Production of metallic iron from iron ore

Abstract

Methods and systems for producing metallic iron are described. In one or more embodiments, a method includes introducing iron ore into an iron ore inlet of a furnace so that the iron ore progresses downward through the furnace from the iron ore inlet. In addition, the method includes introducing hydrogen into the furnace below the iron ore inlet. Further, the method includes reducing at least a portion of the iron ore to metallic iron with a first portion of the hydrogen flowing upward through the furnace. Still further, the method includes combusting a second portion of the hydrogen to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

Description

PRODUCTION OF METALLIC IRON FROM IRON ORECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. provisional patent application serial No. 63 / 531,230, filed August 7, 2023, and entitled “Production of Metallic Iron from Iron Ore,” the contents of which are incorporated by reference herein in their entirety.TECHNICAL FIELD

[0002] The present disclosure provides systems and methods for producing molten iron from iron ore, particularly by utilizing hydrogen in the production as a reductant and as an energy source. The produced molten iron can be substantially carbon-free.BACKGROUND

[0003] The modem blast furnace (BF) has been the primary means of reducing iron ore to metallic iron for the last 200 years. A blast furnace generally comprises a packed bed shaft furnace in which coke, ore, and limestone are continuously added at the top, and molten pig iron (iron containing around 4% carbon) and slag are tapped intermittently at the bottom. A hot blast of oxy gen-enriched air is blown through the lower section of the blast furnace to facilitate combustion and the chemical reactions that lead to the production of molten iron. The coke (that is, carbon) is both the fuel and the reductant. The combustion of the coke provides heat and carbon monoxide, which is a reductant in the process. More recently, alternatives for blast furnace processing utilize syngas (that is, a mixture of hydrogen and carbon monoxide) to produce solid metallic iron known as Direct Reduced Iron (“DRI”). DRI is a solid material with a sponge-like structure that contains around 85% metallic iron. The remainder of the DRI is carbon, unreacted ore, and gangue, which is unreacted oxides originally present in the iron ore. Although attempts are being made to use 100% hydrogen as the reductant, the current use of syngas leads to carbon and carbon emissions during DRI production. As well, downstream processing of the DRI may require the carbon to be removed, producing carbon dioxide emissions. Other competing commercial processes, such as Corex®, HIsmelt, and Finex®, that reduce iron ore to DRI or liquid iron also exist; however, such processes use carbon-based sources for the reduction of iron, resulting in CO2emissions and an iron product containing 1-4% by weight carbon. The included carbon once again must be removed in downstream processes.BRIEF SUMMARY

[0004] The present disclosure relates to systems and methods for the production of liquid (for example, molten) iron ore using hydrogen as both a fuel and a reductant. The production can be referenced as hot hydrogen reduction of iron ore, or “H2RIO”. With such production, iron ore pellets can be reduced continuously in a counter current reactor by a reductant, specifically hydrogen. In such a process, the iron orepellets may be immediately melted by burners operating at a temperature in a range of from about 1500 °C to about 1900 °C, such as from about 1600 °C to about 1800 °C, or such as from about 1650 °C to about 1750 °C, inclusive of the end values and values in-between 1500 °C and 1900 °C, using hydrogen as a fuel for combustion with oxygen. The metallic iron becomes molten as it is heated above its melting point and collects at the bottom of the furnace. Any unreacted iron ore or gangue are also melted and float on top of the molten iron pool as slag. Both molten iron and slag can be tapped periodically in a manner similar to that used in a blast furnace. The so-produced molten iron canthen be directly charged into an electric arc furnace (EAF) for further processing, if needed. By using hydrogen and eliminating carbon sources as the energy source and reductant, the H2RIO process can be operated with reduced carbon production and thus can be substantially or entirely carbon-free.

[0005] The H2RIO process can provide a direct alternative to the conventional blast furnace approach. In particular, the process can produce liquid iron from iron ore in a single reactor at high throughput, which is not available with other known alternatives to blast furnace production. Moreover, since hydrogen is primarily or solely utilized as both the reductant and the energy source(that is, the fuel), carbon emissions can be near zero or zero (that is, only de minimis or no measurable carbon emissions). This can be achieved because the process can produce substantially or completely without carbon a liquid iron product that can be directly charged into an EAF, bypassing the need for any basic oxygen furnace (BOF). Production of steel via BF+BOF produces approximately 2.2 tons of CO2per ton of iron produced. By contrast, in one or more embodiments, which may be combined with other embodiments, the H2RIO process produces approximately 0.2 tons of CO2per ton of metallic iron produced, such as less than 0.15 tons, or less than 0.1 tons of CO2per ton of metallic iron produced, inclusive of the end value 0.2 tons. Any CO2attributable to the process primarily arises from the iron ore pelletizing process that produces the feed material.

[0006] As seen from the foregoing, H2RIO can provide many advantages and improvements over known systems and methods for iron production, including liquid or molten iron production.

[0007] H2RIO is an improvement on the blast furnace as it does not use carbon either for energy or as a reductant. Rather, the H2RIO process is hydrogen-based and does not produce carbon emissions in any significantly measurable quantities (that is, substantially or completely free of carbon emissions). One exception can be embodiments where limestone may be added to remove sulfur from the iron because chemical reactions with the lime can result in a minor amount of CO2emissions compared to the traditional BF+BOF process.

[0008] H2RIO produces metallic liquid iron that can be directly charged in the EAF. Also, since H2RIO can utilize, for example, a packed-bed continuous reactor, similar to those used in a blast furnace, the end product is in a liquid form and thus can be scalable to the same levels as the blast furnace, that is, in the range of about 3 to 5 million tons of iron per year.

