ELECTROCHEMICAL REACTOR AND METHOD FOR REDUCING IRON FROM AN IRON-CONTAINING FEEDSTOCK

Abstract

An electrochemical reactor, including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode positioned in contact with the channel; and a source of a magnetic field positioned in proximity to the cathode, wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 63/531,212, filed Aug. 7, 2023, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The iron and steel industry is responsible for approximately 10% of global CO₂ emissions, and is the largest industrial consumer of coal. In order to meet global energy and climate goals, the steel industry must incorporate emerging near-zero emission steelmaking technologies into its development plan. A promising direction for reducing CO₂ emissions is the electrolytic reduction of iron oxide in alkaline solutions at moderate temperatures.

There remains a continuing need for improved methods to produce iron metal from iron-containing feedstocks, such as iron ores.

BRIEF DESCRIPTION

Provided is an electrochemical reactor including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode are positioned in contact with the channel; and a source of a magnetic field positioned in proximity to the cathode, wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Also provided is an electrochemical reactor including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode are positioned in contact with the channel; and a source of a magnetic field positioned in proximity to the cathode, wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron metal at a surface of the cathode and in the magnetic field of the source, and wherein the iron-containing feedstock includes magnetite or hematite.

Another aspect provides an electrochemical reactor including a catholyte channel for containing and directing flow of a catholyte stream, wherein the catholyte stream includes a catholyte and an iron-containing feedstock; an anolyte channel for containing and directing flow of an anolyte stream; a cathode positioned in contact with the catholyte channel; an anode positioned in contact with the anolyte channel; a source of a magnetic field positioned in proximity to the cathode; and a separator disposed between the catholyte channel and the anolyte channel, wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency ratio of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Another aspect provides a method of processing an iron-containing feedstock to produce iron metal, the method including flowing an electrolyte stream including the iron-containing feedstock through a channel of an electrochemical cell, the electrochemical cell including an anode and a cathode that are disposed in the channel; applying a magnetic field at the cathode of the electrochemical cell; electrochemically reducing at least a portion of the iron-containing feedstock to produce the iron metal on a surface of the cathode while the magnetic field is applied at the cathode; and collecting the iron metal from the surface of the cathode using the electrolyte stream, wherein the electrochemically reducing is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

The above and other aspects and features are described and exemplified by the following figures and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are exemplary embodiments wherein the like elements are numbered alike.

FIG. 1 is a schematic diagram of an embodiment of an electrochemical reactor system;

FIG. 2 is a graph of voltage, magnetic field, and iron ore or iron concentration, each versus time and each having arbitrary units, and corresponding schematic diagrams of an electrochemical reactor before, during, and after reduction, illustrating an embodiment of a method of producing iron metal from an iron-containing feedstock; and

FIG. 3 is a schematic diagram of an embodiment of an electrochemical reactor including a separator disposed between the anode and the cathode.

DETAILED DESCRIPTION

The present subject matter relates to an electrochemical reactor and a corresponding method for producing iron metal from an iron-containing feedstock. As used herein, the term “iron metal” refers to Fe(0), which is iron with an oxidation state of zero. Also, for convenience the term “iron-containing feedstock” is used, although any suitable feedstock including an iron compound in an oxidized state may be used. The term “iron ore” may be substituted or interchanged for the term “iron-containing feedstock.” The iron-containing feedstock is further described below.

The proposed method applies a magnetic field in proximity to magnetic iron-containing feedstock particles and a cathode current collector. While not wanting to be bound by theory, it is understood that the magnetic field overrides particle characteristics like size or surface energy that may otherwise dictate adsorption or transport of the magnetic iron-containing feedstock particles in the absence of other forces normal to the current collector. For example, vertically oriented electrodes can provide the greatest buoyancy force on bubbles at both electrodes for swift evacuation, however a vertical orientation may not provide optimal particle contact. The magnetic field can be used to achieve improved particle contact when the electrodes are in a vertical electrode configuration. Further, because use of a magnetic field avoids reliance on probabilistic particle contact, the concentration of solid particles in a slurry can be substantially reduced, simplifying slurry handling sub-processes. After a finite period of reduction, the magnetic field can be removed or reduced, releasing the deposit from a poorly adhering current collector to enable continuous or semi-continuous processing.

The disclosed subject matter provides for the production of iron metal, in particular iron metal powder, through the reduction of an iron-containing feedstock by an electrolysis reaction. The relevant chemical reactions are may be described, for example, by one or more of the following equations (1), (2), and/or (3), where the iron species is/are reduced at the cathode and an oxygen evolution reaction (OER) occurs at the anode:

Fe₂O₃→2Fe(0)+3/2O₂  (1)

Fe₃O₄→3Fe(0)+2O₂  (2)

FeO→Fe(0)+O₂  (3)

In an aspect, it may be desirable to restrict particles to a selected region or area of the reactor, for example to reduce electrolyte resistance or to create a different chemical environment at the anode. To this end, a physical separator, such as a frit or membrane, may be susceptible to clogging or fouling by small ore particles. The use of magnetic fields to concentrate ore particles in the cathode reaction zone provides benefits such as extending the life of the physical separator, or avoiding the need for a separator altogether. In alkaline iron electrolysis, physical proximity between the solid ore particles and the cathode (i.e., the working electrode) is desirable. There remains a continuing need for configurations which provide improved physical proximity between the solid iron-containing feedstock particles and working electrode to facilitate electrochemical reduction, in particular to provide for a continuous method to produce iron metal powder from iron-containing feedstocks.

An aspect provides an electrochemical reactor including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock. The electrochemical reactor includes an anode and a cathode that are positioned in contact with the channel, and a source of a magnetic field positioned in proximity to the cathode. For example, the source may be positioned proximal to the cathode and distal to the anode. In an aspect, the source may be disposed on a surface of the cathode. The electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron particle comprising iron metal at a surface of the cathode and in a magnetic field of the source.

As used herein, “in proximity” means that the configuration provides a magnetic field of 0.025 to 10 Tesla (T), preferably 0.05 to 10 Tesla, more preferably 0.05 to 1 Tesla, at the surface of the cathode.

“Magnetoelectrolysis,” as used herein, refers to the application of a magnetic field during electrolysis.

The electrochemical reduction of the at least a portion of the iron-containing feedstock to the iron metal is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. During the electrochemical reduction in the magnetic field (magnetoelectrolysis), the iron-containing feedstock is reduced, and iron metal is collected (e.g., agglomerated, deposited, or the like) on the cathode surface. While not wanting to be bound by theory, it is understood that the application of the magnetoelectrolysis process can be used to improve the efficiency of the electrochemical process by providing a convective flow of the electrolyte stream, thus leading to improved current efficiency.

The electrolyte stream includes an iron-containing feedstock. The iron-containing feedstock may include any suitable iron compound, and may include one or more oxides of iron. The iron-containing feedstock refers to an iron-containing material that is capable of undergoing reduction during operation of the electrochemical reactor. As used herein, the terms “iron ore” and “iron-containing feedstock” may be used synonymously to refer to iron-containing materials that may be used as inputs into the various systems and methods described herein. “Iron ores” and “iron-containing feedstocks” may include iron in any form, such as iron oxides, hydroxides, oxyhydroxides, carbonates, or other iron-containing compounds, ores, rocks, or minerals, including any mixtures thereof, in naturally-occurring states or purified states. The iron-containing feedstock may include materials recognized, known, or referred to in the art as iron ore(s), rock(s), natural rock(s), sediment(s), natural sediment(s), mineral, and/or natural mineral(s), whether in naturally-occurring states or in otherwise purified or modified states. Some embodiments of processes and systems described herein may be particularly useful for iron-containing feedstocks including hematite, maghemite, goethite, magnetite, limonite, siderite, ankerite, turgite, bauxite, or a combination thereof.

Specifically, the iron-containing feedstock may include metallic iron (Fe) and/or one or more iron hydroxides (e.g., Fe(OH)₂, Fe(OH)₃, or the like, or a combination thereof), anhydrous and/or hydrated iron oxyhydroxides (e.g., FeOOH, FeO(OH)·nH₂O where n is a number of water molecules in the hydrated iron hydroxide molecule, or the like), iron oxides, sub-oxides, mixed oxides, including FeO (wustite), FeO₂ (iron dioxide), α-Fe₂O₃ (hematite), γ-Fe₂O₃ (maghemite), Fe₃O₄ (magnetite), Fe₄O₅, Fe₅O₆, Fe₅O₇, Fe₂₅O₃₂, Fe₁₃O₁₉, other iron-containing compounds, a polymorph(s) of these, or a combination of these. For example, in some embodiments, the iron-containing feedstock may include hematite (α-Fe₂O₃), maghemite (γ-Fe₂O₃), magnetite (Fe₃O₄), goethite (α-FeOOH), limonite (FeOOH·nH₂O), pyrite (FeS₂), red mud (i.e., bauxite residue including iron oxides, e.g., hematite), or a combination thereof. In particular embodiments, the iron-containing feedstock may include magnetite (Fe₃O₄) or hematite (α-Fe₂O₃). In particular embodiments, the iron-containing feedstock may include maghemite, magnetite, or a combination thereof. The iron-containing feedstock may be one or more of several sources. In some embodiments, the iron-containing feedstock may include raw material in the form of hematite, maghemite, magnetite, limonite, siderite, bog-iron ore, clay minerals, ores with concentrations of less than about 30 weight percent (wt %) iron, based on a total weight of the ore, scrap metals, magnets, slag, fly ash, red mud, a combination thereof, or other materials that have iron as is known by those of ordinary skill in the art.

