Impurity removal in iron conversion systems

Abstract

A method for producing iron may include, for example, the steps of: feeding a feedstock having iron-containing ore and one or more impurities to a dissolving subsystem having a first electrochemical cell; producing an iron-rich solution in the dissolving subsystem; treating the iron-rich solution to remove at least a portion of the one or more impurities by increasing the pH of the iron-rich solution from an initial pH to an adjusted pH, thereby precipitating at least a portion of the one or more impurities in the treated iron-rich solution; conveying the treated iron-rich solution to an iron plating subsystem having a second electrochemical cell; and depositing the transported formed Fe. 2+ performing a second electrochemical reduction of at least a first portion of the ions to Fe metal; and removing the Fe metal from the second electrochemical cell, thereby producing iron.

Description

Detailed Description of the Invention

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS]

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 165,502, filed March 24, 2021, which is incorporated by reference in its entirety for all purposes unless inconsistent herewith.

[0002] [Government funding]

[0002] The invention in this application was made with Government support under Award No. 2039232 awarded by the National Science Foundation. The Government has certain rights in the inventions herein.

[0003] [Field]

[0003] This application relates generally to the fields of electrochemistry and hydrometallurgy, and more particularly to systems and methods for extracting iron from iron-bearing raw materials using electrochemical and / or hydrometallurgical processes.

[0004] [background]

[0004] Iron oxide ore can be converted to relatively pure metallic iron by removing oxygen (i.e., reducing the oxide) and recovering the metallic iron in a form that can be processed into useful articles in subsequent processes. The iron can then be made into steel by adding small amounts of carbon and other elements, depending on the type of steel being made. For thousands of years, both of these operations (reduction and carbon addition) have been accomplished primarily by heating iron ore to extremely high temperatures (e.g., about 1700°C) in the presence of carbon, typically produced by burning coal (or coke). Carbon monoxide, produced by burning coal or coke, combines with the oxygen in the iron oxide, thereby reducing the oxide to metallic iron and releasing carbon dioxide. In fact, modern steel production accounts for about 10% of global CO2 emissions.

[0005] [overview]

[0005] Provided herein are methods and associated systems for producing substantially pure metallic iron from iron-containing ores and / or other iron-containing raw materials. Described herein are methods and systems, in various embodiments, for converting iron ore from an ore or other non-pure state to metallic iron using chemical and / or electrochemical conversion techniques, without the need for burning fossil fuels. In particular, various embodiments described herein provide for dissolving iron ore material in an acidic solution, chemically and / or electrochemically adjusting the properties of the acidic solution, and electroplating iron (and optionally other metals) from the acidic solution in an electrochemical cell.

[0006]

[0006] Various embodiments of the system and method include at least a first independent electrochemical process for adjusting parameters of the acid solution to enhance or accelerate ore dissolution, and a second independent electrochemical process for electroplating iron from the acid solution.

[0007]

[0007] Optionally, method embodiments disclosed herein may provide a process for electroplating iron from iron-containing ore such that steady state operation is characterized by an overall input consisting essentially of iron-containing ore and an overall output consisting essentially of high purity iron, with water and acid being regenerated as part of the process. Optionally, method embodiments disclosed herein may provide a process for electroplating iron from iron-containing ore, where there is substantially no production of CO2 during steady state operation. Optionally, method embodiments disclosed herein may provide a process for electroplating iron from iron-containing ore, where there is substantially no production of Cl2(g) during steady state operation. Optionally, method embodiments disclosed herein also include a process for making steel using the high purity iron produced according to embodiments herein.

[0008] A method for processing and smelting iron-bearing ores, comprising the steps of: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; dissolving at least a portion of the thermally reduced ore using an acid to form an acidic iron salt solution; wherein the acidic iron salt solution contains protons electrochemically generated in an electrochemical cell.

[0009] A method for processing and smelting iron-bearing ores, comprising the steps of: In the dissolving tank, the iron-bearing ore is contacted with an acid to dissolve at least a portion of the iron-bearing ore, thereby forming dissolved Fe 3+ forming an acidic iron salt solution having ions; recirculating at least a portion of the acidic iron salt solution between the dissolution tank and a cathode chamber of an electrochemical cell, the electrochemical cell comprising a cathode in the presence of at least a portion of the acidic iron salt solution functioning as a catholyte in the cathode chamber, an anode in the presence of an anolyte, and a separator separating the catholyte from the anolyte; Fe dissolved from the catholyte at the cathode 3+ At least a portion of the ions are electrochemically reduced to Fe in the catholyte. 2+ forming ions; electrochemically generating protons in the electrochemical cell and supplying the electrochemically generated protons to a catholyte; wherein the acidic iron salt solution in the dissolution tank is characterized by a steady state concentration of free protons of at least 0.2 M in the presence of iron-containing ore.

[0010] A method for processing and smelting iron-bearing ores, comprising the steps of: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; The reducing agent comprises H2 gas; at least a portion of the H2 gas is generated chemically via a reaction between iron metal and an acid, and / or at least a portion of the H2 gas is generated electrochemically via a parasitic hydrogen evolution reaction of the iron electroplating process; dissolving at least the thermally reduced ore using an acidic solution to form an iron salt solution; and wherein the dissolving step comprises dissolving the formed magnetite in said acidic solution.

[0011] 1. A system for processing and smelting iron-bearing ore, comprising: a first smelting tank for smelting a first iron-bearing ore using a first acid; Dissolution of the first ore in the first acid produces dissolved Fe in the first dissolution tank. 3+ a first dissolution tank for forming a first acidic iron salt solution containing ions; an electrochemical cell fluidly connected to the first dissolving tank; an electrochemical cell comprising a cathode chamber having a catholyte in the presence of a cathode, an anode chamber having an anolyte in the presence of an anode, and a separator separating the catholyte and the anolyte; a first circulation subsystem for circulating at least a portion of the first acidic iron salt solution from the first dissolving tank to the cathode chamber and for circulating at least a portion of the catholyte from the electrochemical cell to the first dissolving tank; Fe from the first acidic iron salt solution 3+ At least a portion of the ions are converted to Fe at the cathode in the catholyte. 2+ ions from the first acidic iron salt solution, thereby 3+ A system for consuming ions is also disclosed.

[0012] 1. A method for producing iron, comprising: providing a feedstock having iron-bearing ore to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; the first anolyte having a different composition than the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+ forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; The formed Fe 2+ transferring the ions from the dissolution subsystem to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; A method is disclosed that includes:

[0013] 1. A method for producing iron, comprising: providing a feedstock having iron-bearing ore to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having H2 gas in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anode chamber from the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; The formed Fe 2+ transferring the ions from the dissolution subsystem to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; Also disclosed is a method comprising:

[0014] 1. A system for producing iron, comprising: a dissolving subsystem having a dissolving tank and a first electrochemical cell fluidly connected to the dissolving tank; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; a dissolution subsystem, wherein the first anolyte has a different composition than the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first inter-subsystem fluid connection between the dissolving subsystem and the iron plating subsystem; Equipped with; A melting tank receives a feedstock having iron-bearing ore; The dissolving tank dissolves at least a portion of the iron-containing ore to produce a dissolved first Fe 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions, The formed Fe 2+ ions are transferred from the dissolution subsystem to the iron plating subsystem via the first inter-subsystem fluid connection; A second electrochemical cell was used to measure the amount of the transferred Fe 2+ a second cathode for reducing at least a first portion of the ions to Fe metal; A system is further disclosed in which Fe metal is removed from the second electrochemical cell.

[0015] 1. A system for producing iron, comprising: a dissolving subsystem having a dissolving tank and a first electrochemical cell fluidly connected to the dissolving tank; a dissolution subsystem, the first electrochemical cell comprising a first anode chamber having H2 gas in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anode chamber from the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first inter-subsystem fluid connection between the dissolving subsystem and the iron plating subsystem; Equipped with; A melting tank receives a feedstock having iron-bearing ore; The dissolving tank dissolves at least a portion of the iron-containing ore to produce a dissolved first Fe 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions, The formed Fe 2+ ions are transferred from the dissolution subsystem to the iron plating subsystem via the first inter-subsystem fluid connection; A second electrochemical cell was used to measure the amount of the transferred Fe 2+ a second cathode for reducing at least a first portion of the ions to Fe metal; A system is further disclosed in which Fe metal is removed from the second electrochemical cell.

[0016] 1. A method for producing iron, comprising: providing a feedstock having an iron-bearing ore and one or more impurities to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+ forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; generating an iron-rich solution in the dissolution subsystem, the iron-rich solution being separated from the formed Fe 2+ at least a portion of the ions and at least a portion of the one or more impurities; At least a first portion of the iron-rich solution is treated to remove at least a portion of one or more impurities from the iron-rich solution, thereby forming Fe 2+ forming a treated iron-rich solution having at least a portion of the ions; a treating step comprising increasing the pH of the iron-rich solution from an initial pH to an adjusted pH, thereby precipitating at least a portion of the one or more impurities in the treated iron-rich solution; conveying at least a first portion of the treated iron-rich solution to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of at least a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; A method is disclosed that includes:

[0017] 1. A system for producing iron, comprising: a dissolving subsystem having a first dissolving tank and a first electrochemical cell fluidly connected to the first dissolving tank; a dissolution subsystem, the first electrochemical cell comprising a first cathode chamber having a first anolyte in the presence of a first anode, a second anode chamber having the first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first impurity removal subsystem; Equipped with; a first dissolving tank receiving a feedstock having one or more iron-bearing ores and one or more impurities; The first dissolving tank dissolves at least a portion of the one or more iron-containing ores to produce a first Fe dissolved in an acidic iron salt solution. 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; First Fe 3+The ions are electrochemically reduced at the first cathode to form Fe in the first catholyte. 2+ Forming ions, In the dissolution subsystem, an iron-rich solution is formed, and the iron-rich solution is dissolved in the Fe 2+ at least a portion of the ions and at least a portion of the one or more impurities; At least a portion of the iron-rich solution is fed to a first impurity removal subsystem to remove at least a portion of one or more impurities from the iron-rich solution, thereby forming Fe 2+ A treated iron-rich solution having at least a portion of the ions is formed; increasing the pH of the iron-rich solution from an initial pH to an adjusted pH in a first impurity removal subsystem to precipitate a removed portion of the one or more impurities; conveying at least a first portion of the treated iron-rich solution from the first impurity removal subsystem to an iron plating subsystem; A second electrochemical cell was used to measure the amount of transported Fe 2+ a second cathode for reducing at least a portion of the ions to Fe metal; A system is also disclosed in which Fe metal is removed from a second electrochemical cell.

[0018] 1. A method for producing iron, comprising: In the first dissolving tank, the first iron-bearing ore is contacted with an acid to dissolve at least a portion of the first iron-bearing ore, thereby producing a dissolved first Fe 3+ forming an acidic iron salt solution having ions; circulating at least a portion of the acidic iron salt solution between the first dissolving tank and the first cathode chamber of the first electrochemical cell, thereby forming a first Fe 3+ providing at least a portion of the ions to a first catholyte in a first cathode chamber; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; First cathode, first Fe 3+ a first electrochemical reduction of at least a portion of the ions to produce Fe in the first catholyte; 2+ forming ions; Electrochemically generating protons in a first electrochemical cell; The circulating step is performed by circulating at least a portion of the electrochemically generated protons and the formed Fe 2+ providing at least a portion of the ions from the first catholyte to the acidic iron salt solution; Fe formed in the dissolution subsystem 2+ generating a first iron-rich solution having ions, the dissolving subsystem comprising a first dissolving tank and a first electrochemical cell; transferring at least a portion of the first iron-rich solution to an iron plating subsystem, the iron plating subsystem comprising a second electrochemical cell; The formed Fe 2+ a second electrochemical reduction of the first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; a second electrochemical cell comprising a second cathode chamber having a second catholyte in the presence of a second cathode, a second anolyte chamber having a second anolyte in the presence of a second anode, and a second separator separating the first anolyte from the first catholyte; removing Fe metal from the second electrochemical cell, thereby producing iron; Further disclosed is a method comprising:

[0019] 1. A system for producing iron, comprising: a dissolving subsystem for producing an iron-rich solution, the dissolving subsystem comprising a first dissolving tank, a first electrochemical cell, and a first circulation subsystem; In the first dissolving tank, the iron-bearing ore is contacted with an acid to dissolve at least a portion of the iron-bearing ore, thereby producing dissolved Fe 3+ An acidic iron salt solution with ions is formed; A first circulation subsystem circulates at least a portion of the acidic iron salt solution between the first dissolving tank and the first cathode chamber of the first electrochemical cell, thereby producing a first Fe 3+ providing at least a portion of the ions to a first catholyte in a first cathode chamber; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; A first electrochemical cell is connected to a first cathode and a first Fe 3+ Electrochemically reducing at least a portion of the ions to form Fe in the first catholyte. 2+ Forming ions; a first electrochemical cell electrochemically generates protons and supplies the electrochemically generated protons to a catholyte, and a first circulation system supplies the electrochemically generated protons from the first catholyte to an acidic iron salt solution; The iron-rich solution generated in the first subsystem is converted into the Fe 2+ and a dissolved subsystem, including ions; a transition subsystem including a first inter-subsystem fluid connection for transferring at least a portion of the iron-rich solution to the iron plating subsystem; an iron plating subsystem comprising a second electrochemical cell; a second electrochemical cell comprising a second cathode chamber having a second catholyte in the presence of a second cathode, a second anode chamber having a second anolyte in the presence of a second anode, and a second separator separating the first anolyte from the first catholyte in the presence of the second cathode; Transported and formed Fe 2+ an iron plating subsystem, in which at least a first portion of the ions are electrochemically reduced to Fe metal at a second cathode; a subsystem for extracting Fe metal from the second electrochemical cell, thereby producing iron; A system comprising: [Brief description of the drawings]

[0020] [Figure 1A] FIG. 1 is a schematic diagram of a possible approach to making iron by combining electroplating with oxygen generation. [Figure 1B] FIG. 1 is a schematic diagram of a possible approach to make iron by dissolving iron source material in sulfuric acid and combining electroplating with oxygen generation using exemplary acid chemistries in the approximate pH range. [Diagram 2] FIG. 2 is a schematic diagram showing the feedstock dissolution and acid regeneration subsystem. [Diagram 3] FIG. 2 is a schematic diagram showing the iron plating subsystem. [Figure 4] FIG. 1 is a schematic diagram showing a two-stage iron conversion system with various subsystems. [Figure 5A] FIG. 1 is a schematic process flow diagram illustrating an alternative process for distributing iron-rich acidic solution from the dissolving subsystem to the anolyte and catholyte tanks of the plating subsystem. [Figure 5B] FIG. 1 is a schematic process flow diagram illustrating an alternative process for distributing iron-rich acidic solution from the dissolving subsystem to the anolyte and catholyte tanks of the plating subsystem. [Figure 6]FIG. 1 is a schematic diagram showing a two-stage iron conversion system having various subsystems, including an acid regeneration subsystem with oxygen generation, and further illustrating possible fluid flows between the subsystems. [Figure 7A] 1 is a graph showing experimental data illustrating the conversion of ferric to ferrous iron and the generation of acid in the acid regeneration cell during dissolution along with acid regeneration and ferric iron reduction. Using a starting solution of 1.8 M ferric sulfate representing the end of the plating process, ferrous iron was produced by electrochemical reduction in electrochemical cell 1 as evidenced by the increase in [Fe2+] concentration. The acid produced allowed for further dissolution of iron oxide, since the total final iron concentration was 2.5 M. [Figure 7B] 1 is a graph showing experimental data illustrating the dissolution rates of hematite and magnetite ores in sulfuric acid of various concentrations. [Figure 7C] 1 is a graph showing experimental data illustrating the dissolution rate of ore in sulfuric acid. [Figure 8A] FIG. 1 is a solubility diagram showing the solubility of various metal hydroxides at varying solution pH values. [Figure 8B] FIG. 1 is a solubility diagram showing the solubility of various iron phosphates and oxides. [Figure 8C] FIG. 1 is a solubility diagram showing the solubility of various iron phosphates and oxides. [Figure 8D] FIG. 1 is a solubility diagram showing the solubility of ferric phosphate and ferric hydroxide. [Figure 8E] FIG. 1 is a solubility diagram showing the solubility of aluminum phosphate and aluminum hydroxide. [Figure 9] FIG. 1 is a process flow diagram illustrating certain exemplary embodiments involving the use of H2 generated during iron electroplating in a process for converting iron oxides, such as hematite, to magnetite followed by dissolution of the magnetite in conjunction with an acid regeneration cell. [Figure 10] FIG. 1 is a schematic system diagram illustrating an exemplary system and process for dissolving various treated ores coupled to an acid regeneration system. [Figure 11]FIG. 1 is a process flow diagram that illustrates generally the process of converting solid ferrous feedstock into pure galvanized iron, including optional intermediate processing steps. [Figure 12] 1 is a plot of alpha (α) versus time for the reduction of hematite to magnetite by 5% H2-95% Ar gas. [Figure 13A] FIG. 2 is a diagram of an exemplary flow cell in accordance with certain embodiments. [Figure 13B] 1 is a plot of efficiency vs. pH for electrowinning using chloride and sulfate chemistries. Fe plating efficiency is greater than 80% at pH 2 or greater in the sulfate chemistry. [Figure 14] FIG. 1 is a diagram of an exemplary acid regeneration cell. For example, the cell can be operated at 400 mA / cm2 for greater than 97% faradaic efficiency. [Figure 15] 1 is a CV sweep chart showing that in hydrochloric acid chemistry, hydrogen generation under pH control via the concentration of HCl occurs at a significantly higher rate at pH below 2. [Figure 16A] Plots of current density versus voltage at 20° C. (FIG. 16A) and 60° C. (FIG. 16B) in the presence of 1 M NH4Cl (FIG. 16A) or 1 M (NH4)SO4 (FIG. 16B), with parameters summarized in the inset. The chloride has lower hydrogen production than the sulfate at room temperature and has similar rates at 60° C. [Figure 16B] Plots of current density versus voltage at 20° C. (FIG. 16A) and 60° C. (FIG. 16B) in the presence of 1 M NH4Cl (FIG. 16A) or 1 M (NH4)SO4 (FIG. 16B), with parameters summarized in the inset. The chloride has lower hydrogen production than the sulfate at room temperature and has similar rates at 60° C. [Figure 17A] Plots of current density versus voltage for Fe(II) / Fe(s) (FIG. 17A) and Fe(III) / Fe(II) chemistries, with certain parameters summarized in the inset. Increasing chloride concentration improves the reversibility of both the Fe(II) / Fe(s) and Fe(III) / Fe(II) couples. [Figure 17B]Plots of current density versus voltage for Fe(II) / Fe(s) (FIG. 17A) and Fe(III) / Fe(II) chemistries, with certain parameters summarized in the inset. Increasing chloride concentration improves the reversibility of both the Fe(II) / Fe(s) and Fe(III) / Fe(II) couples. [Figure 18] FIG. 1 is a schematic diagram illustrating a chemical plant configured to carry out the iron conversion processes described herein. [Figure 19] 1 is an example of a current-voltage curve for an acid regeneration cell. [Figure 20] 1 is an example of a current-voltage curve for a plating cell. [Figure 21A] FIG. 21A is an XRD spectrograph showing that a commercial source of iron ore contains substantial amounts of goethite and hematite. After heat treatment at 450° C., goethite is completely converted to hematite, which has a higher surface area (FIG. 21B). After heat treatment at 450° C. in a 4% hydrogen atmosphere, nearly complete reduction to magnetite is achieved (FIG. 21C). [Figure 21B] FIG. 21A is an XRD spectrograph showing that a commercial source of iron ore contains substantial amounts of goethite and hematite. After heat treatment at 450° C., goethite is completely converted to hematite, which has a higher surface area (FIG. 21B). After heat treatment at 450° C. in a 4% hydrogen atmosphere, nearly complete reduction to magnetite is achieved (FIG. 21C). [Figure 21C] FIG. 21A is an XRD spectrograph showing that a commercial source of iron ore contains substantial amounts of goethite and hematite. After heat treatment at 450° C., goethite is completely converted to hematite, which has a higher surface area (FIG. 21B). After heat treatment at 450° C. in a 4% hydrogen atmosphere, nearly complete reduction to magnetite is achieved (FIG. 21C). [Figure 22] FIG. 1 is a process flow diagram illustrating a process for making green steel and green steel products from iron produced by one or more of the processes described herein. [Diagram 23]FIG. 1 is a schematic illustrating the use of a redox mediator couple to decouple oxygen evolution from the reduction of ferric iron to metallic iron.

[0021] Description of compounds and nomenclature

[0050] Generally, the terms and phrases used herein have their art-recognized meanings, which can be found by reference to standard texts, periodical references, and contexts known to those of ordinary skill in the art. The following definitions are provided to clarify their specific use in the context of this disclosure.

[0022]

[0051] In various embodiments, the present disclosure provides processes, systems, and methods for enabling an efficient low-temperature aqueous hydrometallurgical process for producing pure iron from a variety of iron source materials, including relatively low purity iron feed materials. In broad terms, the iron feed material is dissolved in an acidic aqueous solution and metallic iron is electrolytically plated and removed as a solid. In various embodiments, the iron feed material or the aqueous iron may be converted from one form to another during one or more process steps.

[0023]

[0052] As used herein, the terms "pure iron" and "high purity iron" are used in a relative sense to refer to a metallic iron material that is purer than the iron source material and contains an acceptably low amount of one or more impurities.

[0024]

[0053] As used herein, the terms "iron source material" and "iron feedstock" are used interchangeably to refer to iron-containing materials that may be used as input to the various systems and methods described herein. "Iron source material" and "iron feedstock" may include iron in any form, such as iron oxide, iron hydroxide, iron oxyhydroxide, iron carbonate, or other iron-containing compounds, ores, rocks, or minerals (including any mixtures thereof) in their natural state or in a beneficiated or otherwise refined or modified state. The term "iron-containing ore" or simply "iron ore" may include materials recognized, known, or referred to in the art as iron ore(s), rock(s), natural stone(s), precipitate(s), natural precipitate(s), minerals, and / or natural mineral(s), whether in their natural state or in a beneficiated or otherwise refined or modified state. Some embodiments of the processes and systems described herein may be particularly useful for iron ores that include hematite, goethite, magnetite, limonite, siderite, ankerite, tergite, bauxite, or any combination thereof.

[0025]

[0054] Optionally, the ferrous source material or raw ferrous material may include ferrous metal materials such as, but not limited to, iron dust (e.g., fine particles produced as a by-product of the iron or steel making process in a blast furnace, oxygen furnace, electric arc furnace, etc.), iron powder, scrap steel, and / or scrap cast iron. "Ferrous source material" and "ferrous raw material" may also contain various other non-ferrous materials, commonly referred to as "impurities."

[0026]

[0055] As used herein, the term "impurity" refers to an element or compound other than the desired end product material (e.g., iron). In various embodiments, a given element or compound may or may not be considered an "impurity" depending on the intended end use of the product material. In some cases, one or more elements or compounds that may be impurities to one process or sub-process may be isolated or purified, collected, and sold as a secondary product material.

[0027]

[0056] In various embodiments herein, various compositions, compounds, or solutions may be substantially "isolated" or "purified" to a degree sufficient for the purposes described herein. In various embodiments, a substantially purified composition, compound, or formulation (e.g., a ferrous solution, a ferric solution, or plated iron metal) may have a chemical purity of 90%, optionally in some applications 95%, optionally in some applications 99%, optionally in some applications 99.9%, optionally in some applications 99.99%, and optionally in some applications 99.999% pure (e.g., by molar ion concentration or by weight).

[0028]

[0057] References made herein to a "tank" are intended to include any vessel suitable for containing liquids, such as highly acidic or caustic aqueous solutions, as appropriate. In some embodiments, such vessels may include additional features or components to aid or improve mixing of the solid and / or liquid contents of the vessel. For example, a dissolving tank may include passively or actively operating structures or features for agitating the solution or solid / liquid mixture. Dissolving tanks or other tanks useful in the systems and methods herein may also include features to allow for sparging gas into or through the solid and / or liquid contents of the tank to increase contact of gas with the solid and / or liquid materials in the tank. Various tanks may also include baskets, sieves, pans, filters, or other structures to collect and separate solids from liquids. In some embodiments, the tank may be configured to induce flow of liquid or gas through the tank in a manner to agitate the mixture therein (e.g., flow-inducing structures, pumps, impellers, baffles, impellers, stirring rods, stirring blades, vibrators, cyclone channels, etc.).

[0029]

[0058] In some embodiments described herein, a system for converting iron ore to iron metal (i.e., an "iron conversion system") may comprise two or more subsystems. Some embodiments include a "dissolving subsystem" in which components of an iron-containing feedstock are dissolved in an aqueous solution. Some embodiments further include an "iron plating subsystem" in which the dissolved iron is electrochemically reduced to iron metal in an "electroplating" (or simply "plating") process. The iron metal may then be removed from the iron plating subsystem.

[0030]

[0059] In some embodiments, the aqueous iron-bearing solution may be transferred to and processed in a "transition subsystem" after exiting the dissolution subsystem and before being conveyed to the plating subsystem. Processing within the transition subsystem may include pH adjustment, impurity removal, filtration, or other processes. In some embodiments, any of the above subsystems may be fluidly coupled to one another by "inter-subsystem fluid connections" which may include any combination of fluid carrying conduits (pipes, channels, troughs, etc.) and any number of flow control devices including valves, pumps, expansion chambers, gas-liquid separators, solid-liquid separators, filters, or other similar devices.

[0031]

[0060] The term "iron electroplating" (or "iron plating" used synonymously herein) refers to a process in which dissolved iron is electrochemically reduced to metallic iron on a cathodic surface. The equivalent terms "electrodeposition," "electroforming," and "electrowinning" are also used synonymously herein with "iron electroplating." The shape or form factor of the electroplated iron need not be a "plate" by any definition of that term. For example, the electroplated iron may take any shape or form and may be deposited on any suitable cathodic surface as described in various embodiments herein.

[0032]

[0061] The term "dissolution step" refers to the processes occurring in the dissolution subsystem, including, but not limited to, dissolution of iron oxide materials, and the regeneration of Fe in the acid regeneration cell. 3+ Fe ions 2+ The process of the dissolution step may also include oxidizing water or hydrogen gas in the first electrochemical cell to produce protons, for example, which may allow for the regeneration of acid (in the form of protons) used to facilitate dissolution of the iron-containing feedstock.

[0033]

[0062] The term "iron plating step" refers to the step of plating Fe in a "plating cell", also referred to herein as "plating cell". 2+ The iron plating process also includes the process(es) occurring within the iron plating subsystem, including but not limited to the electrochemical process(es) occurring within or through the claimed "plating cell", including but not limited to the step of "electrochemically reducing" Fe ions to Fe metal. 2+ The second part of the ions is oxidized to Fe 3+ In some embodiments, such Fe ions may be formed. 2+ The ions may be supplied from the first electrochemical cell or from another part of the system.