[0009] In an example embodiment, the present disclosure can provide a method for producing metallic iron. The method can comprise adding iron ore to a furnace; adding hydrogen to the furnace; adding oxygen to the furnace; and operating the furnace such that a portion of the hydrogen reduces the iron ore, such that a majorityof the iron ore by weight is converted to metallic iron, such that a portion of the hydrogen is combusted with the oxygen to produce heat to melt the metallic iron, and such that a molten iron product is provided.

[0010] In an example embodiment, the present disclosure can provide a system for producing metallic iron. The system can comprise: a furnace configured with a top section, a bottom section, and an intermediate section; one or more burners arranged proximate the bottom section of the furnace; an input proximate the top section of the furnace, the input configured to receive iron ore for downward passage through the furnace; a one or more input positioned proximate the bottom section of the furnace and configured for receiving a first hydrogen feed and an oxygen for combustion by the one or more burners and liquifying the iron in the iron ore, and for receiving a second hydrogen feed for reacting with the iron ore at least in the intermediate section of the furnace and reducing the iron into a metallic form of iron; and an output positioned below the one or more burners of the furnace and configured for passage of liquid metallic iron from the furnace.

[0011] One or more embodiments are directed to a method for producing metallic iron. The method may include introducing iron ore into an iron ore inlet of a furnace so that the iron ore progresses downward through the furnace from the iron ore inlet. In addition, the method may include introducing hydrogen into the furnace below the iron ore inlet. Further, the method may include reducing at least a portion of the iron ore to metallic iron with a first portion of the hydrogen flowing upward through the furnace. Still further, the method may include combusting a second portion of the hydrogen to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

[0012] One or more embodiments are directed to a system for producing metallic iron. The system may include a furnace and an iron ore inlet defined on the furnace that is configured to receive iron ore for downward passage through the furnace. In addition, the system may include one or more hydrogen feed inlets defined on the furnace. The one or more hydrogen feed inlets may be positioned below the iron ore inlet and configured to receive hydrogen into the furnace so that a first portion of the hydrogen is configured to reduce at least a portion of the iron ore into metallic iron in the furnace. Further, the system may include one or more burners coupled to the furnace below the iron ore inlet and configured to combust a second portion of the hydrogen and thereby to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

[0013] Embodiments described comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features previously described as well as others will be readily apparent to those having ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. One should appreciate that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same or similar purposes as the disclosed embodiments. One should also realize that such equivalent constructions do not depart from the spirit and scope of the principles disclosed.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Having thus described the disclosure in the foregoing general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, where:

[0015] FIG. 1 is a schematic illustration of a system useful for carrying out a method of converting iron ore to metallic iron, according to one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0016] The present subject matter will now be described more fully with reference to embodiments thereof. These embodiments are described so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. Indeed, the subject matter can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise.

[0017] The present disclosure provides systems and methods where liquid metallic iron can be prepared from iron ore and hydrogen. In one or more embodiments, which may be combined with other embodiments, the inlet burner feed composition comprises a first hydrogen feed. Molecular hydrogen (H2) may be utilized as both the reductant for the conversion of iron ore into metallic iron and as the fuel for combustion, providing reaction heat for melting of the metallic iron, further providing a molten, metallic iron product. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed comprises, consists essentially of, or consists of molecular hydrogen. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed comprises molecular hydrogen in a range of from about 50 mol% (mole percent) or greater, such as about 55 mol% or greater, 60 mol% or greater, such as 65 mol% or greater, such as 70 mol% or greater, such as 75 mol% or greater, such as 80 mol% or greater, such as about 85 mol% or greater, such as about 90 mol% or greater, such as about 95 mol% or greater, such as about 99 mol% or greater, such as about 99.5 mol% or greater, such as about 99.9 mol% or greater, such as about 99.99 mol% or greater, such as about 99.999 mol% or greater, or such as about 99.9999 mol% or greater, inclusive of the end values and values in-between 85 mol% or greater. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed further comprises ammonia (NH3). Any remainder gases in the first hydrogen feed may comprise process inerts, that is, non-reactive to the iron ore or metallic iron.

[0018] In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed comprises, consists essentially of, or consists of ammonia. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed comprises ammonia in a range of from about 50 mol% or greater, such as about 55 mol% or greater, 60 mol% or greater, such as 65 mol% or greater, such as 70 mol% or greater, such as 75 mol% or greater, such as 80 mol% or greater, such as about 85 mol% or greater, such as about 90 mol% or greater, such as about 95 mol% or greater, such as about 99 mol% or greater, such as about 99.5 mol% or greater, such as about 99.9 mol% or greater, such as about 99.99 mol% or greater, suchas about 99.999 mol% or greater, or such as about 99.9999 mol% or greater, inclusive of the end values and values in-between 85 mol% or greater. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed further comprises molecular hydrogen. Any remainder gases in the first hydrogen feed may comprise process inerts, that is, non-reactive to the iron ore or metallic iron.

[0019] The embodiment systems and methods of producing metallic iron can be carried out using a countercurrent stack furnace or reactor. For example, iron ore pellets can be fed into an upper section or top of the furnace where they can be preheated by the rising, hot gas before they are charged. In a lower portion or bottom of the furnace, hydrogen / oxygen burners can be operated to generate hot gases that provide heat. In one or more embodiments, which may be combined with other embodiments, the inlet burner feed composition further comprise oxygen. In one or more embodiments, which may be combined with other embodiments, the oxygen comprises, consists essentially of, or consists of oxygen. In one or more embodiments, the introduced oxygen comprises oxygen in a range of from about 80 mol% or greater, such as about 85 mol% or greater, such as about 90 mol% or greater, such as about 95 mol% or greater, such as about 99 mol% or greater, such as about 99.5 mol% or greater, such as about 99.9 mol% or greater, such as about 99.99 mol% or greater, such as about 99.999 mol% or greater, or such as about 99.9999 mol% or greater, inclusive of the end values and values in-between 85 mol% or greater. Any remainder gases in the introduced oxygen may comprise process inerts, that is, non-reactive to the iron ore or metallic iron.

