of an integrated steelmaking apparatus.

[0110] In that event, the steelmaking method may include producing a hydrogen-reduced DRI in the DRI production apparatus, transferring the DRI to the induction furnace, producing an iron feedstock from the hydrogen-reduced DRI in the induction furnace, transferring the iron feedstock to the steelmaking apparatus, and producing steel from the iron feedstock in the steelmaking apparatus.

[0111] The steelmaking method may include transferring the hydrogen-reduced DRI in a hot state, whether as received material or as compressed briquettes thereof, directly from the DRI production apparatus to the induction furnace.

[0112] Alternatively, or in addition, the steelmaking method may include transferring the iron feedstock in a molten state directly from the induction furnace to the steelmaking apparatus.

[0113] The DRI production apparatus may be the apparatus for producing a hydrogen-reduced DRI in the above-mentioned International applications in the name of the applicant.

[0114] The iron feedstock apparatus may be the above-described apparatus.

[0115] The steelmaking production apparatus may be any suitable apparatus, such as an EAF.

[0116] BRIEF DESCRIPTION OF THE DRAWINGS

[0117] The present invention is described further by way of example with reference to the accompanying drawings, of which:

[0118] Figure l is a diagram that illustrates an embodiment of a method and apparatus for producing steel in accordance with the invention;

[0119] Figure 2 is a diagram of an embodiment of an apparatus for producing iron from hydrogen-reduced iron (DRI) in accordance the invention;

[0120] Figures 3(a), 3(b), and 3(c) are diagrams illustrating a embodiment of a method for producing iron from hydrogen- reduced iron (DRI) in accordance the invention; and

[0121] Figures 4 a), 4(b), 4(c), and 4(d) are diagrams illustrating another, but not the only other, embodiment of a method for producing iron from hydrogen-reduced iron (DRI) in accordance the invention.

[0122] DESCRIPTION OF EMBODIMENTS

[0123] As noted above, in broad terms, the invention is a method and an apparatus for treating a hydrogen-reduced DRI that still contains phosphorous, for example in the form of phosphorus oxide(s) (as a residual after the DRI metallisation process), in an induction melting furnace that includes melting the DRI and at least partially partitioning phosphorus in the DRI into a slag and producing an iron feedstock from the DRI that has a lower phosphorus concentration that is suitable for use as a direct feed material for an in existing steelmaking apparatus such as an EAF.

[0124] In effect, the invention provides a link between a hydrogen-reduced DRI and an existing steelmaking apparatus, such as an EAF, insofar as phosphorus concentrations are concerned. The invention provides an opportunity for a hydrogen-reduced DRI to be a viable feed material for an existing steelmaking apparatus.

[0125] Therefore, the invention is an important invention in the context of ‘green’ steel production.

[0126] With reference to Figure 1, an embodiment of a method and an apparatus for producing steel in accordance with the invention, includes:

[0127] (a) producing a hydrogen-reduced DRI (typically with a phosphorus concentration of greater than 0.07% by weight and at least 95% metallisation) from iron ore fines and hydrogen in a DRI production apparatus 3;

[0128] (b) transferring the hydrogen-reduced DRI as a feed DRI, typically at a temperature of at least 400°C, to an induction furnace 5,

[0129] (c) melting and treating the hydrogen-reduced DRI in the furnace to reduce the phosphorus concentration of the DRI to 0.03% or less by weight to produce a molten iron feedstock which is at least substantially alpha iron typically with a phosphorous concentration of 0.03% or less by weight;

[0130] (d) transferring the molten iron feedstock, typically in a molten state, to a steelmaking production apparatus 7; and

[0131] (e) producing steel in the steelmaking apparatus 7.

[0132] The induction furnace 5 may be any suitable induction furnace for producing molten iron feedstock for steelmaking from hydrogen-reduced iron (DRI).

[0133] The steelmaking apparatus 7 may be any suitable apparatus, such as an EAF, such as an EAF and associated ladle refining furnace.