For example, the iron-containing feedstock may be a magnetite ore. As used herein, “magnetite ore” refers to an iron-containing feedstock that contains greater than 80 wt % of Fe₃O₄ based on total content of iron oxides and/or hydroxides in the iron-containing feedstock, more preferably greater than 90 wt % of Fe₃O₄ or greater than 95 wt % of Fe₃O₄ based on total content of iron oxides and/or hydroxides in the iron-containing feedstock. In some embodiments, the iron-containing feedstock may include a magnetite ore containing greater than 80 wt % of Fe₃O₄, greater than 90 wt % of Fe₃O₄, or greater than 95 wt % of Fe₃O₄ based on total content of iron oxides (Fe₃O₄ and Fe₂O₃) in the iron-containing feedstock. The iron-containing feedstock may comprise greater than 50%, 75 to 99 wt %, 80 to 98 wt %, or 85 to 95 wt % of the iron oxide or hydroxide, based on total weight of the iron-containing feedstock. In one or more embodiments, the electrochemical reactor may be used for the reduction of magnetite ore to metallic iron. As noted above the iron-containing feedstock can be any suitable material, such as an iron-containing fluid from another process. In still other embodiments, the electrolyte stream may include Fe(OH)₂, Fe(OH)₃, Fe₂O₃, Fe₃O₄, FeOOH, or a combination thereof.

The iron-containing feedstock may include one or more impurities or minor components. Examples of impurities or minor components may include oxides and/or complexes of aluminum, magnesium, calcium, carbon, cobalt, chromium, silicon, titanium, phosphorus, sulfur, or a combination thereof. A content of the impurity may be 60 weight percent (wt %) or less, less than 30 wt %, less than 10 wt %, less than 5 wt %, less than 1 wt %, or less than 0.1 wt %, or less than 0.01 wt %, based on a total weight of the iron-containing feedstock. In an aspect, a content of the impurity is 0.001 to 10 wt %, or 0.01 to 4 wt %, or 0.01 to 1 wt %, based on a total weight of the iron-containing feedstock.

In some embodiments, the iron-containing feedstock has a total impurity content between 0.1 wt % and 3 wt %, based on a total weight of the iron-containing feedstock, wherein the iron-containing feedstock includes a silica content of less than 2 wt %, e.g., 0.1 to 2 wt %. In some embodiments, the iron-containing feedstock has a total impurity content between 3 wt % and 10 wt %, based on a total weight of the iron-containing feedstock, wherein the iron-containing feedstock includes a silica content of greater than 2 wt %, e.g., 2 to 10 wt %. In some embodiments, the iron-containing feedstock has a total impurity content of 10 wt % to 60 wt %, based on a total weight of the iron-containing feedstock, wherein the iron-containing feedstock has a silica content of greater than 5 wt %.

In some embodiments, the iron particle may have a total impurity content of less than 3 wt %, based on total weight of the iron particle. For example, the iron particle may have a total impurity content of 0.1 to 3 wt %, based on total weight of the iron particle, optionally wherein the iron particle includes a silica content of less than 2 wt %, such as 0.1 to 2 wt %, based on total weight of the iron particle. The one or more impurities may exist as phases that are not an iron oxide phase or a metallic iron phase.

The iron-containing feedstock in the electrolyte stream may be a slurry or a suspension of iron-containing feedstock particles in the electrolyte material. In some embodiments, the electrolyte stream may include 0.1 to 80 wt %, or 0.1 to 30 wt %, preferably 0.2 to 10 wt %, or 0.1 to 15 wt %, more preferably 0.2 to 2 wt %, or 0.1 to 5 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream. The amount of the iron-containing feedstock in the electrolyte stream may vary based on the type of iron-containing feedstock being used. In some embodiments, the iron-containing feedstock may include hematite, wherein the electrolyte stream may include 1 to 30 wt %, preferably 2 to 30 wt %, more preferably 10 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream. In some embodiments, the iron-containing feedstock may include magnetite, wherein the electrolyte stream may include 0.1 to 30 wt %, or 0.1 to 10 wt %, preferably 0.1 to 5 wt %, more preferably 0.2 to 2 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream. In some embodiment, the iron-containing feedstock may be present in the electrolyte stream in an amount of at least 5 wt %, and preferably greater than 10 wt %, for example, 10 to 80 wt %, based on a total weight of the electrolyte stream.

The electrolyte stream includes an electrolyte. In some embodiments, the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof. The electrolyte may be a solution including water as a solvent and one or more dissolved hydroxides. For example, the electrolyte may include an aqueous solution of NaOH, KOH, LiOH, CsOH, ammonium hydroxide (NH₄OH), or a combination thereof. Typically, the electrolyte may include an aqueous solution of NaOH.

In the electrolyte including the aqueous solution, the alkali hydroxide, the organic hydroxide, or the combination thereof may be present in the aqueous solution in an amount from 20 to 50 weight percent (wt %), 20 to 30 wt %, or 30 to 50 wt %, based on a total weight of the electrolyte. In some embodiments, the electrolyte may include an aqueous solution of an alkali hydroxide, wherein the alkali hydroxide may be present in the aqueous solution in an amount from 20 to 50 wt %, 20 to 30 wt %, or 30 to 50 wt %, based on a total weight of the electrolyte.

The electrolyte stream may optionally contain an additive to promote or inhibit certain desired or undesirable reactions. A combination of additives may be used. Any suitable amount of the additive(s) may be included in the electrolyte stream. For example, the electrolyte may further include hydrogen evolution reaction suppressor (HER suppressors), an iron activator (e.g., a sulfide salt, such as bismuth sulfide (Bi₂S₃) or sodium sulfide (Na₂S)), or the like, or a combination thereof. In some embodiments, electrolyte may further include an alkali metal sulfide or a polysulfide including one or more of lithium sulfide (Li₂S) or polysulfide (Li₂S_x, x=2 to 6), sodium sulfide (Na₂S) or polysulfide (Na₂S_x, x=2 to 6), potassium sulfide (K₂S) or polysulfide (K₂S_x, x=2 to 6), cesium sulfide (Cs₂S) or polysulfide (Cs₂S_x, x=2 to 6), or the like, or a combination thereof. Non-limiting examples of additives include sodium sulfide (Na₂S), potassium sulfide (K₂S), lithium sulfide (Li₂S), iron sulfides (FeS_x, where x=1-2), bismuth sulfide (Bi₂S₃), lead sulfide (PbS), zinc sulfide (ZnS), antimony sulfide (Sb₂S₃), selenium sulfide (SeS₂), tin sulfides (SnS, SnS₂, Sn₂S₃), nickel sulfide (NiS), molybdenum sulfide (MoS₂), mercury sulfide (HgS), bismuth oxide (Bi₂O₃), or the like, or a combination thereof. In addition, the electrolyte stream may include other additives, including those as described herein and those known in the art.

In some embodiments, the HER suppressor additive may include one or more of sodium thiosulfate, sodium thiocyanate, polyethylene glycol (PEG) 1000, trimethylsulfoxonium iodide, zincate (by dissolving ZnO in NaOH), hexanethiol, decanethiol, sodium chloride, sodium permanganate, lead (IV) oxide, lead (II) oxide, magnesium oxide, sodium chlorate, sodium nitrate, sodium acetate, iron phosphate, phosphoric acid, sodium phosphate, ammonium sulfate, ammonium thiosulfate, lithopone, magnesium sulfate, iron(III) acetylacetonate, hydroquinone monomethyl ether, sodium metavanadate, sodium chromate, glutaric acid, dimethyl phthalate, methyl methacrylate, methylpentynol, adipic acid, allyl urea, citric acid, thiomalic acid, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, propylene glycol, trimethoxysilyl propyl diethylene, aminopropyl trimethoxysilane, dimethyl acetylenedicarboxylate (DMAD), 1,3-diethylthiourea, N,N′-diethylthiourea, aminomethyl propanol, methyl butynol, amino modified organosilane, succinic acid, isopropanolamine, phenoxyethanol, dipropylene glycol, benzoic acid, N-(2-aminoethyl)-3-aminopropyl, behenamide, 2-phosphonobutane tricarboxylic, mipa borate 3-methacryloxypropyltrimethoxysilane, 2-ethylhexoic acid, isobutyl alcohol, t-butylaminoethyl methacrylate, diisopropanolamine, propylene glycol n-propyl ether, sodium benzotriazolate, pentasodium aminotrimethylene phosphonate, sodium cocoyl sarcosinate, laurylpyridinium chloride, steartrimonium chloride, stearalkonium chloride, calcium montanate, quaternium-18 chloride, sodium hexametaphosphate, dicyclohexylamine nitrite, lead stearate, calcium dinonylnaphthalene sulfonate, iron(II) sulfide, sodium bisulfide, pyrite, sodium nitrite, complex alkyl phosphate ester (e.g. RHODAFAC® RA 600 Emulsifier), 4-mercaptobenzioc acid, ethylenediaminetetraacetic acid, ethylenediaminetetraacetate (EDTA), 1,3-propylenediaminetetraacetate (PDTA), nitrilotriacetate (NTA), ethylenediaminedisuccinate (EDDS), diethylenetriaminepentaacetate (DTPA), and other aminopolycarboxylates (APCs), diethylenetriaminepentaacetic acid, 2-methylbenzenethiol, 1-octanethiol, bismuth sulfide, bismuth oxide, antimony(III) sulfide, antimony(III) oxide, antimony(V) oxide, bismuth selenide, antimony selenide, selenium sulfide, selenium(IV) oxide, propargyl alcohol, 5-hexyn-1-ol, 1-hexyn-3-ol, N-allylthiourea, thiourea, 4-methylcatechol, trans-cinnamaldehyde, iron(III) sulfide, calcium nitrate, hydroxylamines, benzotriazole, furfurylamine, quinoline, tin(II) chloride, ascorbic acid, tetraethylammonium hydroxide, calcium carbonate, magnesium carbonate, antimony dialkylphosphorodithioate, potassium stannate, sodium stannate, tannic acid, gelatin, saponin, agar, 8-hydroxyquinoline, bismuth stannate, potassium gluconate, lithium molybdenum oxide, potassium molybdenum oxide, hydrotreated light petroleum oil, heavy naphthenic petroleum oil (e.g. sold as Rustlick® 631), antimony sulfate, antimony acetate, bismuth acetate, hydrogen-treated heavy naphtha (e.g. sold as WD-40), tetramethylammonium hydroxide, NaSb tartrate, urea, D-glucose, C₆Na₂O₆, antimony potassium tartrate, hydrazinesulphate, silica gel, triethylamine, potassium antimonate trihydrate, sodium hydroxide, 1,3-di-o-tolyl-2-thiourea, 1,2-diethyl-2-thiourea, 1,2-diisopropyl-2-thiourea, N-phenylthiourea, N,N′-diphenylthiourea, sodium antimony L-tartrate, rhodizonic acid disodium salt, sodium selenide, or the like, or a combination thereof.