[0020] The inlet burner feed composition, comprising the first hydrogen feed is supplied to the burners in an amount that is greater than the atomic stoichiometric amount necessary for full combustion of the atomic hydrogen present in the first hydrogen feed. A remainder of atomic (H+) and molecular (H2) hydrogen exists in the product hot combustion gases to function as the reductant while also maintaining the flame temperature at the burners in the aforementioned range. In one or more embodiments, which may be combined with other embodiments, the atomic ratio of hydrogen to oxygen in the inlet burner feed composition is in a range of from about greater than 2: 1, such as 2.5: 1, 3: 1, 3.5:1, 4:1, 5:1, 6: 1, 7: 1, 8: 1, 9: 1, and 10: 1, inclusive of the end values and values in-between greater than 2: 1. In one or more embodiment, which may be combined with other embodiments, the flame temperature is maintained in a range of from about 1500 °C to about 1900 °C, such as from about 1600 °C to about 1800 °C, or such as from about 1650 °C to about 1750 °C, inclusive of the end values and values in-between 1500 °C and 1900 °C. Such control is useful since a stoichiometric hydrogen / oxygen combustion reaction is known to produce temperatures up to 2550 °C, which is unnecessary for the liquidation of the iron and is potentially wasteful of the reductant in side-reactions with non-iron materials in the iron ore. The excess hot hydrogen (H+, H2) serves as the active reductant, allowing the iron ore pellets to be chemically reduced continuously along the length of the furnace.

[0021] In one or more embodiment, which may be combined with other embodiments, supplemental hydrogen, such as a second hydrogen feed, may be introduced above the burners, such as in an upper part of the lower section or in the intermediate section, to facilitate the reduction reaction of the iron in the iron ore. In one or more embodiments, which may be combined with other embodiments, the second hydrogen feed comprises molecular hydrogen in a range of from about 50 mol% or greater, such as about 55 mol% or greater,60 mol% or greater, such as 65 mol% or greater, such as 70 mol% or greater, such as 75 mol% or greater, such as 80 mol% or greater, such as about 85 mol% or greater, such as about 90 mol% or greater, such as about 95 mol% or greater, such as about 99 mol% or greater, such as about 99.5 mol% or greater, such as about 99.9 mol% or greater, such as about 99.99 mol% or greater, such as about 99.999 mol% or greater, or such as about 99.9999 mol% or greater, inclusive of the end values and values in-between 85 mol% or greater. In one or more embodiments, which may be combined with other embodiments, the second hydrogen feed further comprises ammonia (NH3). Any remainder gases in the introduced hydrogen may comprise process inerts, that is, non-reactive to the iron ore or metallic iron.

[0022] In one or more embodiments, the second hydrogen feed comprises ammonia in a range of from about 50 mol% or greater, such as about 55 mol% or greater, 60 mol% or greater, such as 65 mol% or greater, such as 70 mol% or greater, such as 75 mol% or greater, such as 80 mol% or greater, such as about 85 mol% or greater, such as about 90 mol% or greater, such as about 95 mol% or greater, such as about 99 mol% or greater, such as about 99.5 mol% or greater, such as about 99.9 mol% or greater, such as about 99.99 mol% or greater, such as about 99.999 mol% or greater, or such as about 99.9999 mol% or greater, inclusive of the end values and values in-between 85 mol% or greater. In one or more embodiments, which may be combined with other embodiments, the introduced hydrogen further comprises molecular hydrogen. Any remainder gases in the introduced hydrogen may comprise process inerts, that is, non-reactive to the iron ore or metallic iron. Although not wanting to be bound by theory, it is believed that ammonia introduced above the burners may have some or all its hydrogens cracked from the atomic nitrogen, functioning as the hydrogen donor for the chemical reduction of iron ore into metallic iron. The remaining nitrogen may be utilized as a furnace diluent.

[0023] Depending on many operational and financial factors, molecular hydrogen and ammonia may be utilized in the embodiment system in different feeds. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed predominantly comprises, that is, comprises greater than 50 mol%, molecular hydrogen and the second hydrogen feed predominantly comprises molecular hydrogen. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed predominantly comprises molecular hydrogen and the second hydrogen feed predominantly comprises ammonia. In one or more embodiments, which may be combined with other embodiments, the first hydrogen feed predominantly comprise ammonia and the second hydrogen feed predominantly comprises molecular hydrogen. In one or more embodiments, which may be combined with other embodiments, the first and second hydrogen feeds predominantly comprise ammonia. In one or more embodiments, which may be combined with other embodiments, there is no second hydrogen feed.

[0024] By the time the iron ore pellets traverse from their introduction higher in the furnace and to the burners in the lower section, the iron ore can be substantially or fully reduced to metallic iron. In one or more embodiment, which may be combined with other embodiments, the amount of that reduced to metallic iron is in a range of at least about 80 wt.% (weight percent), such as least 85 wt.%, such as at least 90 wt.%, and such as at least 95 wt.% of the iron originally present in the iron ore, inclusive of the end value 80 wt.%. The ironore pellets, now in reduced form, reaching the lower section of the furnace proximate the burners may comprise in a range of from about 80 wt.% to about 99 wt.% metallic iron, such as about 82 wt.% to about 98 wt.%, or about 85 wt.% to about 95 wt.% metallic iron, inclusive of the end values and values in-between 80 wt.% to about 99 wt.%. The remainder of the reduced iron ore pellets comprise unreacted iron ore and gangue. Due to the temperatures proximate to the burners, all the constituents are heated greater than their respective melting points and are molten. The metallic iron, which is heavier than the unreacted iron ore and gangue, sinks to the bottom of the fluid; the unreacted iron ore and gangue float on the top of the fluid as molten slag.