[0134] In another, although not the only other embodiment of the invention, the induction furnace 5 has a dual function of producing a molten iron feedstock with a low phosphorous concentration, typically with a phosphorous concentration of 0.03% or less by weight, and then processing the feedstock and producing steel or an intermediate feedstock for producing steel. By way of example, the method may comprise carburising and heating the molten iron feedstock to form the intermediate steelmaking feedstock with a selected carbon concentration suitable for steelmaking.

[0135] The embodiment of the induction furnace 5 for producing molten iron from a hydrogen- reduced iron (DRI) shown in Figure 2 comprises a refractory material-lined base 9 and a side wall 11 and a removable refractory material-lined lid (not shown). The induction furnace 5 includes an induction coil 13 in the side wall 11 of the furnace. The coil is connected to a supply of alternating current (not shown).

[0136] The refractory material may be any suitable material.

[0137] The induction furnace 5 may be any suitable size.

[0138] Figures 3 and 4 illustrate two of a larger number of embodiments of a method for producing an iron feedstock for steelmaking from hydrogen-reduced iron (DRI) in accordance the invention using the embodiment of the induction furnace 5 shown in Figure 2.

[0139] In these embodiments, the induction furnace 5 can contain of the order of 3 tonnes of molten metal and slag. The invention is not confined to this furnace capacity.

[0140] Both embodiments in Figures 3 and 4 operate on a batch basis, noting that the invention is not confined to batch operation.

[0141] With regard to Figure 3(a), a first step in the embodiment is to form a heel 15 of molten metal in the induction furnace 5. The molten metal may be, for example, a part of the molten iron feedstock produced in a previous batch produced in the induction furnace. The molten metal may be a molten iron feedstock produced in another induction furnace. The molten metal may be a molten iron feedstock produced in a suitable purpose-specific furnace. The next step is to supply hydrogen-reduced feed DRI to the induction furnace 5 as a solid, typically in a hot state. Typically, the feed DRI has a phosphorus concentration of greater than 0.07% by weight and at least 95% metallisation. The feed DRI is supplied as one batch in the Figure 3 embodiment, and the options to do this are well known to a skilled person. In other embodiments, the feed DRI is supplied as a series of smaller batches or in a smaller continuous feed to the induction furnace 5 by any suitable means, and the options to do this are well known to a skilled person.

[0142] The induction furnace 5 heats and melts the feed DRI, with the heel 15 of molten metal ensuring heat transfer in early stages of the method.

[0143] During the course of the melting step, slag-forming materials, which are typically solid, are added to the induction furnace 5 and form a molten basic slag (typically with a slag basicity < 2) to facilitate partitioning of phosphorus and other impurities in the DRI from the DRI to the slag. The slag-forming materials may be supplied as one batch or as a series of smaller batches or in a smaller continuous feed to the induction furnace 5 by any suitable means, and the options to do this are well known to a skilled person. The total of the slag-forming materials is adjusted having regard to the amounts of slag-forming materials already in the feed DRI.

[0144] While the feed DRI and the solid slag-forming materials are melting and after the materials have melted, phosphorus and other impurities in the DRI partition to the slag layer 17, thereby reducing the phosphorus concentration in the molten DRI.

[0145] The composition of the molten DRI and the molten slag in the induction furnace 5 are monitored at least periodically to assess chemistries (such as phosphorus concentration) and other factors, such as slag basicity, and adjustments are made to slag-forming materials additions and operating temperature, as required.

[0146] After the molten DRI reaches a target phosphorus concentration in the induction furnace 5, the molten metal is a suitable iron feedstock, substantially alpha iron, for steelmaking, with a high metallisation and a low phosphorus concentration, typically < 0.3% by weight. At this point, the slag is tapped and thereafter, the iron feedstock is tapped and transferred to a steelmaking apparatus (not shown).

[0147] Figure 3(b) shows very conceptually the induction furnace 5 during the melting step of the method, with the heel 15 of molten metal in a lower section of the induction furnace 5, a layer of molten slag 17 in an upper section of the induction furnace 5, and a layer of new molten metal 19 that is partly processed between the heel 15 and the slag layer 17.