[0034]

[0063] As used herein, unless otherwise specified, a "ferrous iron solution" or "ferrous solution" refers to a solution that is at least predominantly (i.e., 50% to 100%) Fe. 2+ (i.e. "ferrous") ions, and the remainder of the dissolved iron is "ferric" Fe 3+ Similarly, the term "ferrous ion" can refer to an aqueous solution containing dissolved iron, which is in the form of ferrous iron (Fe 2+ ) ions.

[0035]

[0064] As used herein, unless otherwise specified, "ferric iron solution" or "ferric solution" refers to a solution that is at least predominantly (i.e., 50% to 100%) Fe. 3+ (i.e. "ferric") ions, and the remainder of the dissolved iron is "ferrous" Fe 2+ Similarly, the term "ferric ion" can refer to an aqueous solution containing dissolved iron, which is in the form of ferric iron (Fe 3+ ) state. Either a "ferric solution" or a "ferrous solution" may also contain other dissolved ions or colloidal or particulate material, including impurities.

[0036]

[0065] As used herein, any reference to "PEM" or "proton exchange membrane" may be construed as also including "CEM" or "cation exchange membrane," both of which terms may include any available membrane material that selectively passes positively charged cations and / or protons. The abbreviation "AEM" is used to refer to anion exchange membranes selective for negatively charged aqueous ions, and includes any available anion selective membranes.

[0037]

[0066] As used herein, aqueous protons and electrochemically generated protons are intended to include aqueous protons and aqueous hydronium ions.

[0038]

[0067] As used herein, the term "raw ore" refers to iron-bearing ore that has not been thermally reduced or air roasted according to embodiments disclosed herein. Raw ore is optionally an iron-bearing raw ore.

[0039]

[0068] As used herein, electrochemically generated ions, such as electrochemically generated protons and electrochemically generated iron ions (e.g., Fe 2+ , Fe3+ ) refers to ions produced or produced in an electrochemical reaction. For example, the electrochemical oxidation of water at the anode may result in electrochemically generated protons and electrochemically generated oxygen.

[0040]

[0069] As used herein, the term "thermal reduction" refers to heat treatment at high temperatures in the presence of a reducing agent. Thermal reduction is also referred to in the art as reduction roasting. Optionally, the thermal reduction is performed at a temperature selected from the range of 200°C to 600°C. Optionally, the reducing agent is a gas, including hydrogen (H2) gas. Additional descriptions and potentially useful embodiments of thermal reduction can be found in the following references, which are incorporated herein in their entirety: "Hydrogen reduction of hematite ore fines to magnetite ore fines at low temperatures," Hindawi, Journal of Chemistry, Volume 2017, Article ID 1919720.

[0041]

[0070] As used herein, the term "parasitic hydrogen" or "hydrogen (H2) from the parasitic hydrogen generation reaction of the iron electroplating process" refers to hydrogen (H2) generated in the same electrochemical cell as the iron electroplating reaction (e.g., Fe 2+ From Fe or Fe 3+ From Fe 2+ Parasitic hydrogen generation refers to hydrogen (H2) gas that is electrochemically produced by a side reaction occurring simultaneously with the reaction of iron with Fe via a hydrogen atom. Additional description and potentially useful embodiments of parasitic hydrogen generation can be found in the following references, which are incorporated herein in their entirety: "An investigation into factors affecting the iron plating reaction for an all-iron flow battery," Journal of the Electrochemical Society 162 (2015) A108.

[0042]

[0071] As used herein, the term "air roasting" refers to a heat treatment carried out at high temperatures in the presence of air. Air roasting of ores, such as iron-bearing ores, may refine the ore or reduce the average particle size of the ore. Optionally, air roasting is carried out at a temperature selected from the range of 300°C to 500°C. Additional descriptions and potentially useful embodiments of air roasting can be found in the following references, which are incorporated herein in their entirety: "Study of the calcination process of two limonitic iron ores between 250°C and 950°C", Revista de la Facultad de Ingeneria, p.33 (2017).

[0043]

[0072] As used herein, the term "redox pair" refers to two chemical species, such as ions and / or molecules, that correspond to the reduced and oxidized species of an electrochemical reaction or half-cell reaction. For example, Fe 3+ Ion to Fe 2+ In the electrochemical reduction of cations to cations, the corresponding redox couple is Fe 3+ / Fe 2+ and Fe 3+ is an oxidized species, and Fe 2+ is the reduced species. As used herein, the order in which redox pairs are written (e.g., Fe 3+ / Fe 2+ vs. Fe 2+ / Fe 3+ ) is not intended to indicate which species is the reduced species and which is the oxidized species. Additional explanations of redox couples and potentially useful embodiments can be found in the following references, which are incorporated herein in their entirety: "Redox - Principles and Advanced Applications": Book by Mohammed Khalid, Chapter 5: Redox Flow Battery Fundamental and Applications.

[0044]

[0073] As used herein, the terms "steady state" and "at steady state" generally refer to a condition or set of conditions characterizing a process, method step, reaction(s), solution, (sub-)system, etc. that are true longer than are not true during operation or execution of the process, method step, reaction(s), solution, (sub-)system, etc. For example, the dissolution of an ore or feedstock may be characterized by steady state conditions that are true for at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90%, optionally at least 95% of the time that dissolution is occurring. For example, steady state conditions may exclude conditions that characterize the transient start-up and shutdown phases of a process, such as the dissolution of a feedstock.

[0045]

[0074] The term "cathode chamber" refers to the area, compartment, reservoir, etc. that contains the cathode, or at least a portion of its surface, and the catholyte. The term "anode chamber" refers to the area, compartment, reservoir, etc. that contains the anode, or at least a portion of its surface, and the anolyte.

[0046]

[0075] As used herein, the term "iron-rich solution" may also be referred to as "ferrous iron-rich solution" or "ferrous product solution," which corresponds to the solution rich in iron ions formed in the ore dissolution subsystem.

[0047]

[0076] As used herein, the term "ore dissolution subsystem" may also be referred to as "dissolution subsystem," "first subsystem," and "Step 1." The "dissolution subsystem" includes the "acid regenerator" described herein.

[0048]

[0077] As used herein, the term "iron plating subsystem" may also be referred to as the "second subsystem" and "Step 2."

[0049]

[0078] As used herein, the term "precipitation pH" refers to the pH at which one or more ions or salts mentioned are thermodynamically favorable to precipitate or are expected to precipitate from the host aqueous solution. In general, the solubility of dissolved ions and salts in an aqueous solution may depend on the pH of the aqueous solution. With increasing pH in the acidic region, many metal ions form metal hydroxides, which tend to precipitate from the host solution due to their decreasing solubility. Herein, the precipitation pH is defined as the pH corresponding to the point at which the solubility of a given ion or salt falls below a concentration threshold. The precipitation pH may be an upper limit above which the solubility of a given ion or salt is less than 1 mM, optionally less than 0.1 mM.

[0050]

[0079] As used herein, the term "metallic iron" refers to materials containing metallic iron, such as, but not limited to, scrap iron, electroplated iron, iron powder, and the like.

[0051]

[0080] As used herein, the terms "supporting salt" and "supporting ion" refer to salts and ions that correspond to or function as a supporting electrolyte, or that at least partially form a supporting electrolyte upon dissolution, to increase the conductivity of the host solution. In some embodiments, for example, the electrolytes and solutions of both the dissolution subsystem and the plating subsystem may contain dissolved iron species, an acid, and additionally an inert salt that functions as a supporting electrolyte to improve the conductivity of the electrolyte, which may be particularly beneficial at low ferrous concentrations, and the inert salt that functions as a supporting electrolyte to improve the conductivity may be referred to as a supporting salt. The supporting salt may include any electrochemically inert salt, such as sodium chloride, potassium chloride, ammonium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, sodium chloride, potassium chloride, ammonium chloride, etc., or combinations of salts. The concentration of the supporting salt in the solution, if used, may range, for example, from about 0.1 to about 1 M.

[0052]

[0081] As used herein, the term "wt.%" or "wt%" refers to weight percent, or mass fraction expressed as a percentage by mass. The term "at.%" or "at%" refers to atomic percent, or atomic ratio expressed as a percentage of a type of atom relative to total atoms in a given substance, e.g., molecule, compound, material, nanoparticle, polymer, dispersion, etc. The term "mol.%" refers to mole percent, or percent by mole. The term "vol.%" refers to volume percent.

[0053]

[0082] As used herein, the term "and / or" is used herein to refer to only a single element or any combination of elements from the list in which the term and / or appears in the description and claims of this specification. In other words, a list of two or more elements with the term "and / or" is intended to encompass embodiments having only any of the individual elements of the listed elements, or any combination thereof. For example, the phrase "element A and / or element B" is intended to encompass embodiments having only element A, only element B, or both elements A and B together. For example, the phrase "element A, element B, and / or element C" is intended to encompass embodiments having only element A, only element B, only element C, elements A and B together, elements A and C together, elements B and C together, or elements A, B, and C together.

[0054]

[0083] As used herein, the term "±" refers to an inclusive range of values, such as "X±Y" (where X and Y are each independently a number) refers to an inclusive range of values ​​selected from the range XY to X+Y. For "X±Y" (where Y is a percentage, e.g., 1.0±20%), the inclusive range of values ​​is selected from the range XZ to X+Z (where Z is equal to X×(Y / 100)). For example, 1.0±20% refers to an inclusive range of values ​​selected from the range 0.8 to 1.2.

[0055] [Detailed Description]

[0084] In the following description, many specific details of devices, device components, and methods are described to provide a complete description of the exact nature of the various inventions described herein. However, it will be apparent to those skilled in the art that the various inventions may be practiced without these specific details. Without wishing to be bound by any particular theory, a discussion of the beliefs or understandings of the basic principles related to the devices and methods disclosed herein may be made herein. It is recognized that, regardless of the ultimate accuracy of any mechanistic explanation or hypothesis, the embodiments of the devices and methods may nevertheless function and be useful.

[0056]

[0085] Steel, a trillion-yen commodity, is a fundamental building block of an industry that accounts for 3 gigatonnes or about 10% of global carbon dioxide emissions per year. The traditional steelmaking process generates large amounts of CO2 emissions because coke (refined coal) is used as a reducing agent for iron ore (i.e. to reduce iron oxide to iron metal) and coal is used as fuel to heat and melt the iron. Coal-based iron and steel production has been the most common and cheapest process for centuries. Unfortunately, the true societal costs have only been deferred until now, and increasing atmospheric CO2 threatens to cause increasingly catastrophic climate change.

[0057]

[0086] As the cost of renewable, zero-carbon energy falls, switching from fossil fuels to clean electricity for steelmaking is becoming an increasingly attractive alternative. However, the intermittent nature of renewable energy sources and the complexities of melting and reducing iron ore and removing impurities make electrically powered iron production very challenging.

[0058]

[0087] The need for compatibility with the intermittency of renewable energy is especially at odds with high temperature processes that are difficult to shut down or interrupt unless large backup stores of energy are available to maintain the high temperatures. Thus, there is a need for a low temperature, electricity-based process for producing sufficiently pure iron from iron ore that also exhibits good compatibility with the intermittency of renewable energy.

[0059]

[0088] Conventional wisdom among those skilled in the art of hydrometallurgy and iron processing suggests that hydrometallurgical processing of iron is economically impractical due to recognized thermodynamic and economic constraints on the rate of dissolution of iron raw materials, particularly iron oxide ores. Such practitioners believe that the hydrometallurgical processing of iron is economically impractical due to recognized thermodynamic and economic constraints on the rate of dissolution of iron raw materials, particularly iron oxide ores. 2+ , Fe 3+ , and Fe 0 The ability to efficiently extract iron by electroplating has been further questioned due to the possibility of electrochemical "shutting" between conditions. The systems and methods herein provide various mechanisms for overcoming these perceived obstacles.

[0060]

[0089] In various embodiments, the present disclosure provides processes, systems, and methods for enabling an efficient low-temperature aqueous metallurgical process for producing relatively pure metallic iron from a variety of ferrous source materials, including relatively low-purity ferrous feed materials that may be incompatible with other available iron and steelmaking processes. Solution-based iron extraction processes such as those described herein generally enable extremely cost-efficient separation and removal of impurities from ferrous feed materials of various purities without greenhouse gas emissions by using clean electrical energy sources. In some cases, waste materials generated during one process step may be advantageously used to improve other process steps. Various examples of these and other advantages will be apparent from the description herein.

[0061]

[0090] In various embodiments described herein, metallic iron may be extracted from iron source materials (including those that contain large amounts of iron oxide, such as most iron-bearing ores) by dissolving the iron source material in an acidic solution, optionally treating the solution to remove certain impurities, and then electrolytically precipitating the metallic iron from the solution into a solid form that can be removed and used in subsequent processes to make steel or other metal-containing products.

[0062]

[0091] Most iron oxide ores contain iron in the iron(III) state. For example, the very common mineral hematite (Fe2O3) is entirely in the iron(III) state, and magnetite (Fe3O4) contains Fe(III) in addition to Fe(II). When dissolved, hematite becomes Fe 3+ ions, and magnetite is Fe 3+ and Fe 2+ In order to electrolytically deposit iron, any Fe 3+ First of all, Fe 2+ In some embodiments of the systems and methods described herein, Fe 3+ From Fe 2+ The reduction of Fe to FeO and electroplating can be carried out in a single electrolysis cell, but typically at the expense of substantial parasitic hydrogen generation due to the concomitant electrochemical reduction of protons to form hydrogen gas. In some embodiments, such hydrogen generation is termed "parasitic" because it consumes charge and reactants from the cell and, under certain conditions, can be used to react with more desirable reactions, such as Fe 2+ In other embodiments herein, the reduction of Fe may be thermodynamically favorable over the reduction of Fe 3+ From Fe 2+ The reduction to ZnO and the electrolytic deposition steps are separated into two separate electrolytic cells, which allows for decoupling of the processes and further facilitates impurity removal and other beneficial processes in the system.

[0063]

[0092] Optional features, benefits, and / or embodiments of the systems and methods disclosed herein may include any of the following: (i) any acid may be used to dissolve the ferrous source material, including, but not limited to, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid, oxalic acid, citric acid, boric acid, perboric acid, carbonic acid, methanesulfonic acid, or any mixture or combination of these or other acids; (ii) the ferrous source may include any iron-containing material that may be dissolved in an acid in a system such as those described herein, including scrap steel, scrap cast iron, iron dust, iron powder, iron ore, or other iron-containing ores; i) the iron ore may include any iron oxide, such as, but not limited to, hematite (Fe2O3), maghemite, ferrihydrite, magnetite (Fe3O4), or hydroxide, such as goethite (FeOOH), akaganeite, lepidocrocite, ferrihydrite, limonite, or any combination thereof; (iv) the various electrochemical cells and systems described herein may be operated over a wide range of pH within the acidic range from below 0 to 7; and / or (v) hydrogen oxidation or other reactions may be used to replace water oxidation at the anode of the electrochemical cell.

[0064]

[0093] To make pure iron for bulk steelmaking, it is desirable for the iron-containing feedstock to be a relatively low-cost iron source material. Iron ore exists in a wide range of purities, with common impurities including silicates, kaolinite (a silicate clay mineral), phosphorus, aluminum, sulfur, magnesium, calcium, and other elemental or mineral compounds. Because existing steelmaking processes require relatively high purity iron ore, low purity ore and scrap materials containing large amounts of impurities may be available at lower cost. The various aqueous iron production systems and methods described herein may be used with iron feedstocks of any purity, including high purity iron ore, low purity iron ore, iron or steel scrap, iron dust, or other iron-containing feedstock materials, including many that would otherwise be considered waste due to incompatibility with existing bulk steelmaking processes. For example, "fines" or "tailings" from mining and ore beneficiation processes may also be used as iron feedstock materials in various embodiments of the systems and methods herein.

[0065]

[0094] In some embodiments, iron ore (and other iron feedstocks) can be converted to an aqueous solution by dissolving the feedstock material in acid, a process that is not always easy or fast at low temperatures. Provided herein are several exemplary embodiments for pre-treating some iron feedstock materials to improve the dissolution process and / or subsequent impurity removal. These may advantageously include recycling waste materials produced by other process steps.

[0066]

[0095] Iron can be made at low temperatures (broadly defined as below 120° C., and in some specific embodiments below 80° C. or below 70° C.) via electroplating of solutions containing dissolved iron salts. Without the need to continuously maintain high temperatures, such low temperature processes are much more compatible with the intermittent nature of renewable energy sources.

[0067]

[0096] In various embodiments herein, iron dissolved in aqueous solution can be electrochemically converted to metallic iron in either a single step or multiple steps. Iron is converted to "ferric" Fe in solution. 3+ Ion or "ferrous" Fe 2+ It may exist in the form of an ion. Any dissolved Fe 3+ The ions are converted to iron metal (Fe 0 ), they must first be converted to Fe 2+ In some embodiments, the Fe ion must be reduced to 3+ From Fe 2+ and reduction to Fe 2+ From Fe 0 The reduction of ferric iron, Fe, may be carried out in a single cell. In other embodiments (e.g., as described herein with reference to Figures 2-6), 3+ Ferrous iron (Fe) 2+ The reduction to Fe 2+ Metallic iron (Fe) 0 may be separated from the reduction to

[0068] Single-step iron conversion

[0097] In some embodiments, metallic iron can be made by reducing ferric and / or ferrous iron (from dissolving an iron source in acid) to iron metal via electroplating in the cathode chamber of an electrochemical cell, while oxidizing water to produce oxygen in the anode half-cell chamber.

[0069]

[0098] The iron source material may be converted to an aqueous solution (e.g., as described in various embodiments elsewhere herein) by dissolving the source in an acid. Once in solution, the ferric iron may be converted directly to iron metal using an electrolytic electrochemical cell, where reduction of ferric iron to metallic iron occurs at the cathode and oxidation of water to oxygen occurs at the anode according to the following equation: Anode half-reaction: HO → 2H + +1 / 2O2+2e (formula 1) Cathode half-reaction: Fe 3+ +3e→Fe (Formula 2) Total reaction: 2Fe 3+ +3H2O→6H + +3 / 2O2+2Fe (Formula 3)

[0070]

[0099] FIG. 1A shows a schematic of the conversion by this process. However, dissolution of iron ore oxides in acid is generally not rapid, and in most cases ferric iron (Fe 3+ ) salts. The presence of mainly ferric salts in the dissolved ore solution can result in poor metallic iron plating due to interactions between the ferric iron in solution and the plated iron metal. More seriously, when a proton exchange membrane (PEM) is used as the separator membrane in the electrochemical cell, an acid is generated on the cathode side, which is also the plating side. As a result, the generated acid tends to attack the plated iron, resulting in extremely low Coulombic (or Faradaic) efficiency in the cell.

[0071]

[0100] Additionally, the low pH of the acidic solution may result in a parasitic hydrogen evolution reaction during iron plating. Such hydrogen evolution further reduces the Coulombic (or Faradaic) efficiency of the one-step iron conversion process. However, any hydrogen that is produced may be captured and reused for other purposes as described elsewhere herein.

[0072]

[0101] Alternatively, an anion exchange membrane (AEM) may be used, as shown in Figure 1B. In this case, the acid is generated on the anode side, and although direct attack of the plated iron by the acid is prevented, the acid is mixed with the water side resulting in significant dilution, and the acid cannot be easily recovered for further use in iron ore dissolution. This implies unrecoverable acid and large amounts of acid waste generation.

[0073]

[0102] In an alternative embodiment, instead of oxidizing water at the anode of the electrolysis cell, a stream of hydrogen gas can be directed to the anode chamber and oxidized at the anode. In some embodiments, such "hydrogen-depolarized" anodes can be made of lower cost materials than may be required for some embodiments of oxygen evolving anodes. In various embodiments, the hydrogen in such embodiments can be supplied from a hydrogen storage system or from a hydrogen generation system, such as a water electrolyzer (e.g., a PEM water electrolyzer, an AEM water electrolyzer, or an alkaline water electrolyzer).

[0074]

[0103] The alternative two-step iron conversion process overcomes the above-mentioned drawbacks while introducing new synergistic advantages.

[0075] Two-step iron conversion

[0104] 2, 3, 4, and 6, in some embodiments, the iron conversion system 100 can be divided into two main subsystems: a melting subsystem 102 and a plating subsystem 130. The melting subsystem 102 can generally be configured to efficiently and relatively quickly melt the iron source material 152 at low temperatures to form the molten iron solution 122. The melting subsystem 102 is configured to convert the ferric iron (Fe 2 O 3 ) in the molten iron solution 122 into ferric iron (Fe 3 O 3 ) in an “acid regeneration” cell 104 before the molten iron solution 122 is transferred to a plating cell 132 in the plating subsystem 130. 3+ ) ions to ferrous (Fe 2+ ) ions. The plating subsystem 130 may generally be configured to electrolytically plate the dissolved ferrous ions into a solid form that may be removed at 148 and sold as relatively pure iron, and the plating subsystem 130 is prepared for further plating. Once the dissolved iron solution 122 has been sufficiently depleted of ferrous iron by the plating cell 132, it may be sent back to the dissolving subsystem 102 for use in subsequent dissolving in conjunction with the acid regeneration cell 104.

[0076]

[0105] As described further below, in some embodiments, the dissolved iron solution 122 may be divided into a plating anolyte and a plating catholyte. The plating anolyte may be recirculated between a plating anolyte tank 144 and an anode chamber 138 of a plating cell 132, where species in the plating anolyte are oxidized at an anode electrode 140. The plating catholyte may be recirculated between a plating catholyte tank 142 and a cathode chamber 134 of a plating cell 132, where iron is electroplated onto a cathode electrode 108. Iron may be removed at 148 from the plating cell 132 by various methods, examples of which are described below. In some cases, hydrogen gas may be evolved (146) from the cathode chamber 134 of the plating cell. Such hydrogen gas may be captured and stored for use in other sub-processes described herein.

[0077]

[0106] Decoupling the reduction of ferric iron to ferrous iron from the reduction of ferrous iron to ferrous metal allows for substantial improvements and cost savings in the overall system 100 compared to performing both reduction steps in a single plating cell (e.g., as described with reference to Figures 1A and 1B).

[0078]

[0107] As shown, the acid regeneration cell 104 can be configured to oxidize a depleted reactant provided from a reactant source 116 at the anode 112 while reducing ferric ions (generated during dissolution of the feedstock 120) to ferrous ions in the cathode chamber 106. In some embodiments, the anode reactant can be water, and the anode 112 can generate oxygen 111 from the anode chamber 110. In alternative embodiments, the acid regeneration cell anode 110 can be configured to oxidize a hydrogen gas reactant provided from the reactant source 116, which can be a storage system or a hydrogen generation system, such as a water electrolyzer.

[0079]

[0108] In various embodiments, one or more processing steps 124, 126, 128, 125, 127 may be performed to condition the dissolved iron solution 122 to remove materials or increase or decrease the concentration of one or more components of the solution. For example, the processing step 124 (FIG. 2, FIG. 6) may include directing the dissolved iron solution 122 exiting the dissolving tank 118 through a processing vessel configured to remove solid particles and / or colloidal dispersions of materials released during dissolving. In some cases, silica from the iron source may enter the dissolved iron solution 122 as a gel-like substance in a colloidal dispersion, which may interfere with operation in the acid regeneration cell 104. The processing step 124 may include contacting the solution with a flocculant, such as polyethylene glycol, polyethylene oxide, or other flocculant known to be effective in removing colloidal silica from the solution. The processing step 124 may further include any other solid-liquid separation techniques, devices, or additives as required to remove materials that may be detrimental to operation in the acid regeneration cell 104.

[0080]

[0109] The plating subsystem 130 may include a plating cell 132 having a cathode electrode 136 in a cathode chamber 134 fluidly coupled to a catholyte tank 142 and an anode electrode 140 in an anode chamber 138 fluidly coupled to an anolyte tank 144. In the cathode chamber 134 of the plating cell 132, ferrous ions may be reduced to plated metallic iron, while in the anode chamber 138 of the plating cell 132, ferrous ions are oxidized to ferric ions.

[0081] Dissolution of ferrous materials assisted by acid regeneration:

[0110] Applicants have discovered that dissolution of iron ore (and other ferrous raw materials) can be greatly accelerated by the use of an acid regeneration cell coupled to a dissolving tank 118. As shown in FIG. 2, the acid regeneration cell 104 can be configured to recirculate an acid dissolving solution 122 between the cathode chamber 106 of the acid regeneration cell 104 and one or more dissolving tanks 118. A source 116 of a consumed reactant 117 oxidizable to protons (e.g., water, hydrogen gas, or another gaseous or aqueous substance that can be oxidized to form protons) can be fluidly coupled to the anode chamber of the acid regeneration cell 104.

[0082]

[0111] Dissolution of the iron source material 120 coupled with the acid regeneration cell 104 involves dissolution of the iron source material in an aqueous acid solution, where the acid is electrochemically regenerated by the electrolytic acid regeneration cell 104. An example is described below with reference to FIG. 2 for a hydrochloric acid (HCl) solution, but the process is not limited to hydrochloric acid and may be carried out in substantially the same manner with any acid, including sulfuric acid, nitric acid, citric acid, acetic acid, boric acid, methanesulfonic acid, oxalic acid, or other acids. Similarly, although hematite (Fe2O3) is shown as an example of an iron ore source material, the process applies to all other iron source materials, including goethite, magnetite (Fe3O4), siderite (FeCO3), and other ores, as well as any other iron source material.

[0083]

[0112] In some embodiments, the ferrous feedstock 120 may be milled or crushed to form particles within a desired range before being introduced into the melting tank 122. In other embodiments, the feedstock 122 may be pre-treated by air roasting and / or thermal reduction (as described herein with reference to Figures 9 and 10) before being introduced into the melting tank 118.

[0084]

[0113] When hematite is dissolved in a hydrochloric acid solution, the following reaction occurs: Fe2O3+6HCl→2Fe 3+ +6Cl - +3H2O (formula 4)

[0085]

[0114] Hematite becomes ferric chloride when dissolved in hydrochloric acid solution. Dissolution of iron oxide is generally not a rapid reaction, and experiments have shown that increasing the concentration of ferric chloride (FeCl3), a product of hematite dissolution, tends to slow the rate of dissolution. On the other hand, increasing the acid concentration tends to support more rapid dissolution. Experiments have also shown that ferrous metals (FeCl3), such as ferrous chloride (the reduced form of ferric chloride), tend to dissolve the hematite more quickly. 2+ It has been shown that the addition of .) salts tends to increase the dissolution rate as well. Indeed, the combination of these effects can result in substantially complete dissolution of the hematite or goethite ore within an acceptable time frame of less than about 24-30 hours.