[0025] FIG. 1 is a schematic illustration of a system 1000 useful for carrying out a method of converting iron ore to metallic iron. There are several feed and product lines traversing the bounds of system 1000. Line 1 introduces iron ore into the system via an iron ore inlet defined on the furnace 100. Lines 3 and 9 introduce a first and second hydrogen feed, respectively. Line 9 is an optional feed. Line 5 introduces an oxygen feed. Line 7 introduces a cooling water feed, and line 15 passes process water from the system. Line 11 passes a molten or liquid metallic iron product for further processing outside of the system. Line 13 passes a molten slag byproduct for further processing outside of the system. Additional lines may traverse the system boundary, including liquid and gas purge lines, heating and cooling lines, and other supporting material, thermal and signal lines. A person of ordinary skill in the art appreciates that FIG. 1 is a simplified drawing that is non-limiting to represent a general description of embodiment configurations and process flows.

[0026] The term “lines,” such as previously used to refer to the lines 1, 3, 5, 7, 9, 11, 13, 15, and used elsewhere herein, may include any suitable conveyance member or device for transporting solids or fluids (that is, liquids or gases). For instance, the term “lines” specifically includes pipes, hoses, conveyors, open channels, ports, tubing, among other conveyance devices.

[0027] Within system 1000, a DRI furnace or reactor 100 (which may be more simply referred to herein as “furnace 100”) has several sections, including a first or upper section 110, a second or middle section 120, and a third or lower section 130. The middle section 120 may be positioned between the upper section 110 and lower section 130 along the height of the furnace 100. The line 1 is coupled to upper section 110 to introduce iron ore into an iron ore inlet defined on the top of the furnace 100.

[0028] The furnace 100 also includes a first hydrogen feed inlet 122 is positioned between the middle section 120 and lower section 130. In addition, the furnace 100 includes a second hydrogen feed inlet 112 that is positioned between the upper section 110 and middle section 120, and thus positioned above the first hydrogen feed inlet 122. In some instances, the second hydrogen feed inlet 112 may be optional.

[0029] One or more burners 123 may be coupled to the furnace 100, at or proximate to the first hydrogen feed inlet 122. For instance, the hydrogen flowing into the furnace 100 via the first hydrogen feed inlet 122 may do so through the bumer(s) 123. The line 5 may be coupled to the first hydrogen feed inlet 112 to introduce oxygen into the middle section 120 of the furnace 100. In one or more embodiments, oxygen introduced into the furnace 100 via the first hydrogen feed inlet 112 may also progress into the furnace via the bumer(s) 123. The hydrogen flowing into the furnace 100 through the first hydrogen feed inlet 122 may be combusted via the bumer(s) 123, and the oxygen flowing into the furnace 100 via the line 5 and first hydrogenfeed inlet 122 may function as an oxidant to facilitate this combustion reaction. One of skill in the art based upon the prior disclosure may reasonably assume that the bumer(s) 123 for the furnace 100 may be positioned in the middle section 120 or within proximity thereof.

[0030] The line 13 is coupled to the lower section 130 to pass molten slag (represented in relief by molten slag 21) from furnace 100. Likewise, the line 11 is also coupled to the lower section 130 to pass molten metallic iron (represented in relief by molten metallic iron 23) from furnace 100.

[0031] System 1000 has several other units for supporting the iron reduction reaction and formation of molten metallic iron. For instance, a particulate filter 200 is configured to remove any solids entrained in gases egressing from the top of the furnace 100. In addition, a first heat exchanger 300 may be utilized the cool the hot gases flowing outward from the particulate filter 200 and pre-heat a first hydrogen stream introduced into first heat exchanger 300 via line 3. Likewise, a second heat exchanger 350 may be utilized to further cool hot gases that are discharged from the first heat exchanger 300 via line 29 and to pre-heat a second hydrogen feed stream introduced in to the second heat exchanger 450 via line 9. Depending on the use of the optional second hydrogen feed stream via line 9, the second heat exchanger 450 may also be optional. A blower or compressor 400 configured to motivate and potentially pressurize cooled gases from the furnace 100 may be utilized. A cooler, such as a direct contact cooler (DCC) 500, configured to further reduce the temperature of and remove water from the furnace gases, may be utilized before such gases may be reintroduced into the furnace 100 as a feedstock. DCC 500 shows line 7 introducing cooling water and line 15 purging process water from system 1000.

[0032] In one or more embodiments, which may be combined with other embodiments, iron ore is introduced into the furnace. Specifically, with reference to FIG. 1, iron ore, which can be pre-heated in a separate furnace or similar unit (not shown), can be introduced proximate a top of the upper portion 110 of furnace (reactor) 110 via line 1 and passed downward along a height of the furnace (curvy dashed arrow 19). While doing so, the iron ore is heated by hot gases, which are the product of combustion as well as radiative heating, rising upward (curvy dashed arrow 17) from the bumer(s) 123 positioned proximate the first hydrogen feed inlet 122 as previously described.