In some embodiments, the electrolyte stream may further include a solid conductive additive, such as carbon. In an embodiment, the electrolyte stream may further include carbon in an amount from 0.01 to 10 wt %, based on a total weight of the electrolyte stream.

The iron-containing feedstock may have a particle size of less than 0.001 millimeter (mm) to 0.5 mm, preferably 0.001 to 0.5 mm, for example 0.03 to 0.5 mm, or 0.05 to 0.3 mm, depending on the phase and internal structure of the iron-containing feedstock. The average particle size may be, for example, an average particle diameter D50. The iron-containing feedstock may have a specific magnetic susceptibility of greater than 1×10⁻⁸ cubic meters per kilogram (m³/kg), and preferably of greater than 1×10⁻⁶ m³/kg.

The electrochemical reactor includes an anode. The anode includes a suitable anode current collector. The anode current collector may be a metal, metal alloy, or a combination thereof. In some embodiments, the anode may include lead, nickel, platinum, iridium, ruthenium, tantalum, titanium, an alloy thereof, or a combination thereof. In some embodiments, the anode current collector may be coated with mixed metal oxides of iridium, ruthenium, tantalum, or the like, or a combination thereof.

In some embodiments, the anode may include a catalyst. Exemplary catalysts include metal oxide catalysts, such as manganese oxide (MnO₂, Mn₂O₃, Mn₃O₄, Mn_xO_y (where x=1 to 3 and y=1 to 8)), nickel-doped manganese oxide (Ni—Mn_xO_y), nickel oxide (NiO_x), nickel oxyhydroxide (NiO_x(OH)_y), iron oxide (FeO_x), iron oxyhydroxide (FeO_x(OH)_y (where x=0 to 2 and y=0 to 3)), cobalt oxide (Co₃O₄, Co_xO_y (where x=1 to 3 and y=1 to 8)), manganese cobalt oxide (MnCo₂O₄, Mn_1+xCo_2−xO₄ (where x=0 to 2)), cobalt manganese oxide (CoMn₂O₄), nickel manganese oxide (NiMnO_x (where x=2 to 4)), manganese iron oxide (MnFe₂O₄, Mn_1+xFe_2−xO₄ (where x=0 to 1)), nickel-doped manganese oxide (Ni—Mn_xO_y (where x=1 to 3 and y=1 to 8)), manganese cobalt iron oxide (Mn_xCo_yFe_zO₄ (where x=0 to 4 and y=0 to 4 and z=0 to 4)), zinc cobalt manganese oxide (ZnCoMnO₄, Zn_xCo_yMn_zO₄ (where x=0 to 4 and y=0 to 4 and z=0 to 4)), cobalt nickel oxide (CoNiO_x (where x=0 to 4)), calcium manganese oxide (CaMnO_x (where x=0 to 4)), lanthanum manganese oxide (LaMnO₃), lanthanum cobalt oxide (LaCo₂O₄, La_1+xCo_2−xO₄ (where x=0 to 2), lanthanum nickel oxide (LaNiO₃), lanthanum calcium aluminum manganese oxide (La_xCa_yAl_zMn_vO₃ (where x=0 to 3 and y=0 to 3 and z=0 to 2 and v=0 to 3)), nickel iron oxide (Ni_zFe_1−zO_x (where z=0 to 1 and x=0.5 to 2.5)), manganese ferrite (MnFe₂O₄), zinc ferrite (ZnFe₂O₄), nickel cobaltite (NiCo₂O₄), lanthanum strontium manganate (La_0.8Sr_0.2MnO₃), or the like, other transition metal oxides or nitrides (such as Fe₃N, FeCN, ZrN, Mn₄N, or a combination thereof), or a combination thereof. The particles of the catalyst may be coated by electrodeposition, electroless plating, or other chemical deposition process(es); for example, atomic layer deposition (ALD), thermal evaporation, sputtering, spray pyrolysis, solution-based deposition, hot dip coating, inkjet printing, or a combination thereof.

The anode current collector may have a thickness in the range from 0.05 to 0.5 centimeters (cm), such as from 0.1 to 0.3 cm. In some embodiments, the anode current collector may be at least partially porous.

The electrochemical reactor also includes a cathode. The cathode includes a suitable cathode current collector. Preferably, the current collector of the cathode is selected to minimize or prevent adhesion of the iron-containing feedstock and/or the iron metal thereto. Exemplary materials that are suitable for use in the cathode include, but are not limited to, aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof. For example, the cathode may include a stainless steel alloy such as 316, 316L, 304, or the like. In some embodiments, the cathode current collector may include steel, graphite, nickel, iron, a nickel-iron alloy, or a combination thereof. In some embodiments, the cathode may further include an inert conductive matrix including carbon black, graphite powder, charcoal powder, coal powder, nickel-coated carbon steel mesh, nickel-coated stainless-steel mesh, nickel-coated steel wool, or the like, or a combination thereof.

In some embodiments, the cathode may further include one or more additive(s) to enhance the electronic and/or physical properties of the cathode. In some embodiments, the additive in the cathode may include one or more of bismuth (III) oxide (Bi₂O₃), bismuth (III) sulfide (Bi₂S₃), barium oxide (BaO), barium sulfate (BaSO₄), barium hydroxide (Ba(OH)₂), calcium oxide (CaO), calcium sulfate (CaSO₄), calcium hydroxide (Ca(OH)₂), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)₂), carbon nanotubes, carbon nanofibers, graphene, or a combination thereof.

In some embodiments, the cathode may further include one or more binder compound(s). In some embodiments, the binder compound may include polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), polypropylene (PP), polyethylene (PE), polyacrylonitrile, styrene butadiene rubber, sodium carboxymethyl cellulose (Na-CMC), or the like, or a combination thereof.

The cathodic material may be positively charged or negatively charged. The cathodic material may be charged by a direct current (“DC”) source, by an alternating current (“AC”) source, and/or by a pulsed current.

The cathode current collector may have a thickness in the range from 0.05 to 0.5 cm, such as from 0.1 to 0.3 cm. In some embodiments, the cathode current collector may be at least partially porous.

The interelectrode gap may also be varied, with a well-known impact on the ohmic drop. In some embodiments, the interelectrode gap may be 1 millimeters (mm) to 100 mm. For example, the interelectrode gap may be 2 mm to 50 mm, or 3 mm to 30 mm, or 4 mm to 20 mm.

In some embodiments, the electrochemical cell may have a zero-gap configuration. As used herein, a “zero-gap cell” refers to an electrochemical cell in which at least one electrode is in contact with the separator. Alternatively, mentioned is a cell in which at least one electrode has a non-zero gap between the electrode surface and the separator, such as an electrode surface to separator distance of 0.001 to 2 cm, or 0.01 to 1 cm. The anode may be in contact with the separator or situated at an offset from the separator. The electrodes in zero-gap electrochemical cells are preferably porous to enable ion transport between the catholyte stream, the anolyte stream, and the separator. In some embodiments, at least one of the anode or the cathode is directly on the separator, preferably wherein the at least one of the anode or the cathode contacts the separator.

In other embodiments, at least one of the anode and the cathode may be separated from the separator by a suitable distance. In some embodiments, a distance between a surface of the anode and the separator may be 0.001 centimeter (cm) to 2 cm, or 0.01 to 1 cm. The cathode may be separated from the separator by any suitable distance. In some embodiments, a distance between a surface of the cathode and the separator may be 0.001 cm to 2 cm, or 0.01 to 1 cm.

In some embodiments, the voltage of the electrochemical cell may be from 1.5 to 5.0 Volts (V), preferably from 1.6 to 2.9 V, and more preferably from 1.7 to 2.8 V. In still other embodiments, the voltage of the electrochemical cell may be from 2.6 to 5.0 V, or from 2.8 to 4.0 V. The mechanism for optimizing cell voltage within the electrochemical cell will vary in accordance with various exemplary aspects and embodiments described herein. Moreover, the overall cell voltage achievable is dependent upon a number of other interrelated factors, including reaction chemistry, electrode spacing, the configuration and materials of construction of the electrodes, the configuration and materials of construction of the separators, electrolyte concentrations and iron concentration in the electrolyte, current density, electrolyte temperature, and, to a smaller extent, the nature and amount of any additives to the electrochemical process (such as, for example, flocculants, surfactants, or the like).

The electrochemical reactor includes a source of a magnetic field that is positioned in proximity to the cathode. Any suitable source may be used. For example, the source may be an electromagnet that may be controlled to selectively apply a magnetic field of a desired strength in the proximity of the cathode. Suitable electromagnets include, for example, current coils, and may comprise Helmholtz coils or anti-Helmholtz coils. Suitable sources may be permanent magnets or temporary magnets. Suitable permanent magnets may include, for example, neodymium iron boron (NdFeB or NIB) magnets, samarium cobalt (SmCo) magnets, alnico magnets, or ceramic or ferrite magnets. In some examples, the source may be a current coil.

In some embodiments, the source is not a current collector of the cathode, such that the reduction of the iron-containing feedstock does not occur on a surface of the source. The magnetic strength of the source may be selected based on the amount of iron-containing feedstock in the electrolyte stream, for example to limit the thickness of any layers formed from unreduced magnetite on the cathode current collector. In some embodiments, the orientation of the magnetic field with respect to the electrical field may be chosen to minimize the adhesion of the reduced iron metal to the cathode current collector. In some embodiments, the orientation of the magnetic field may be varied over time, for example by using a rotating magnetic field or an alternating magnetic field.