[0086]

[0115] In one embodiment, the feedstock dissolution process may be coupled with an electrochemical process as shown in Figure 2. The dissolution tank 118 may be partially filled with a solid iron feedstock 120 (e.g., hematite and / or goethite in this example) and an acid solution 122 (hydrochloric acid in this example). The hematite and / or goethite feedstock is partially dissolved by the acid to produce a ferric chloride solution (i.e., Fe in solution). 3+ and Cl - ions) and produce water while consuming acid in the process. If other types of iron ore are used, such as magnetite (Fe3O4) or siderite (FeCO3), the formation of ferrous chloride in addition to ferric iron can also occur.

[0087]

[0116] Ferrous and ferric chloride solutions 123 (Fe in Fig. 2) 2+ +Fe 3+ ) may be fed from a dissolution tank 118 to the cathode chamber 106 of the acid regeneration cell 104 (which may be a stack of multiple cells). The acid regeneration cell 104 includes a cathode 108, an anode 112, and a separator membrane 114. The separator membrane 114 may be of any available type, including a proton exchange membrane (PEM) (or cation exchange membrane), an anion exchange membrane (AEM), a polymeric or ceramic microporous separator, or other porous separator, an ionomer, or a combination thereof.

[0088]

[0117] In some embodiments, the acid regeneration cell separator 114 is advantageously a PEM membrane or a microporous separator or a combination thereof to provide regeneration of acid (protons) in the catholyte by crossing protons generated at the anode 112 to the cathode chamber 106. Water from a reservoir 116 may be fed into the anode chamber 110 of the acid regeneration cell 104. When a current is applied to the cell 104, water is oxidized to produce oxygen gas and protons according to half reaction (5). Anode half-reaction: HO → 2H + +1 / 2O2+2e (formula 5)

[0089]

[0118] When a proton exchange membrane (PEM) or a microporous separator is used as the separator membrane between the anode and cathode, protons generated by water electrolysis (according to equation (5)) migrate from the anode chamber 110 to the cathode chamber 106.

[0090]

[0119] At the cathode 108, reduction of ferric iron to ferrous iron occurs according to the following: Fe 3+ +e →Fe 2+ (Formula 6)

[0091]

[0120] It should be noted that the reaction can be controlled to stop at ferrous iron production without going all the way to iron metal deposition in the acid regeneration cell 104, or even simply to hydrogen production. Iron deposition occurs when the Fe metal is introduced into the acid regeneration cell 104 at the current density being operated. 3+ It may be caused by an insufficient supply of ions, i.e., Fe 3+ Fe ions from freshly dissolved raw materials 3+ ions at a rate faster than they can be replaced by Fe ions (e.g., at too low a flow rate or too high a current for a given flow rate). 2+ If iron is electrochemically reduced to ferric iron, the next most likely reaction would be reduction of water to form hydrogen gas, followed by iron deposition. This, if it occurs, would be detectable as a dramatic increase in cell voltage of at least 0.77 V above steady-state ferric iron reduction. Thus, if a cell voltage significantly higher (e.g., 0.77 V or greater) than the ferric to ferrous iron conversion potential is detected, hydrogen production and / or iron deposition may be stopped or even prevented by increasing the flow rate of the ferric solution and / or by decreasing the current density applied to the acid regeneration cell 104. In some embodiments, the acid regeneration cell current density may be increased or decreased in response to an increase or decrease in available power from an intermittent or renewable energy source being detected or communicated.

[0092]

[0121] On the other hand, any precipitated iron will be converted to new ferric iron (Fe 3+ ), some amount of iron deposition in the acid regeneration cell 104 is not necessarily a problem. Thus, in some embodiments, in response to detecting iron deposition in the acid regeneration cell 104, the catholyte flow rate may be increased and / or the current applied to the acid regeneration cell 104 may be increased until the voltage returns to the "normal" range due to the increased concentration of ferric ions.

[0093]

[0122] The same result can occur if a ferric solution is converted to a ferrous solution (i.e., less available Fe 3+may become too low for the applied current). Thus, in some embodiments, it may be beneficial to operate the acid regeneration cell according to a so-called CC-CV protocol, where the acid regeneration cell is operated under constant current (CC) and the voltage is varied until a threshold voltage is reached, which indicates the onset of iron deposition (or the mixed-potential average voltage between ferric to ferrous conversion and iron plating). Once the threshold cell (or half-cell) voltage is reached, the acid regeneration cell 104 is operated under a constant voltage below the threshold voltage, allowing the current to decrease and asymptotically approach zero. The constant voltage is adjusted to a target current or current density (e.g., about 0.1 mA / cm2). 2 ~about 10mA / cm 2 , optionally about 0.1mA / cm 2 ~about 0.5mA / cm 2 ) or until "sufficient" Fe 3+ Fe 2+ The target current and / or the period of time necessary to reach "sufficient" may be determined empirically and based on economic factors.

[0094]

[0123] Protons coming from the anode 112 of the acid regeneration cell 104 form acid with the anions made available from ferric salt reduction (e.g., hydrochloric acid can form with chloride ions made available from ferric chloride reduction). Thus, the solution 125 leaving the cathode chamber 106 of the acid regeneration cell 104 is rich in ferrous salts and acid (e.g., ferrous chloride and hydrochloric acid). Since iron metal formation is generally prevented in this step, there is no efficiency loss due to acid attack of the metal. The solution 125 is then sent back to the dissolution tank where the newly generated acid is used to dissolve more iron feedstock 120 and convert it to ferric salts (e.g., ferric chloride) and the process continues. The acid is thereby regenerated for further iron ore dissolution.

[0095]

[0124] On the anode 112 side of the acid regeneration cell 104, the solution 117r exiting the anode chamber 110 may be fed through a gas-liquid separation device (not shown in FIG. 2) to remove oxygen from the solution before sending the remaining water back to the water reservoir and then back to the anode chamber of the acid regeneration cell 104. Alternatively, or additionally, gas separation may take place directly in the water reservoir 116.

[0096]

[0125] One function of the electrochemical acid regeneration cell 104 is to reduce ferric iron to ferrous iron, thereby converting the dissolution products to different products of reduced oxidation states. This removal of ferric ions avoids the accumulation of dissolution products and has been found to substantially improve the dissolution rate of the iron ore to a greater extent than would be expected. In addition, the process converts ferric iron, the accumulation of which may inhibit further dissolution, to ferrous iron, a compound that has been found to have a beneficial effect on iron oxide dissolution. During the dissolution process with continuous liquid recirculation, the acid regeneration cell 104 increases the ferrous iron concentration while keeping the ferric iron concentration relatively low, thereby providing a dual benefit to the dissolution of iron feedstocks containing substantial amounts of iron oxide.

[0097]

[0126] A second function of the acid regeneration cell 104 is to regenerate the acid consumed by the dissolution of the ferrous raw material. Without the acid regeneration cell 104, the acid concentration would gradually decrease as the dissolution proceeds and acid is consumed in the dissolution reaction. When a PEM is used as the separator membrane in the acid regeneration cell 104, the acid is regenerated and mixed with the ferrous rich solution in the cathode chamber 106 and returned to the dissolution tank 118, both of which have a positive benefit to the dissolution of the ferrous raw material 120.

[0098]

[0127] In some embodiments, the dissolution tank 118 may be maintained at a temperature above ambient temperature, as higher temperatures aid in dissolution. Typical temperature ranges may be 20-120° C., preferably 40-100° C. in some embodiments, and more particularly about 50° C. to about 90° C. In various embodiments, the acid regeneration cell 104 may be operated at a temperature of about 40° C. to 80° C., preferably about 60° C.+ / -10° C. The current density applied to the acid regeneration cell 104 is about 0.1 A / cm 2 ~About 2A / cm 2 may be also possible.

[0099]

[0128] In some embodiments, the final dissolved iron concentration target may typically be between 0.1 M and 4 M, and preferably in some embodiments between 0.5 and 2 M. In general, the iron concentration should be kept below its solubility limit in the solution used so as to avoid undesirable precipitation.

[0100]

[0129] The flow rate of catholyte through the cathode chamber 106 of the acid regeneration cell 104 can be controlled (as described herein above) to provide at least a stoichiometric ratio of ferric ions to electrons for a given applied current across the acid regeneration cell 104. Similarly, the flow of water (or other reactant) in the anode chamber 110 is preferably maintained to exceed the stoichiometric requirements of water splitting (or other reactant-consuming reactions) at the current applied to the acid regeneration cell 104. In various embodiments, the current applied to the acid regeneration cell 104 is about 0.1 mA / cm 2 ~Approx. 2,000mA / cm 2 in the range of about 0.5 mA / cm2 to about 1,000 mA / cm2 in some more specific embodiments. 2 or may vary within that range depending on the available ferric iron concentration and / or the availability of electricity. As will be apparent based on this disclosure and the accompanying drawings, the acid regeneration cell 104 may be operated at a different current density than the plating cell 132.

[0101]

[0130] In some embodiments, the cathode 108 of the acid regenerated cell 104 may be any carbon or graphite based electrode, such as carbon or graphite felt, paper or cloth, or any electrode material stable in a ferric / ferrous salt environment. The anode 112 of the acid regenerated cell 104 may be any typical electrode available in the art of water electrolysis, including, but not limited to, precious metal electrodes (e.g., mixed metal oxides including metals such as Ir, Ru, Pt, Rh, Pd, and oxides or other compounds), dimensionally stable anodes (DSA), lead and lead dioxide electrodes, other oxide-based electrodes, and the like. The metals or mixed metal oxides may be supported or unsupported on a catalyst support, including titanium particles, and the like. In some embodiments described herein, the anode 112 of the acid regenerated cell 104 may be a hydrogen depolarized anode configured to oxidize hydrogen gas, and thus may include any suitable hydrogen oxidation catalyst similar to those conventionally used in PEM-based hydrogen fuel cells, including platinum on carbon or any other hydrogen oxidation catalyst. The acid regeneration cell 104 can operate over a wide temperature range, from 20 to 100°C, and preferably from 40 to 80°C in some embodiments.

[0102]

[0131] The aqueous solution provided to the anode chamber 110 of the acid regeneration cell 104 may be pure water or may contain salts to increase the osmotic pressure relative to the catholyte as described further below. For example, in the case of sulfate chemistry, the salts may include any soluble sulfate salt, such as ferric sulfate, sodium sulfate, potassium sulfate, ammonium sulfate, etc. Such supporting salts may be particularly beneficial in the plating cell to maintain the conductivity of the electrolyte, since the ferrous iron is pulled out of solution by the plating reaction. This water may come from an external source, or may be withdrawn from the system as dissolution of iron ore produces water, or may be a combination of both external and internally withdrawn water.

[0103]

[0132] As described herein, water is generated by dissolution of ore (which in some cases may itself contain water). As a result, as more ore dissolves, the water content continues to increase in the acid regenerated cell catholyte (i.e., the iron-rich acid solution that is ultimately transferred to the plating cell), resulting in further dilution of the solution. At the same time, water is being decomposed (and thereby consumed) in the anolyte of the acid regenerated cell 104. Thus, it may be desirable to extract water from the catholyte of the acid regenerated cell 104 and add the extracted water to the source of water that feeds the anolyte. In some embodiments, this may be accomplished by osmosis. Thus, in some embodiments, the anolyte 117 of the acid regenerated cell 104 may be provided with a salt concentration that exceeds the maximum salt concentration in the acid regenerated catholyte 123 to create an osmotic pressure for water to cross from the catholyte to the anolyte. In alternative embodiments, water may be extracted from the acid regenerated cell catholyte by more active methods, such as flash distillation, membrane distillation, reverse osmosis, or other methods. The separated water may be filtered or otherwise purified if necessary and then added to the acid regenerated cell anolyte at any convenient point.

[0104]

[0133] In some embodiments, the acid solution may be continuously circulated between the cathode chamber of the acid regeneration cell 104 and the dissolution tank 118. With each cycle through the dissolution tank 118, a portion of the acid is consumed by the dissolution reaction (e.g., equation 4 above), and with each cycle through the acid regeneration cell 104, a portion of the acid is simultaneously regenerated with a portion of the ferric iron being reduced. Thus, by continuously recirculating the acid catholyte between the acid regeneration cell 104 and the dissolution tank 118, a steady state concentration of acid (e.g., as measured by proton concentration or pH) may be maintained in the catholyte throughout most of the dissolution process. For example, in some embodiments, a concentration of protons in the catholyte of at least 0.2 M may be maintained during steady state operation of dissolution combined with acid regeneration. In some embodiments, during normal operation, the initial state, defined as the start of a new cycle, corresponds to a mostly ferric iron solution being returned from the plating subsystem having a low acid content. In some embodiments, the initial acid concentration (after electrolyte return from the acid regeneration subsystem and before restarting the acid regenerator) is typically at the lowest point in the cycle, generally less than 0.2 M (moles per liter). Reduction of the returned ferric iron in the acid regeneration cell can form acid.

[0105]

[0134] As shown in FIG. 6, the "dissolving tank" 118 may comprise a number of separate tanks 118 that may be used sequentially or otherwise to further decouple the dissolving subsystem process and apparatus 102 from the plating process and apparatus 130, providing additional benefits with respect to managing the different reaction rates of the two steps. For example, in some embodiments, the acid solution may be recirculated between the acid regeneration cell 104 and the first dissolving tank 118 until a desired dissolution stopping point is reached, at which point a valve or other flow control device may be operated to stop the flow between the acid regeneration cell 104 and the first dissolving tank 118 and to couple the acid regeneration cell 104 with the second dissolving tank 118. Alternatively, or additionally, in some embodiments, the acid solution (acid regenerated catholyte) may remain in the dissolving tank 118 for a period of time before flow is resumed with the acid regeneration cell 104. In these and other embodiments, a single acid regeneration cell 104 may be coupled to multiple different dissolving tanks 118 at different times.

[0106]

[0135] In some embodiments, Fe 3+ From Fe 2+The (ferric to ferrous) conversion may typically be driven as far as possible to asymptotically approach a solution of 0% ferric and 100% ferrous. In practice, some ferric ions may remain in solution even when the dissolution process is considered "complete", and the acidic pH may remain lower than the natural pH of a pure ferrous solution. If the solution pH remains too low (i.e., lower than the natural pH of a pure ferrous solution) during the iron plating process, a parasitic hydrogen evolution reaction may occur until excess protons are evolved. In some embodiments, some acid remaining near the end of the dissolution process may be consumed by contacting the acid solution with a quantity of a highly soluble ore material (e.g., magnetite), as described herein with reference to FIG. 10. Alternatively, any residual acid or ferric iron present at the end of dissolution may be consumed in an "auxiliary iron" process (which may also result in hydrogen evolution), as described herein below. Any hydrogen evolved by such reactions may also be captured and reused for other purposes, as described elsewhere herein.

[0107]

[0136] In various embodiments, the acid solution in the catholyte 122 of the acid regeneration cell 104 can have a variable acid concentration ranging from 0.01 M to 6 M. As dissolution proceeds, acid is consumed. The acid regeneration cell 104 advantageously recovers one mole of protons for each mole of ferric iron reduced. Nevertheless, each mole of ferric iron dissolved from the feedstock consumes three moles of protons, and thus further dissolution of the feedstock further reduces the total proton concentration in the catholyte.

[0108]

[0137] Thus, in some embodiments, the dissolution process may be stopped once the acid concentration (e.g., as measured by pH or other measurement of proton concentration) reaches a predetermined low point. For example, in some embodiments, the dissolution process may be stopped when the proton concentration in the acid regenerated catholyte drops to or below a low point of 0.4M, 0.3M, 0.2M, 0.1M (corresponding to a pH of 0.4, 0.52, 0.7, and 1, respectively).

[0109]

[0138] Alternatively, or in addition, the dissolution process may reduce the total iron concentration (i.e., Fe 2+ and Fe 3+ The dissolution process may be stopped when the total iron concentration (sum of iron concentrations) reaches a desired maximum. In various embodiments, the desired maximum iron concentration may be from about 1 M to about 4 M. The total iron concentration may be measured by coulometric titration techniques, by optical methods such as UV-visible spectroscopy, red / green / blue (RGB) analysis, or other optical or spectroscopic techniques. In some particular embodiments, the dissolution process may be stopped when the desired iron concentration reaches a maximum of 1 M, 1.5 M, 2 M, 2.5 M, 3 M, 3.5 M, 4 M or more, e.g., depending on the acid chemistry.

[0110]

[0139] In some embodiments, once the end of dissolution condition has been identified, the ferrous-rich acid solution may be transferred from the acid regeneration cell 104 to a subsequent process step. In some embodiments, the next step may be an "auxiliary iron" treatment as described below. In other embodiments, the ferrous-rich solution may be transferred directly to a plating subsystem.

[0111]

[0140] In other embodiments, once an end of dissolution condition is identified, the current to the acid regeneration cell may be stopped to stop acid regeneration, and the iron-rich acid catholyte may be contacted with a thermally reduced ore, such as magnetite, to consume a portion of the remaining acid. In some embodiments, magnetite may be added to the dissolution tank after (or immediately before, or at about the same time as) the current to the acid regeneration cell is stopped. In other embodiments, the catholyte may be transferred to a separate tank containing substantially only magnetite ore. Because magnetite dissolves very quickly compared to other ore types (as described herein), contacting the catholyte with magnetite at the end of dissolution tends to consume a portion of the remaining acid (protons), thereby reducing the amount of acid removed or consumed in subsequent steps (e.g., in the plating cell, polishing cell, or "auxiliary iron" processing described herein). In various embodiments, other processes involving sequential dissolution of differently processed ores are possible, some embodiments of which are described herein below with reference to Figures 5A and 5B.

[0112]

[0141] In other embodiments, once an end of dissolution condition is identified, the current to the acid regeneration cell 104 may be terminated to stop acid regeneration, and the iron-rich acid catholyte may be contacted with reduced ore, such as magnetite, to consume a portion of the remaining acid. In some embodiments, magnetite may be added to the dissolution tank 118 after (or immediately before, or at about the same time as) the current to the acid regeneration cell 104 is terminated. In other embodiments, the catholyte may be transferred to a separate tank containing substantially only magnetite ore (as further described below with reference to FIG. 10 ). Because magnetite dissolves very quickly compared to other ore types (as described herein), contacting the catholyte with magnetite at the end of dissolution tends to consume a portion of the remaining acid (protons), thereby reducing the amount of acid removed or consumed in subsequent steps (e.g., in the plating cell, polishing cell, or “auxiliary iron” processes described herein). In various embodiments, other processes involving sequential smelting of differently processed ores are possible, some embodiments of which are described herein below with reference to FIG.

[0113]

[0142] In some embodiments, an optional solid-liquid separation step 124 may be performed after each cycle through the dissolving tank, as described elsewhere herein. In some cases, dissolving the iron source may cause a certain amount of silica (or other undissolved material) to enter the liquid as particles or colloidal dispersions. Thus, in some embodiments, it may be desirable to separate the solid material(s) from the solution before returning the solution to the acid regeneration cell 104. In some embodiments, solids may be removed at this stage by any suitable solid-liquid separation device or technique, including filtration, gravity settling, hydrocyclones, flocculation, high or low shear cross-flow separation, or any combination of these or others. In some embodiments, colloidal materials such as silica may be removed by flocculation with flocculants such as polyethylene glycol, polyethylene oxide, or similar materials. In some embodiments, additional processing steps 126 (FIG. 4), such as supplemental iron processing, solid-liquid separation, or other processing processes, may be performed on all of the liquid exiting the dissolving subsystem 102. In some embodiments, insoluble materials, such as, for example, quartz, may be separated by filtration or other solid-liquid separation. In some embodiments, insoluble but finely divided suspensions, such as, for example, colloidal silica, may be removed in a separate step, such as flocculation, optionally with filtration, sedimentation, and / or other physical separation means.

[0114]

[0143] In various embodiments, the acid regeneration cell 104 may be configured as a single cell or as a cell stack in which multiple electrochemical acid regeneration cells are combined into a common unit 104 in an electrically series connected bipolar configuration, or in an electrically parallel connected monopolar configuration, or combinations thereof. The acid regeneration cell stack may be configured in any manner common in electrochemical cell stacks, including a filter press configuration (e.g., compressed by hydraulic pistons or by tie rods or other compression devices) or other configurations. In various embodiments, additional components typical of an electrochemical stack may include current collectors, bipolar plates, flow paths, end plates, etc.

[0115]

[0144] In various embodiments, additional components or equipment, such as, for example, filtration systems, pumps, and heat exchangers, may be included to provide other operations, including fluid transfer from the dissolving tank to the acid regeneration cell 104 and to / from other subsystems, and to allow for temperature control. In some embodiments, the raw ore, roasted ore, and / or reduced ore may be fed into the same dissolving tank, for example, in a selected order, to selectively vary the conditions of the feedstock. In some embodiments, instead of using multiple tanks, the raw ore, roasted ore, and / or reduced ore may be fed into the same dissolving tank, for example, in a selected order, to selectively vary the conditions of the feedstock.

[0116] Supplemental iron treatment

[0145] In some embodiments, all or a portion of the iron-rich acid solution at the completion of the dissolution process may be directed to a reaction vessel where a "auxiliary iron treatment" process may take place. Depending on the state of the iron-rich acid solution at the end of dissolution and the desired state of the solution delivered to the plating subsystem, one or more of three possible reactions may occur: acid consumption, ferric iron reduction, and / or impurity precipitation.

[0117]

[0146] Metallic iron used to react with or otherwise modify the composition of the iron-rich acid solution is referred to herein as "auxiliary iron" and may include any material that contains metallic iron in particles of a size small enough to facilitate the desired reaction with the solution. The auxiliary iron material may include, but is not limited to, scrap steel, scrap iron, iron dust (e.g., fine-particle iron-containing dust from other industrial processes), pig iron, electrolytic iron, or recycled iron from any of the iron conversion processes described herein, or combinations of these or other metallic iron-containing materials. The auxiliary iron material may be of any particle size, although smaller particles may generally allow for faster reaction rates. However, even relatively large particles (e.g., particles larger than 2 cm) may be used as "auxiliary iron" in some embodiments.

[0118]

[0147] When an iron-rich acid solution is contacted with metallic iron, any remaining acid reacts with the metallic iron to convert it to ferrous iron (Fe 2+ ) ions while releasing hydrogen gas. Fe+2H + →Fe 2+ +H2 (formula 7)

[0119]

[0148] Thus, in some embodiments, the supplemental iron reaction vessel (e.g., a tank or other vessel in which a solution may be contacted with the supplemental iron) may be configured as a closed vessel in which the evolved hydrogen gas may be collected and directed to another process or subsystem described elsewhere herein.

[0120]

[0149] In some embodiments, any residual Fe present in the iron-rich acid solution upon completion of the dissolution process may be 3+ The ion is Fe 3+ ions to dissolved iron metal which reacts with ferric ions, converting both to ferrous ions, resulting in the formation of Fe 2+ For example, Fe 3+ is produced by flowing a mostly ferrous solution over or through a quantity of metallic iron particles ("auxiliary iron"). 2+ This can be reduced to metallic iron and Fe in solution according to the following equation: 3+ Part of the Fe 2+ has the effect of converting Fe 3+ +Fe → 2Fe 2+ (Formula 8)

[0121]

[0150] Advantageously, these two reactions (acid consumption and ferric iron reduction) occur at the same rate as Fe 3+ and reducing the occurrence of parasitic hydrogen evolution reactions during iron plating, thereby increasing the efficiency of iron plating in the plating subsystem.

[0122]

[0151] In some embodiments, the excess acid and ferric ions are combined to form the remaining Fe 3+Fe 2+ and consumed in a separate electrochemical cell ("polishing cell") configured to increase the pH of the catholyte by consuming acid. Such a cell may allow for decoupling of impurity removal from processes that consume excess acid and ferric iron. In some embodiments, the polishing cell may be configured substantially similarly to the plating cell, but need not provide for removal of metallic iron. In some embodiments, the polishing cell may be configured to provide H generation without any electroplating and without the use of a noble metal electrode, such as Pt, at the cell cathode.

[0123] Removal of impurities

[0152] Some impurities, including kaolinite and other silicate minerals, are generally insoluble in the acid solution produced in the acid regeneration cell. Thus, when ores or other raw materials containing such insoluble impurities are ground into small particles and placed in a dissolving tank connected to the acid regeneration cell 104, the insoluble impurities may be filtered from the solution, collected at the bottom of the tank and removed from the tank as solids, or removed by any other suitable solid-liquid separation technique or device. In various embodiments, the collected solid impurities may be treated and discarded, or may be used in other processes in which the "impurities" may be a raw material.

[0124]

[0153] Some solid impurities, including some forms of amorphous silica, may tend to form colloidal dispersions in acid solutions. Such materials may be separated from the solution by flocculation with flocculants such as polyethylene glycol or polyethylene oxide. Some silica may nevertheless remain dissolved.

[0125]

[0154] Some impurities may form compounds of relatively low solubility with iron or other materials in solution. The term "solubility" refers to the thermodynamic solubility limit of a compound for a given solution, which is the concentration limit beyond which the compound begins to precipitate from solution as a solid.

[0126]

[0155] Highly soluble impurities include aluminum, silicon, titanium and phosphorus, among others. Aluminum compounds dissolve and form Al 3+ cations, phosphorus typically dissolves to form phosphate PO4 3- These impurities can present a variety of problems for downstream processes such as pumping, filtration, acid regeneration, iron plating, etc. Aluminum impurities can be present in iron ore in amounts up to about 10 percent by weight of the raw ore. Phosphorus tends to be present in much smaller amounts (e.g., typically less than 1%, but can be more), but even small amounts of phosphorus must be removed prior to the steelmaking process and are therefore undesirable in the plated iron produced by the plating cell. In particular, aluminum and phosphorus impurities have been found to interfere with the iron electroplating process.

[0127]

[0156] As shown in FIG. 8A, the solubility of aluminum hydroxide decreases significantly as the pH increases above 3 (e.g., a six order of magnitude drop in solubility between pH 3 and 5). Although not shown, iron(II) hydroxide (Fe(OH)2, or "ferrous" hydroxide) has a higher solubility within this pH range. This suggests that aluminum hydroxide (Al(OH)3) may be precipitated without substantial precipitation of iron ions by increasing the pH from above 3 to about 5 (e.g., from a pH of about 1 or 2 at the end of dissolution). Similarly, iron or aluminum phosphates may also be precipitated without necessarily precipitating substantial amounts of iron for similar reasons. In some cases, colloidal silica may also be removed by increasing the solution pH (e.g., by flocculation along with the precipitation of other species). Titanium hydroxide, if present, also precipitates within a similar pH range, and may also be separated and removed from the solution.

[0128]

[0157] Generally, it is desirable to increase the pH of the dissolved ore solution without adding new elements to the solution (as any such new elements may further affect and / or complicate other processes). Thus, in some embodiments, metallic "auxiliary iron" may be used to raise the solution pH sufficiently to precipitate these impurities.