[0033] The rising, hot gases 17 include hydrogen, which reacts with the iron ore, reducing most of the iron 19 in the iron ore to metallic iron. Specifically, the hydrogen feed stream flowing into the first hydrogen feed inlet 122 may have an amount of hydrogen that is greater than the atomic stoichiometric amount necessary for full combustion of the atomic hydrogen present in the first hydrogen feed stream via the bumer(s) 123. As a result, the combustion of the hydrogen in the first hydrogen feed stream introduced via inlet 122 may result in hot gases 17 that include un-combusted hydrogen therein that then may be used to reduce the iron 19 in the iron ore as previously described. In one or more embodiments, additional hydrogen is added into the hot gases 17 above (and thus downstream of) of the burner(s) 123 via the second hydrogen feed stream that is introduced via the second hydrogen feed inlet 112. In one or more embodiments that utilize the second hydrogen feed inlet 112, all or substantially all of the hydrogen flowed into the furnace 100 via the first hydrogen feed inlet 112 may be combusted in the bumer(s) 123. As previously described, the hydrogen flowed into the furnace100 via one or both of the first hydrogen feed inlet 112 and the second hydrogen feed inlet 122 may comprise hydrogen in the form of ammonia, molecular hydrogen, or a combination thereof.

[0034] Although having been reduced, the metallic iron may remain in pellet, that is, solid, form until reaching a lower portion 130 in the furnace 100. As the metallic iron solids traverse down the furnace (as indicated by line 19), the metallic iron solids may traverse below the level of the burners 123 and first hydrogen feed inlet 122. Positioned below the burners 123, the metallic iron solids are heated to a temperature more than the melting point of metallic iron, and also more than the melting point of other ore solids, such as noniron metal oxides, silicates, and other impurities from the iron ore. As a result, the metallic iron solids are converted to molten iron 23 that collects in the lower section 130 of furnace 100. The molten iron 23 may be mostly, if not completely, in metallic form at this point and may be removed as a product from an outlet at or proximate to the bottom of the lower section 130 of the furnace 100 via line 11. Thus, the molten iron 23 may be removed from lower section 130 at a point that is below the bumer(s) 123. The lighter molten impurities and any remaining solids, such as slag 21, may be removed from the lower section 130 of the furnace 100 utilizing an outlet positioned above the outlet for discharging the liquid metallic iron outlet into line 11. The hot gases 17 rising through the furnace, which comprise hydrogen and water (that is, superheated steam), may pass from an outlet in the upper section 110 of the furnace through a line 25 as a top gas stream. The line 25 may direct these hot top gas stream to the particulate filter 200. After traversing particulate filter 200, the filtered top gases pass through line 27 and into first heat exchanger 300. First heat exchanger 300 and, optionally, second heat exchanger 350, extract heat from the filtered top gases passing through lines 27 and 29, respectively, by utilizing the content of the first and, optionally, second hydrogen feeds provided for in line 3 and, optionally, line 9, respectively.

[0035] Specifically, the first hydrogen feed stream flowing in the line 3 may be pre-heated in the first heat exchanger 300 by the filtered top gasses flowing in line 27. The heated first hydrogen feed stream may then be discharged from the first heat exchanger 300 via the line 41, and the filtered top gas stream (at least somewhat cooled due to the heat exchange within first heat exchanger 300) is discharged from first heat exchanger 300 via line 29. In addition, when present, the second hydrogen feed stream flowing in the line 9 may be similarly pre-heated in the second heat exchanger 350 by the filtered top gases flowing in line 29, downstream of first heat exchanger 300. The heated second hydrogen feed stream may then be discharged from the second heat exchanger 350 via line 51, and the filtered top gas stream (which is further cooled due to the heat exchanger within the second heat exchanger 350) is discharged from the second heat exchanger 350 via line 31.

[0036] The cooled top gases, comprising hydrogen and water, traverse line 31 into compressor 400, where the pressure of the stream is elevated. For embodiments where the second hydrogen feed stream and line 9 are omitted (so that the second heat exchanger 350 is also omitted), the cooled top gases passing out of first heat exchanger 300 via line 29 may be directed into the compressor 400. Line 33 contains pressurized top gas that is discharged from the compressor 400 and introduced into the bottom of the DCC 500, where cooling water introduced to the DCC 500 via line 7 is utilized to further cool the pressurized top gas so as to condensewater therefrom. In addition, the cooling water introduced to the DCC 500 may also strip any water-soluble components from the pressurized top gas and thereby form a recycled hydrogen feed that is discharged from the top of the DCC 500 via a line 35 (which may be referred to herein as a “recycle line”).

[0037] Downstream of the DCC 500, the contents of line 35 may optionally split into a first recycled hydrogen feed line 37 and a second recycled hydrogen feed line 39. A first portion of the recycled hydrogen feed may be flowed through the line 37 and combined with the pre-heated hydrogen stream flowing in the line 41 to provide a combined first hydrogen feed stream that may be introduced into the furnace via first hydrogen feed inlet 122 via line 43. A second portion of the recycled hydrogen feed may be flowed through line 39 and combined with the pre-heated hydrogen stream flowing in the line 51 to provide a combined second hydrogen feed stream that may be introduced into the furnace 100 via the second hydrogen feed inlet 112.

[0038] In one or more embodiments, which may be combined with other embodiments, only the first recycled hydrogen feed line 37 is present and all the recycled hydrogen feed is directed to the furnace 100 with the first hydrogen feed via the first hydrogen feed inlet 122. In such instances, all the recycled hydrogen feed in lines 35 and 37 is combined with the first hydrogen feed in line 41 and introduced into the furnace as the first hydrogen feed via first hydrogen feed inlet 122. In addition, in such instance, the second hydrogen feed line 9 and downstream lines (including line 39) are not present.