In some embodiments, the source may be positioned to modify the kinetics of iron-containing feedstock assembly on the cathode current collector, such as to enhance deposition kinetics. This may be done over an entire surface of the cathode or may be done in particular positions. In some embodiments, the source may enhance deposition over substantially the entire surface of the cathode, such as by providing a magnet having a size substantially correlating to a size of the surface of the cathode. In some embodiments, one or more magnets may be positioned at particular locations of the cathode to preferentially pull materials susceptible to magnetization to those locations. In some embodiments, one or more current coils may be associated with the cathode and a power source or signal generator associated with those current coils. By turning on certain coils, thereby activating the magnetic field of the coil, the thickness of the deposited material may be varied over a surface through the use of selectively positioned sources.

In some embodiments, the source may be positioned external to the channel that includes the electrolyte stream, wherein the source does not contact the electrolyte stream. In this embodiment, the reduction of the iron-containing feedstock may not occur on a surface of the source, since the source is not in physical contact with the electrolyte stream.

In other embodiments, at least a portion of the source may be positioned within the channel comprising the electrolyte stream, such that at least a portion of the source (e.g., 10%, 20%, 30%, 50%, 70%, 80%, 90%, or 100%) may be in physical contact with the electrolyte stream. For example, at least a portion of the source that is in contact with the electrolyte stream may be enclosed within a protective sheath to prevent corrosion from the electrolyte. In some embodiments, the entire source may be positioned with the channel including the electrolyte stream, and the source may be enclosed within a protective sheath. Exemplary materials that may be used to provide the protective sheath to the source include, for example, polymeric materials, metal-containing materials (e.g., such as those having a similar composition to the cathode current collector), or a combination thereof.

The electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source.

In some aspects, the iron-containing feedstock may not be subjected to electrochemical reduction before the electrochemical reduction in the magnetic field of the electrochemical reactor.

The electrochemical reduction of the at least a portion of the iron-containing feedstock to the iron metal may be at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. The current efficiency may represent the Coulombic current efficiency, which is a ratio of Coulombic charge used for the reduction of the iron-containing feedstock to a total Coulombic charge provided to the cathode. For example, the electrochemical reduction of the at least a portion of the iron-containing feedstock to the iron metal may be at a current efficiency of at least 0.8, at least 0.9, or at least 0.95 wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. In some embodiments, the electrochemical reduction of the at least a portion of the iron-containing feedstock to the iron metal may be at a current efficiency of 0.8 to 1, preferably 0.9 to 1, more preferably 0.95 to 1, or 0.75 to 0.99, or 0.8 to 0.98, or 0.85 to 0.95, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

The current efficiency may be determined using any suitable method. For example, the current efficiency may be a cathodic current efficiency (CCE) that is based on Faraday's law and is described as the percentage of iron-containing feedstock that is actually reduced on the surface of the cathode current collector during electrochemical reduction compared to the theoretical ideal case, when all, i.e. 100%, of the current passing through the cathode is used to reduce the iron-containing feedstock to the iron metal. In other embodiments, the current efficiency may be determined, for example, based on the amount of hydrogen evolution reaction (HER) by analysis of gasses evolved from the electrochemical reactor.

The iron metal that is formed via the electrochemical reduction may have any suitable form. In some embodiments, the iron metal may be an iron metal powder. For example, the iron metal may be a powder having an average particle size of less than or equal to 200 micrometers (μm), and more preferably may be 50 μm or less. The average particle size may be, for example, an average particle diameter D50.

The electrochemical reactor may be operated at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C. For example, the electrolyte stream may be at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C. before the electrolyte stream is introduced to the electrochemical reactor, such that the temperature of the electrolyte stream in the electrochemical reactor may be 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C. The operating temperature of the electrochemical reactor may refer to the temperature during which the magnetic field is applied to the electrochemical reactor.

The operating temperature of the electrolyte in the electrochemical reactor may be controlled through any one or more of a variety of means, including, for example, heat exchange, an immersion heating element, an in-line heating device (e.g., a heat exchanger), or the like, preferably coupled with one or more feedback temperature control means for efficient process control. The operating temperature of the electrolyte in the electrochemical reactor may be achieved through self-heating of the electrochemical reactor due to heat generation associated with operating at less than 100% energy efficiency. In the case of self-heating, a cooling system may be implemented to prevent the electrochemical cell from reaching temperatures greater than the optimal operating range.

In some embodiments, a current density at the cathode for the reduction of the iron-containing feedstock may be 40 to 5,000 milliamperes per square centimeter (mA/cm²), preferably 150 to 1,000 mA/cm², more preferably 200 to 800 mA/cm², based on a total area of the cathode. In some embodiments, the current density at the cathode may be selected to promote the formation of iron dendrites at the surface of the cathode. The current density may be periodically pulsed, modulated, or a combination of pulsing and modulation to control the iron metal dendrite growth or to limit the competing HER at the cathode.

The electrochemical reactor may operate with a suitable fluid flow, which may be varied based on operating conditions. The fluid flow may be a laminar flow, a turbulent flow, or a combination thereof. The fluid flow may be present as a flow rate. Any suitable flow rate may be used. The flow rate may include, but is not limited to, at least 0.01 liters per minute per square meter of cathode area (L/min/m²), for example, 0.05 to 5 L/min/m², or 0.1 to 2.5 L/min/m².

In some embodiments, the channel may be arranged vertically. For example, the channel may be arranged to provide a vertical flow channel relative to the ground.

The electrochemical reactor may be configured to flow the electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock. In some embodiments, the flow of the electrolyte stream may be continuous. In some embodiments, the flow of the electrolyte stream may be in a direction from a top of the electrochemical reactor to a bottom of the electrochemical reactor. In some embodiments, the flow of the electrolyte stream may be in a direction from the bottom of the electrolyte reactor to the top of the electrochemical reactor.

The electrochemical reactor may be configured to include a mechanical stirrer or other means of agitating the electrolyte stream within the electrochemical reactor (e.g., within the channel). In an aspect, the electrolyte stream may be agitated by the flow of the electrolyte stream through the electrochemical reactor, by magnetohydrodynamic flow, or a combination thereof. In an aspect, the electrochemical reactor does not include any additional means to stir or agitate the electrolyte in addition to the flow of the electrolyte stream through the electrochemical reactor and/or magnetohydrodynamic flow.

In some embodiments, the electrochemical reactor may further include a separation unit that is disposed downstream of the channel. The separation unit may be configured to separate at least a portion of the iron metal from the electrolyte stream, for example after the electrochemical reduction of the iron-containing feedstock. Exemplary separation units are further described below in conjunction with FIG. 1. For example, 80 wt % or greater, 90 wt % or greater, or 100 wt % of the iron metal based on the total weight of the iron metal in the electrolyte stream may be removed from the electrolyte stream.

According to another aspect, an electrochemical reactor includes a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock. The electrochemical reactor includes an anode and a cathode that are positioned in contact with the channel, and a source of a magnetic field is positioned in proximity to the cathode. The electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, wherein the iron-containing feedstock includes magnetite, hematite, or combination thereof. For example, 50 wt % or greater, 60 wt % or greater, 70 wt % or greater, 80 wt % or greater, 90 wt % or greater, or 100 wt % of the iron-containing feedstock based on a total weight of the iron-containing feedstock may be reduced. In some aspects, the electrochemical reactor provides for the reduction of a magnetite ore, a hematite ore, or an ore comprising magnetite and hematite, such as a magnetite ore containing greater than 80 wt % of Fe₃O₄, greater than 90 wt % of Fe₃O₄, or greater than 95 wt % of Fe₃O₄ based on total content of iron oxides (Fe₃O₄ and Fe₂O₃) in the iron-containing feedstock. In some embodiments, the magnetite ore is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field.

Shown in FIG. 1 is a schematic diagram of an embodiment of the electrochemical reactor system. The electrochemical reactor system 1000 comprises an electrochemical reactor 100, a feedstock handling system 200, and a product handling system 300. The electrochemical reactor 100 includes a cathode 120, e.g., a working electrode, and an anode 110, e.g., a counter electrode, which are spaced apart and disposed in a channel 150 of the electrochemical reactor 100, wherein the cathode 120 and the anode 110 are in contact with an electrolyte stream 130 including an iron-containing feedstock. The iron-containing feedstock includes a feedstock 135 that is susceptible to magnetization. In proximity to the cathode is a source 140. The source 140 may include an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof or other source of a magnetic field as provided herein. In operation, the feedstock 135 (e.g., the iron-containing feedstock) is reduced to provide iron metal 145.

The electrolyte stream 130 is provided to the channel 150 of the electrochemical reactor 100 by the feedstock handling system 200. The feedstock handling system 200 optionally includes a mixing tank 210 for mixing a concentrated ore slurry from a concentrated ore unit 220 with an electrolyte from an electrolyte unit 230. A feedstock unit 290 including an iron-containing feedstock may be in fluid communication with the concentrated ore unit 220 (as shown in FIG. 1), with the mixing tank 210, or with the electrochemical reactor 100 to provide replenishment of the iron-containing feedstock reduced to iron metal and oxygen during the electrolysis process. Optionally provided is an electrolyte purification unit 240 providing electrolyte purification. The electrolyte purification unit 240 may optionally include a filter, may optionally control a pH or a temperature of the electrolyte, and/or may optionally provide an additive to the electrolyte. Any suitable electrolyte additive may be used, including combinations of two or more additives. Additives may include an alkali hydroxide, an organic hydroxide, or a combination thereof to replenish the electrolyte chemical components. When the purification unit 240 includes a filter, the filter may be used to remove unwanted solids from the electrolyte to provide purified electrolyte. The purified electrolyte may be charged downstream of the electrolyte purification unit 240 to the electrolyte unit 230.