[0148] The “new” metal in the layer 19 is molten DRI with a lower concentration of phosphorus than the feed DRI as a result of phosphorus partitioning to the slag layer 17.

[0149] It is noted that, in practice, the heel 15 and the new molten metal layer 19 will not be separate layers with a defined interface between the layers. There will be mixing of the molten metal in the layers. The mixing may be as a consequence of metal movement due to magnetic and electric fields in the induction furnace 5 or as a result of a mechanical mixing device (not shown).

[0150] Figure 3(c) shows very conceptually the induction furnace 5 at the end of the method, after molten slag layer 15 has been tapped from the induction furnace 5. The layer of new molten metal 19 may be tapped into a ladle or other suitable hot metal transport option and transferred to a steelmaking furnace 7 (Figure 1). As a preliminary step before tapping molten metal, the molten metal may be heated and carburised by the addition of graphite as a pre-treatment for steelmaking in the steelmaking furnace 7. The remaining heel 15 of molten metal is retained in the induction furnace 5 for use to process a successive batch of feed DRI. This retention of the heel 15 is indicated by the arrow 21.

[0151] As is the case with Figure 3(b), in practice, the heel 15 and the new molten metal layer 19 will not be separate layers with a defined interface between the layers. There will be mixing of the molten metal in the layers. The mixing may be as a consequence of metal movement due to magnetic and electric fields in the induction furnace 5 or as a result of a mechanical mixing device (not shown). The embodiment of the method shown in Figure 4 is substantially the same as the Figure 3 embodiment. The main difference is that in the Figure 4 embodiment, the hydrogen-reduced DRI is added to the induction furnace 5 in two tranches. This two-step addition is shown in Figures 4(b) and 4(c).

[0152] The invention is based on test work carried out by a Group company of the applicant that includes the following test work.

[0153] Laboratory scale testing was undertaken on hydrogen-reduced DRI of the compositions set out below in an induction furnace of the applicant at Bundoora, Victoria, Australia. The following Examples report the results of some of the test work.

[0154] Example 1

[0155] Cold hydrogen-reduced DRI was mixed with a flux (CaO and MgO for an aim CaO / SiCh of 1.5 and MgO / ALCE of 0.5) and graphite (2.5%) (in part to counter oxidation of Fe to FeO). The mixture was placed in a crucible and the induction furnace power was turned on and ramped up until the DRI / mix melted. The temperature was monitored during this process. Once molten, a steel bar was used to wick slag to obtain a slag sample and a quartz tube was used to obtain a metal sample. The chemistries of the samples are set out below.

[0156] Hydrogen-reduced DRI chemistry, % by weight:

[0157] Fe (Tot): 91.5% (94% metallised),

[0158] P: 0.17%,

[0159] A12O#: 1.48%,

[0160] SiO2: 2.25%.

[0161] Slag chemistry, % by weight:

[0162] FeO: 5.3%,

[0163] Basicity: 1.58,

[0164] P2O5: 0.46%,

[0165] C: 0.02%, A12O3: 18.5%,

[0166] SiO2: 25.5%,

[0167] CaO: 35.0%,

[0168] MgO: 7.3%.

[0169] Hot metal chemistry, % by weight:

[0170] C: 0.4%,

[0171] P: 0.02%,

[0172] Si: 0.01%,

[0173] Mn: <0.01%,

[0174] Al: <0.01%,

[0175] Ca: 0.01%,

[0176] S: 0.01%.

[0177] It is evident from the above chemistries that there was substantial partitioning of phosphorus in the DRI into the slag, with the resultant iron feedstock having a low phosphorus concentration (0.02% by weight).

[0178] Example 2

[0179] Cold hydrogen-reduced DRI (98 % metallised, Pilbara Blend DRI) was mixed with a flux (CaO and MgO for an aim CaO / SiO2of 1.5 and MgO / Al2O3of 0.5) and no carbon source (unlike Example 1). The mixture was placed in a crucible and the induction furnace power was turned on and ramped up until the DRI / flux melted at a temperature of about 1540°C. The hot metal was just liquid.