[0039] In one or more embodiments, which may be combined with other embodiments, the second recycled hydrogen feed line 9 is present and all the recycled hydrogen feed flowing in line 35 is directed to the furnace 100 with the second hydrogen feed flowing in line 9. In such instances, all the recycled hydrogen feed in lines 35 and 39 is combined with the second hydrogen feed in line 51 and introduced into the furnace 100 as the second hydrogen feed via second hydrogen feed inlet 112. In such instances, although first hydrogen feed line 43 is present and introduced into the furnace 100, the recycle hydrogen feed 35 is not in one-way fluid communication with it via the line 37.

[0040] As previously described, the hydrogen provided into the furnace via one or both of the first hydrogen feed inlet 122 and, optionally, the second hydrogen feed inlet 112 may be in the form of molecular hydrogen, ammonia, or a combination thereof. For instances, the concentrations of molecular hydrogen or ammonia for the hydrogen flowing into the furnace 100 via one or both of the inlet 122 and, optionally, the inlet 122 may be within the ranges previously described in one or more embodiments.

[0041] The H2RIO process as shown in FIG. 1 was prophetically modeled in Aspen Plus® (Aspen Technology Inc; Bedford, MA) to validate the system and method. The prophetic model generated process requirements for hydrogen and oxygen inputs per kilogram of iron ore input as well as heat exchanger duties, water generation, and recycle equipment duties. The endothermic heat requirement for the reduction was also calculated, as well as heat available to pre-heat the iron ore. The model confirmed that excess hydrogen or steam could be used to limit the combustor flame temperature to a value of about 1700 °C such that heated, excess hydrogen could serve as the reducing agent for reaction with the iron ore. The model determined a heat of reaction approximately similar to the known heat of reaction (99.5 kJ / mol (Kilojoules per molehydrogen) expected vs. 99.7 kJ / mol calculated) and the anticipated hydrogen consumption for the iron ore to metallic iron reduction reaction.

[0042] In one or more embodiments, which may be combined with other embodiments, the inlet burner feed composition may further comprise an inert diluent. In such instances, burner temperature control may be achieved by utilizing a stoichiometric feed of hydrogen to oxygen with a gaseous, non-reactive dilutant, for example, nitrogen or water. In doing so, the heat of reaction at the burners is diluted such that the flame temperature is maintained as previously described in a range of from about 1500 °C to about 1900 °C. In instances where ammonia is utilized in part or total as the supply of hydrogen, the nitrogen from the combustion of ammonia also produces nitrogen, which may act as the diluent.

[0043] In embodiments where lime addition at the top of the furnace along with iron ore pellets is used, such as to remove sulfur, a choice may be made. In one or more embodiment, which may be combined with other embodiments, calcium carbonate, also known as CaCO,. limestone, or lime, is introduced into the furnace intermixed with the iron ore pellets. In one or more embodiment, which may be combined with other embodiments, calcium hydroxide, also known as Ca(OH)2or slaked lime, is introduced into the furnace intermixed with the iron ore pellets. Introduction of limestone will cause the formation of a relatively small amount of CO2in the furnace as the lime converts into CaO, calcium oxide, or quicklime. Slaked lime externalizes the CO2formation from the furnace 100. CO2formation within the furnace 100 may act as a dilutant proximate to the bumer(s) 123 and up-fumace from the bumer(s) 123 as conversion of the calcium carbonate occurs, assisting somewhat in maintaining the flame temperature and heat upon the traversing iron ore pellets.

[0044] As explained previously and reiterated here, the present disclosure includes, without limitation, the following embodiments and example implementations.

[0045] Clause 1 : A method for producing metallic iron, the method comprising: introducing iron ore into an iron ore inlet of a furnace so that the iron ore progresses downward through the furnace from the iron ore inlet; introducing hydrogen into the furnace below the iron ore inlet; reducing at least a portion of the iron ore to metallic iron with a first portion of the hydrogen flowing upward through the furnace; and combusting a second portion of the hydrogen to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

[0046] Clause 2: The method of any of the clauses, further comprising: producing a top gas stream from the furnace; separating a recycle hydrogen stream from the top gas stream; and recycling the recycle hydrogen stream to the furnace as at least a portion of the hydrogen introduced into the furnace.

[0047] Clause 3 : The method of any of the clauses, where introducing hydrogen into the furnace comprises introducing the first portion and the second portion the hydrogen together into a first hydrogen feed inlet that is positioned below the iron ore inlet, and where combusting the second portion of the hydrogen comprises subjecting both the first portion and the second portion to a combustion process so that the first portion of the hydrogen is un-combusted and the second portion of the hydrogen is combusted.

[0048] Clause 4 : The method of any of the clauses, further comprising: pre-heating a hydrogen feed stream via the top gas stream to form a pre-heated hydrogen feed stream; and combining the recycle hydrogen stream with the pre-heated hydrogen feed stream to form the hydrogen introduced into the furnace.

[0049] Clause 5 : The method of any of the clauses, where introducing hydrogen into the furnace comprises: introducing the second portion of the hydrogen into a first hydrogen feed inlet of the furnace that is positioned below the iron ore inlet; and introducing the first portion of the hydrogen into a second hydrogen feed inlet of the furnace that is positioned below the iron ore inlet and above the first hydrogen feed inlet.

[0050] Clause 6: The method of any of the clauses, where recycling the recycle hydrogen stream to the furnace comprises introducing the recycle hydrogen stream into the first hydrogen feed inlet as at least a portion of the second portion of the hydrogen.

[0051] Clause 7: The method of any of the clauses, where recycling the recycle hydrogen stream to the furnace comprise introducing the recycle hydrogen stream into the second hydrogen feed inlet at a least a portion of the first portion of the hydrogen.