From the electrochemical reactor 100 an electrolyte product stream 310 including the electrolyte, and optionally the iron metal product or unreacted iron-containing feedstock particles, to the product handling system 300. The product handling system may optionally include a separation unit 320. The separation unit 320 may be configured to separate the iron metal product from unreacted iron-containing feedstock material and oxygen gas, and may include a magnetic separator or a physical separator. The product handling system 300 may optionally include a post processing unit 330. The post processing unit 330 may wash and/or dry and/or densify the product. The post processing unit 330 may be fluidly connected to the separation unit 320 via product post-processing stream 280. The product handling system 300 may also optionally include residuals separation unit 340 configured to separate residual iron-containing feedstock from the electrolyte stream. The separation unit 320 may be fluidly connected upstream to the residuals separation unit 340 via residuals separation stream 270. The residual iron-containing feedstock may be provided by the concentrated ore slurry to the concentrated ore unit 220 via ore stream 260 and the electrolyte provided to the electrolyte unit 230 via electrolyte steam 250. In some embodiments, the electrolyte stream may be transported to the separation unit 320, where at least a portion of the iron metal may be separated from the electrolyte stream and other processing may occur as described herein, and the electrolyte stream is recirculated back to an upstream region of the channel, such as into the mixing tank 210.

Shown in FIG. 2 are graphs of voltage (arbitrary units), magnetic field (arbitrary units), ore concentration (arbitrary units), and iron concentration (arbitrary units), each versus time (arbitrary units) with corresponding schematic diagrams of the electrochemical reactor to illustrate an embodiment of the disclosed process. In a first step 2A, with the source of the magnetic field off, the electrolyte stream and the iron-containing feedstock (labeled with arrow 2000) may be added to the electrochemical reactor. As shown in FIG. 2, the iron-containing feedstock concentration increases upon addition. The source is then turned on to attract iron-containing feedstock particles to the cathode. Increasing the voltage results in reduction of the iron-containing feedstock to iron metal, indicated by the increasing content (e.g., concentration) of iron in the electrochemical reactor as shown in step 2B. Also, while illustrated to have the magnetic field on before the voltage is increased, also disclosed is an aspect in which the voltage is increased before the magnetic field is increased. In an aspect, the iron-containing feedstock may be continuously provided to the electrochemical reactor, thus the concentration of ore in the electrical corrector is constant. In an aspect, the electrolyte and unreacted ore may exit the electrochemical reactor as shown with arrows 2010 in FIGS. 2A and 2B and be recycled to the electrochemical reactor.

Harvesting the iron product may be facilitated by reducing the voltage and reducing the magnetic field, as shown in step 2C. When the magnetic field is reduced or the source is turned off, the iron metal product may release from the cathode, facilitating recovery of the product. As shown in step 2C with arrow 2020, the electrolyte, unreacted ore, and the product may exit the electrochemical reactor for separation of the product and recycling of the unreacted ore and the electrolyte to the electrochemical reactor. Also, the voltage may be modulated, or turned off, to select the particle characteristics of the product or to facilitate harvesting of the product. In step 2C, while illustrated to have the magnetic field decreased after the voltage is decreased, also disclosed is an aspect in which the voltage is decreased after the magnetic field is decreased or removed. Alternatively, in step 2C, the magnetic field may be stopped entirely during the harvesting step.

The embodiment shown in FIG. 1 is provided with two electrochemical reactors, each adjacent to a common source disposed between a pair of cathodes. Use of two or four reactors may provide improved efficiency by making more effective use of the magnetic field. Also, while shown with a single source and adjacent electrochemical reactors, additional electrochemical reactors could be added in any suitable combination of series and/or parallel configurations.

According to still another aspect, an electrochemical reactor may include a catholyte channel for containing and directing flow of a catholyte stream, wherein the catholyte stream includes a catholyte and an iron-containing feedstock. The electrochemical reactor also includes an anolyte channel for containing and directing flow of an anolyte stream. A cathode is positioned in contact with the catholyte channel, an anode is positioned in contact with the anolyte channel, and a source is positioned in proximity to the cathode. The electrochemical reactor includes a separator disposed between the catholyte channel and the anolyte channel. The electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

In an aspect, a separator may be provided between the cathode and the anode as shown in FIG. 3. In the embodiment shown in FIG. 3, the electrochemical reactor 3000 includes a separator 3150 between the anode 3100 and the cathode 3200. The separator may be in the form of a membrane, such as a microporous polyolefin membrane, an ion-exchange membrane, or may be a porous compact separator such a glass frit, for example. The separator is further described below.

When the separator is present, the anolyte 3110 and the catholyte 3210 may be different. For example, in an aspect including the separator, the catholyte may be alkaline (basic) and the anolyte may be acidic. The alkaline electrolyte and representative cathode materials are discussed above and not repeated for clarity.

Representative acidic electrolytes include aqueous solutions of strong acids having a pKa of 2 or less. For example, the anolyte may include HCl, HNO₃, H₂SO₄, HClO₄, H₃PO₄, or a combination thereof, or simply an electrolyte for conductivity, preferably MClO₄, MNO₃, M₂SO₄, MF, MCl, MBr, or MI, where M=Li, Na, or K, or tetra-n-butylammonium X, where X is F, Cl, Br, I, or hexafluorophosphate; and water, and optionally further including a nonaqueous solvent, such as acetonitrile, dimethylsulfoxide, dimethylformamide, methanol, ethanol, 1-propanol, isopropanol, ether, diglyme, tetrahydrofuran, glycerol, or the like, or a combination thereof. In some embodiments, the anolyte may include one or more strong acids, optionally one or more electrolytes for conductivity, and water. For example, the anolyte may include an aqueous solution of a strong acid, preferably HCl, H₂SO₄, or a combination thereof, and optionally a supporting electrolyte compound, preferably one or more of M₂SO₄, MCl, MBr, MI, or a combination thereof, where M is Li, Na, or K.

In an aspect where the anolyte is acidic, acid compatible anode materials may be used. Representative materials for the anode when an acidic anolyte is used include, but are not limited to, carbon, titanium, platinum, iridium, ruthenium, titanium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, tin, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof. The anode may further include one or more binder compound(s), which may include polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), polypropylene (PP), polyethylene (PE), polyacrylonitrile, styrene butadiene rubber, sodium carboxymethyl cellulose (Na-CMC), or the like, or a combination thereof.

The anolyte may be provided from an anolyte reservoir 3120 using pump 3130. The catholyte may be provided by a feedstock handling system, such as feedstock handling system 200 previously described. The catholyte may be further connected to a product handling system (such as 300 in FIG. 1), which is not shown in FIG. 3.

The separators as used in the process may be passive separators, such as conventional diaphragm separators, or may be active separators, such as ion exchange membranes. In some embodiments, a separator may be chosen based on an ability to allow selective transfer of desired molecules or materials while substantially limiting or preventing transfer of undesired molecules or materials. For example, some separator membranes are ion-selective and allow the transfer of negative (or positive) ions while substantially preventing transfer of positive (or negative) ions. In other examples, separator materials may be chosen based on an ability to allow or prevent the cross-over of gas bubbles from one side (associated with one electrode) to the opposite side (associated with the counter-electrode).

In some embodiments, the separator may be formed of a dielectric material, or a porous material, which is permeable to positive ions, such as Li⁺, K⁺, Na⁺, Cs⁺, and/or NH₄⁺ ions, or the like, or a combination thereof, or negative ions, such as hydroxide ions, or the like.

The separator may be impermeable or effectively impermeable to active materials of the catholyte and anolyte. In some embodiments, the separator may be a membrane, such as a membrane formed from a polymer with a tetrafluoroethylene backbone and side chains of perfluorovinyl ether groups terminated with sulfonate groups (e.g., a sulfonated tetrafluoroethylene membrane, a membrane made of polymers sold under the Nafion brand name, etc.), or the like.

In some embodiments, the separator may include an anion exchange membrane (AEM), a cation exchange membrane (CEM), a zwitterionic membrane, a porous membrane having an average pore diameter of less than 10 nanometers, a polybenzimidazole-containing membrane, a polysulfone-containing membrane, polycarboxylic-containing membrane, a polyetherketone-containing membrane, a membrane including polymer(s) of intrinsic microporosity (PIM), or the like, or a combination thereof. Preferably, the separator includes an anion exchange membrane (AEM) or a cation exchange membrane (CEM). In some embodiments, the separator may include a composite membrane including an inorganic material and an organic material. In some embodiments, the inorganic material may include a metal oxide or a ceramic material. In some embodiments, the organic material may include a polyether ether ketone (PEEK), a polysulfone, a polystyrene, a polypropylene, a polyethylene, or the like, or a combination thereof.

In some embodiments, a separator may be used that provides a physical barrier between the anolyte and the catholyte. For example, the separator may include a porous polyolefin film, a glass fiber mat, a cotton fabric, a rayon fabric, cellulose acetate, paper, or the like, or a combination thereof.

Still another aspect provides a method of processing an iron-containing feedstock to produce iron metal that includes continuously flowing an electrolyte stream including the iron-containing feedstock through a channel of an electrochemical cell, wherein the electrochemical cell includes an anode and a cathode disposed in the channel. A magnetic field is applied at the cathode of the electrochemical cell, at least a portion of the iron-containing feedstock is electrochemically reduced to produce the iron metal on a surface of the cathode while the magnetic field is applied at the cathode, and the iron metal powder is collected from the surface of the cathode using the electrolyte stream. The electrochemically reducing is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. In some embodiments, the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode.

In some embodiments, the step of collecting may further include stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream. For example, the step of stopping the electrochemical reduction may include substantially reducing the applied voltage to the cathode. In some embodiments, the step of stopping the electrochemical reduction may include stopping the applied voltage to the cathode. In some embodiments, the step of stopping the electrochemical reduction may include reducing the voltage applied to the cathode to stop the electrochemical reduction of the iron-containing feedstock.