[0129]

[0158] Iron is not necessarily consumed in removing phosphorus, since increasing the pH through additional consumption of supplemental iron (i.e., by reacting with acid to form hydrogen gas) tends to cause phosphorus to precipitate primarily as aluminum phosphate salts. Al 3+ (aq) +PO4 3- (aq) (When pH=1) → AlPO 4(s) (When pH=3) (Equation 9)

[0130]

[0159] In the case of metal cations such as aluminum, iron displaces the cation in solution and precipitates the metal as a hydroxide. In systems designed to produce substantially pure iron, the amount of impurity may be expressed in terms of the molar ratio of impurity to iron. For example, according to Equation 10, 1.5 moles of supplemental iron should be used for each mole of aluminum removed (using sulfuric acid as a non-limiting example). Al2(SO4) 3(aq) +3Fe+6H2O→2Al(OH) 3(s) +3FeSO 4(aq) +3H2 (Equation 10)

[0131]

[0160] This reaction consumes water and produces hydrogen gas. The protons removed were acidic due to hydrolysis from the cation (Equation 11 below). In some cases, at least a portion of the hydrogen gas generated may be collected and used in another process within the system as described herein. Al 3+ +H2O→AlOH 2+ +H + (Formula 11)

[0132]

[0161] In some cases, it may be beneficial to remove impurities by adding iron to only a portion of the iron-rich acid solution used for iron electroplating (i.e., the portion of the solution used as the plating catholyte). Thus, when an acid regenerator is used and the electrolyte is split into two portions for the electroplating step, only the portion designated as the plating cell catholyte (e.g., about 1 / 3 of the electrolyte exiting the acid regenerator) may be treated with the addition of auxiliary iron metal.

[0133]

[0162] When metallic iron dissolves in solution, it also dissolves any soluble ferric iron (Fe 3+ ) to ferrous iron (Fe 2+ For example, (for example, in the case of sulfuric acid) 0.5 moles of metallic iron are consumed for each mole of ferric sulfate that is converted to ferrous sulfate according to Equation 12. Fe2(SO4)3+Fe→3FeSO4 (Eq. 12)

[0134]

[0163] The dissolved metallic iron may also consume residual acid in the treated electrolyte in a 1:1 molar ratio according to Equation 13. H2SO4+Fe→FeSO4+H2 (Formula 13)

[0135]

[0164] Thus, the amount of supplemental iron added to a quantity of electrolyte may be determined based on the measured, estimated or predicted amounts of impurities (e.g., especially aluminum and / or phosphorus), residual ferric iron, and residual acid. It may be beneficial to expose the electrolyte to excess supplemental iron (i.e., more metallic iron than is necessary to achieve the reactions of Eqs. 10, 11, 12, and 13, so that some metallic iron remains after those reactions have proceeded as far as possible). If necessary, the supplemental iron may be separated from the precipitated impurities by any of a variety of separation methods, including flotation, filtration, and magnetic separation. Similarly, precipitated impurities may be removed from the solution by any suitable solid-liquid separation device or technique. In some embodiments, the treated solution may be pumped out of the tank where the impurity removal (and / or supplemental iron) treatment takes place, and the iron metal and precipitated impurities may be left in the tank for the next treatment cycle.

[0136]

[0165] Even in the absence of aluminum, phosphorus can be efficiently removed by precipitation of iron phosphate, as suggested by the solubility diagrams in Figures 8B and 8C, which show the solubility of various iron phosphate and oxide compounds. At the beginning of the treatment stage, there is always a residual ferric concentration. As seen in Figure 8C, ferric phosphate has very low solubility, and therefore, as soon as the pH increases due to the reaction in Equation 7, iron phosphate precipitates out of solution.

[0137]

[0166] Various other methods of controlling or removing impurities may be used depending on the type of impurity. For example, insoluble impurities may simply be removed as solids by filtration, gravity, centrifugation, or other mechanical separation. Soluble impurities that may interfere with iron plating may be removed by forming compounds with other materials such as iron (including those in "auxiliary iron" processes), aluminum, etc., or may simply be precipitated with the iron if the concentration of such impurities in the final plating material is acceptable (which may depend on the particular product or end use of the iron material produced).

[0138]

[0167] Soluble impurities that are harmless to plating may simply be left in solution. Eventually, the concentration of such impurities may build up to a point where they can be removed by extracting the water. Alternatively, the concentration of rare impurities may build up enough to eventually be removed (e.g., over sufficient dissolution and plating cycles) by precipitation due to a pH shift, or by other methods. In yet other embodiments, when such impurities have built up to sufficient levels, the electrolyte solution may simply be replaced.

[0139] Iron Plating Subsystem

[0168] In some embodiments, the one-step iron conversion process described above with reference to Figures 1A and 1B may be configured for use in converting ferrous iron produced in the acid regeneration cell 104 to metallic iron in a second electrochemical cell configured differently from the plating cell 132 described above. In such embodiments, the ferrous iron solution from the acid regeneration cell 104 may be used to oxidize water at the anode of an electrochemical plating cell (not shown) while plating Fe metal at the cathode of the same plating cell. Here, an anion exchange membrane may be used such that acid is produced on the anode side (i.e., the oxidizing side of the water, thereby minimizing acid reaction with the plated iron). However, such embodiments have the disadvantage that the water splitting electrodes may be relatively expensive and therefore may be most economically operated at high current densities, while the iron plating reaction proceeds relatively slowly and may not be driven effectively at high current densities.

[0140]

[0169] In some embodiments, a lead oxide electrode may be used as a relatively low-cost oxygen evolution anode in the plating cell, which may make operation at lower current densities more economically practical. In an alternative embodiment, the plating cell anode may be a hydrogen oxidation anode configured to oxidize hydrogen gas supplied from a source such as a hydrogen storage device or directly from a water electrolyzer (e.g., a PEM, AEM, or alkaline water electrolyzer). Another approach to lowering the cost of the plating cell is to couple the iron deposition (ferrous reduction) reaction with a different oxidation reaction, such as the oxidation of a portion of the ferrous solution from the dissolution subsystem.

[0141]

[0170] With reference to FIG. 6 (but also to other figures), some embodiments of the iron conversion system 100 may include a plating subsystem 130 configured to produce iron metal from the aqueous iron solution produced in the dissolving subsystem. As described above, the dissolving process in the dissolving subsystem 102 may be operated until the iron concentration in the solution reaches a desired value. At that point (or after subsequent processing, such as "auxiliary iron" processing), the solution is preferably a predominantly ferrous solution. In some embodiments, the solution may then be split into two separate streams representing the catholyte and anolyte for use in the plating cell 132.

[0142]

[0171] The solution exiting the dissolving subsystem 102 may be transported to the plating subsystem 130 via transport system 164. Transport system 164 is shown as a simple conduit, but may include any number of flow control or process control devices as desired. Similarly, at the end of the plating process, a portion of the spent electrolyte solution(s) may be transported from the plating subsystem 130 to the dissolving subsystem 102 in transport 166, which may also include any number of flow control or process control devices as desired.

[0143]

[0172] In some embodiments, the solution entering the plating subsystem 130 may be split into catholyte and anolyte streams in a ratio of approximately one-third and two-thirds of the original volume of the liquid entering the plating subsystem 130. One-third of the volume may be directed and stored in one or more catholyte storage tanks 142, and two-thirds of the volume may be directed and stored in one or more separate anolyte storage tanks 144. For ease of explanation, it is assumed herein that there is one catholyte storage tank and one anolyte storage tank. In various embodiments, the two tanks 142, 144 may have different volumes or may have the same volume, and the volumes may be used at different volumetric ratios. The catholyte 142 and anolyte 144 tanks may be fluidly connected to the cathode chamber 134 and anode chamber 138 of the electrochemical plating cell 132, respectively.

[0144]

[0173] The plating cell 132 may include a cathode chamber 134 having a cathode electrode 136, an anode chamber 138 having a membrane 150 and an anode electrode 140. The two electrodes 136, 140 are separated by the membrane 150, which may be a PEM, AEM, or a microporous separator. Additional components typical of an electrochemical cell or stack may include current collectors, bipolar plates, flow paths, end plates, etc., depending on the plating cell configuration selected. Exemplary plating cell configurations are described elsewhere herein, but any plating cell configuration may be used.

[0145]

[0174] As shown in FIG. 4, the plating 132 cell plates metallic iron at the cathode electrode 136 while the Fe 2+ Some of the ions are Fe 3+ ions. In this configuration, the cost of an oxygen evolving anode is avoided by using very low cost carbon or graphite anode materials.

[0146]

[0175] When a current is applied across the plating cell, iron metal is electroplated onto the cathode by reducing ferrous iron according to the following: Fe 2+ +2e→Fe (Formula 14)

[0147]

[0176] Simultaneously, the anolyte stream of ferrous solution may be oxidized to ferric iron on the anode of the plating cell according to the following: 2Fe 2+ →2Fe 3+ +2e (Equation 15)

[0148]

[0177] Combining (Eq. 14) and (Eq. 15) gives the overall plating cell reaction: 3Fe 2+ →2Fe 3+ +Fe (Eq. 16)

[0149]

[0178] The iron electroplating reaction is 2+ ) ion, while ferrous to ferric (Fe 3+ ) requires only one electron per ion. To reach charge balance, twice as many ferrous ions are required on the anode side 138 of the plating cell 132 than on the cathode side 134. This is why the ferrous solution entering the plating subsystem is split into 1 / 3 (catholyte) and 2 / 3 (anolyte) portions of the initial ferrous solution from the acid regeneration cell 104. This implies that the anolyte flow rate through the anode side 138 of the plating cell 132 can be twice the catholyte flow rate through the cathode side 134. In some embodiments, the anolyte flow rate can be more than twice the catholyte flow rate. In some embodiments, the anolyte flow rate can be less than twice the catholyte flow rate.

[0150]

[0179] In some embodiments, the ferrous solution entering the plating subsystem 130 may be split into anolyte and catholyte portions of differing proportions depending on the efficiency of one or both electrodes, the total iron concentration, or other factors. Thus, in various embodiments, the ferrous solution entering the plating subsystem may be split into catholyte and anolyte portions with a catholyte / anolyte ratio of about 90% / 10% to about 20% / 80%, optionally 70% / 30% to about 30% / 70%, and in some specific embodiments, the catholyte / anolyte ratios may include 80% / 20%, 70% / 30%, 75% / 25%, 70% / 30%, 65% / 45%, 60% / 40%, 65% / 35%, 50% / 50%, 45% / 65%, 40% / 60%, 35% / 65%, 33% / 67%, 30% / 70%, 25% / 75%, 20% / 80% (all values ​​may vary + / - 3%).

[0151]

[0180] The plating anolyte and catholyte may be recirculated between the respective tanks 144, 142 and the respective half-cell chambers 138, 134 in the plating cell 132 for any number of plating cycles (one plating cycle includes a complete replacement of the anolyte and catholyte volumes in the plating cell). In some embodiments, the fluid circulation of the plating anolyte and plating catholyte may be continuous when an electric current is applied.

[0152]

[0181] In some embodiments, the plated iron may be removed from the cathode chamber 134 and / or the cathode substrate at 148, and the plating electrolyte may be recycled to the dissolving subsystem 102 for reuse in further dissolving and acid regeneration operations. In some embodiments, the plating process may be completed once a desired amount of iron has been plated in a batch mode. In other embodiments, the plated iron may be continuously removed from the plating cathode chamber 134, and the electrolyte may be recycled to the dissolving subsystem 102 for reuse in further dissolving and acid regeneration operations. 2+ ) may be replaced once it has been consumed beyond a desired point.

[0153]

[0182] In various embodiments, the plating cathode half-cell 134 may be configured to plate iron in any manner that allows for removal of the plated iron material. A variety of plating and metal removal methods are used in other wet smelting plating operations, any of which may be configured for use in this iron plating system.

[0154]

[0183] Depending on the selected method of plating and removing the iron from the cathode half-cell, the plating cell may be operated in a batch mode, with plating being stopped once the desired amount of iron has been plated so that the iron may be removed. Alternatively, the plating cell may be configured such that plating operates in a continuous mode, with iron being continuously removed from the cathode chamber. In some embodiments, the continuous removal of plated iron may be similar to the configuration used in some conventional zinc and copper electrowinning systems.

[0155]

[0184] For example, iron may be plated as a plate or sheet onto a solid metal or graphite substrate (e.g., steel, copper, lead, zinc, nickel, or other material coated or plated with one or more of these or other metals or their alloys). In various embodiments, the plating cathode electrode and / or substrate 136 may be removable from the cathode chamber 134, or may be configured such that the iron may be removed from the cathode chamber 134 without removing the cathode electrode 136 or the substrate. In some embodiments, the substrate may be removable from the cathode electrode. In some embodiments, such substrates may be substantially flat, and the plated iron may be removed in a batch mode by scraping, peeling, scraping, folding, or otherwise separating the flat iron plate from the substrate. In other embodiments, the substrate may be cylindrical, and the plated iron may be continuously removed by rotating the cylinder against one or more knives that separate the plated iron as a continuous sheet, wire, strip, or other material. In yet other embodiments, the iron may be plated onto a continuous belt that moves past the plating cell cathode and the iron may be separated from the belt at a location outside the cathode chamber. In other embodiments, the iron may be plated onto seed particles that may increase in size in a particle growth mode and the particles may be removed from the cathode chamber by any suitable separation mechanism. A variety of other iron plating and removal processes may also be used.

[0156]

[0185] In various embodiments, the end of plating may be determined based on the mass of iron plated, the measured residual concentration of ferrous ions in the plating catholyte, the cell voltage, or other metrics. For example, in some embodiments, the plating cycle may be complete when a target thickness of about 1 mm to about 10 mm is reached.

[0157]

[0186] Once the plating anolyte and catholyte reactants, i.e., ferrous iron, are substantially depleted, the electrolyte may be directed to another process. In some embodiments, the catholyte may have a lower ferrous iron content than initially, and the anolyte may have primarily ferric iron instead of ferrous species. In some embodiments, the spent anolyte and catholyte may be combined and directed back to the dissolving tank or acid regeneration cell 104 of the dissolving subsystem to be reused for a new dissolving cycle.

[0158]

[0187] In some embodiments, during plating, Fe in the plating catholyte 2+ It may be desirable to maintain at least a minimum concentration of ions. Experiments have shown that plating cell efficiency and plating quality tend to decrease when the ferrous iron concentration in the plating catholyte falls below about 0.25M. Thus, in some embodiments, it may be desirable to maintain a ferrous iron concentration of at least 0.25M or greater throughout the plating process.

[0159]

[0188] Alternative approaches to establishing the anolyte and catholyte volumes for the plating subsystem may be used to effectively maintain a minimum ferrous concentration and optimize electrolyte usage. For example, to maintain a minimum ferrous concentration in the plating catholyte, it may be beneficial to stop plating when the ferrous concentration of the catholyte drops to a nadir (e.g., as measured optically, spectroscopically, or by other methods) or when the plating cell voltage rises above a set point (e.g., above about 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, or 3V in various embodiments) and then use the "spent" catholyte as the anolyte in a new plating process.

[0160]

[0189] 13A shows an experimental plating cell 1300 with compression end plates 1302 and 1314, current collector plates 1304, 1312, electrode retaining plates 1306 and 1310 supporting an anode 1318 and a cathode electrode 1320 with a gap 1316 through which the plated iron can expand. A separator 1308 separates the anode-containing chamber from the cathode-containing chamber.

[0161]

[0190] 5A and 5B show an embodiment for storing and using plating anode and cathode solutions that advantageously facilitates maintaining at least a minimum ferrous concentration in the plating cathode solution while producing a ferric-rich solution that is returned to the dissolving subsystem upon completion of plating. FIG. 5A shows a process 500 in which, after completion of the dissolving process 502 (and optionally after performing an "auxiliary iron" step), 100% of the iron-rich solution may be directed to the plating cathode solution tank while the plating anolyte tank contains "spent" cathode solution from a previous plating cycle at block 510. A plating process may then be performed to plate iron from the cathode solution and oxidize the ferrous iron to ferric iron in the anolyte. At the end of the plating process 506, the spent anolyte may be returned to the dissolving subsystem at 508 and the spent catholyte may be directed to the plating anolyte tank for the next plating cycle at 510. In various embodiments, "directing the spent catholyte to the anolyte tank" can include actually moving the spent catholyte to a separate tank or simply modifying controls (e.g., valves, pumps, etc.) to designate the tank containing the spent catholyte as the new anolyte tank.

[0162]

[0191] 5B illustrates an alternative process 550 in which, after completion of the dissolution cycle 552 (and optionally after performance of the "auxiliary iron" step), the iron-rich solution from the dissolution subsystem may be split into approximately 1 / 3 catholyte volume and 2 / 3 anolyte volume at 554 and plating may proceed as described above. At the end of plating (556), the spent plating anolyte (containing primarily ferric iron) may again be directed to the acid regenerator of the dissolution subsystem at 558 and the spent plating catholyte may be directed to the hematite dissolution step near the end of the dissolution process in the dissolution subsystem at block 560. In one embodiment, for example, the anolyte and catholyte are combined together and at least a portion of the combined solution is sent to the dissolution subsystem / acid regeneration cell.

[0163]

[0192] In some embodiments, the electrolytes and solutions of both the dissolution subsystem and the plating subsystem may contain dissolved iron species, an acid, and additionally an inert salt that functions as a supporting electrolyte to improve the conductivity of the electrolyte, which may be particularly beneficial at low ferrous concentrations. The supporting salt may include any electrochemically inert salt, such as sodium chloride, potassium chloride, ammonium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, etc., or combinations of salts. The concentration of the supporting salt in the solution, if used, may range from about 0.1 to about 1 M.

[0164]

[0193] In various embodiments, the ferrous oxide anode of the plating cell may be any carbon or graphite based electrode, such as carbon / graphite felt, paper or cloth, or any electrode material stable in a ferric / ferrous salt environment. The plating electrode, the cathode of the plating cell, may be any conductive substrate suitable for electroplating, including but not limited to sheets, plates, meshes, etc., and may be made of any material, including carbon, graphite, steel, stainless steel, copper, zinc, titanium, or alloys or other combinations of these or other materials. Furthermore, the substrate may comprise a multi-layer structure, where the core is made of one type of material (e.g., metal) for structural purposes and the surface is made of another type of material for compatibility with the plating process and / or acid solution. Examples of such multi-layer structures include copper-clad or aluminum-clad steel or stainless steel, copper-plated steel or stainless steel, or other multi-layer materials.

[0165]

[0194] FIG. 19 shows the current density (mA / cm 2 Figure 20 shows the experimentally determined relationship between current density (measured in mA / cm) and cell voltage for the iron plating cell. 2 FIG. 1 shows an experimentally determined relationship between the cell voltage (measured at 1000 V) and the cell voltage. As can be observed, the acid regeneration cell can be operated at much higher current densities before reaching the cell voltage achieved by the plating cell at much lower current densities. The water splitting reaction in the acid regeneration cell may also typically use more expensive catalysts, resulting in increased capital costs for such cells. These factors suggest that it may be more cost-effective to operate the acid regeneration cell at higher current densities to obtain value from the more expensive cell. On the other hand, the iron plating reaction may be best performed at a relatively low current density to achieve plated iron with the desired properties. Iron plating cells also typically use less expensive electrodes, making it more economically viable to operate the plating cell at lower current densities. In various embodiments, the current density applied to the plating cell is about 20-300 mA / cm. 2 may be in the range.

[0166]

[0195] In various embodiments, the plating catholyte tank and the plating anolyte tank may be maintained at a temperature of 40-80° C., and the plating cell may be operated in a similar temperature range.

[0167]

[0196] As can be seen with reference to the drawings, decoupling of the feedstock dissolution and acid regeneration steps from the iron plating (precipitation) step provides substantial benefits at little or no theoretical cost since both processes consume essentially the same total theoretical energy as the one-step iron conversion process described above. Relatedly, decoupling of the dissolution tank from the plating anolyte and catholyte tanks may provide further advantages in managing the differing reaction rates of the two processes.

[0168]

[0197] In various embodiments, the iron plating cell(s) may have a current of about 20 mA / cm 2 ~about 500mA / cm 2 , optionally 20mA / cm 2 ~about 200mA / cm 2 , and optionally 20mA / cm 2 ~Approx. 100mA / cm 2 , in some embodiments, about 50 mA / cm 2 ~about 300mA / cm 2 , optionally 50mA / cm 2 ~about 200mA / cm 2 , and optionally 50mA / cm 2 ~Approx. 100mA / cm 2 , and in some embodiments, about 75 mA / cm 2 ~about 250mA / cm 2 , optionally 75mA / cm 2 ~about 200mA / cm 2 , and optionally 75mA / cm 2 ~Approx. 100mA / cm 2 In one embodiment, the iron plating cell(s) may be advantageously operated at a current density of 500 mA / cm 2 Below 400mA / cm 2Below 300mA / cm 2 Below 200mA / cm 2 Below, 100mA / cm 2 It may be operated at the following current densities: In some embodiments, the plating current density may be variable during the plating operation depending on process conditions and / or electricity availability.

[0169] Pretreatment of iron raw materials to aid in melting

[0198] FIG. 9 shows a very high level schematic of an iron conversion system 100 according to some embodiments. The schematic in FIG. 9 shows the dissolving subsystem 102, which includes a pretreatment section 920, a dissolving section 908, an acid regeneration section 910 (each of which is described above), and a plating section 130, from which iron may be removed (922). Oxygen may be generated from the acid regeneration section 910, and hydrogen may be generated from the plating section 130 and / or an impurity processing section 918 between the acid regeneration 910 and plating 130 sections. The generated hydrogen may be sent back to the pretreatment section 920 for use in some pretreatment. Additional impurity removal steps (e.g., removal of solid impurities, organic impurities, undissolved solids, or other impurities) 914 and 916 may be present between the pretreatment section 920 and the dissolving subsystem 102. As shown in FIG. 9, for example, goethite and hematite may be thermally reduced to magnetite, and optionally, the reactant is H2 gas generated during plating. As shown in FIG. 9 , for example, impurities may be removed at various stages in the process, such as within the dissolution subsystem (e.g., between the dissolution and the acid regenerator (first electrochemical cell)) and / or between the dissolution subsystem and the iron plating subsystem.

[0170]

[0199] As shown, prior to the smelting subsystem 102, the iron feedstock, and in particular some iron ores, may be treated or modified to facilitate smelting. In some embodiments, goethite ore 902 may be converted to hematite ore 904, and hematite ore may be converted to magnetite ore 906. In other embodiments, a portion of the ore may be maintained in the goethite or hematite form.

[0171]

[0200] The ferrous raw material may contain iron or iron oxide in one or more of many possible forms, including steel, steel mixed with other metals and nonmetals, scrap steel (or scrap iron), metallic iron of various purities, or iron oxide (including iron hydroxide and iron oxyhydroxide). However, some iron oxides commonly present in iron-bearing ores dissolve relatively slowly. The following paragraphs relate to improvements in the dissolution of iron-bearing ores.

[0172]

[0201] Different iron oxides have different dissolution kinetics. For example, magnetite (Fe3O4, Fe 3+ and Fe 2+ (containing both Fe 3+ Magnetite dissolves much more readily than oxides that contain only hematite, such as hematite (Fe2O3) and goethite (FeO(OH)). The difference in dissolution kinetics can be as much as 40-fold between hematite and magnetite, for example. Many commercially available and economically viable iron ores contain large amounts of hematite and / or goethite. Optional embodiments herein include converting at least a portion of the iron oxides, such as hematite and / or goethite, in the iron-containing ore to magnetite for faster dissolution. Conversion to magnetite may also provide the advantage of allowing magnetic separation of magnetite-containing materials from less magnetic forms of iron prior to dissolution in acid. Processing of the raw ore to convert certain iron oxides to magnetite is an optional aspect that may be advantageous in some applications, but is not required for the operation of the methods disclosed herein.

[0173]

[0202] In other cases, simply heating hematite or goethite ores to a sufficient temperature even in an air atmosphere (i.e., "air roasting") can bring about sufficient morphological changes in the ore structure to permit acid dissolution of those "roasted" ores in an acceptable time frame (e.g., on the order of about 24 hours + / - 6 hours), especially when dissolution is coupled with an acid regeneration cell 104 as described herein. In some cases, even completely unprocessed "raw" ores can be dissolved in an acceptable time frame when dissolution is coupled with an acid regeneration cell 104.

[0174]

[0203] As shown in the X-ray diffraction patterns shown in Figures 21A, 21B, and 21C, goethite can be converted to hematite by air roasting at temperatures between about 200°C and 600°C, and hematite can be thermally reduced to magnetite in hydrogen at temperatures between 300°C and 600°C.

[0175]

[0204] In various embodiments, "air roasting" may be performed by heating the ore in an air atmosphere to a temperature of about 200°C to about 600°C for a period of about 1 minute to about 1 hour. In some particular embodiments, air roasting may include heating the ore to a temperature of about 200°C to about 400°C. In various embodiments, air roasting of the ore may include a ramp-up period from a starting temperature (e.g., ambient or room temperature) to reach a target temperature. In some embodiments, the period of air roasting may begin once the ore material reaches a first target temperature.

[0176]

[0205] In various embodiments, "thermal reduction" may be performed by heating the ore in a reducing atmosphere to a temperature of about 300°C to 600°C for a period of about 1 minute to about 5 hours, depending on the degree of reduction required and the morphology of the material being reduced. In some embodiments, the reducing atmosphere may contain a gas mixture of about 1% to about 10% hydrogen gas (or other reducing gas), and the remainder an inert gas, such as nitrogen, argon, or other inert gas. In some embodiments, gas mixtures with much higher hydrogen content, even approaching 100% H2, may be used. In some embodiments, the thermal reducing atmosphere may also be humidified to contain about 5% to about 10% water vapor.

[0177]

[0206] In some specific embodiments, the thermal reduction may include holding the ore at a temperature between about 300° C. and about 500° C., and in some specific embodiments, about 375° C., 400° C., 425° C., 450° C., 500° C., 525° C., 550° C., or higher. In various embodiments, when thermally reducing the ore, the ore may be exposed to an air (or other non-reducing) atmosphere during the heat-up period to reach the target temperature in order to conserve hydrogen gas, which may become ineffective before the target temperature is reached. In some embodiments, the period of thermal reduction may begin once the ore material has reached the first target temperature.

[0178]

[0207] In some embodiments, it may be desirable to stop the thermal reduction of the iron ore before complete reduction to ferrous metal, for example, by removing the ore, reducing the temperature, or maintaining a humidity level sufficient to prevent reduction to ferrous metal. In other embodiments, a portion of the ore may be reduced to ferrous metal before proceeding to the smelting step.

[0179]

[0208] Hematite can be reduced to magnetite using a reducing agent such as hydrogen, carbon monoxide, syngas, etc. This can be done for many different purposes, particularly for iron beneficiation using magnetic separation. It is contemplated herein that iron making processes, such as electroplating, can optionally include generating a reducing agent such as hydrogen as a side reaction (e.g., via a parasitic reaction or during iron plating) or as a direct result of an intermediate process step (e.g., an "auxiliary iron processing" step as described herein).