[0180] The temperature was monitored during this process. Once molten, a steel bar was used to wick slag to obtain a slag sample and a quartz tube was used to obtain a metal sample. The metal bath was basically sampled not long after it was all molten.

[0181] The hot metal chemistry of the sample was % by weight:

[0182] P: 0.02%,

[0183] C: < 0.005%,

[0184] Fe: balance. The hot metal phosphorus of 0.02 wt.% is the same hot metal phosphorus as the other test work with small additions of carbon (with 0. 4% C in hot metal) - see Example 1.

[0185] As is the case with Example 1, it is evident from the above hot metal chemistry and by inference that there was substantial partitioning of phosphorus in the DRI into the slag, with the resultant iron feedstock having a low phosphorus concentration (0.02% by weight).

[0186] The above results support the invention. In particular, the above results show that it is possible to melt and treat hydrogen-reduced DRI and partition phosphorus into a slag.

[0187] Many modifications may be made to the embodiments of the invention described above without departing from the spirit and scope of the invention.

[0188] By way of example, whilst the Figure 1 embodiment transfers DRI at a temperature of at least 400°C to an induction furnace 5, the invention is not so limited and extends to embodiments in which the DRI is transported at higher or lower temperatures.

[0189] In addition, whilst the Figure 1 embodiment transfers molten iron from the induction furnace 5 to a steelmaking production apparatus 7, the invention is not so limited and extends to embodiments in which the iron is in a solid form.

[0190] In addition, whist the embodiment of the induction furnace 5 in Figure 2 comprises a particular arrangement of a refractory material-lined base and side walls, a removable refractory material-lined lid, and an induction coil in the wall of the furnace, the invention is not so limited and extends to any suitable forms of induction furnaces.

[0191] In addition, whilst the embodiments of the method described in relation to Figures 3 and 4 operate on a batch basis, the invention is not so limited, and the method may be operated on a continuous basis or a semi-continuous basis.

[0192] For example, a continuous / semi-continuous method may comprise the use of a channel-type induction furnace, where filling and pouring operations may proceed at the same time. Such a furnace may have a backward titling feature to facilitate slag removal from the bath surface. Such furnaces (at least for the general processing of molten iron) are offered by companies like Otto Junker GmbH. In addition, whilst the embodiments of the invention relate to processing iron ore as a starting material for producing DRI, it is noted that the invention extends to processing any other suitable iron oxide-containing material.1Phosphorous Control in Induction Furnace Steel melting using LD Slag, International Journal of Engineering

[0193] Research & Technology (IJERT) Vol. 5 Issue 06, June-2016.

Claims

CLAIMS1. A method for producing an iron feedstock having a phosphorous concentration suitable for directly forming steel in a steelmaking apparatus, typically of less than 0.03% by weight, from a hydrogen-reduced DRI having a higher phosphorous concentration using an electric induction furnace includes:(a) feeding a hydrogen-reduced feed DRI into a chamber in an induction furnace;(b) operating the induction furnace and melting the DRI via a magnetic field induced in the chamber and forming a molten DRI-containing bath;(c) forming a basic slag in the chamber that at least partially partitions phosphorus in molten DRI to the slag, with the molten DRI becoming a molten iron feedstock which is at least substantially alpha iron with a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight from the molten DRI;(d) removing, for example by tapping or raking, at least a part of the slag from the furnace; and(e) removing, for example by tapping, at least a part of the iron feedstock from the furnace at the same time or other times as removing the slag from the furnace.

2. The method defined in claim 1 includes initially selecting and then controlling a slag composition during the method to be any suitable composition to facilitate partitioning phosphorus in the molten DRI to the slag.

3. The method defined in claim 1 or claim 2 includes controlling a slag composition during the method to have a FeO concentration in a range of 5-20% by weight.