The electrolyte stream may be continuously flowed through the electrochemical cell during the step of electrochemically reducing the iron-containing feedstock to the iron metal, which may maintain a substantially constant concentration of iron-containing feedstock species during the reduction step. Any non-reduced iron oxide and/or iron hydroxide species in the iron-containing feedstock of the electrolyte stream may be separated from the iron metal collecting on the cathode current collector during the collecting step. The unreduced iron-containing feedstock in the electrolyte stream may be returned to an input electrolyte stream that feeds the electrochemical cell.

The iron metal (for example, the iron powder) that is formed in the electrochemical cell may be harvested or collected from the surface of the cathode, for example, by releasing or partially releasing the magnetic field from the surface of the cathode. Any suitable method may be used to harvest the iron metal product from the cathode in accordance with various aspects. The optimal harvesting mechanism will depend largely on a number of interrelated factors, primarily current density, iron concentration in the electrolyte, electrolyte flow rate, and electrolyte temperature. Other contributing factors include the level of mixing within the electrochemical reactor, the frequency and duration of the harvesting method, and/or the presence and amount of any process additives (such as, for example, flocculant, surfactants, or the like).

In situ harvesting configurations, either by self-harvesting (described below) or by other in situ devices, may be desirable to minimize the need to remove and handle cathodes to facilitate the removal of iron metal from the electrochemical cell. Moreover, in situ harvesting configurations may advantageously permit the use of fixed electrode cell designs. As such, any number of mechanisms and configurations may be used.

Examples of possible harvesting mechanisms include vibration (e.g., one or more vibration and/or impact devices affixed to one or more cathodes to displace iron metal from the cathode surface at predetermined time intervals), a pulse flow system (e.g., electrolyte flow rate increased dramatically for a short time to displace iron metal from the cathode surface), use of a pulsed power supply to the cell, use of ultrasonic waves, and/or use of other mechanical displacement means to remove iron metal from the cathode surface, such as intermittent or continuous air bubbles. Alternatively, under some conditions, “self-harvest” or “dynamic harvest” may be achievable, when the electrolyte flow rate is sufficient to displace iron metal from the cathode surface as it is formed, or shortly after reduction occurs.

Referring again to FIG. 1, in accordance with an aspect of an exemplary embodiment, an electrolyte mixture that includes an iron metal slurry from the channel may be subjected to any apparatus for separating at least a portion of the electrolyte from the iron metal, such as, for example, a clarifier, a spiral classifier, other screw-type devices, a countercurrent decantation (CCD) circuit, a thickener, a filter, a conveyor-type device, a gravity separation device, a magnet, or other suitable apparatus.

The disclosed method of electrolytic reduction of iron oxides at moderate temperatures can provide iron metal with a reduced carbon footprint in comparison to traditional blast furnace iron making processes. For example, the iron metal produced by the disclosed method may have a specific total embedded emissions of less than 0.8 tons of CO₂ per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism (CBAM). In an aspect, the iron metal may have a specific direct embedded emissions of less than 1.5 tons of CO₂ per ton of the iron metal and less than 0.2 tons of CO₂ per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under CBAM.

In some aspects, the iron metal produced by the method may have a carbon emission intensity of less than 1100 kilograms of CO₂ per ton of the iron metal, when determined according to ISO 14404, of less than 800 kilograms of CO₂ per ton of the iron metal, when determined according to the Intergovernmental Panel on Climate Change Methodology 2006 Guidelines for National Greenhouse Gas Inventories, of less than 1500 kilograms of CO₂ per ton of the iron metal, when determined according to the 2017 World Steel Life Cycle Inventory Methodology, of less than 1300 kilograms of CO₂ per ton of the iron metal, when determined according to the 2008 World Resource Institute Iron and Steel Greenhouse Gas Protocol, of less than 750 kilograms of CO₂ per ton of the iron metal, when determined according to the European Union (EU) Commission Implementing Regulation 2018/2066, a specific total embedded emissions of less than 0 tons of CO₂ per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism, or a combination thereof. When the specific total embedded emissions or the carbon emission intensity is less than zero tons of CO₂ per ton of the iron metal, the process provides a net negative emission of carbon dioxide during the processing of the iron-containing feedstock to produce the iron metal. For example, under reaction conditions to produce a caustic product such as NaOH, the produced NaOH may be used for CO₂ removal from air or ocean water, enabling the possibility for net-negative emissions ironmaking.

This disclosure further encompasses the following aspects.

Aspect 1. An electrochemical reactor, including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode positioned in contact with the channel; and a source positioned in proximity to the cathode, wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Aspect 2. The electrochemical reactor of aspect 1, wherein the iron metal includes an iron metal powder.

Aspect 3. The electrochemical reactor of aspect 1 or 2, wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof.

Aspect 4. The electrochemical reactor of any one of the preceding aspects, wherein the iron-containing feedstock includes magnetite.

Aspect 5. The electrochemical reactor of any one of the preceding aspects, wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source.

Aspect 6. The electrochemical reactor of any one of the preceding aspects, wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, preferably NaOH, KOH, LiOH, CsOH, ammonium hydroxide (NH₄OH), or a combination thereof, more preferably NaOH.

Aspect 7. The electrochemical reactor of aspect 6, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, preferably from 30 to 50 wt %, based on a total weight of the electrolyte.

Aspect 8. The electrochemical reactor of any one of the preceding aspects, wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C.

Aspect 9. The electrochemical reactor of any one of the preceding aspects, wherein the electrolyte stream includes from 0.1 to 30 wt %, preferably from 0.1 to 15 wt %, more preferably from 0.1 to 5 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 10. The electrochemical reactor of any one of the preceding aspects, wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof.

Aspect 11. The electrochemical reactor of any one of the preceding aspects, wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 12. The electrochemical reactor of any one of aspects 1 to 10, wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream.

Aspect 13. The electrochemical reactor of any one of the preceding aspects, wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof.

Aspect 14. The electrochemical reactor of any one of the preceding aspects, wherein the anode includes carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof.

Aspect 15. The electrochemical reactor of any one of the preceding aspects, wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm², preferably from 150 to 1,000 mA/cm², more preferably 200 to 800 mA/cm², based on a total area of the cathode.

Aspect 16. The electrochemical reactor of any one of the preceding aspects, wherein the channel is arranged vertically.

Aspect 17. The electrochemical reactor of any one of the preceding aspects, further including a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream.

Aspect 17a. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, preferably magnetite; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, and wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte.

Aspect 17b. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, preferably magnetite; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; and wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 17c. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, preferably magnetite; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; and wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 17d. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, preferably magnetite; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; and wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm².

Aspect 17e. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, preferably magnetite; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream; and wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm².

Aspect 17f. The electrochemical reactor of any one of the preceding aspects, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes maghemite, magnetite, or a combination thereof; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream; and wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm².

Aspect 18. An electrochemical reactor, including: a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode positioned in contact with the channel; and a source positioned in proximity to the cathode, wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the iron-containing feedstock includes magnetite or hematite.

Aspect 18a. An electrochemical reactor, including: a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode positioned in contact with the channel; and a source positioned in proximity to the cathode, wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the iron-containing feedstock includes magnetite, maghemite, or a combination thereof.

Aspect 19. The electrochemical reactor of aspect 18, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field.

Aspect 20. The electrochemical reactor of aspect 18 or 19, wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Aspect 21. The electrochemical reactor of any one of aspects 18 to 20, wherein the iron metal includes an iron metal powder.

Aspect 22. The electrochemical reactor of any one of aspects 18 to 21, wherein the iron-containing feedstock further includes hematite, maghemite, goethite, limonite, pyrite, red mud, or a combination thereof.

Aspect 23. The electrochemical reactor of any one of aspects 18 to 21, wherein the iron-containing feedstock consists essentially of magnetite or hematite.

Aspect 23a. The electrochemical reactor of any one of aspects 18 to 21, wherein the iron-containing feedstock consists essentially of magnetite, maghemite, or a combination thereof.

Aspect 24. The electrochemical reactor of any one of aspects 18 to 23, wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source.

Aspect 25. The electrochemical reactor of any one of aspects 18 to 24, wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, preferably NaOH, KOH, LiOH, CsOH, ammonium hydroxide (NH₄OH), or a combination thereof, more preferably NaOH.

Aspect 26. The electrochemical reactor of aspect 25, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, preferably from 30 to 50 wt %, based on a total weight of the electrolyte.

Aspect 27. The electrochemical reactor of any one of aspects 18 to 26, wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C.

Aspect 28. The electrochemical reactor of any one of aspects 18 to 27, wherein the electrolyte stream includes from 0.1 to 30 wt %, preferably from 0.1 to 15 wt %, more preferably from 0.1 to 5 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 29. The electrochemical reactor of any one of aspects 18 to 28, wherein the source includes an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof.

Aspect 30. The electrochemical reactor of any one of aspects 18 to 29, wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 31. The electrochemical reactor of any one of aspects 18 to 29, wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream.

Aspect 32. The electrochemical reactor of any one of aspects 18 to 31, wherein the cathode includes aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof.

Aspect 33. The electrochemical reactor of any one of aspects 18 to 32, wherein the anode includes carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof.

Aspect 34. The electrochemical reactor of any one of aspects 18 to 33, wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm², preferably from 150 to 1,000 mA/cm², more preferably 200 to 800 mA/cm², based on a total area of the cathode.

Aspect 35. The electrochemical reactor of any one of aspects 18 to 34, wherein channel is arranged vertically.

Aspect 36. The electrochemical reactor of any one of aspects 18 to 35, further including a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream.

Aspect 36a. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Aspect 36b. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; and wherein the iron metal includes an iron metal powder.

Aspect 36c. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; wherein the iron metal includes an iron metal powder; and wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof.

Aspect 36d. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; wherein the iron metal includes an iron metal powder; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; and wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte.