[0180]

[0209] Instead of being wasted, reducing agents such as hydrogen produced by parasitic or incidental reactions can be captured and used to reduce iron oxides such as hematite and goethite in the ore to magnetite, so that part of the energy "wasted" by producing reducing agents as by-products in different processes (e.g. hydrogen from electroplating or other processes) can be recovered in this way, and at the same time the reduced ore becomes much easier to dissolve.

[0181]

[0210] In general, according to certain embodiments, at least a portion of the reductant, such as H2, may be a product of any part, step, or reaction of the iron-making process.

[0182]

[0211] According to certain embodiments, a reducing agent such as H2 may be generated prior to and / or external to the iron electroplating process or its electrochemical cell. H2 generation may occur during the electroplating process, for example, when the pH is low (e.g., there is an excess of residual acid in the input stream delivered to the electroplating cell), resulting in a reduction in the faradaic efficiency of the electroplating, which allows for side reactions (or parasitic reactions) that generate H2 simultaneously with the iron electroplating. Thus, once plating begins, significant H2 generation may occur until the pH is increased to about 2 (or other value depending on the acid chemistry used). In some embodiments, the plating cell or a similarly configured polishing cell may be configured to allow for the collection and storage of hydrogen gas generated during such operation.

[0183]

[0212] According to certain embodiments, the systems and methods disclosed herein may include a combination of the above approaches as a solution to improve iron dissolution in acid. According to certain embodiments, the methods disclosed herein may include the use of products (e.g., hydrogen) or by-products of side reactions in the iron making process for the conversion of non-magnetite iron ores or non-magnetite iron oxide compounds in iron-bearing ores to magnetite to improve the dissolution rate. According to certain embodiments, the methods disclosed herein may include a combination of (i) the reduction of iron oxide (e.g., oxide ores) to magnetite and (ii) the dissolution of the resulting material (magnetite) with acid.

[0184]

[0213] According to certain embodiments, the methods disclosed herein may include the starting material being an iron-containing ore (e.g., ore, iron ore, rock, sediment, mineral). According to certain embodiments, the methods disclosed herein may include the reducing agent (for converting non-magnetite iron oxide to magnetite) being a by-product of another reaction step in the overall iron making process. According to certain embodiments, the methods disclosed herein may include the generation of the reducing agent (for converting non-magnetite iron oxide to magnetite) from a combination of an internal source (e.g., a by-product of the overall iron making process) and an external source including a hydrogen reservoir, a natural gas reforming system providing hydrogen gas, or a water electrolyzer. According to certain embodiments, the methods disclosed herein may include the reducing agent (for converting non-magnetite iron oxide to magnetite) being hydrogen, carbon monoxide, natural gas, syngas, or a combination thereof. According to certain embodiments, the methods disclosed herein may include using a by-product of an electrochemical plating reaction to drive a different reaction, for example using a hydrogen by-product to reduce iron oxide. The by-products can be produced directly in the plating cell or in a separate reactor prior to the plating cell with a similar net production of hydrogen gas.

[0185]

[0214] According to certain embodiments, included herein is a method for dissolving iron-bearing iron ore having one or more non-magnetite iron oxide materials, the method comprising exposing the iron ore to a reducing agent at a temperature between 200° C. and 600° C., converting at least a portion of the iron oxide in the ore to magnetite, thereby forming a processed ore, and dissolving the processed ore using an acid to form an iron salt solution. Optionally, the reducing agent is a by-product of another reaction in the iron making process.

[0186]

[0215] In various embodiments, the systems and methods herein may be configured to dissolve a quantity of differently treated iron-bearing ore materials to achieve a desired target dissolved iron concentration within an acceptable period of time (e.g., within about 24 or 30 hours). Overall, as described herein, it has been found that dissolution of iron oxide is substantially improved in the presence of ferrous iron and in the presence of sufficient acid, such as that provided by an acid regenerator. Nevertheless, reduction of hematite ore to magnetite has shown substantial improvement in dissolution rate and completeness in any environment.

[0187]

[0216] As shown in FIG. 10, the smelting subsystem 1000 may include an acid regenerator 104 coupled to a plurality of ore-containing smelting tanks 1010, 1012, 1014 (or more or less in other embodiments). As shown, each tank may contain differently processed ore material. For example, the first tank 1010 may contain "raw" ore that has not been thermally pretreated. Such raw ore may include goethite and / or other ore types. The second tank 1012 may contain ore that has been "roasted", e.g., air roasted, as described above, and may also contain hematite and / or other ore types. The third tank 1014 may contain thermally reduced ore as described above, and may also contain substantial amounts of magnetite and other ore types.

[0188]

[0217] As discussed above and shown in Figure 7C (which shows the dissolution times of ores with different treatments for excess sulfuric acid), the reduced ore dissolves very quickly, reaching complete dissolution in just a few hours, while the roasted ore dissolves much more slowly, although the dissolution rate can be increased somewhat by increasing the temperature and / or the amount of ferrous ions in solution. Although not shown, the raw ore is shown to dissolve more slowly than the roasted ore.

[0189]

[0218] Relatedly, in FIG. 7B, trace 708 shows the dissolution of magnetite in 0.1 M sulfuric acid compared to the dissolution of hematite 706 in 0.1 M sulfuric acid, hematite 704 in 0.3 M sulfuric acid, and hematite 702 in 0.5 M sulfuric acid.

[0190]

[0219] The system of FIG. 10 illustrates several possible processes that may be applied to selectively direct the acid-enhanced dissolution solution from the acid regenerator 104 to one or more of the dissolution tanks 1010, 1012, 1014. For illustrative purposes, a process is described in which the acid solution is recirculated between the acid regenerator 104 and one or more of the tanks 1010, 1012, 1014 in one ten cycles, each cycle beginning at the outlet of the acid regenerator 104. While ten cycles are described in this example, any number of cycles may be used depending on various details of a particular implementation. In other cases, the "cycles" may simply represent the relative duration that the solution is contacted with each of the ore types, and different arrangements of tanks, fluid conduits, valves, etc. may be used. For example, instead of changing where the fluid is directed, the solids content of a single dissolution tank may be changed for various periods of time that roughly correspond to the number of cycles described in the following example.

[0191]

[0220] During a first group of ten cycles, the acid solution may be directed to the ore tank 1010 by opening valve 1030. The acid solution exiting the ore tank 1010 may be sent back to the acid regeneration cell 104 by opening valve 1022. During a second group of ten cycles, the acid solution may be directed to the roasted ore tank 1012 by opening valve 1032. The acid solution exiting the roasted ore tank 1012 may be sent back to the acid regeneration cell 104 by opening valve 1024. In some embodiments, during a third group of ten cycles, the acid solution may be directed to the reduced ore tank 1014 by opening valve 1034. The acid solution exiting the roasted ore tank 1014 may be sent back to the acid regeneration cell 104 by opening valve 1026, or alternatively (or in addition) may be directed to a downstream process 1016 (e.g., impurity removal, auxiliary iron processing, plating, etc.) by opening valve 1028.

[0192]

[0221] Thus, by varying the number of "cycles" through each dissolution tank, the acid solution may be contacted with differently treated ores for different periods of time. In various examples, the acid solution may be contacted with the raw ore 1010 for 0-9 cycles, with the roasted ore 1012 for 0-9 cycles, and with the reduced ore 1014 for 1-10 cycles. Generally, it is desirable to contact the acid solution with the reduced ore 1014 for at least a final cycle before directing the solution to downstream process steps 1016. Because dissolution of the reduced ore proceeds relatively quickly, ending the dissolution process with the reduced ore helps consume some of the remaining acid, further simplifying the downstream steps described elsewhere herein.

[0193]

[0222] Any of the combinations of cycles (or proportional residence times) in Table 1 below may be used.

[0194] [Table 1]

[0195]

[0223] In some embodiments, the method may include dissolving a source of iron in acid; electroplating metallic iron from a ferric solution at the cathode of the electrochemical cell or during the treatment step while generating oxygen gas from water at the anode of the electrochemical cell, and generating hydrogen in a side reaction at the cathode of the electrochemical cell; collecting the hydrogen; transporting the hydrogen to a reaction chamber; and thermally reducing the source of iron with the hydrogen in the reaction chamber.

[0196]

[0224] In some embodiments, the method includes the steps of dissolving an iron source material in an aqueous acid solution in a dissolving tank; circulating the solution from the dissolving tank to an acid regeneration cell; converting ferric iron in the solution to ferrous iron at the cathode of the acid regeneration cell while generating oxygen from water at the anode of the acid regeneration cell; transferring a first portion of the solution (the anolyte) to an anolyte tank of an iron plating system; and transferring a second portion of the solution (the catholyte) to a catholyte tank of an iron plating system, optionally including a treatment step to remove impurities and form H2. circulating the anolyte and catholyte between the tank and an iron plating cell; electroplating metallic iron from the ferrous iron in the catholyte at the cathode of the plating cell while oxidizing ferrous iron to ferric iron in the anolyte at the anode of the plating cell, and optionally generating parasitic hydrogen at the cathode during electroplating and / or using H2 generated from the processing step to remove impurities to form H2; collecting the hydrogen, transporting the hydrogen to a reaction chamber, and thermally reducing an iron feedstock with the hydrogen in the reaction chamber.

[0197]

[0225] In some aspects, the method may include producing hydrogen by mixing an aqueous acidic solution with metallic iron, collecting the hydrogen, transporting the hydrogen to a reaction chamber, and thermally reducing an iron feedstock with the hydrogen in the reaction chamber.

[0198]

[0226] In some aspects, the method may include combining an aqueous acidic ferrous solution with metallic iron, converting residual ferric ions in the aqueous acidic ferrous solution to ferrous ions while producing hydrogen from a reaction between the residual acid and the metallic iron, collecting the hydrogen, transporting the hydrogen to a reaction chamber, and thermally reducing an iron source in the reaction chamber with the hydrogen.

[0199]

[0227] In some aspects, embodiments disclosed herein include a method for dissolving an iron oxide material in an acidic solution, the method comprising the steps of: providing a feedstock comprising the iron oxide material; providing a dissolving tank; providing an electrochemical cell having a cathode, a membrane, and an anode; and dissolving the feedstock in the dissolving tank using an acidic solution, wherein the dissolving produces Fe. 3+ releasing Fe into the acid solution; and circulating the acid solution between the dissolution tank and the cathode of the electrochemical cell to obtain Fe. 3+ Fe 2+ and simultaneously producing protons, wherein the circulating step comprises electrochemically reducing the acid and Fe 2+ The reduced and acidified solution containing the ions is returned to the dissolving tank to dissolve more of the iron oxide material.

[0200] Example: Ore pretreatment and melting

[0228] This example provides certain illustrative and optional embodiments of methods for processing iron-bearing ores to increase the content of magnetite in the ores. Processing of the raw ore to convert certain iron oxides to magnetite is an optional aspect that may be advantageous in some applications, but is not required for the operation of the methods disclosed herein to produce high purity iron.

[0201]

[0229] In one aspect, a method for processing an iron-bearing ore having one or more non-magnetite iron oxide materials includes processing the iron-bearing ore to form a processed ore, the processing step including exposing the one or more non-magnetite iron oxide materials of the iron-bearing ore to a reducing agent at a temperature selected from the range of 200° C. to 600° C. to convert at least a portion of the one or more non-magnetite iron oxide materials to magnetite, thereby forming the processed ore; and dissolving at least a portion of the magnetite using an acidic solution to form an iron salt solution; the reducing agent is, at least in part, a product of an electrochemical process, a process for making iron, a chemical reaction involving iron as a reagent, and / or a chemical reaction between a metal and an acid.

[0202]

[0230] Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is a product of an electrochemical and / or chemical reaction of an iron making process. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is a product of an iron electroplating process. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is electrochemically generated H2. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is chemically generated H2. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is H2 generated via water electrolysis. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is H2 generated from a reaction between a metal, such as iron, and an acid. Optionally, in the method for processing an iron-containing ore, at least a portion of the reducing agent is a combination of H2, electrochemically generated H2, and a product of a chemical reaction between a metal and an acid.

[0203]

[0231] The reducing agent may be provided from a process that is part of the method for processing the iron-containing ore and / or from a separate method. Optionally, in the method for processing the iron-containing ore, the method includes a process for making iron. Optionally, in the method for processing the iron-containing ore, the method includes electroplating iron metal, collecting reducing agent produced during the electroplating step, and providing reducing agent to the processing step. Optionally, in the method for processing the iron-containing ore, the method includes an electrochemical process, a process for making iron, a chemical reaction involving iron as a reagent, and / or a chemical reaction between a metal and an acid. Optionally, in the method for processing the iron-containing ore, the method includes a process for making electrochemically produced H2. Optionally, in the method for processing the iron-containing ore, the method includes a process for making H2 via a reaction between a metal, such as iron, and an acid.

[0204]

[0232] Optionally, in the method for processing iron-containing ore, the reducing agent comprises H2, CO, natural gas, syngas, or any combination thereof.

[0205]

[0233] Optionally, in the method for processing iron-bearing ore, the method includes the step of extracting at least a portion of the magnetite from the processed ore between the processing and smelting steps.

[0206]

[0234] In some embodiments, the conversion of the non-magnetite iron oxide to magnetite may be incomplete after the first performing of the exposing step, resulting in some amount of unconverted non-magnetite iron oxide, which may then be further processed. Optionally, in the method for processing an iron-containing ore, the processed ore includes unconverted non-magnetite iron oxide material, the method further includes the steps of separating at least a portion of the unconverted non-magnetite iron oxide material from the magnetite of the processed ore; and recycling the separated unconverted non-magnetite iron oxide back to the step of processing the unconverted non-magnetite iron oxide material to convert it to magnetite. Optionally, in the method for processing iron-containing ore, the dissolving step comprises exposing the processed ore to an acidic solution, wherein at least a portion of the exposed processed ore is not dissolved in the acidic solution, and the undissolved portion of the processed ore comprises unconverted non-magnetite iron oxide material, and the method further comprises recycling the unconverted non-magnetite iron oxide material back to the processing step to convert the unconverted non-magnetite iron oxide material to magnetite.

[0207]

[0235] Optionally, in the method for processing iron-containing ore, the one or more non-magnetite iron oxide materials include hematite and / or goethite.

[0208]

[0236] Optionally, in the method for processing iron-containing ore, the acidic solution (for dissolving at least a portion of the magnetite) comprises hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid, oxalic acid, boric acid, or any combination thereof.

[0209]

[0237] Optionally, in the method for processing iron-containing ore, the iron salt solution comprises an aqueous Fe 2+ and / or Fe 3+ Contains ions.

[0210]

[0238] In another aspect, a method for processing an iron-bearing ore having one or more non-magnetite iron oxide materials includes processing the iron-bearing ore to form a processed ore, the processing step including exposing the one or more non-magnetite iron oxide materials of the iron-bearing ore to a reducing agent at a temperature selected from the range of 200° C. to 600° C. to convert at least a portion of the one or more non-magnetite iron oxide materials to magnetite, thereby forming the processed ore; and using an acidic solution to dissolve at least a portion of the magnetite to form an iron salt solution.

[0211] Additives to improve dissolution

[0239] A mixed solution of sulfate and chloride salts can be used, for example by using a mixture of sulfuric acid and hydrochloric acid. In some embodiments, such a mixture may be generated by mixing chloride salts with a sulfuric acid solution, or by mixing sulfate salts with a hydrochloric acid solution. In other embodiments, other acid mixtures may be used to dissolve the iron ore material.

[0212] Acid Chemical Selection

[0240] In various embodiments, the systems and methods described herein may be used with any acid for dissolving the iron source material and / or as a base for the ferrous solution used in iron plating. Suitable acids may include, but are not limited to, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid, oxalic acid, citric acid, boric acid, methanesulfonic acid, or any combination thereof. As will be understood with reference to this description and the accompanying figures, the selection of the acid chemistry may provide various advantages and tradeoffs. The selection of a particular acid chemistry may be based on these or other technical and / or economic factors, among others. Various considerations in the selection are listed in Table 2.

[0213]

[0241] [Table 2]

[0214]

[0242] In some embodiments, the electrolyte or acid solutions used in either the acid regeneration cell (anolyte and / or catholyte) or the plating cell (anolyte and / or catholyte) may include supporting salts or other additives in addition to the acids and dissolved species described herein. For example, the supporting salts in any of the above electrolyte solutions may include sodium sulfate, potassium sulfate, ammonium sulfate, sodium chloride, potassium chloride, ammonium chloride, etc., or any combination thereof.

[0215]

[0243] In some embodiments, the plating cell catholyte may include one or more additives configured to improve plating efficiency, such as, for example, weak acids for pH buffering including citric acid, boric acid, and / or surfactants including low foaming non-ionic surfactants, such as Hopax EN16-80, EA15-90, and typical additives used in the electroplating industry.

[0216] Overall Process Example

[0244] 4, 6 and 9 show various schematic diagrams of examples of the iron conversion process described herein.

[0217]

[0245] FIG. 11 shows an example of a complete process 1100 for converting ferrous feedstock to pure iron while recycling process solutions, including various optional intermediate steps. At 1102, the process 1100 may optionally include grinding the feedstock material to a desired particle size. At 1104, the process may include heat treatment, which may include roasting and / or thermally reducing the ferrous feedstock material in the presence of hydrogen (including, for example, hydrogen produced in one or more process steps in the process 1100). The heat treatment step 1104 may optionally be omitted if the feedstock is suitable for direct melting without such processing. At 1106, the feedstock may be added to a dissolving tank connected to an acid regenerator. At 1108, the feedstock may be dissolved in the dissolving tank with acid and the ferrous solution produced by the acid regenerator. After the iron concentration reaches a desired value, this ferrous solution in the dissolving tank may be treated with iron at 1110 (e.g., the "auxiliary iron" treatment described elsewhere herein) to increase the pH and further convert any remaining ferric iron to ferrous iron. At 1112, the ferrous solution may be transferred to catholyte and anolyte tanks associated with the plating cell. At 1114, the plating cell may be operated to produce ferric iron in the anolyte while plating metallic iron. At 1115, the deposited metallic iron may be removed from the cell, for example, by removing the cathode electrode. At 1116, the ferric plating anode solution may be sent back from the plating system to the dissolving tank of the acid regenerator system and recycled to produce at least some ferrous iron before the feedstock is added to the dissolving tank in a subsequent cycle at 1106. In some embodiments, a supporting salt may be optionally added to the electrolyte at 1120. Alternatively, a supporting salt may be added to the electrolyte at any other point in the process (e.g., in the electrolyte or with the feedstock). In some embodiments, supporting salts are not added every cycle, for example, because they may not be consumed (or may not be substantially consumed) in the process.

[0218]

[0246] In some aspects, embodiments disclosed herein include a method for producing high purity iron from an iron oxide feedstock, the method comprising the steps of: providing a dissolution tank; providing a first electrochemical cell (e.g., an acid regenerator cell) having a cathode, a membrane, and an anode; dissolving the feedstock in an acid solution in the dissolution tank, wherein the dissolution reaction produces Fe 3+ and circulating the solution to the cathode of the first electrochemical cell to produce Fe. 3+ Fe 2+ and simultaneously generating protons. 2+ The method includes the steps of: returning the reduced and acidified solution containing ions to the dissolving tank to form a solution containing a ferrous salt (a "ferrous transfer solution"); splitting the ferrous solution from the dissolving tank of the dissolving subsystem into two streams stored in two separate tanks for a plating anolyte and a plating catholyte; providing a second electrochemical cell (e.g., a plating cell); circulating solution from the catholyte tank to the cathode of the second electrochemical cell and circulating anolyte from the anolyte tank to the anode of the second electrochemical cell; 2+ The anode of the second electrochemical cell is then charged with Fe while the cathode of the second electrochemical cell is then charged with Fe. 2+ Ion to Fe 3+ removing the plated iron metal; and 3+ The system further includes an iron plating subsystem configured to produce iron metal from the ferrous solution produced in the dissolving subsystem by returning the ferric solution having ions to the dissolving tank or acid regeneration cell of the dissolving subsystem.

[0219]

[0247] In some further aspects, the catholyte and anolyte solutions from the catholyte and anode sides of the plating cell may be optionally combined to form a return ferric solution that is returned back to the dissolving subsystem. In some embodiments, the acid regeneration cell may be operated for one or more cycles prior to adding the solid feedstock to the dissolving tank, thereby producing enough acid and ferrous iron (Fe 2 O 3 ) to begin dissolving the solid feedstock material. 2+ ) solution may be produced.

[0220]

[0248] FIG. 18 illustrates certain embodiments of chemical processes and chemical plants configured to carry out aspects of the methods and systems for producing iron described herein. For example, "Acid regenerator + Fe3 reducer" corresponds to certain aspects of the dissolution subsystem described herein. For example, "Fe electroplating" corresponds to certain aspects of the iron plating subsystem described herein. The schematics show various embodiments of inputs, outputs, and communication between the dissolution subsystem and the iron plating subsystem. FIG. 18 also illustrates an example water management system for transferring water from the acid regenerator catholyte to the acid regenerator anolyte, including an alternative use of collected hydrogen in the system (recombining with collected oxygen to form water). The system of FIG. 18 also illustrates an example of the use of sodium chloride supporting salt in the plating system.

[0221] Industrial and commercial uses of water-based electrocast iron.

[0249] In various embodiments, iron produced electrolytically by the systems, methods, and processes described herein can be used for many commercial purposes that are generally not economically viable with other sources of iron.

[0222]

[0250] Various embodiments described herein are particularly suited to intermittent (e.g., renewable) energy sources that may have increasing or decreasing power availability over time, since the acid regeneration cell, plating cell, and other ancillary systems may generally be run at higher or lower power in response to fluctuating power availability. Thus, in some embodiments, the current supplied to the acid regeneration cell, plating cell, or other system components may vary in response to a measured or communicated (e.g., by any smart grid or demand response communication system or protocol) decrease or increase in available or usable power. Such increases or decreases in current (or power) may generally occur within the ranges of current densities described herein, but may occur outside of those ranges in some embodiments, including selectively shutting off total power to one or more cells, stacks, subsystems, or the entire system.

[0223]

[0251] 22 shows a process 2200 for producing green steel and green steel products using iron produced by any embodiment of the systems or processes for making pure iron described herein. According to process 2200, iron ore can be converted into "green iron" in 2202 using substantially only renewable or carbon-free energy (e.g., wind, solar, tidal, geothermal, or nuclear power energy). In 2204, the green iron can be removed from the plating cell as described herein.

[0224]

[0252] At 2206, the green iron may be melted using preferably only substantially renewable or zero carbon energy (e.g., wind, solar, tidal, geothermal, or nuclear power energy). In various embodiments, the iron may be melted only with electrical energy using an induction furnace, microwave, electric arc furnace, or other system. In some embodiments, a conventional basic oxygen furnace may be used to melt the iron.

[0225]

[0253] At 2208, the molten iron may be mixed with various additives and alloying materials to create a desired grade of molten steel. Examples of such additives and / or alloying elements may include carbon, chromium, molybdenum, vanadium, manganese, nickel, cobalt, silicon, lead, boron, aluminum, copper, cerium, niobium, titanium, tungsten, tin, zinc, zirconium, or any combination thereof.

[0226]

[0254] At 2210, the molten steel may be formed into a steel product or product precursor by extrusion, molding, casting, or other melt-solid steel forming steps. Additional manufacturing steps may be used to create steel products, including rolling, forging, welding, stamping, machining, etc., or any combination thereof.

[0227]

[0255] The pure iron produced by the systems, methods and processes described herein essentially represents an energy carrier (e.g., in the form of "metal electricity") that can be deployed for a variety of market purposes, such as to form dispatchable hydrogen, seasonal storage, and metallic fuels that enable a circular iron economy.

[0228]

[0256] Dispatchable hydrogen refers to the delivery of hydrogen on-site and on demand. In some embodiments, the iron produced by the systems and methods herein can be delivered to a location where hydrogen gas is desired and reacted with water (e.g., at high temperature) or acid (which may be produced on-site by an acid generator or otherwise obtained). The reaction of the iron with the acid spontaneously produces hydrogen gas while oxidizing the iron. The oxidized iron can then be returned and used as a feedstock in one of the iron conversion processes described herein.

[0229]

[0257] The iron produced by the conversion processes described herein can be used to make primary (single discharge) or secondary (rechargeable) iron electrode batteries (e.g., nickel-iron batteries, iron-air batteries, all-iron flow batteries, etc.), which can be used for seasonal storage (i.e., time-shifting renewable energy from high generation seasons to lower generation seasons, e.g., summer to winter for solar, weekly or monthly), or daily storage (i.e., time-shifting renewable energy from high generation hours to low generation hours, e.g., day to evening, night or morning for solar).

[0230]

[0258] The iron produced by the conversion processes described herein may be made into particles small enough to be burned as a solid fuel in a furnace (e.g., a coal furnace). The burning of iron consumes oxygen to form iron oxide (typically hematite) but does not release greenhouse gases.

[0231]

[0259] In any of the above applications, "spent" iron that has reached its useful life in those processes (typically after being oxidized to one or more oxide forms) can be returned to an iron conversion process such as the one described herein and converted back to metallic iron.

[0232] A "redox mediator" framework for uncoupling the iron reduction step

[0260] The decoupling of ferric-ferrous reduction from ferrous reduction in the various embodiments and examples herein can theoretically be understood as the use of a "redox mediator" pair that mediates iron reduction and oxygen evolution as shown by the following equation: Acid regeneration anode: 3 / 2H2O → 3H + +3 / 4O2+3e (Equation 17a) Acid regenerated cathode: 3Fe 3+ +3e→3Fe 2+ (Equation 17c) Plating cell anode: 2Fe 2+ →2Fe 3+ +2e (Equation 18a) Plating cell cathode: Fe2+ +2e→Fe (Equation 18c)

[0233]

[0261] The half-reaction at the plating cell anode (22a) is the exact reverse of the half-reaction at the acid regenerated cathode (21c). In essence, the redox couple Fe 3+ / Fe 2+ is the oxidation reaction of water and Fe 3+ From Fe 0 The ferric iron oxide serves as a redox mediator, allowing the reduction of ferric iron to ferrous iron to be decoupled into two separate electrochemical cells, the first cell only performing the reduction of ferric iron to ferrous iron, while the second cell reduces ferrous iron to iron metal by plating. 3+ / Fe 2+ The "shuttle" action can be exploited and used advantageously to produce substantial practical and cost-saving benefits in addition to improved overall efficiency and control over the total system response. Among other advantages, decoupling can allow the acid regeneration cell and the plating cell to be operated at substantially different current densities, which can be particularly advantageous in view of the differing economic and operational characteristics of the two cells.