4. The method defined in claim 3 includes controlling a slag composition during the method to have a FeO concentration below 10% by weight.

5. The method defined in any one of the preceding claims includes controlling a slag composition during the method to have a CaO to SiO2 ratio of < 2.0.

6. The method defined in any one of the preceding claims includes controlling a slag composition during the method to have a MgO to AI2O3 ratio of 0.4-0.6.

7. The method defined in any one of the preceding claims includes maintaining a slag composition that comprises 5% by weight FeO, a CaO to SiCh ratio of 1.5, and a MgO to AI2O3 ratio of 0.5.

8. The method defined in any one of the preceding claims includes maintaining the molten bath at a temperature of 1540°C.

9. The method defined in any one of the preceding claims includes forming the molten bath at a temperature up to 20°C above a liquidus temperature of the alpha iron.

10. The method defined in any one of the preceding claims includes forming the molten bath at a temperature up to 30°C above a liquidus temperature of the alpha iron.

11. The method defined in any one of the preceding claims includes forming the molten bath at a temperature no more than 90°C above a liquidus temperature of the alpha iron.

12. The method defined in any one of the preceding claims includes forming the molten bath at a temperature no more than 80°C above a liquidus temperature of the alpha iron.

13. The method defined in any one of the preceding claims includes controlling the method so that at least 2 / 3 of the phosphorous in the feed DRI partitions to the slag.

14. The method defined in any one of the preceding claims includes supplying the feed DRI to the furnace in a hot state at a temperature of at least at 400°C.

15. The method defined in any one of the preceding claims includes supplying the feed DRI to the furnace as at least 97% metallised DRI.

16. The method defined in any one of the preceding claims includes operating on a batchbasis, with successive batches of the molten iron feedstock being formed in the method.

17. The method defined in claim 16 includes forming a heel of molten iron feedstock in the furnace and then carrying out steps (a) to (e).

18. The method defined in any one of the preceding claims includes removing the molten slag and the molten iron feedstock periodically after forming a full melt in the furnace.

19. The method defined in any one of claims 1 to 17 includes removing the molten slag periodically before forming a full melt in the furnace to maintain the remaining slag in the furnace with desired properties and to ensure it remains fluid for tapping the slag.

20. The method defined in any one of the preceding claims includes supplying the DRI into the furnace in a gradual manner, along with any required slag forming materials, and melting the DRI requiring bath temperatures well in excess of the liquidus temperature of the alpha iron.

21. The method defined in any one of the preceding claims includes operating a plurality of the above-described induction furnaces and producing the iron feedstock in the abovedescribed method.

22. The method defined in any one of the preceding claims includes casting the molten iron feedstock directly into ingots for subsequent downstream use as a ‘cold feed’ to a steelmaking apparatus.

23. The method defined in any one of the preceding claims includes, before removing (for example, by tapping) the molten iron feedstock from the induction furnace, but after removing (for example, by tapping) slag, heating the molten iron feedstock to ensure that the molten iron feedstock has enough superheat to enable it to be poured into a transport vessel, such as a ladle, and taken away for either remote casting activities or further downstream processing.

24. The method defined in any one of the preceding claims includes, after removing (for example, by tapping) slag from the induction furnace, converting alpha iron of the molten iron feedstock into steel by adding carbon and other alloy additives into the melt and forming molten steel, followed by removing (for example, by tapping) the molten steel with enough superheat to enable it to be poured into a transport vessel, such as a ladle and taken away for remote casting activities or further downstream processing.

25. An apparatus for producing an iron feedstock having a phosphorous concentration suitable for directly forming steel in a steelmaking apparatus, typically 0.03 % or less, by weight, from a hydrogen-reduced DRI using an electric induction furnace that is configured to melt the DRI via a magnetic field induced in the induction furnace and form a bath of molten DRI and a molten basic slag, with the slag having a composition that can at least partially partition phosphorus in the molten DRI so that the molten DRI is treated in the furnace and forms a molten iron feedstock which is at least substantially alpha iron with a phosphorous concentration suitable for directly forming steel in a steelmaking apparatus, typically a phosphorous concentration of 0.03% or less by weight, with the furnace including a chamber for melting and treating the DRI, an inlet for supplying the DRI to the chamber, and an outlet for discharging slag from the chamber, and an outlet for discharging molten iron feedstock from the chamber.