[0052] Clause 8: The method of any of the clauses, further comprising: preheating a first hydrogen feed stream via the top gas stream; preheating a second hydrogen feed stream via the top gas stream; introducing the first hydrogen feed stream into the first hydrogen feed inlet as at least a portion of the second portion of the hydrogen; and introducing the second hydrogen feed stream into the second hydrogen feed inlet as at least a portion of the first portion of the hydrogen.

[0053] Clause 9 : The method of any of the clauses, where introducing hydrogen into the furnace comprises introducing at least some of the hydrogen into the furnace as ammonia.

[0054] Clause 10: The method of any of the clauses, where further utilizing nitrogen from the ammonia as a diluent for the combustion of the second portion of the hydrogen.

[0055] Clause 11 : The method of any of the clauses, further comprising maintaining a temperature of the combustion of the second portion of the hydrogen in a range of from about 1500 °C to about 1900 °C.

[0056] Clause 12: A system for producing metallic iron, the system comprising: a furnace; an iron ore inlet defined on the furnace that is configured to receive iron ore for downward passage through the furnace; one or more hydrogen feed inlets defined on the furnace, the one or more hydrogen feed inlets being positioned below the iron ore inlet and configured to receive hydrogen into the furnace so that a first portion of the hydrogen is configured to reduce at least a portion of the iron ore into metallic iron in the furnace; and one or more burners coupled to the furnace below the iron ore inlet and configured to combust a second portion of the hydrogen and thereby to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

[0057] Clause 13 : The system of any of the clauses, further comprising a first outlet defined on the furnace below the one or more burners that is configured to discharge the molten iron product from the furnace.

[0058] Clause 14: The system of any of the clauses, further comprising a second outlet defined on the furnace below the one or more burners and above the first outlet that is configured to discharge slag from the furnace.

[0059] Clause 15 : The system of any of the clauses, further comprising: a third outlet defined on the furnace that is configured to discharge a top gas stream emitted from the furnace; and one or more heat exchangers in fluid communication with the third outlet that are configured to preheat one or more hydrogen feed streams via the top gas stream.

[0060] Clause 16: The system of any of the clauses, further comprising: a cooler that is in fluid communication with the one or more heat exchangers, where the cooler is configured to separate a recycle hydrogen stream from the top gas stream; and a recycle line coupled to the cooler that is configured to communicate the recycled hydrogen stream from the cooler to the one or more hydrogen feed inlets of the furnace.

[0061] Clausel7: The system of any of the clauses, where the one or more hydrogen feed inlets comprises a first hydrogen feed inlet, and where both the first portion and the second portion of the hydrogen is introduced into the furnace via the first hydrogen feed inlet.

[0062] Clause 18: The system of any of the clauses, where the one or more hydrogen feed inlets comprises: a first hydrogen feed inlet that is configured to introduce the second portion of the hydrogen into the furnace; and a second hydrogen feed inlet that is configured to introduce the first portion of the hydrogen into the furnace, where the second hydrogen feed inlet is positioned below the iron ore inlet and above the first hydrogen feed inlet.

[0063] Clause 19: The system of any of the clauses, where the one or more heat exchangers comprise: a first heat exchanger that is configured to pre-heat a first hydrogen feed stream via the top gas stream and communicate the first hydrogen feed stream to the first hydrogen feed inlet; and a second heat exchanger that is configured to pre-heat a second hydrogen feed stream via the top gas stream and communicate the second hydrogen feed stream to the second hydrogen feed inlet.

[0064] Clause 20: The system of any of the clauses, where the recycle line is configured to combine a first portion of the recycle hydrogen stream with the first hydrogen feed stream downstream of the first heat exchanger to form the second portion of the hydrogen, and where the recycle line is also configured to combine a second portion of the recycle hydrogen stream with the second hydrogen feed stream downstream of the second heat exchanger to form the first portion of the hydrogen.

[0065] The terms “about”, “substantially”, and “generally” as used herein can indicate that certain recited values or conditions are intended to be read as encompassing the expressly recited value or condition and values or conditions that are or are recognized as being relatively close. For example, unless otherwise indicated, a value of “about” a certain number or “substantially” or “generally” a certain value or result can indicate the specific number, value, or result as well as numbers, values, or results that vary plus or minus (±) 10% or less, such as ±5% or less, such as ±2% or less, such as ±1% or less, or such as ±0.5% or less, or such as ±0.1% or less. Similarly, unless otherwise indicated, a condition that substantially exists can indicate the condition is met exactly as described or claimed or is within typical manufacturing tolerances or would appear to meet the required condition upon casual observation even if not perfectly meeting the required condition.In some embodiments, the values or conditions may be defined as being express and the term “about” or “substantially” (and thus the noted variances) may be excluded from the express value.

[0066] Where a plurality of possible reduced end values and a plurality of possible greater end values are provided for a particular parameter, it is understood that all possible combinations of values inclusive of any of the lower end values and any of the upper end values are encompassed for describing the parameter.

[0067] Many modifications and other embodiments of the presently disclosed subject matter will come to mind to one skilled in the art to which this subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the present disclosure is not to be limited to the specific embodiments described. Modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0068] The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0069] In the description and in the claims, the terms “including” and “comprising” are used in an open- ended fashion, and thus should be interpreted to mean “including, but not limited to ....” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections.

[0070] Throughout this application, where patents or publications are referenced, the disclosures of these references in their entireties are intended to be incorporated by reference into this application to more fully describe the state of the art to which the invention pertains, except when these references contradict the statements made here.