Aspect 36e. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; wherein the iron metal includes an iron metal powder; wherein the electrolyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; and wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 36f. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; wherein the iron metal includes an iron metal powder; wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; and wherein the source is positioned external to the channel including the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 36g. The electrochemical reactor of any one of aspects 18 to 35, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field; wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode; wherein the iron metal includes an iron metal powder; wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream; wherein the source is positioned external to the channel including the electrolyte stream, wherein the source does not contact the electrolyte stream; and wherein the iron-containing feedstock includes maghemite, magnetite, or a combination thereof.

Aspect 37. An electrochemical reactor, including: a catholyte channel for containing and directing flow of a catholyte stream, wherein the catholyte stream includes a catholyte and an iron-containing feedstock; an anolyte channel for containing and directing flow of an anolyte stream; a cathode positioned in contact with the catholyte channel; an anode positioned in contact with the anolyte channel; a source positioned in proximity to the cathode; and a separator disposed between the catholyte channel and the anolyte channel, wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency ratio of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Aspect 38. The electrochemical reactor of aspect 37, wherein the iron metal includes an iron metal powder.

Aspect 39. The electrochemical reactor of aspect 37 or 38, wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof.

Aspect 40. The electrochemical reactor of any one of aspects 37 to 39, wherein the iron-containing feedstock includes magnetite.

Aspect 41. The electrochemical reactor of any one of aspects 37 to 40, wherein the iron-containing feedstock consists essentially of magnetite or hematite.

Aspect 42. The electrochemical reactor of any one of aspects 37 to 41, wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source.

Aspect 43. The electrochemical reactor of any one of aspects 37 to 42, wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, preferably NaOH, KOH, LiOH, CsOH, ammonium hydroxide (NH₄OH), or a combination thereof, more preferably NaOH.

Aspect 44. The electrochemical reactor of aspect 43, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, preferably from 30 to 50 wt %, based on a total weight of the catholyte.

Aspect 45. The electrochemical reactor of any one of aspects 37 to 44, wherein the anolyte includes an aqueous solution including: a strong acid, preferably HCl, H₂SO₄, or a combination thereof; and a supporting electrolyte compound, preferably M₂SO₄, MCl, MBr, MI, or a combination thereof, wherein M is Li, Na, or K.

Aspect 46. The electrochemical reactor of any one of aspects 37 to 45, wherein the separator includes an anion exchange membrane, a cation exchange membrane, a zwitterionic membrane, a porous membrane having an average pore diameter of less than 10 nm, a polybenzimidazole-containing membrane, a polysulfone-containing membrane, a polycarboxylic-containing membrane, a polyetherketone-containing membrane, a membrane comprising a polymer of intrinsic microporosity, or a combination thereof; preferably an anion exchange membrane or a cation exchange membrane.

Aspect 47. The electrochemical reactor of any one of aspects 37 to 46, wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C.

Aspect 48. The electrochemical reactor of any one of aspects 37 to 47, wherein the catholyte stream includes from 0.1 to 30 wt %, preferably from 0.1 to 15 wt %, more preferably from 0.1 to 5 wt % of the iron-containing feedstock, based on a total weight of the catholyte stream.

Aspect 49. The electrochemical reactor of any one of aspects 37 to 48, wherein the source includes an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof.

Aspect 50. The electrochemical reactor of any one of aspects 37 to 49, wherein the source is positioned external to the catholyte channel comprising the catholyte stream, wherein the source does not contact the catholyte stream.

Aspect 51. The electrochemical reactor of any one of aspects 37 to 49, wherein at least a portion of the source is positioned within the catholyte channel comprising the catholyte stream.

Aspect 52. The electrochemical reactor of any one of aspects 37 to 51, wherein the cathode includes aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof.

Aspect 53. The electrochemical reactor of any one of aspects 37 to 52, wherein the anode includes carbon, titanium, platinum, iridium, ruthenium, titanium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, tin, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof.

Aspect 54. The electrochemical reactor of any one of aspects 37 to 53, wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm², preferably from 150 to 1,000 mA/cm², more preferably 200 to 800 mA/cm², based on a total area of the cathode.

Aspect 55. The electrochemical reactor of any one of aspects 37 to 54, wherein catholyte channel is arranged vertically.

Aspect 56. The electrochemical reactor of any one of aspects 37 to 55, further including a separation unit disposed downstream of the catholyte channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the catholyte stream.

Aspect 56a. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; and wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof.

Aspect 56b. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; and wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof.

Aspect 56c. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; and wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the catholyte.

Aspect 56d. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the catholyte; and wherein the anolyte includes an aqueous solution including a strong acid; and optionally a supporting electrolyte compound.

Aspect 56e. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the catholyte; wherein the anolyte includes an aqueous solution including a strong acid; and optionally a supporting electrolyte compound; and wherein the catholyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the catholyte stream.

Aspect 56f. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the catholyte; wherein the anolyte includes an aqueous solution including a strong acid; and optionally a supporting electrolyte compound; wherein the catholyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the catholyte stream; and wherein the source is positioned external to the catholyte channel including the catholyte stream, wherein the source does not contact the catholyte stream.

Aspect 56g. The electrochemical reactor of any one of aspects 37 to 56, wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes maghemite, magnetite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the catholyte; wherein the anolyte includes an aqueous solution including a strong acid; and optionally a supporting electrolyte compound; wherein the catholyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the catholyte stream; and wherein the source is positioned external to the catholyte channel including the catholyte stream, wherein the source does not contact the catholyte stream.

Aspect 57. The electrochemical reactor of any one of aspects 1 to 36, 17a-17f, 18a, 23a, or 36a to 36 g, wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock.

Aspect 58. The electrochemical reactor of aspect 57, wherein the electrochemical reactor is configured to continuously flow an electrolyte stream through the channel.

Aspect 59. The electrochemical reactor of any one of aspects 37 to 56 or 56a to 56g, wherein the electrochemical reactor is configured to flow an electrolyte stream through the catholyte channel and/or the anolyte channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the catholyte channel and or the anolyte channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock.

Aspect 60. The electrochemical reactor of aspect 56, wherein the electrochemical reactor is configured to continuously flow an electrolyte stream through the catholyte channel and/or the anolyte channel.

Aspect 61. A method of processing an iron-containing feedstock to produce iron metal, the method including: flowing an electrolyte stream including the iron-containing feedstock through a channel of an electrochemical cell, the electrochemical cell including an anode and a cathode disposed in the channel; applying a magnetic field at the cathode of the electrochemical cell; electrochemically reducing at least a portion of the iron-containing feedstock to produce the iron metal on a surface of the cathode while the magnetic field is applied at the cathode; and collecting the iron metal from the surface of the cathode using the electrolyte stream, wherein the electrochemically reducing is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

Aspect 62. The method of aspect 61, wherein the step of collecting further includes stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream.

Aspect 63. The method of aspect 61 or 62, wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode.

Aspect 64. The method of any one of aspects 61 to 63, wherein the iron metal includes an iron metal powder.

Aspect 65. The method of any one of aspects 61 to 64, wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof.

Aspect 66. The method of any one of aspects 61 to 65, wherein the iron-containing feedstock includes magnetite.

Aspect 67. The method of any one of aspects 61 to 66, wherein the iron-containing feedstock consists essentially of magnetite or hematite.

Aspect 68. The method of any one of aspects 61 to 67, wherein at least a portion of the iron-containing feedstock is substantially reduced on the surface of the cathode while the magnetic field is applied to the cathode.

Aspect 69. The method of any one of aspects 61 to 6684, wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, preferably NaOH, KOH, LiOH, CsOH, ammonium hydroxide (NH₄OH), or a combination thereof, more preferably NaOH.

Aspect 70. The method of any one of aspects 61 to 69, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, preferably from 30 to 50 wt %, based on a total weight of the electrolyte.

Aspect 71. The method of any one of aspects 61 to 70, wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C., 50° C. to 70° C., 70° C. to 120° C., or 85° C. to 110° C.

Aspect 72. The method of any one of aspects 61 to 71, wherein the electrolyte stream includes from 0.1 to 30 wt %, preferably from 0.1 to 15 wt %, more preferably from 0.1 to 5 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 73. The method of any one of aspects 61 to 72, wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof.

Aspect 74. The method of any one of aspects 61 to 73, wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 75. The method of any one of aspects 61 to 73, wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream.

Aspect 76. The method of any one of aspects 61 to 75, wherein the cathode includes aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof.

Aspect 77. The method of any one of aspects 61 to 76, wherein the anode includes carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof.

Aspect 78. The method of any one of aspects 61 to 77, wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 mA/cm², preferably from 150 to 1,000 mA/cm², more preferably 200 to 800 mA/cm², based on a total area of the cathode.

Aspect 79. The method of any one of aspects 61 to 78, wherein the channel is arranged vertically.

Aspect 80. The method of any one of aspects 61 to 79, further including: transporting the electrolyte stream to a separation unit located downstream of the channel; and separating at least a portion of the iron metal from the electrolyte stream.

Aspect 81. The method of any one of aspects 61 to 80, further including: transporting the electrolyte stream to a separation unit located downstream of the channel; separating at least a portion of the iron metal from the electrolyte stream; and recirculating the electrolyte stream to an upstream region of the channel.

Aspect 81a. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; and wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode.

Aspect 81b. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; and wherein the iron metal includes an iron metal powder.

Aspect 81c. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; and wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof.

Aspect 81d. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; and wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof.

Aspect 81e. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; and wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte.

Aspect 81f. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; and wherein the electrolyte stream includes from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream.

Aspect 81g. The method of any one of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes hematite, maghemite, magnetite, goethite, limonite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; and wherein the source is positioned external to the channel including the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 81h. The method of any of aspects 61 to 81, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream; wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode; wherein the iron metal includes an iron metal powder; wherein the iron-containing feedstock includes maghemite, magnetite, or a combination thereof; wherein the catholyte includes an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 wt %, based on a total weight of the electrolyte; and wherein the source is positioned external to the channel including the electrolyte stream, wherein the source does not contact the electrolyte stream.