26. A steelmaking method comprising making steel in a steelmaking apparatus from an iron feedstock having a phosphorous concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight, made by the method for producing an iron feedstock from a hydrogen-reduced DRI defined in any one of claims 1 to 24.

27. The method defined in claim 26 wherein the hydrogen-reduced DRI contains phosphorus in a concentration greater than 0.07% by weight.

28. A steelmaking method comprising:(a) producing a hydrogen-reduced DRI from an iron ore having a phosphorous concentration of greater than 0.07% by weight in a DRI production apparatus;(b) melting and treating the DRI in an induction furnace and reducing the phosphorusconcentration of the DRI to a concentration suitable for directly forming steel in the steelmaking apparatus, typically 0.03% or less by weight, by partitioning phosphorus in the DRI into a slag in the furnace, including controlling the temperature in the furnace to be no more than 90°C above a liquidus temperature of the DRI, with the treated DRI becoming an iron feedstock that is at least substantially alpha iron; and(c) making steel from the iron feedstock in a steelmaking apparatus.

29. The steelmaking method defined in claim 28 comprising maintaining the temperature in the induction furnace to be no more than 90°C above the liquidus temperature of the DRI, at least until a majority of slag is removed, for example, by being tapped or raked, from the furnace.

30. The method defined in claim 28 or claim 29 wherein, when the DRI production apparatus, the induction furnace, and the steelmaking apparatus are each be in quite separate and spaced-apart locations, the steelmaking method includes producing compressed briquettes of the hydrogen-reduced DRI produced in the DRI production apparatus, transporting the compressed briquettes while hot to the induction furnace, producing iron feedstock from the hydrogen-reduced DRI in the induction furnace, casting or granulating the iron feedstock, transporting the cast or granulated iron feedstock to the steelmaking apparatus, and making steel from the iron feedstock in the steelmaking apparatus.

31. The steelmaking method defined in claim 28 or claim 29 wherein, when the DRI production apparatus and the induction furnace are in close proximity and the steelmaking apparatus is in a quite separate and spaced-apart location to that of the DRI production apparatus and the induction furnace, the steelmaking method includes producing the iron feedstock in the DRI production apparatus and the induction furnace, casting or granulating the iron feedstock, and transporting the iron feedstock to the steelmaking apparatus, and making steel from the iron feedstock in the steelmaking apparatus.

32. The steelmaking method defined in claim 28 or claim 29 wherein, when the DRI production apparatus is in one location and the induction furnace and the steelmaking apparatus are in close proximity in a quite separate and spaced-apart location to that of theDRI production apparatus, the steelmaking method includes producing compressed briquettes of the hydrogen-reduced DRI produced in the DRI production apparatus, transporting the briquettes while hot to the induction furnace, producing iron feedstock for the hydrogen- reduced DRI in the induction furnace, and making steel from the iron feedstock in the steelmaking apparatus.

33. The steelmaking method defined in claim 28 or claim 29 wherein, when the DRI production apparatus, the induction furnace, and the steelmaking apparatus are a part of an integrated steelmaking apparatus, the steelmaking method includes producing a hydrogen- reduced DRI in the DRI production apparatus, transferring the DRI to the induction furnace, producing an iron feedstock from the hydrogen-reduced DRI in the induction furnace, transferring the iron feedstock to the steelmaking apparatus, and producing steel from the iron feedstock in the steelmaking apparatus.

34. The steelmaking method defined in claim 33 includes transferring the hydrogen- reduced DRI in a hot state directly from the DRI production apparatus to the induction furnace.

35. The steelmaking method defined in claim 33 or claim 34 includes transferring the iron feedstock in as hot state directly from the induction furnace to the steelmaking apparatus.

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