[0234]

[0262] In the above embodiments and examples, Fe 3+ / Fe 2+ For example, the typical redox mediator pair shown in FIG. 23 is an oxidizing mediator (M O ) and reduced mediator (M R ) between O / M R and the half-reaction using one electron is: M R →M O +1e - (Formula 19)

[0235]

[0263] A redox mediator couple can be used to decouple the iron plating and water oxidation reactions into two cells as follows: Cell 1: Anode: H2O → 1 / 2O2 + 2H + +2e (Formula 20) Cathode: 2M O +2e - →2M R (Formula 21) Overall: H2O+2M O →1 / 2O2+2H + +2M R (Formula 22) Cell 2: The reduced mediator M produced in the first cell R Using: Anode: 2M R →2M O +2e - (Formula 23) Cathode: Fe 2+ +2e - →Fe(Formula 24) Overall: Fe 2+ +2M R →Fe+2M O (Formula 25)

[0236]

[0264] In this way, M O / M R The couple may act as a "redox mediator" to decouple the iron feedstock dissolution process from the iron plating process, as shown in FIG. 23. In various embodiments, other redox couples may be used to achieve a similar functional decoupling through different electrochemical reactions. Various exemplary alternative redox mediator couples include, but are not limited to, Cu 2+ / Cu 0 , V 5+ / V 4 +, V 3+ / V 2+ , Zn 2+ / Zn 0 , any other salt, any organic redox couple such as quinone / hydroquinone, H + / H 2 etc. In some embodiments, the metal redox mediator may be provided to the solution by dissolution or may be separately extracted from the solution by plating, solvent extraction, or other methods.

[0237]

[0265] Various embodiments are contemplated herein, some of which are described in the following paragraphs. It is expressly contemplated that any embodiment or portion thereof may be combined to form an embodiment. Furthermore, it is expressly contemplated that any reference to embodiment A1 includes a reference to embodiment A1a, A1b, A1c, and / or A1d; any reference to embodiment B1 includes a reference to embodiment B1a, B1b, B1c, and / or B1d; any reference to embodiment C1 includes a reference to embodiment C1a and / or C1b; any reference to embodiment D1 includes a reference to embodiment D1a and / or D1b. Furthermore, although the following embodiments are subdivided into embodiments A, B, C, and D, it is expressly contemplated that the embodiments in each of the subdivisions A, B, C, and D may be combined in any manner. Further, the term "any of the above aspects" refers to any aspect that appears before an aspect that includes such phrase (in other words, "method or system of aspect B13: aspect B8, or any of the above aspects" means to refer to any aspect before aspect B13, including all of the "A" aspects, such as aspects B1-12 and aspects A1-A97). For example, it is contemplated that, optionally, any of the systems or methods of any of the following aspects may be useful with or in combination with any other aspect described below. Further, for example, it is contemplated that any of the embodiments described above may be optionally combined with any of the aspects listed below.

[0238]

[0266] Aspect A1a: A method for processing and smelting iron-bearing ore, comprising: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; dissolving at least a portion of the thermally reduced ore using an acid to form an acidic iron salt solution; wherein the acidic iron salt solution comprises protons electrochemically generated in an electrochemical cell.

[0239]

[0267] Aspect A1b: A method for processing and smelting iron-bearing ores, comprising: In the dissolving tank, the iron-bearing ore is contacted with an acid to dissolve at least a portion of the iron-bearing ore, thereby forming dissolved Fe 3+ forming an acidic iron salt solution having ions; recirculating at least a portion of the acidic iron salt solution between the dissolution tank and a cathode chamber of an electrochemical cell, the electrochemical cell comprising a cathode in the presence of at least a portion of the acidic iron salt solution functioning as a catholyte in the cathode chamber, an anode in the presence of an anolyte, and a separator separating the catholyte from the anolyte; Fe dissolved from the catholyte at the cathode 3+ At least a portion of the ions are electrochemically reduced to Fe in the catholyte. 2+ forming ions; electrochemically generating protons in the electrochemical cell and supplying the electrochemically generated protons to a catholyte; wherein the acidic iron salt solution in the dissolution tank is characterized by a steady state concentration of free protons of at least 0.2M (optionally, e.g., at least 0.2, 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5M, optionally the steady state free proton concentration is less than 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6M, such values ​​may be combined in any manner to form a range, such as 0.2 to 6M).

[0240]

[0268] Aspect A1c: A method of processing and smelting iron-bearing ore, comprising: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; The reducing agent comprises H2 gas; at least a portion of the H2 gas is generated chemically via a reaction between iron metal and an acid, and / or at least a portion of the H2 gas is generated electrochemically via a parasitic hydrogen evolution reaction of the iron electroplating process; dissolving at least the thermally reduced ore using an acidic solution to form an iron salt solution; and wherein the dissolving step comprises dissolving the formed magnetite in said acidic solution.

[0241]

[0269] Aspect A1d: A system for processing and smelting iron-bearing ores, comprising: a first smelting tank for smelting a first iron-bearing ore using a first acid; Dissolution of the first ore in the first acid produces dissolved Fe in the first dissolution tank. 3+ a first dissolution tank for forming a first acidic iron salt solution containing ions; an electrochemical cell fluidly connected to the first dissolving tank; an electrochemical cell comprising a cathode chamber having a catholyte in the presence of a cathode, an anode chamber having an anolyte in the presence of an anode, and a separator separating the catholyte and the anolyte; a first circulation subsystem for circulating at least a portion of the first acidic iron salt solution from the first dissolving tank to the cathode chamber and at least a portion of the catholyte from the electrochemical cell to the first dissolving tank; from a first acidic iron salt solution; 3+ At least a portion of the ions are converted to Fe at the cathode in the catholyte. 2+ ions from the first acidic iron salt solution, thereby 3+ ions consuming,system.

[0242]

[0270] Aspect A2: The method or system of any of the above aspects, including providing at least a portion of the catholyte having said electrochemically generated protons during the dissolving step from the electrochemical cell to the acidic iron salt solution, thereby providing electrochemically generated protons to the acidic iron salt solution in the presence of thermally reduced ore.

[0243]

[0271] Aspect A3: The method or system of Aspect A2 or any of the preceding aspects, wherein the dissolving step occurs in a dissolving tank; the dissolving tank and the electrochemical cell are fluidly connected; and an acidic iron salt solution is circulated between the dissolving tank and the electrochemical cell.

[0244]

[0272] Aspect A4: The method or system of aspect A3 or any of the preceding aspects, wherein all of the acidic iron salt solution is circulated between the dissolving tank and the electrochemical cell during at least a portion of the dissolving step.

[0245]

[0273] Aspect A5: The method or system of any one of aspects A2-A4 or any of the preceding aspects, wherein the reaction between the thermally reduced ore being dissolved and the acidic iron salt solution produces water, thereby consuming protons of the acidic iron salt solution; and the supplied electrochemically generated protons replace at least a portion of the consumed protons in the acidic iron salt solution.

[0246]

[0274] Aspect A6: The method or system of any one of Aspects A2-A5 or any of the preceding aspects, wherein electrochemically generated protons are continuously supplied to the acidic iron salt solution during at least a portion of the dissolving step.

[0247]

[0275] Aspect A7: The method or system of any one of aspects A2-A6 or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state concentration of free protons of at least 0.2 M (e.g., at least 0.2, 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5 M, optionally the steady state free proton concentration is less than 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6 M, such values ​​may be combined in any manner to form a range, such as from 0.2 to 6 M), during dissolution of the thermally reduced ore.

[0248]

[0276] Aspect A8: The method or system of aspect A7 or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state concentration of free protons selected from the range of 0.2M to 3M (e.g., 0.4-2.8M, 0.6-2.6M, 0.8-2.2M, 1-2M, 1.2-1.8M, 0.2-0.8M, 0.8-1.4M, 1.4-2M, 2-2.5M, or 2.5-3M).

[0249]

[0277] Aspect A9: The method or system of aspect A7 or A8, or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state pH of less than 0.7 (e.g., less than 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, optionally the steady state pH is at least 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, such values ​​may be combined in any manner to form a range, such as from -1 to 0.7).

[0250]

[0278] Aspect A10: In the same or a different electrochemical cell, Fe from an acidic iron salt solution 3+ ions, electrochemically generated Fe 2+ ions by electrochemical reduction to Fe 2+ 23. The method or system of any one of the preceding aspects, comprising generating ions electrochemically.

[0251]

[0279] Aspect A11: Electrochemically produced Fe in the presence of thermally reduced ore during the dissolving step 2+ The method or system of embodiment A10 or any of the preceding embodiments, comprising providing ions to the acidic iron salt solution.

[0252]

[0280] Aspect A12: An electrochemical cell comprising: 2+ The method or system of embodiment A10 or A11 or any of the preceding embodiments, wherein: both the iron salt and the ions are generated; the dissolving step occurs in a dissolving tank; and the dissolving tank and the electrochemical cell are fluidly connected, and the acidic iron salt solution is circulated between the dissolving tank and the electrochemical cell.

[0281] Aspect A13: An electrochemical cell comprising a cathode in the presence of a catholyte, an anode in the presence of an anolyte, and a separator separating the catholyte from the anolyte; the catholyte comprises an acidic iron salt solution; Fe from acidic iron salt solutions 3+ A step of electrochemically reducing ions is carried out at the cathode to produce electrochemically generated Fe in the catholyte. 2+ Forming ions; The method is electrochemically generating electrochemically generated protons in an electrochemical cell; providing electrochemically generated protons to the catholyte; The method or system of embodiment A8 or any of the preceding embodiments, further comprising:

[0253]

[0282] Aspect A14: The method or system of aspect A13 or any of the preceding aspects, wherein the step of electrochemically generating electrochemically generated protons comprises electrochemically oxidizing water at the anode.

[0254]

[0283] Aspect A15: The method or system of aspect A13 or any of the preceding aspects, wherein the step of electrochemically generating electrochemically generated protons comprises electrochemically oxidizing H2 gas at the anode.

[0255]

[0284] Aspect A16: The method or system of aspect A14 or A15 or any of the preceding aspects, wherein the step of providing electrochemically generated protons comprises transporting electrochemically generated protons from the anolyte to the catholyte through a separator.

[0256]

[0285] Aspect A17: The method or system of any one of Aspects A13-A16 or any of the preceding embodiments, wherein the electrochemical cell is characterized by a coulombic efficiency of greater than 80% (e.g., greater than 80%, 85%, 90%, 95%, or 99%, optionally the coulombic efficiency is less than 80%, 85%, 90%, 95%, 99%, or 100%, such values ​​may be combined in any manner to form a range, such as 80-100%).

[0257]

[0286] Aspect A18: The method or system of any one of A13-A17 or any of the preceding aspects, wherein the electrochemically generated protons at least partially form an acid in the catholyte.

[0258]

[0287] Aspect A19: The method or system of any one of Aspects A13-A18 or any of the preceding aspects, comprising providing water from the catholyte to the anolyte.

[0259]

[0288] Aspect A20: The method or system of aspect 14 or 16 or any of the preceding aspects, wherein the water oxidized at the anode comprises water produced by dissolution of iron-containing ore during the dissolving step.

[0260]

[0289] Aspect A21: The method or system of A19 or A20 or any of the preceding aspects, wherein water is supplied from the catholyte to the anolyte through the separator by osmosis.

[0261]

[0290] Aspect A22: The method or system of any one of aspects A13-A21 or any of the preceding aspects, wherein the anolyte is characterized by a higher total salt concentration than the total salt concentration of the catholyte.

[0262]

[0291] Aspect A23: The method or system of any one of Aspects A13-A22 or any of the preceding aspects, comprising separating water from the catholyte by membrane distillation and providing the separated water to the anolyte.

[0263]

[0292] Aspect A24: The method or system of any one of Aspects A13-A23 or any of the preceding aspects, comprising separating water from the catholyte by flash distillation and providing the separated water to the anolyte.

[0264]

[0293] Aspect A25: The method or system of any one of Aspects A13-A24 or any of the preceding aspects, comprising separating water from the catholyte by reverse osmosis, and providing the separated water to the anolyte.

[0265]

[0294] Aspect A26: The method or system of any one of A13-A25 or any of the preceding aspects, wherein the anolyte has a different composition than the catholyte.

[0266]

[0295] Aspect A27: The method or system of any one of A13-A26 or any of the preceding aspects, wherein the first anolyte has a different pH than the first catholyte.

[0267]

[0296] Aspect A28: The method or system of any one of A13-A27 or any of the above aspects, wherein the first catholyte has a lower pH than the first anolyte.

[0268]

[0297] Aspect A29: The method or system of any one of A13-A28 or any of the preceding aspects, wherein the first anolyte includes dissolved salts of a different composition than the composition in the first catholyte.

[0269]

[0298] Aspect A30: The method or system of Aspects A13-A29 or any of the preceding aspects, wherein the first anolyte contains one or more dissolved ferric salts; and the first analyte is characterized by a total concentration of the one or more dissolved ferric salts greater than or equal to a total iron ion concentration in the first catholyte.

[0270]

[0299] Aspect A31: The method or system of any one of Aspects A13-A30 or any of the preceding aspects, wherein the first catholyte comprises one or more supporting salts.

[0271]

[0300] Aspect A32: The method or system of Aspect A31 or any of the preceding aspects, wherein the first catholyte comprises one or more supporting salts at a concentration selected from the range of 0.1 to 1 M (e.g., 0.2 to 0.8 M, 0.4 to 0.6 M, 0.1 to 0.4 M, 0.4 to 0.8 M, or 0.8 to 1 M).

[0272]

[0301] Aspect A33: The method or system of Aspect A31 or A32 or any of the preceding embodiments, wherein the one or more supporting salts comprise one or more metal sulfate compounds and / or one or more metal chloride compounds.

[0273]

[0302] Embodiment A34: The method or system of embodiment A33 or any of the preceding embodiments, wherein the one or more metal sulfate compounds comprise potassium sulfate, sodium sulfate, ammonium sulfate, lithium sulfate, potassium chloride, sodium chloride, ammonium chloride, lithium chloride, or a combination thereof.

[0274]

[0303] Aspect A35: The method or system of any one of A13-A34 or any of the preceding aspects, wherein the first anolyte is characterized by at least one redox pair different from the first catholyte.

[0275]

[0304] Aspect A36: The method or system of any one of A13-A35 or any of the preceding aspects, wherein the first anolyte comprises a higher total concentration of dissolved salts than the first catholyte.

[0276]

[0305] Aspect A37: The method or system of any one of A1-A21, A23-A29, or A31-35, or any of the preceding aspects, wherein the first anolyte comprises a lower total concentration of dissolved salts than the first catholyte.

[0277]

[0306] Aspect A38: The anolyte comprises Fe 2+ and Fe 3+The method or system of any one of aspects A1-A29 or A31-A35 or any of the preceding aspects, which is essentially free of ions.

[0278]

[0307] Aspect A39: The method or system of any one of aspects A13-A38 or any of the preceding aspects, wherein the catholyte is characterized by a maximum salt concentration selected from the range of 1-8M (e.g., 1-5M, 2-5M, 1-8M, 2-7M, 3-6M, 4-5M, 1-3M, 3-5M, 5-8M, 1-4M, 3-5M, or 3-8M).

[0279]

[0308] Aspect A40: The method or system of any one of aspects A13-A39 or any of the preceding aspects, wherein the catholyte is characterized by a maximum iron ion concentration selected from the range of 0.5-5M (e.g., 1-5M, 1-4M, 1-3M, 0.5-5M, 0.5-4M, 2-4M, 2-5M, 1-2M).

[0280]

[0309] Aspect A41: The method or system of any one of aspects A13-A40 or any of the preceding aspects, comprising electrochemically generating oxygen (O2) at the anode.

[0281]

[0310] Aspect A42: The electrochemical reaction at the anode is O2 / H2O, H2O / H2, H2 / H + , H + The method or system of any one of aspects A13-A41 or any of the above aspects, characterized by one or more redox pairs selected from the group consisting of:

[0282]

[0311] Aspect A43: The method or system of any one of Aspects A13-A42 or any of the preceding aspects, wherein the first anolyte is in ionically connected with the first catholyte through a first separator.

[0283]

[0312] Aspect A44: The method or system of aspect A43 or any of the preceding aspects, wherein the first anolyte is fluidly separated from the first catholyte.

[0284]

[0313] Aspect A45: The method or system of any one of A13-A44 or any of the preceding aspects, wherein the separator is an ion exchange membrane.

[0285]

[0314] Aspect A46: The method or system of aspect 45 or any of the preceding aspects, wherein the separator is a proton exchange membrane (PEM).

[0286]

[0315] Aspect A47: Fe 2+ 4. The method or system of any one of the preceding aspects, comprising producing an iron-rich solution having ions.

[0287]

[0316] Aspect A48: The method or system of aspect A47 or any of the preceding aspects, wherein the produced iron-rich solution is characterized by a total iron ion concentration selected from the range of 0.5 to 5M (e.g., 1 to 4M, 1 to 5M, 0.5 to 4M, 1 to 4M, 1 to 3M, 0.5 to 4M, 2 to 4M, 2 to 5M, or 1 to 2M).

[0288]

[0317] Aspect A49: The method or system of aspect A47 or A48 or any of the preceding aspects, comprising removing the produced iron-rich solution from the electrochemical cell and / or the vessel in which the dissolving step is carried out.

[0289]

[0318] Aspect A50: The method or system of any one of aspects A3-A49 or any of the preceding aspects, comprising the step of increasing the pH of the acidic iron salt solution by fluidly isolating the dissolving tank from the electrochemical cell and / or turning off the electrochemical cell during and prior to completion of the dissolving step.

[0290]

[0319] Aspect A51: The method or system of any one of aspects A47-A50 or any of the above aspects, comprising raising the pH of the produced iron-rich solution to a pH selected from the range of 2 to 7 (e.g., 2 to 6.5, 2 to 6, 2 to 5, 3 to 7, 3 to 6, 3 to 5, 3 to 4, 4 to 7, 4 to 6, 4 to 5, 5 to 7, 5 to 6, or 6 to 7), thereby producing a pH-adjusted iron-rich solution.

[0291]

[0320] Aspect A52: The method or system of any one of aspects A47-A51 or any of the preceding aspects, comprising raising the pH of the produced iron-rich solution to a pH selected from 2 to less than 7 (e.g., 2 to 6.5, 2 to 6, 2 to 5, 3 to less than 7, 3 to 6, 3 to 5, 3 to 4, 4 to less than 7, 4 to 6, 4 to 5, 5 to less than 7, 5 to 6, or 6 to less than 7), thereby producing a pH-adjusted iron-rich solution.

[0292]

[0321] Aspect A53: The method or system of aspect A51 or A52 or any of the preceding aspects, wherein the step of increasing the pH comprises providing metallic iron and / or one or more iron oxide materials in the presence of the generated iron-rich solution.

[0293]

[0322] Aspect A54: The method or system of aspect A53 or any of the preceding aspects, wherein the step of increasing the pH comprises providing magnetite, metallic iron, or both magnetite and metallic iron in the presence of the generated iron-rich solution.

[0294]

[0323] Aspect A55: The method or system of aspect A54 or any of the preceding aspects, wherein the step of increasing the pH comprises providing magnetite or both magnetite and metallic iron in the presence of the generated iron-rich solution.

[0295]

[0324] Aspect A56: The method or system of any one of aspects A51-A55 or any of the preceding aspects, wherein the step of increasing the pH comprises providing metallic iron in an amount sufficient to increase the pH of the produced iron-rich solution to a pH selected from the range of 2 to 7 (e.g., 2 to 6.5, 2 to 6, 2 to 5, 3 to 7, less than 3 to 7, 3 to 6, 3 to 5, 3 to 4, 4 to 7, less than 4 to 7, 4 to 6, 4 to 5, 5 to 7, less than 5 to 7, 5 to 6, 6 to 7, or less than 6 to 7); in some embodiments, the metallic iron is a material comprising metallic iron.

[0296]

[0325] Aspect A57: The method or system of any one of aspects A47-A56 or any of the preceding aspects, comprising precipitating or crystallizing one or more ferrous salts from the produced iron-rich solution.

[0297]

[0326] Aspect A58: The method or system of any one of aspects A47-A57 or any of the preceding aspects, comprising removing one or more ferrous salts from the produced iron-rich solution by one or more processes other than electroplating.

[0298]

[0327] Aspect A59: The step of thermally reducing the one or more non-magnetite iron oxide materials of the iron-containing ore is performed at a temperature between 200° C. and 600° C. (e.g., 200-550, 200-500, 200-450, 200-400, 200-350, 200-300, 200-250, 250-600, 250-550, 250-500, 250-400, 300-600, 300-550, 300-500, 300-450, 300-40 350-600, 350-550, 350-500, 350-450, 400-600, 400-550, 400-500, 450-600, 450-550, or 500-600 (temperature (°C)), thereby converting at least a portion of the one or more non-magnetite iron oxide materials to magnetite.

[0299]

[0328] Aspect A60: The method or system of any one of the preceding aspects, wherein the reducing agent comprises H2 gas; at least a portion of the H2 gas is generated chemically via a reaction between iron metal and an acid, and / or at least a portion of the H2 gas is generated electrochemically via a parasitic hydrogen evolution reaction of an iron electroplating process.

[0300]

[0329] Aspect A61: The method or system of aspect A59 or any of the preceding aspects, wherein the iron-bearing ore is exposed to an elevated temperature for a thermal treatment time during the thermal reducing step, and the iron-bearing ore is exposed to a reducing agent for the entire thermal treatment time.

[0301]

[0330] Aspect A62: The method or system of aspect A59 or any of the preceding aspects, wherein the iron-bearing ore is exposed to an elevated temperature for a thermal treatment time during the thermal reducing step, and the iron-bearing ore is exposed to a reducing agent for a portion of the thermal treatment time.

[0302]

[0331] Aspect A63: The method or system of aspect A62 or any of the preceding aspects, comprising air roasting the iron-bearing ore by exposing the iron-bearing ore to air during an initial portion of the heat treatment time.

[0303]

[0332] Aspect A64: In the presence of air, at least a portion of the iron-containing ore is heated to 200°C to 600°C (e.g., 200 to 550, 200 to 500, 200 to 450, 200 to 400, 200 to 350, 200 to 300, 200 to 250, 250 to 600, 250 to 550, 250 to 500, 250 to 400, 300 to 600, 300 to 550, 300 to 500, 300 to 450, 3 350-400, 350-600, 350-550, 350-500, 350-450, 400-600, 400-550, 400-500, 450-600, 450-550, or 500-600 (temperature (°C)) to form an air roasted ore.

[0304]

[0333] Aspect A65: The method or system of aspect A64, or any of the preceding aspects, wherein the air roasting step occurs prior to or separate from the thermally reducing step, and the air roasted ore is not thermally reduced prior to air roasting.

[0305]

[0334] Aspect A66: The method or system of aspect A64 or A65 or any of the preceding aspects, wherein the step of thermally reducing comprises thermally reducing the air roasted ore to form at least a portion of the thermally reduced ore; the air roasted ore comprises one or more non-magnetite iron oxide materials.

[0306]

[0335] Aspect A67: The method or system of aspect A64, A65, or A66 or any of the preceding aspects, wherein the melting step comprises simultaneously and / or sequentially melting at least a portion of the air roasted ore and at least a portion of the thermally reduced ore.

[0307]

[0336] Aspect A68: The method or system of aspect A67 or any of the preceding aspects, wherein the melting step includes melting at least a portion of the air roasted ore in a melting tank separate from the thermally reduced ore during at least a portion of the melting step.

[0308]

[0337] Aspect A69: the dissolving step includes dissolving the ore mixture; the ore mixture is dissolved in a mixture of 0 wt.% to 100 wt.% (e.g., 0-100, 1-100, 1-90, 1-80, 1-70, 1-60, 1-50, 1-40, 1-30, 1-20, 1-10, 5-100, 5-90, 5-80, 5-70, 5-60, 5-50, 5-40, 5-30, 5-20, 5-10, 10-100, 10-90, 10-80, 10-70, 10-60, 10-50, 10-40, 10-30, 10-20, 20-100, 20-90, 20 ~80, 20~70, 20~60, 20~50, 20~40, 20~30, 40~100, 40~80, 40~60, 50~100, 50~80, 50~60, 60~100, 60~80, 70~100, 70~80, 80~100 wt.%) of thermally reduced ore, 5wt.%~100wt.% (e.g. 5~100, 5~90, 5~80, 5~70, 5~60, 5~50, 5~40, 5~30, 5~20, 5~10, 10~100, 10~90, 10~80, 10~70, 10~60, 10~50, 10~40, 10~30, 1 Roasted ore with a concentration of 0-20, 20-100, 20-90, 20-80, 20-70, 20-60, 20-50, 20-40, 20-30, 40-100, 40-80, 40-60, 50-100, 50-80, 50-60, 60-100, 60-80, 70-100, 70-80, 80-100 wt.% and 0wt.%-90wt.% (e.g. 0-90, 1-90, 1-80, 1-70, 1-60, 1-50, 1-40, 1-30, 1-20, 1-10, 5-90, 5-80, 5-70, 5-60, 5-50, 5-40, 5-60, 5-70, 5-80, 5-90, 5-80, 5-90, 5-80, 5-90, 5-10 ... 50-90, 50-80, 50-60, 60-90, 70-90, 70-80, 80-90 wt.% of the roasted magnetite-containing ore.

[0309]

[0338] Aspect A70: The method or system of any one of aspects A64-A69 or any of the preceding aspects, wherein the dissolving step includes circulating a dissolving solution between the electrochemical cell and at least one of a first dissolving tank, a second dissolving tank, and a third dissolving tank; the first dissolving tank contains at least a portion of the thermally reduced ore, the second dissolving tank contains air roasted ore, and the third dissolving tank contains the iron-bearing ore; and the ore is iron-bearing ore that has not been thermally reduced or air roasted.

[0310]

[0339] Aspect A71: The circulating step includes circulating the dissolution solution for a total circulation time or a total number of circulation cycles; the dissolution solution is circulated between the electrochemical cell and the third dissolution tank for 0-99% (e.g., 0-95, 1-99, 1-95, 5-90, 10-85, 15-80, 20-75, 25-70, 30-65, 35-60, 40-55, 1-90, 1-80, 1-70, 1-60, 1-50, 1-20, 5-99, 5-80, 5-70, 5-60, 5-40, 5-20 , 10-95, 10-80, 10-60, 20-95, 20-80, 20-60, 40-99, 40-80, 60-99, 60-80, 70-95, or 80-95% of the total circulation time or the total number of circulation cycles; the dissolution solution is circulated between the electrochemical cell and the second dissolution tank for 0-99% (e.g., 0-95, 1-99, 1-95, 5-90, 10-85, 15-80, 20-75, 25-70, 30-65, 35-60, 40-55, 1-90, 1-80, 1-70, 1-60, 1-50, the dissolution solution is circulated between the electrochemical cell and the first dissolution tank for 1-100% (e.g., 1-99, 5-100, 1-95, 5-90, 10-100, 10-85, 15-80, 20-100, 20-7 ... , 25-70, 30-65, 35-60, 40-100, 40-55, 1-90, 1-80, 1-70, 1-60, 1-50, 1-20, 5-99, 5-80, 5-70, 5-60, 5-40, 5-20, 10-95, 10-80, 10-60, 20-95, 20-80, 50-100, 20-60, 40-99, 70-100, 40-80, 60-99, 60-80, 70-95, 80-100, or 80-95% of the total amount of the mixture.