Aspect 82. The method of any of aspects 61 to 81 or 81a to 81h, wherein the flowing the electrolyte stream is unidirectional from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode, preferably wherein the flowing the electrolyte stream is continuous.

Aspect 83. The method of any of aspects 61 to 82 or 81a to 81h, wherein the iron metal has

• • i) a specific total embedded emissions of less than 0.8 tons of CO₂ per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism;
  • ii) a carbon emission intensity of less than 1100 kilograms of CO₂ per ton of the iron metal, when determined according to ISO 14404;
  • iii) a carbon emission intensity of less than 800 kilograms of CO₂ per ton of the iron metal, when determined according to the Intergovernmental Panel on Climate Change Methodology 2006 Guidelines for National Greenhouse Gas Inventories;
  • iv) a carbon emission intensity of less than 1500 kilograms of CO₂ per ton of the iron metal, when determined according to the 2017 World Steel Life Cycle Inventory Methodology;
  • v) a carbon emission intensity of less than 1300 kilograms of CO₂ per ton of the iron metal, when determined according to the 2008 World Resource Institute Iron and Steel Greenhouse Gas Protocol;
  • vi) a carbon emission intensity of less than 750 kilograms of CO₂ per ton of the iron metal, when determined according to European Union Commission Implementing Regulation 2018/2066;
  • vii) a specific total embedded emissions of less than 0 tons of CO₂ per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism; or
  • viii) a combination thereof.

Aspect 84. The method of any of aspects 61 to 83 or 81a to 81h, wherein the iron metal is a powder having an average particle size of less than or equal to 200 micrometers, and more preferably is 50 micrometers or less.

The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, which are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt %, or, more specifically, 5 wt % to 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “some embodiments,” “an embodiment,” “an aspect,” and so forth, means that a particular element described in connection with the embodiment and/or aspect is included in at least one embodiment and/or aspect described herein, and may or may not be present in other embodiments and/or aspects. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments and/or aspects. A “combination thereof” is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

Claims

1. An electrochemical reactor, comprising:

a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream comprises an electrolyte and an iron-containing feedstock;

an anode and a cathode positioned in contact with the channel; and

a source of a magnetic field positioned in proximity to the cathode,

wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and

wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

2. The electrochemical reactor of claim 1, wherein the iron metal comprises an iron metal powder.

3. The electrochemical reactor of claim 1, wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof.

4. The electrochemical reactor of claim 1, wherein the iron-containing feedstock comprises magnetite or hematite.

5. The electrochemical reactor of claim 1, wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source.

6. The electrochemical reactor of claim 1, wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof.

7. The electrochemical reactor of claim 1, wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 weight percent, based on a total weight of the electrolyte.

8. The electrochemical reactor of claim 1, wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.

9. The electrochemical reactor of claim 1, wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock.

10. The electrochemical reactor of claim 1, wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream.

11. The electrochemical reactor of claim 1, wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof.

12. The electrochemical reactor of claim 1, wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream.

13. The electrochemical reactor of claim 1, wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream.

14. The electrochemical reactor of claim 1, wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof; or

wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof; or

a combination thereof.

15. The electrochemical reactor of claim 1, wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode.

16. The electrochemical reactor of claim 1, wherein the channel is arranged vertically.

17. The electrochemical reactor of claim 1, further comprising a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream.

18. An electrochemical reactor, comprising:

a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream comprises an electrolyte and an iron-containing feedstock;

an anode and a cathode positioned in contact with the channel; and

a source of a magnetic field positioned in proximity to the cathode,

wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron metal at a surface of the cathode and in the magnetic field of the source, and

wherein the iron-containing feedstock comprises magnetite or hematite.

19. The electrochemical reactor of claim 18, wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field.

20. The electrochemical reactor of claim 18, wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

21. The electrochemical reactor of claim 18,

i) wherein the iron metal comprises an iron metal powder;

ii) wherein the iron-containing feedstock further comprises maghemite, goethite, limonite, pyrite, red mud, or a combination thereof;

iii) wherein the iron-containing feedstock consists essentially of magnetite or hematite;

iv) wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source;

v) wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;

vi) wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 weight percent, based on a total weight of the electrolyte;

vii) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;

viii) wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream;

ix) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;

x) wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream;

xi) wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream;

xii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;

xiii) wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;

xiv) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;

xv) wherein the channel is arranged vertically;

xvi) wherein the electrochemical reactor further comprises a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream;

xvii) wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock;

xviii) wherein the electrochemical reactor is configured to continuously flow an electrolyte stream through the channel; or

xix) a combination thereof.

22. An electrochemical reactor, comprising:

a catholyte channel for containing and directing flow of a catholyte stream, wherein the catholyte stream comprises a catholyte and an iron-containing feedstock;

an anolyte channel for containing and directing flow of an anolyte stream;

a cathode positioned in contact with the catholyte channel;

an anode positioned in contact with the anolyte channel;

a source of a magnetic field positioned in proximity to the cathode; and

a separator disposed between the catholyte channel and the anolyte channel,

wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and

wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency ratio of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

23. The electrochemical reactor of claim 22,

i) wherein the iron metal comprises an iron metal powder;

ii) wherein the electrochemical reactor is configured to provide continuous flow of the electrolyte stream;

iii) wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock;

iv) wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof;

v) wherein the iron-containing feedstock comprises magnetite or hematite;

vi) wherein the iron-containing feedstock consists essentially of magnetite or hematite;

vii) wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the magnet;

viii) wherein the catholyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;

ix) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;

x) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;

xi) wherein the source is positioned external to the catholyte channel comprising the catholyte stream, wherein the source does not contact the catholyte stream;

xii) wherein at least a portion of the source is positioned within the catholyte channel comprising the catholyte stream;

xiii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;

xiv) wherein the anode comprises carbon, titanium, platinum, iridium, ruthenium, titanium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, tin, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;

xv) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;

xvi) wherein catholyte channel is arranged vertically;

xvii) wherein the electrochemical reactor further comprises a separation unit disposed downstream of the catholyte channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the catholyte stream; or

xviii) a combination thereof.

24. The electrochemical reactor of claim 22, wherein the anolyte comprises an aqueous solution comprising:

a strong acid; and

optionally a supporting electrolyte compound.

25. The electrochemical reactor of claim 22, wherein the separator comprises an anion exchange membrane, a cation exchange membrane, a zwitterionic membrane, a porous membrane having an average pore diameter of less than 10 nanometers, a polybenzimidazole-containing membrane, a polysulfone-containing membrane, a polycarboxylic-containing membrane, a polyetherketone-containing membrane, a membrane comprising a polymer of intrinsic microporosity, or a combination thereof.

26. The electrochemical reactor of claim 22, wherein the catholyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the catholyte stream.

27. A method of processing an iron-containing feedstock to produce iron metal, the method comprising:

flowing an electrolyte stream comprising the iron-containing feedstock through a channel of an electrochemical cell, the electrochemical cell comprising an anode and a cathode disposed in the channel;

applying a magnetic field at the cathode of the electrochemical cell;

electrochemically reducing at least a portion of the iron-containing feedstock to produce the iron metal on a surface of the cathode while the magnetic field is applied at the cathode; and

collecting the iron metal from the surface of the cathode using the electrolyte stream,

wherein the electrochemically reducing is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

28. The method of claim 27, wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream.

29. The method of claim 27, wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode.

30. The method of claim 27, wherein the iron metal comprises an iron metal powder.

31. The method of claim 27, wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof,

wherein the iron-containing feedstock comprises magnetite or hematite, or

wherein the iron-containing feedstock consists essentially of magnetite or hematite.

32. The method of claim 27, wherein at least a portion of the iron-containing feedstock is substantially reduced on the surface of the cathode while the magnetic field is applied to the cathode.

33. The method of claim 27,

i) wherein the flowing the electrolyte stream is unidirectional from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode;

ii) wherein the catholyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;

iii) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;

iv) wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream;

v) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;

vi) wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream or wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream;

vii) wherein at least a portion of the magnet is positioned within the channel comprising the electrolyte stream;

viii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;

ix) wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;

x) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;

xi) wherein the channel is arranged vertically; or

xii) a combination thereof.

34. The method of claim 27, further comprising:

transporting the electrolyte stream to a separation unit located downstream of the channel; and

separating at least a portion of the iron metal from the electrolyte stream.

35. The method of claim 27, further comprising:

transporting the electrolyte stream to a separation unit located downstream of the channel;

separating at least a portion of the iron metal from the electrolyte stream; and

recirculating the electrolyte stream to an upstream region of the channel.

36. The method of claim 27, wherein the iron metal has

i) a specific total embedded emissions of less than 0.8 tons of CO2 per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism;

ii) a carbon emission intensity of less than 1100 kilograms of CO2 per ton of the iron metal, when determined according to ISO 14404;

iii) a carbon emission intensity of less than 800 kilograms of CO2 per ton of the iron metal, when determined according to the Intergovernmental Panel on Climate Change Methodology 2006 Guidelines for National Greenhouse Gas Inventories;

iv) a carbon emission intensity of less than 1500 kilograms of CO2 per ton of the iron metal, when determined according to the 2017 World Steel Life Cycle Inventory Methodology;

v) a carbon emission intensity of less than 1300 kilograms of CO2 per ton of the iron metal, when determined according to the 2008 World Resource Institute Iron and Steel Greenhouse Gas Protocol;

vi) a carbon emission intensity of less than 750 kilograms of CO2 per ton of the iron metal, when determined according to European Union Commission Implementing Regulation 2018/2066;

vii) a specific total embedded emissions of less than 0 tons of CO2 per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism; or

viii) a combination thereof.

37. An iron metal produced by the method of claim 27, wherein the iron metal is a powder having an average particle size of less than or equal to 200 micrometers.