Claims

CLAIMSWhat is claimed is:

1. A method for producing metallic iron, the method comprising: introducing iron ore into an iron ore inlet of a furnace so that the iron ore progresses downward through the furnace from the iron ore inlet; introducing hydrogen into the furnace below the iron ore inlet; reducing at least a portion of the iron ore to metallic iron with a first portion of the hydrogen flowing upward through the furnace; and combusting a second portion of the hydrogen to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

2. The method of claim 1, further comprising: producing a top gas stream from the furnace; separating a recycle hydrogen stream from the top gas stream; and recycling the recycle hydrogen stream to the furnace as at least a portion of the hydrogen introduced into the furnace.

3. The method of claim 2, where introducing hydrogen into the furnace comprises introducing the first portion and the second portion the hydrogen together into a first hydrogen feed inlet that is positioned below the iron ore inlet, and where combusting the second portion of the hydrogen comprises subjecting both the first portion and the second portion to a combustion process so that the first portion of the hydrogen is uncombusted and the second portion of the hydrogen is combusted.

4. The method of claim 3, further comprising: pre-heating a hydrogen feed stream via the top gas stream to form a pre-heated hydrogen feed stream; and combining the recycle hydrogen stream with the pre-heated hydrogen feed stream to form the hydrogen introduced into the furnace.

5. The method of claim 2, where introducing hydrogen into the furnace comprises: introducing the second portion of the hydrogen into a first hydrogen feed inlet of the furnace that is positioned below the iron ore inlet; and introducing the first portion of the hydrogen into a second hydrogen feed inlet of the furnace that is positioned below the iron ore inlet and above the first hydrogen feed inlet.

6. The method of claim 5, where recycling the recycle hydrogen stream to the furnace comprises introducing the recycle hydrogen stream into the first hydrogen feed inlet as at least a portion of the second portion of the hydrogen.

7. The method of claim 5, where recycling the recycle hydrogen stream to the furnace comprise introducing the recycle hydrogen stream into the second hydrogen feed inlet at a least a portion of the first portion of the hydrogen.

8. The method of claim 5, further comprising: preheating a first hydrogen feed stream via the top gas stream; preheating a second hydrogen feed stream via the top gas stream; introducing the first hydrogen feed stream into the first hydrogen feed inlet as at least a portion of the second portion of the hydrogen; and introducing the second hydrogen feed stream into the second hydrogen feed inlet as at least a portion of the first portion of the hydrogen.

9. The method of claim 1, where introducing hydrogen into the furnace comprises introducing at least some of the hydrogen into the furnace as ammonia.

10. The method of claim 9, where further utilizing nitrogen from the ammonia as a diluent for the combustion of the second portion of the hydrogen.

11. The method of claim 10, further comprising maintaining a temperature of the combustion of the second portion of the hydrogen in a range of from about 1500 °C to about 1900 °C.

12. A system for producing metallic iron, the system comprising: a furnace; an iron ore inlet defined on the furnace that is configured to receive iron ore for downward passage through the furnace; one or more hydrogen feed inlets defined on the furnace, the one or more hydrogen feed inlets being positioned below the iron ore inlet and configured to receive hydrogen into the furnace so that a first portion of the hydrogen is configured to reduce at least a portion of the iron ore into metallic iron in the furnace; and one or more burners coupled to the furnace below the iron ore inlet and configured to combust a second portion of the hydrogen and thereby to produce heat at a temperature effective to melt the metallic iron into molten iron product in the furnace.

13. The system of claim 12, further comprising a first outlet defined on the furnace below the one or more burners that is configured to discharge the molten iron product from the furnace.

14. The system of claim 13, further comprising a second outlet defined on the furnace below the one or more burners and above the first outlet that is configured to discharge slag from the furnace.

15. The system of claim 12, further comprising: a third outlet defined on the furnace that is configured to discharge a top gas stream emitted from the furnace; and one or more heat exchangers in fluid communication with the third outlet that are configured to preheat one or more hydrogen feed streams via the top gas stream.

16. The system of claim 15, further comprising: a cooler that is in fluid communication with the one or more heat exchangers, where the cooler is configured to separate a recycle hydrogen stream from the top gas stream; and a recycle line coupled to the cooler that is configured to communicate the recycled hydrogen stream from the cooler to the one or more hydrogen feed inlets of the furnace.

17. The system of claim 16, where the one or more hydrogen feed inlets comprises a first hydrogen feed inlet, and where both the first portion and the second portion of the hydrogen is introduced into the furnace via the first hydrogen feed inlet.

18. The system of claim 16, where the one or more hydrogen feed inlets comprises: a first hydrogen feed inlet that is configured to introduce the second portion of the hydrogen into the furnace; and a second hydrogen feed inlet that is configured to introduce the first portion of the hydrogen into the furnace, where the second hydrogen feed inlet is positioned below the iron ore inlet and above the first hydrogen feed inlet.

19. The system of claim 18, where the one or more heat exchangers comprise: a first heat exchanger that is configured to pre-heat a first hydrogen feed stream via the top gas stream and communicate the first hydrogen feed stream to the first hydrogen feed inlet; and a second heat exchanger that is configured to pre-heat a second hydrogen feed stream via the top gas stream and communicate the second hydrogen feed stream to the second hydrogen feed inlet.

0. The system of claim 19, where the recycle line is configured to combine a first portion of the recycle hydrogen stream with the first hydrogen feed stream downstream of the first heat exchanger to form the second portion of the hydrogen, and where the recycle line is also configured to combine a second portion of the recycle hydrogen stream with the second hydrogen feed stream downstream of the second heat exchanger to form the first portion of the hydrogen.

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