[0311]

[0340] Aspect A72: The method or system of aspect A70 or A71, or any of the preceding aspects, wherein during the circulating step, the dissolution solution is circulated between the electrochemical cell and any two or any three of the first, second and third dissolution tanks sequentially in any order and / or simultaneously.

[0312]

[0341] Aspect A73: The method or system of aspect A72 or any of the preceding aspects, wherein the circulating step includes first circulating the dissolving solution between the electrochemical cell and a third dissolving tank having the raw ore, then circulating the dissolving solution a second time between the electrochemical cell and a second dissolving tank having the air roasted ore, and then circulating the dissolving solution a third time between the electrochemical cell and the first dissolving tank having the thermally reduced ore.

[0313]

[0342] Aspect A74: The method or system of any one of aspects A70-A73 or any of the preceding aspects, wherein the dissolution solution is or comprises an acidic iron salt solution.

[0314]

[0343] Aspect A75: The method or system of any one of aspects A64-A74 or any of the preceding aspects, wherein the first dissolving tank further contains air roasted ore, raw ore, or both during any portion of the dissolving step.

[0315]

[0344] Aspect A76: The method or system of any one of aspects A64-A75 or any of the preceding aspects, wherein the second dissolving tank further contains thermally reduced ore, raw ore, or both during any portion of the dissolving step.

[0316]

[0345] Aspect A77: The method or system of any one of aspects A64-A76 or any of the preceding aspects, wherein the third dissolving tank further contains air roasted ore, thermally reduced ore, or both during any portion of the dissolving step.

[0317]

[0346] Aspect A78: The method or system of any one of the preceding aspects, wherein the dissolving step occurs in at least one dissolving tank; and the dissolving step further comprises introducing the air roasted ore, the raw ore, or both into an acidic iron salt solution in the at least one dissolving tank in the presence of the thermally reduced ore.

[0318]

[0347] Embodiment A79: The method or system of any one of the preceding embodiments, wherein the one or more non-magnetite iron oxide materials include hematite and / or goethite.

[0319]

[0348] Aspect A80: The method or system of any one of the preceding aspects, wherein the acid comprises hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid, oxalic acid, boric acid, methanesulfonic acid, or any combination thereof.

[0320]

[0349] Aspect A81: A method for processing and smelting iron-bearing ores, comprising: In the dissolving tank, the iron-bearing ore is contacted with an acid to dissolve at least a portion of the iron-bearing ore, thereby forming dissolved Fe 3+ forming an acidic iron salt solution having ions; recirculating at least a portion of the acidic iron salt solution between the dissolution tank and a cathode chamber of an electrochemical cell, the electrochemical cell comprising a cathode in the presence of at least a portion of the acidic iron salt solution functioning as a catholyte in the cathode chamber, an anode in the presence of an anolyte, and a separator separating the catholyte from the anolyte; Fe dissolved from the catholyte at the cathode 3+ At least a portion of the ions are electrochemically reduced to Fe in the catholyte. 2+ forming ions; electrochemically generating protons in the electrochemical cell and supplying the electrochemically generated protons to a catholyte; wherein the acidic iron salt solution in the dissolution tank is characterized by a steady state concentration of free protons of at least 0.2M (optionally, e.g., at least 0.2, 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5M, optionally the steady state free proton concentration is less than 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6M, such values ​​may be combined in any manner to form a range, such as 0.2 to 6M).

[0321]

[0350] Aspect A82: A method of processing and smelting iron-bearing ores, comprising: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; The reducing agent comprises H2 gas; at least a portion of the H2 gas is generated chemically via a reaction between iron metal and an acid, and / or at least a portion of the H2 gas is generated electrochemically via a parasitic hydrogen evolution reaction of the iron electroplating process; dissolving at least the thermally reduced ore using an acidic solution to form an iron salt solution; and wherein the dissolving step comprises dissolving the formed magnetite in said acidic solution.

[0322]

[0351] Aspect A83: A system for processing and smelting iron-bearing ores, comprising: a first smelting tank for smelting a first iron-bearing ore using a first acid; Dissolution of the first ore in the first acid produces dissolved Fe in the first dissolution tank. 3+ a first dissolution tank for forming a first acidic iron salt solution containing ions; an electrochemical cell fluidly connected to the first dissolving tank; an electrochemical cell comprising a cathode chamber having a catholyte in the presence of a cathode, an anode chamber having an anolyte in the presence of an anode, and a separator separating the catholyte and the anolyte; a first circulation subsystem for circulating at least a portion of the first acidic iron salt solution from the first dissolving tank to the cathode chamber and at least a portion of the catholyte from the electrochemical cell to the first dissolving tank; from a first acidic iron salt solution; 3+ At least a portion of the ions are converted to Fe at the cathode in the catholyte. 2+ ions from the first acidic iron salt solution, thereby 3+ ions consuming,system.

[0323]

[0352] Aspect A84: The method or system of aspect A83 or any of the preceding aspects, wherein protons are electrochemically generated in the electrochemical cell and supplied to the catholyte, thereby at least partially replenishing acid consumed during dissolution.

[0324]

[0353] Aspect A85: The method or system of aspect A84 or any of the preceding aspects, wherein protons are electrochemically generated in the anolyte and pass through the separator towards the catholyte.

[0325]

[0354] Aspect A86: The acidic iron salt solution in the dissolving tank is characterized by a steady state concentration of free protons of at least 0.2 M in the presence of iron-containing ore (optionally, e.g., at least 0.2, 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5 M, optionally the steady state free proton concentration is less than 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6 M, such values ​​may be combined in any manner to form a range, such as 0.2 to 6 M). and / or is characterized by a steady state pH of 0.7 or less (e.g., 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1 or less, optionally the steady state pH is at least 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, such values ​​may be combined in any manner to form a range, such as from -1 to 0.7).

[0326]

[0355] Embodiment A87: The method or system of any one of the preceding embodiments, wherein the anolyte comprises water or a saltwater solution; water is electrochemically oxidized at the anode to generate protons in the anolyte; and the generated protons are transported through the separator to the catholyte.

[0327]

[0356] Embodiment A88: The method or system of any one of the preceding embodiments, wherein the anolyte has a different composition than the catholyte.

[0328]

[0357] Embodiment A89: The method or system of any one of the preceding embodiments, wherein the first iron-bearing ore comprises a thermally reduced ore having magnetite.

[0329]

[0358] Aspect A90: In the presence of a reducing agent, the reaction temperature is adjusted to 200°C to 600°C (e.g., 200 to 550, 200 to 500, 200 to 450, 200 to 400, 200 to 350, 200 to 300, 200 to 250, 250 to 600, 250 to 550, 250 to 500, 250 to 400, 300 to 600, 300 to 550, 300 to 500, 300 to 450, 300 to 400, 350 to 600, 350 to 550, 350 to 500, 350 to 450, 4 The method or system of embodiment A69 or any of the above embodiments, further comprising a thermal reduction subsystem configured to form a thermally reduced ore by converting non-magnetite material to magnetite at an elevated temperature selected from the ranges of temperatures (°C) of 00-600, 400-550, 400-500, 450-600, 450-550, or 500-600, wherein the thermally reduced ore is delivered from the thermal reduction subsystem to the first dissolving tank.

[0330]

[0359] Aspect A91: In the presence of air, 200°C to 600°C (e.g., 200 to 550, 200 to 500, 200 to 450, 200 to 400, 200 to 350, 200 to 300, 200 to 250, 250 to 600, 250 to 550, 250 to 500, 250 to 400, 300 to 600, 300 to 550, 300 to 500, 300 to 450, 300 to 400, 350 to 600, 350 to 55 The method or system of embodiment A90 or any of the preceding embodiments, comprising an air roasting subsystem configured to form an air roasted ore by air roasting the iron-containing ore at an elevated temperature selected from the ranges of: 0, 350-500, 350-450, 400-600, 400-550, 400-500, 450-600, 450-550, or 500-600 (temperature (°C)).

[0331]

[0360] Embodiment A92: The method or system of embodiment A91 or any of the preceding embodiments, wherein the air torrefaction subsystem and the thermal reduction subsystem are the same.

[0332]

[0361] Aspect A93: The method or system of any one of the above aspects comprising a second dissolution tank having air roasted ore, wherein the air roasted ore is not thermally reduced and is dissolved at 200° C. to 600° C. (e.g., 200 to 550, 200 to 500, 200 to 450, 200 to 400, 200 to 350, 200 to 300, 200 to 250, 250 to 600, 250 to 550, 250 to 50 an iron-containing ore exposed to air at an elevated temperature selected from the range of temperatures (°C) of 0, 250-400, 300-600, 300-550, 300-500, 300-450, 300-400, 350-600, 350-550, 350-500, 350-450, 400-600, 400-550, 400-500, 450-600, 450-550, or 500-600; The dissolution of the air roasted ore is carried out in a second dissolution tank to produce dissolved Fe 3+ in the presence of a second acidic iron salt solution containing ions; the system further comprising a second circulation subsystem that circulates at least a portion of the second acidic iron salt solution from the second dissolving tank to the cathode chamber and at least a portion of the catholyte from the electrochemical cell to the second dissolving tank; Fe from the second acidic iron salt solution 3+ At least a portion of the ions are converted to Fe at the cathode in the catholyte. 2+ ions from the second acidic iron salt solution, thereby 3+ A method or system for consuming ions.

[0333]

[0362] Aspect A94: The method or system of any one of the preceding aspects comprising a third dissolving tank having raw ore, the raw ore being an iron-bearing ore that has not been thermally reduced or air roasted; The dissolution of the air roasted ore is carried out in the third dissolution tank to produce dissolved Fe 3+ in the presence of a third acidic iron salt solution containing ions, the system further comprising a third circulation subsystem that circulates at least a portion of the third acidic iron salt solution from the third dissolving tank to the cathode chamber and at least a portion of the catholyte from the electrochemical cell to the third dissolving tank; Fe from the third acidic iron salt solution 3+ At least a portion of the ions are converted to Fe at the cathode in the catholyte. 2+ ions from the third acidic iron salt solution, thereby 3+ A method or system for consuming ions.

[0334]

[0363] Embodiment A95: The method or system of any one of the preceding embodiments, configured to generate an iron-rich solution having an iron ion concentration selected from the range of 1 M to 4 M (e.g., 1 to 3.5, 1 to 3, 1 to 2.5, 1 to 2, 1 to 1.5, 1.5 to 4, 1.5 to 3.5, 1.5 to 3, 1.5 to 2.5, 1.5 to 2, 2 to 4, 2 to 3.5, 2 to 3, 2 to 2.5, 2.5 to 4, 2.5 to 3.5, 2.5 to 3, 3 to 4, or 3 to 3.5).

[0335]

[0364] Aspect A96: The method or system of any of the above or below aspects, wherein the dissolving step is stopped when the proton concentration (optionally the steady state proton concentration) in the acidic iron salt solution is less than or equal to 0.4M (optionally 0.3M, optionally 0.2M, optionally 0.1M) (optionally after exceeding this threshold for the majority of the time that the dissolving step is performed).

[0336]

[0365] Aspect A97: The method or system of any of the above or below aspects, wherein the dissolving step is stopped when the total iron ion concentration in the first catholyte, the acidic iron salt solution, and / or the produced iron-rich solution reaches a desired maximum value (optionally a steady state value) of 1M, optionally 2M, optionally 3M, optionally 4M, optionally any value or range between 1M and 4M inclusive.

[0337]

[0366] Aspect B1a: A method for producing iron, comprising: providing a feedstock having iron-bearing ore to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; the first anolyte having a different composition than the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+ forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; The formed Fe 2+ transferring the ions from the dissolution subsystem to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; The method includes:

[0338]

[0367] Aspect B1b: A method for producing iron, comprising: providing a feedstock having iron-bearing ore to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having H2 gas in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anode chamber from the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; The formed Fe 2+ transferring the ions from the dissolution subsystem to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; The method includes:

[0339]

[0368] Aspect B1c: A system for producing iron, comprising: a dissolving subsystem having a dissolving tank and a first electrochemical cell fluidly connected to the dissolving tank; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; a dissolution subsystem, wherein the first anolyte has a different composition than the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first inter-subsystem fluid connection between the dissolving subsystem and the iron plating subsystem; Equipped with A melting tank receives a feedstock having iron-bearing ore; The dissolving tank dissolves at least a portion of the iron-containing ore to produce a dissolved first Fe 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions, The formed Fe 2+ ions are transferred from the dissolution subsystem to the iron plating subsystem via the first inter-subsystem fluid connection; A second electrochemical cell was used to measure the amount of the transferred Fe 2+ a second cathode for reducing at least a first portion of the ions to Fe metal; The system wherein Fe metal is removed from the second electrochemical cell.

[0340]

[0369] Aspect B1d: A system for producing iron, comprising: a dissolving subsystem having a dissolving tank and a first electrochemical cell fluidly connected to the dissolving tank; a dissolution subsystem, the first electrochemical cell comprising a first anode chamber having H2 gas in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anode chamber from the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first inter-subsystem fluid connection between the dissolving subsystem and the iron plating subsystem; Equipped with A melting tank receives a feedstock having iron-bearing ore; The dissolving tank dissolves at least a portion of the iron-containing ore to produce a dissolved first Fe 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions, The formed Fe 2+ ions are transferred from the dissolution subsystem to the iron plating subsystem via the first inter-subsystem fluid connection; A second electrochemical cell was used to measure the amount of the transferred Fe 2+ a second cathode for reducing at least a first portion of the ions to Fe metal; The system wherein Fe metal is removed from the second electrochemical cell.

[0341]

[0370] Aspect B2: The method or system of any of the above aspects, comprising electrochemically generating protons in a first electrochemical cell and supplying the electrochemically generated protons to the acidic iron salt solution during the dissolving step.

[0342]

[0371] Aspect B3: The method or system of aspect B2 or any of the above aspects, wherein the electrochemically generated protons being generated and provided to the acidic iron salt solution promote an acidic iron salt solution characterized by a steady state pH of 0.7 or less (e.g., 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1 or less during the dissolving step, optionally the steady state pH is at least 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, such values ​​may be combined in any manner to form a range, such as from -1 to 0.7).

[0343]

[0372] Aspect B4: The method or system of aspect B2 or aspect B3 or any of the above aspects, wherein the electrochemically generated protons being generated and provided to the acidic iron salt solution promote, during the dissolving step, an acidic iron salt solution characterized by a steady state free proton concentration of 0.2 M or greater (e.g., 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5 M or greater, optionally the steady state free proton concentration is less than 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6 M, such values ​​may be combined in any manner to form a range, such as 0.2-6 M).

[0344]

[0373] Aspect B5: During the dissolving step, Fe is dissolved from the acidic iron salt solution. 3+ The first Fe ion is continuously removed from the first catholyte. 3+4. The method or system of any one of the preceding aspects, comprising promoting dissolution of the iron-bearing ore by a first electrochemical reduction of ions.

[0345]

[0374] Aspect B6: The method or system of any one of the preceding aspects, wherein the first anolyte has a different pH than the first catholyte.

[0346]

[0375] Aspect B7: The method or system of any one of the preceding aspects, wherein the first catholyte has a lower pH than the first anolyte.

[0347]

[0376] Aspect B8: The method or system of any one of the preceding aspects, wherein the first anolyte comprises dissolved salts of a different composition than the composition in the first catholyte.

[0348]

[0377] Aspect B9: The method or system of any one of the above aspects, wherein the first anolyte contains one or more dissolved ferric salts and the first analyte is characterized by a total concentration of the one or more dissolved ferric salts greater than or equal to a total iron ion concentration in the first catholyte.

[0349]

[0378] Embodiment B10: The method or system of any one of the preceding embodiments, wherein the first catholyte comprises one or more supporting salts.

[0350]

[0379] Aspect B11: The method or system of Aspect B10 or any of the preceding aspects, wherein the first catholyte comprises one or more supporting salts at a concentration selected from the range of 0.1 to 1 M (e.g., 0.2 to 0.8 M, 0.4 to 0.6 M, 0.1 to 0.4 M, 0.4 to 0.8 M, or 0.8 to 1 M).

[0351]

[0380] Aspect B12: The method or system of aspect B10 or B11 or any of the preceding aspects, wherein the one or more supporting salts comprise one or more metal sulfate compounds and / or one or more metal chloride compounds.

[0352]

[0381] Embodiment B13: The method or system of embodiment B12 or any of the preceding embodiments, wherein the one or more metal sulfate compounds comprise potassium sulfate, sodium sulfate, ammonium sulfate, lithium sulfate, potassium chloride, sodium chloride, ammonium chloride, lithium chloride, or a combination thereof.

[0353]

[0382] Aspect B14: The method or system of any one of the preceding aspects, wherein the first anolyte is characterized by at least one redox pair different from the first catholyte.

[0354]

[0383] Aspect B15: The method or system of any one of the preceding aspects, wherein the first anolyte comprises a higher total concentration of dissolved salts than the first catholyte.

[0355]

[0384] Aspect B16: The method or system of any one of Aspects B1-B8 and B10-B14 or any of the preceding aspects, wherein the first anolyte comprises a lower total concentration of dissolved salts than the first catholyte.

[0356]

[0385] Aspect B17: The method or system of any one of the preceding aspects, wherein the first anolyte is in ionically connected with the first catholyte through a first separator.

[0357]

[0386] Aspect B18: The method or system of aspect B17 or any of the preceding aspects, wherein the first anolyte is fluidly separated from the first catholyte.

[0358]

[0387] Aspect B19: The method or system of any one of the above aspects, wherein the first separator is an ion exchange membrane.

[0359]

[0388] Aspect B20: The method or system of aspect B19 or any of the preceding aspects, wherein the first separator is a proton exchange membrane (PEM).

[0360]

[0389] Aspect B21: the dissolution subsystem comprises a first dissolution tank fluidly connected to the first electrochemical cell; Melted first Fe 3+ a dissolving step is performed in the dissolving tank such that ions are generated in the dissolving tank; The method includes a first step of circulating at least a portion of an acidic iron salt solution between a dissolving tank and a first electrochemical cell; The first circulation step is a first Fe 3+ The first circulation step includes feeding at least a portion of the acidic iron salt solution having at least a portion of the ions from the dissolution tank to a first cathode chamber, the first circulation step being carried out to obtain a first cathode chamber having at least a portion of the formed Fe 2+ The method or system of any one of the preceding aspects, further comprising providing ions from the first catholyte to the first dissolution tank.

[0361]

[0390] Aspect B22: The method or system of aspect B21 or any of the preceding aspects, wherein a portion of the acidic iron salt solution provided to the first cathode chamber serves as at least a portion of the first catholyte such that the first catholyte comprises at least a portion of the acidic iron salt solution.

[0362]

[0391] Aspect B23: The method or system of aspect B21 or B22 or any of the preceding aspects, wherein all of the acidic iron salt solution is circulated between the first dissolving tank and the first electrochemical cell.

[0363]

[0392] Aspect B24: The method or system of aspect B21, B22, or B23, or any of the preceding aspects, comprising: electrochemically generating aqueous protons by oxidizing water in the first anolyte and supplying the electrochemically generated protons to the first catholyte; and the circulating step comprises supplying the electrochemically generated aqueous protons from the first catholyte to the dissolving tank such that during the dissolving step, the acidic iron salt solution in the first dissolving tank contains electrochemically generated protons.

[0364]

[0393] Aspect B25: The method or system of aspect B24 or any of the preceding aspects, wherein the water oxidized in the first electrochemical cell is produced by dissolution of iron-bearing ore in a dissolution tank; and the circulating step includes supplying produced water from the first dissolution tank to the first catholyte.

[0365]

[0394] Aspect B26: The method or system of any one of the preceding aspects, comprising providing water from the first catholyte to the first anolyte.

[0366]

[0395] Aspect B27: Fe formed in the dissolution subsystem 2+ forming an iron-rich solution having Fe ions; 2+ 4. The method or system of any one of the preceding aspects, wherein the step of transferring ions includes removing at least a portion of the iron-rich solution from the dissolving subsystem and transferring the transferred iron-rich solution to the iron plating subsystem; and the transferred iron-rich solution includes at least a portion of the removed iron-rich solution.

[0367]

[0396] Aspect B28: Formed Fe 2+ The method or system of embodiment B27 or any of the preceding embodiments, wherein the delivered iron-rich solution having ions is characterized by a pH of greater than 0.5 (e.g., greater than 0.5, 0.6, 0.7, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, optionally a pH less than 0.6, 0.7, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, such pHs may be combined in any manner to form a range such as from 0.5 to 6).

[0368]

[0397] Aspect B29: The method or system of aspect B28 or any of the preceding aspects, wherein the delivered iron-rich solution is characterized by a pH of 1 or greater (e.g., greater than 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6; optionally, the pH is less than 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, such pHs may be combined in any manner to form a range such as from 1 to 6).

[0369]

[0398] Aspect B30: The method or system of aspect B29 or any of the preceding aspects, wherein the delivered iron-rich solution is characterized by a pH selected from the range of 2 to 6 (e.g., greater than 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6; optionally, the pH is less than 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, such pHs may be combined in any manner to form a range).

[0370]

[0399] Aspect B31: The transported iron-rich solution is 3+ Fe ions at higher concentrations 2+ The method or system of any one of aspects B27-B30 or any of the preceding aspects, comprising ions.

[0371]

[0400] Aspect B32: The transported iron-rich solution has an Fe content of 0.01 or less. 2+ Fe ions 3+ The method or system of any one of embodiments B27-B31 or any of the preceding embodiments, characterized by a ratio of concentrations of ions (e.g., less than or equal to 0.01, 0.0075, 0.005, 0.0025, or 0.001, optionally the ratio is greater than or equal to 0.0075, 0.005, 0.0025, or 0.001, such values ​​may be combined in any manner to form a range, such as from 0.001 to 0.01).

[0372]

[0401] Aspect B33: The method or system of any one of aspects B27-B32 or any of the preceding aspects, wherein the delivered iron-rich solution is delivered directly or indirectly to a second cathode chamber; and the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode.

[0373]

[0402] Aspect B34: The method or system of aspect B33 or any of the above aspects, wherein at least 70% (e.g., at least 70%, 75%, 80%, 85%, 90%, 95%, 99%, or 100%, optionally such values ​​being less than 75%, 80%, 85%, 90%, 95%, 99%, or 100%, and which may be combined in any manner to form a range, such as 70-99%) of the delivered iron-rich solution is delivered directly or indirectly to the second cathode chamber.

[0374]

[0403] Aspect B35: The method or system of aspect B34 or any of the preceding aspects, wherein at least 90% of the delivered iron-rich solution is delivered directly or indirectly to the second cathode chamber.

[0375]

[0404] Aspect B36: The method or system of any one of aspects B33-B35 or any of the preceding aspects, wherein the second electrochemical reducing step forms a second spent catholyte, the second spent catholyte having a lower concentration of iron ions than the delivered iron-rich solution; at least a portion of the second spent catholyte is provided to the second anodic chamber; and the second electrochemical cell comprises a second anodic chamber having the second anolyte in the presence of a second anode.

[0376]

[0405] Aspect B37: The method or system of aspect B36 or any of the preceding aspects, wherein a spent second catholyte is formed when the second electrochemical reducing step is completed or stopped.

[0377]

[0406] Aspect B38: The method or system of aspect B36 or B37 or any of the preceding aspects, wherein the spent second catholyte is characterized by a concentration of iron ions that is between 60% and 70% (e.g., 62-68%, 64-66%, 60-65%, or 65-70%) of the concentration of iron ions in the delivered iron-rich solution.

[0378]

[0407] Aspect B39: The method or system of aspect B37 or any of the preceding aspects, wherein the second electrochemical reducing step is completed or stopped when the concentration of iron ions in the second catholyte falls to between 60% and 70% (e.g., between 62-68%, between 64-66%, between 60-65%, or between 65-70%) of the concentration of iron ions in the delivered iron-rich solution.

[0379]

[0408] Aspect B40: The method or system of any one of aspects B27-B33 or any of the preceding aspects, wherein a first portion of the delivered iron-rich solution is delivered directly or indirectly to a second cathode chamber; a second portion of the delivered iron-rich solution is delivered directly or indirectly to a second anodic chamber; the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode, and the second electrochemical cell comprises a second anodic chamber having a second anolyte in the presence of a second anode.

[0380]

[0409] Aspect B41: The method or system of aspect B40 or any of the preceding aspects, wherein the first portion is between 25 vol.% and 45 vol.% (e.g., between 30 and 40 vol.%, between 32 and 38 vol.%, between 25 and 35 vol.%, or between 35 and 45 vol.%) of the delivered iron-rich solution and the second portion is between 55 vol.% and 75 vol.% (e.g., between 60 and 70 vol.%, between 62 and 68 vol.%, between 55 and 65 vol.%, or between 65 and 75 vol.%) of the delivered iron-rich solution.

[0381]

[0410] Aspect B42: The first portion is Fe of the transported iron-rich solution 2+and a second portion comprising 25 mol.% to 45 mol.% (e.g., 30-40 mol.%, 32-38 mol.%, 25-35 mol.%, or 35-45 mol.%) of the delivered iron-rich solution. 2+ The method or system of embodiment B40 or B41 or any of the preceding embodiments, comprising 55 mol.% to 75 mol.% (e.g. 60 to 70 mol.%, 62 to 68 mol.%, 55 to 65 mol.%, or 65 to 75 mol.%) of the

[0382]

[0411] Aspect B43: The method or system of any one of aspects B27-B42 or any of the preceding aspects, wherein the transferring step further comprises treating the removed portion of the iron-rich solution prior to the conveying step, thereby forming a treated iron-rich solution; and the conveyed iron-rich solution comprises at least a portion of the treated iron-rich solution.

[0383]

[0412] Aspect B44: The method or system of aspect B43 or any of the preceding aspects, wherein the treating step comprises increasing the pH of the removed portion of the iron-rich solution.

[0384]

[0413] Aspect B45: The method or system of aspect B43 or B44 or any of the preceding aspects, wherein the treating step comprises increasing the pH of the removed portion of the iron-rich solution by providing metallic iron in the presence of the removed portion of the iron-rich solution; and a reaction between the removed portion of the iron-rich solution and the provided metallic iron consumes protons of the removed portion of the iron-rich solution.

[0385]

[0414] Aspect B46: The method or system of aspect B45 or any of the preceding aspects, wherein increasing the pH of the removed portion of the iron-rich solution further comprises providing magnetite in the presence of the removed portion of the iron-rich solution prior to and / or simultaneously with providing metallic iron in the presence of the removed portion of the iron-rich solution.

[0386]

[0415] Aspect B47: The method or system of aspect B45 or B46 or any of the preceding aspects, wherein the reaction between the removed portion of the iron-rich solution and the provided metallic iron chemically produces H2 gas; and the method further comprises collecting the chemically produced H2 gas.

[0387]

[0416] Aspect B48: The method or system of any one of aspects B43-B47 or any of the preceding aspects, wherein the treated ferrous solution has a pH selected from the range of 2 to less than 7 (e.g., 2 to 4, 4 to 6, 6 to less than 7, 3 to less than 7, 3 to 6, or 4 to 5).

[0388]

[0417] Aspect B49: Fe 2+ ions are electrochemically oxidized to produce a second Fe 3+ forming ions; the second electrochemical cell comprising a second cathode chamber having a second catholyte in the presence of a second cathode, and the second electrochemical cell comprising a second anodic chamber having a second anolyte in the presence of a second anode.

[0389]

[0418] Aspect B50: The method includes recycling a first recycled solution from the iron plating subsystem to the dissolving subsystem; the recycled solution containing a second Fe anolyte formed in the second anolyte. 3+ The method or system of embodiment B49 or any of the preceding embodiments, comprising ions.

[0390]

[0419] Aspect B51: The method or system of aspect B50 or any of the preceding aspects, wherein the recycling step occurs after the second electrochemical reducing step is completed or stopped.

[0391]

[0420] Aspect B52: The method or system of aspect B50 or B51 or any of the preceding aspects, wherein the first recycle solution is provided to a first dissolving tank; and the dissolving step occurs in the first dissolving tank containing the iron-bearing ore and an acidic iron salt solution.

[0392]

[0421] Aspect B53: The method or system of aspect B50, B51, or B52 or any of the preceding aspects, wherein the first recycle solution comprises at least a portion of the second catholyte and the second anolyte from the second electrochemical cell.

[0393]

[0422] Aspect B54: The method or system of any one of aspects B27-B53 or any of the preceding aspects, wherein the second electrochemical reducing step is completed or stopped when the second catholyte of the second electrochemical cell is characterized by a total concentration of iron ions that is between 60% and 70% (optionally between 50 and 80%, optionally between 62 and 68%, 64 and 66%, 60 and 65%, or 65 and 70%) of the concentration of iron ions in the (i) delivered iron-rich solution or (ii) produced iron-rich solution.

[0394]

[0423] Aspect B55: Any of the above aspects.

[0395]

[0424] Aspect B56: Any of the above aspects.

[0396]

[0425] Aspect B57: The method or system of any one of the preceding aspects, wherein the second electrochemical reducing step is completed or stopped when the average thickness of the formed Fe metal on the second cathode of the second electrochemical cell is selected from the range of 1 mm to 10 mm (e.g., 1-10, 1-8, 1-6, 1-4, 1-2, 2-10, 2-8, 2-6, 2-4, 4-10, 4-8, 4-6, 6-10, 6-8, or 8-10 average thickness (mm)).

[0397]

[0426] Aspect B58: Any of the above aspects.

[0398]

[0427] Aspect B59: The method or system of any one of the preceding aspects, wherein the iron plating subsystem comprises a first circulation tank configured to circulate the second catholyte between the second cathode chamber of the second electrochemical cell and the first circulation tank; and the iron plating subsystem comprises a second circulation tank configured to circulate the second anolyte between the second anode chamber of the second electrochemical cell and the second circulation tank.

[0399]

[0428] Aspect B60: The method or system of aspect B59 or any of the preceding aspects, wherein the iron-rich solution that is indirectly delivered to the second cathode chamber is delivered to the first circulation tank.

[0400]

[0429] Aspect B61: The method or system of any one of the preceding aspects, wherein the second electrochemical cell comprises a second catholyte and a second anolyte separated by a second separator.

[0401]

[0430] Aspect B62: The method or system of aspect B61, wherein the second separator is a PEM or an anion exchange membrane (AEM) or a microporous separator.

[0402]

[0431] Aspect B63: The method or system of any one of the preceding aspects, wherein the first electrochemical cell is operated at a different current density than the second electrochemical cell.

[0403]

[0432] Embodiment B64: The method or system of any one of the preceding embodiments, wherein the first electrochemical cell is operated simultaneously at a different current density than the second electrochemical cell.

[0404]

[0433] Embodiment B65: The method or system of embodiment B63 or B64, or any of the preceding embodiments, wherein the first electrochemical cell is operated at a higher current density than the second electrochemical cell.

[0405]

[0434] Aspect B66: The first electrochemical cell has a current density of 0.1 to 2 A / cm 2A current density selected from the range of (for example, a current density (A / cm) of 0.1 to 2, 0.1 to 1.5, 0.1 to 1, 0.1 to 0.5, 0.5 to 2, 0.5 to 1.5, 0.5 to 1, 1 to 2, 1 to 1.5, or 1.5 to 2 2 ) and the second electrochemical cell is operated at 20-300 mA / cm 2 A current density (mA / cm) selected from the range of 20 to 300, 20 to 250, 20 to 200, 20 to 150, 20 to 100, 20 to 50, 50 to 300, 50 to 250, 50 to 200, 50 to 150, 50 to 100, 100 to 300, 100 to 250, 100 to 200, 100 to 150, 150 to 300, 150 to 250, 150 to 200, 200 to 300, 200 to 250, or 250 to 300 2 The method or system of embodiment B63, B64 or B65 or any of the preceding embodiments, wherein the method or system operates as follows:

[0406]

[0435] Aspect B67: The method or system of any one of the preceding aspects, comprising repeating the method for at least 5 cycles (e.g., at least 5, 6, 7, 8, 9, 10, 15, 20, 30, 50, or 100 cycles, optionally the cycles are less than 6, 7, 8, 9, 10, 15, 20, 30, 50, 100, or 150, each such value may be combined in any manner to form a range, such as from 5 to 150).

[0407]

[0436] Aspect B68: The method or system of any one of the preceding aspects, wherein the iron-bearing ore comprises one or more iron oxide materials.

[0408]

[0437] Aspect B69: The method or system of any of the above aspects, wherein the one or more iron oxide materials comprise hematite, maghemite, ferrihydrite, magnetite, goethite, akaganeite, lepidocrocite, ferroxyhite, or any combination thereof.

[0409]

[0438] Aspect B70: The method or system of any one of the preceding aspects, wherein the dissolving step comprises dissolving magnetite in the iron-containing ore.

[0410]

[0439] Aspect B71: The method or system of any one of the preceding aspects, comprising generating H2 gas and collecting the generated H2 gas.

[0411]

[0440] Aspect B72: The method or system of aspect B47 or B71 or any of the preceding aspects, wherein at least a portion of the collected H2 gas is oxidized and used as a reducing agent in a process for the thermal reduction of iron-bearing ore.

[0412]

[0441] Aspect B73: The method or system of any one of the preceding aspects, comprising electrically controlling the first electrochemical cell to prevent Fe metal electroplating at the first cathode.

[0413]

[0442] Aspect B74: The method or system of any one of the preceding aspects, wherein the second electrochemical cell is operated at a temperature selected from the range of 40°C to 80°C (e.g., 45-75°C, 50-70°C, 55-65°C, 40-55°C, 55-70°C, 40-70°C, or 50-80°C).

[0414]

[0443] Aspect B75: The method or system of any one of the preceding aspects, wherein the second electrochemical cell comprises a second catholyte and a second anolyte; and the second anolyte has a lower pH than the second catholyte.

[0415]

[0444] Aspect B76: The method or system of aspect B75 or any of the preceding aspects, wherein the pH of the second anolyte is lower than the pH of the solubility limit of Fe(III)(OH)2.

[0416]

[0445] Aspect B77: The method or system of aspect B75 or B76 or any of the preceding aspects, wherein the second catholyte has a pH of less than 6 during the second electrochemical reducing step (e.g., less than 6, 5.5, 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, 0, -0.5, or -1, optionally the pH is at least 5.5, 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, 0, -0.5, or -1, any of such values ​​may be combined in any manner to form a range from -1 to 6, etc.).

[0417]

[0446] Embodiment B78: The method or system of any one of the preceding embodiments, wherein the removed Fe metal comprises at least 99 wt.% (e.g., at least 99 wt.%, at least 99.5 wt.%, at least 99.9 wt.%, or 100 wt.%) Fe.

[0418]

[0447] Embodiment B79: The method or system of any one of the preceding embodiments, wherein the first anode has a composition including lead, lead oxide, manganese oxide, mixed metal oxide, iridium oxide, ruthenium oxide, or any combination thereof.

[0419]

[0448] Embodiment B80: The method or system of any one of the preceding embodiments, wherein the first cathode has a composition including carbon, graphite, titanium, or any combination thereof.

[0420]

[0449] Embodiment B81: The method or system of any one of the preceding embodiments, wherein the second anode has a composition including carbon, graphite, lead, lead oxide, mixed metal oxides, or any combination thereof.

[0421]

[0450] Embodiment B82: The method or system of any one of the preceding embodiments, wherein the second cathode has a composition comprising steel, low carbon steel, stainless steel, copper, a copper alloy, or any combination thereof.

[0422]

[0451] Aspect B83: A system for producing iron, comprising: a dissolving subsystem having a dissolving tank and a first electrochemical cell fluidly connected to the dissolving tank; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; a dissolution subsystem, wherein the first anolyte has a different composition than the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first inter-subsystem fluid connection between the dissolving subsystem and the iron plating subsystem; Equipped with A melting tank receives a feedstock having iron-bearing ore; The dissolving tank dissolves at least a portion of the iron-containing ore to produce a dissolved first Fe 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions; The formed Fe 2+ ions are transferred from the dissolution subsystem to the iron plating subsystem via the first inter-subsystem fluid connection; A second electrochemical cell was used to measure the amount of the transferred Fe 2+ a second cathode for reducing at least a first portion of the ions to Fe metal; The system wherein Fe metal is removed from the second electrochemical cell.

[0423]

[0452] Embodiment B84: The method or system of embodiment B83 or any of the preceding embodiments, wherein the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode, and the second electrochemical cell comprises a second anodic chamber having a second anolyte in the presence of a second anode.

[0424]

[0453] Aspect B85: Fe 2+ The ions are converted to Fe in the second anolyte. 3+ The method or system of embodiment B84 or any of the preceding embodiments, wherein the ions are oxidized to ions.

[0425]

[0454] Aspect B86: The dissolution subsystem comprises a formed Fe 2+ The method or system of any one of embodiments B83-B85 or any of the preceding embodiments, producing an iron-rich solution having ions; and the system comprising a transfer subsystem for removing at least a portion of the produced iron-rich solution and processing the removed portion of the iron-rich solution, thereby forming a processed iron-rich solution.

[0426]

[0455] Embodiment B87: The method or system of any one of embodiments B84-B87 or any of the preceding embodiments, comprising a spent electrolyte recycling system configured to recycle the first recycled solution from the second electrochemical cell to the dissolution subsystem.

[0427]

[0456] Aspect B88: The method or system of aspect B87 or any of the preceding aspects, wherein the first recycle solution comprises at least a portion of the second anolyte and at least a portion of the second catholyte.

[0428]

[0457] Aspect B89: The first recycled solution comprises Fe 2+ The method or system of embodiment B87 or any of the preceding embodiments, wherein the second anolyte is formed by mixing at least a portion of the second catholyte with at least a portion of the second anolyte after reduction of ions to Fe metal is completed or stopped.

[0429]

[0458] Aspect B90: A method for producing iron, comprising: providing a feedstock having iron-bearing ore to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having H2 gas in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anode chamber from the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+ forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; The formed Fe 2+ transferring the ions from the dissolution subsystem to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; The method includes:

[0430]

[0459] Aspect B91: The method or system of aspect B90 or any of the preceding aspects, comprising oxidizing H2 gas at the first anode to electrochemically produce protons.

[0431]

[0460] Aspect B92: The method or system of any of the above or below aspects, wherein the dissolving step is stopped when the proton concentration (optionally the steady state proton concentration) in the acidic iron salt solution is less than or equal to 0.4M (optionally 0.3M, optionally 0.2M, optionally 0.1M) (optionally after exceeding this threshold for the majority of the time that the dissolving step is performed).

[0432]

[0461] Aspect B93: The method or system of any of the above or below aspects, wherein the dissolving step is stopped when the total iron ion concentration in the first catholyte, the acidic iron salt solution, and / or the produced iron-rich solution reaches a desired maximum value (optionally a steady state value) of 1M, optionally 2M, optionally 3M, optionally 4M, optionally any value or range between 1M and 4M inclusive.

[0433]

[0462] Aspect C1a: A method for producing iron, comprising: providing a feedstock having an iron-bearing ore and one or more impurities to a smelting subsystem comprising a first electrochemical cell; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; Using an acid to dissolve at least a portion of the iron-containing ore to obtain a dissolved first Fe 3+ forming an acidic iron salt solution having ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; The first Fe in the first catholyte 3+ ions are first electrochemically reduced to Fe 2+ forming ions; Producing an iron-rich solution in the dissolution subsystem, the iron-rich solution comprising the formed Fe 2+ having at least a portion of the ions and at least a portion of the one or more impurities; At least a first portion of the iron-rich solution is treated to remove at least a portion of one or more impurities from the iron-rich solution, thereby forming Fe 2+ forming a treated iron-rich solution having at least a portion of the ions; a treating step comprising increasing the pH of the iron-rich solution from an initial pH to an adjusted pH, thereby precipitating at least a portion of the one or more impurities in the treated iron-rich solution; conveying at least a first portion of the treated iron-rich solution to an iron plating subsystem having a second electrochemical cell; Transported and formed Fe 2+ a second electrochemical reduction of at least a first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; removing Fe metal from the second electrochemical cell, thereby producing iron; The method includes:

[0434]

[0463] Aspect C1b: A system for producing iron, comprising: a dissolving subsystem having a first dissolving tank and a first electrochemical cell fluidly connected to the first dissolving tank; a dissolution subsystem, the first electrochemical cell comprising a first cathode chamber having a first anolyte in the presence of a first anode, a second anode chamber having the first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first impurity removal subsystem; Equipped with a first dissolving tank receiving a feedstock having one or more iron-bearing ores and one or more impurities; The first dissolving tank dissolves at least a portion of the one or more iron-containing ores to produce a first Fe dissolved in an acidic iron salt solution. 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+ providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; First Fe 3+ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions, In the dissolution subsystem, an iron-rich solution is formed, and the iron-rich solution is dissolved in the Fe 2+ at least a portion of the ions and at least a portion of the one or more impurities; At least a portion of the iron-rich solution is fed to a first impurity removal subsystem to remove at least a portion of one or more impurities from the iron-rich solution, thereby forming Fe 2+ A treated iron-rich solution having at least a portion of the ions is formed; increasing the pH of the iron-rich solution from an initial pH to an adjusted pH in a first impurity removal subsystem to precipitate a removed portion of the one or more impurities; conveying at least a first portion of the treated iron-rich solution from the first impurity removal subsystem to an iron plating subsystem; A second electrochemical cell was used to measure the amount of transported Fe 2+ a second cathode for reducing at least a portion of the ions to Fe metal; The system wherein Fe metal is removed from the second electrochemical cell.

[0435]

[0464] Aspect C2: The method or system of aspect C1a or C1b or any of the preceding aspects, wherein dissolving at least a portion of the iron-bearing ore produces insoluble impurities; and the method further comprises separating and removing at least a portion of the insoluble impurities.

[0436]

[0465] Aspect C3: The method or system of aspect C2 or any of the preceding aspects, wherein removing at least a portion of the insoluble impurities is by filtering and / or separating the insoluble impurities.

[0437]

[0466] Aspect C4: The method or system of aspect C2 or C3, or any of the preceding aspects, wherein the insoluble impurities include quartz, gypsum, and any combination thereof.

[0438]

[0467] Aspect C5a: The adjusted pH is equal to or greater than the precipitation pH of one or more impurities, and Fe 2+ 4. The method or system of any one of the preceding aspects, wherein the pH is below the precipitation pH of the ions, thereby precipitating at least a portion of the one or more impurities.

[0439]

[0468] Aspect C5b: The adjusted pH is equal to or greater than the solubility limit of one or more impurities, and Fe 2+ 4. The method or system of any one of the preceding embodiments, wherein the solubility of the ion is below the solubility limit of the one or more impurities, thereby precipitating at least a portion of the one or more impurities.

[0440]

[0469] Aspect C6a: The adjusted pH is equal to or greater than the precipitation pH of aluminum, titanium, and phosphate ions, and Fe 2+ The method or system of embodiment C5a or C5b or any of the preceding embodiments, wherein the pH is below the precipitation pH of the ions, thereby precipitating at least a portion of the aluminum, titanium, and phosphorus-containing ions.

[0441]

[0470] Aspect C6b: The adjusted pH is equal to or greater than the solubility limits of aluminum, titanium, and phosphate ions, and Fe 2+ C5a or C5b or the method or system of any of the preceding embodiments, wherein the concentration of the aluminum, titanium, and phosphorus-containing ions is below the solubility limit of the ions, thereby precipitating at least a portion of the aluminum, titanium, and phosphorus-containing ions.

[0442]

[0471] Aspect C7: The method or system of any one of aspects C3-C6 or any of the preceding aspects, comprising precipitating titanium hydroxide, aluminum hydroxide, aluminum phosphate, and / or iron phosphate.

[0443]

[0472] Aspect C8: The method or system of any one of Aspects C3-C7 or any of the preceding aspects, comprising removing at least a portion of the precipitated impurities.

[0444]

[0473] Aspect C9: The method or system of any one of aspects C1-C8 or any of the preceding aspects, wherein the adjusted pH is selected from the range of 3 to 7 (e.g., 3 to 6.5, 3 to 6, 3 to 5.5, 3 to 5, less than 3 to 7, 3 to 6, 3 to 5, 3 to 4, 4 to 7, less than 4 to 7, 4 to 6, 4 to 5, 5 to 7, less than 5 to 7, 5 to 6, 6 to 7, or less than 6 to 7).

[0445]

[0474] Aspect C10: The method or system of aspect C9 or any of the preceding aspects, wherein the adjusted pH is selected from the range of 4 to less than 7 (e.g., 4 to 6.5, 4 to 5.5, 4 to less than 7, 4 to 6, 4 to 5, 5 to less than 7, 5 to 6, or 6 to less than 7).

[0446]

[0475] Embodiment C11: The method or system of any one of embodiments C1-C10 or any of the preceding embodiments, wherein the adjusted pH also results in coagulation of the colloidal silica caused by precipitation of other impurities; the method further comprises removing at least a portion of the colloidal silica.

[0447]

[0476] Aspect C12: The method or system of any one of aspects C1-C11 or any of the preceding aspects, wherein the step of increasing the pH includes providing an iron metallic and / or iron oxide material in the presence of an iron-rich solution; and a reaction between the removed portion of the iron-rich solution and the provided iron metallic and / or iron oxide material consumes protons in the iron-rich solution, thereby increasing its pH.

[0448]

[0477] Aspect C13: The method or system of aspect C12 or any of the preceding aspects, wherein the step of increasing the pH comprises first providing the iron oxide material in the presence of an iron-rich solution, and then providing metallic iron in the presence of an iron-rich solution.

[0449]

[0478] Embodiment C14: The method or system of embodiment C12 or any of the preceding embodiments, wherein increasing the pH of the removed portion of the iron-rich solution further comprises providing an iron oxide material in the presence of the removed portion of the iron-rich solution prior to and / or simultaneously with providing metallic iron in the presence of the removed portion of the iron-rich solution.

[0450]

[0479] Embodiment C15: The method or system of any one of embodiments C12-C14 or any of the preceding embodiments, wherein the iron oxide material comprises magnetite.

[0451]

[0480] Embodiment C16: The method or system of any one of embodiments C12-C15 or any of the preceding embodiments, wherein the provided iron oxide material comprises thermally reduced iron-bearing ore.

[0452]

[0481] Embodiment C17: The method or system of any one of embodiments C12-C16 or any of the preceding embodiments, wherein the metallic iron is part of Fe metal formed during the second electrochemical reducing step.

[0453]

[0482] Aspect C18: The treated ferrous product solution comprises: a concentration of aluminum ions of 1 mM or less than 0.2M (e.g. less than 0.2M, 0.15M, 0.12M, 0.1M, 80mM, 60mM, 50mM, 20mM, 10mM, 5mM, 1mM, optionally the concentration of aluminum ions is 0mM or at least 0.15M, 0.12M, 0.1M, 80mM, 60mM, 50mM, 20mM, 10mM, 5mM, 1mM, each of such values ​​may be combined in any manner to form a range of 0-0.2M or 1mM-0.1M, etc.); and / or

[0036] The method or system of any one of the preceding aspects, characterized by a concentration of phosphorus-containing ions of 1 mM or less than 0.2M (e.g., less than 0.2M, 0.15M, 0.12M, 0.1M, 80mM, 60mM, 50mM, 20mM, 10mM, 5mM, 1mM, optionally the concentration of phosphorus-containing ions is 0mM or at least 0.15M, 0.12M, 0.1M, 80mM, 60mM, 50mM, 20mM, 10mM, 5mM, 1mM, each of such values ​​may be combined in any manner to form a range of 0 to 0.2M or 1mM to 0.1M, etc.).

[0454]

[0483] Embodiment C19: The method or system of any one of the preceding embodiments, wherein the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode, a second anolyte chamber having a second anolyte in the presence of a second anode, and a second separator separating the second catholyte from the second anolyte.

[0455]

[0484] Embodiment C20: The method or system of embodiment C19 or any of the preceding embodiments, wherein the treated iron-rich solution is conveyed directly or indirectly to a second cathode chamber.

[0456]

[0485] Embodiment C21: The method or system of embodiment C20 or any of the preceding embodiments, wherein the treated iron-rich solution is not conveyed to the second anode chamber.

[0457]

[0486] Aspect C22: The method or system of aspect C20 or C21 or any of the preceding aspects, comprising conveying, directly or indirectly, a second portion of the produced iron-rich solution to a second anode chamber; wherein the second portion of the iron-rich solution is untreated or is subjected to a different treatment than the first portion of the iron-rich solution.

[0458]

[0487] Aspect C23: The method or system of any one of the preceding aspects, wherein the iron-rich solution comprises colloidal silica; and the treating step comprises removing at least a portion of the colloidal silica.

[0459]

[0488] Embodiment C24: The method or system of embodiment C23 or any of the preceding embodiments, wherein removing the colloidal silica comprises agglomerating at least a portion of the colloidal silica to produce aggregated colloidal silica.

[0460]

[0489] Aspect C25: The method or system of aspect C23 or C24 or any of the preceding aspects, wherein the step of removing colloidal silica comprises adding polyethylene oxide to the iron-rich solution to promote aggregation of the colloidal silica, thereby producing aggregated colloidal silica.

[0461]

[0490] Aspect C26: The method or system of any one of aspects C23-C25 or any of the preceding aspects, wherein removing the colloidal silica is by filtration, sedimentation, and / or any solid-liquid separation process.

[0462]

[0491] Aspect C27: The method or system of any one of the preceding aspects, wherein the treated iron-rich solution has a colloidal silica content of 10 mM or less (e.g., 10 mM, 8 mM, 6 mM, 5 mM, 4 mM, 2 mM, or 1 mM or less, optionally the colloidal silica content is 0 mM or at least 8 mM, 6 mM, 5 mM, 4 mM, 2 mM, or 1 mM, each of which such values ​​may be combined in any manner to form a range such as 0-10 mM or 1-8 mM).

[0463]

[0492] Aspect C28: The method or system of any one of the preceding aspects, wherein the initial pH is within the range of 0.5 to 1.5 (e.g., 0.5 to 1, 1 to 1.5, 0.8 to 1.3, or 0.7 to 1.4).

[0464]

[0493] Aspect C29: An iron-rich solution is characterized by an initial pH and contains Fe 3+ Fe ions at higher concentrations 2+ 23. The method or system of any one of the preceding aspects, further comprising an ion.

[0465]

[0494] Aspect C30: The iron-rich solution has an Fe content of 0.1 or less. 2+ Fe ions 3+ 3. The method or system of any one of the preceding aspects, characterized by a ratio of concentrations of ions (e.g., 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, or 0.005 or less, optionally the ratio is at least 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, or 0.005, each of which such values ​​may be combined in any manner to form a range of 0.005 to 0.1, or 0.02 to 0.08, etc.).

[0466]

[0495] Aspect C31: The method or system of any one of the preceding aspects, wherein the pH of the treated iron-rich solution is decreased during plating.

[0467]

[0496] Aspect C32: The method or system of aspect C31, wherein the pH during plating is within the range of 2 to 6 (e.g., 2 to 6, 2 to 5, 2 to 4, 2 to 3, 3 to 6, 3 to 5, 3 to 4, 4 to 6, or 4 to 5).

[0468]

[0497] Embodiment C33: The method or system of any one of the preceding embodiments, wherein the feedstock comprises magnetite, hematite, goethite, or any combination thereof.

[0469]

[0498] Embodiment C34: The method or system of any one of the preceding embodiments, wherein the one or more impurities include aluminum compounds, titanium compounds, phosphate compounds, silicon compounds, or any combination thereof.

[0470]

[0499] Aspect C35: The method or system of any one of the preceding aspects, wherein the feedstock comprises one or more impurities at a concentration selected from the range of 1-50 wt.% (e.g., 1-50, 1-45, 1-40, 1-35, 1-30, 1-25, 1-20, 1-15, 1-10, 1-5, 5-50, 5-45, 5-40, 5-35, 5-30, 5-25, 5-20, 5-15, 5-10, 10-50, 10-45, 10-40, 10-35, 10-30, 10-25, 20-50, 20-40, 20-30, 30-50, 30-40, or 40-50 wt.%).

[0471]

[0500] Aspect C36: The method or system of any one of the preceding aspects, comprising a step of subjecting the second anolyte and / or the second catholyte from the second electrochemical cell to a second treatment to adjust pH, change composition, and / or remove impurities.

[0472]

[0501] Aspect C37: The method or system of any one of the preceding aspects, wherein the second treating step occurs after the second electrochemical reducing step is completed or stopped.

[0473]

[0502] Aspect C38a: The extracted Fe metal is a concentration of aluminum less than 0.1 wt.% or less than 0.5 wt.% (e.g. a wt.% of aluminum less than 0.5, 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, or 0.005, optionally the wt.% is at least 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, or 0.005, such values ​​may be combined in any manner to form ranges such as 0.005-0.5 or 0.01-0.1); and / or % or less than 0.5 wt.% of phosphorus ions (optionally less than 0.5, 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, or 0.001 wt.% of phosphorus; optionally the wt.% is at least 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, 0.001, or 0.0005, such values ​​may be combined in any manner to form ranges such as 0.0005-0.5 or 0.001-0.01).

[0474]

[0503] Aspect C38b: The extracted Fe metal is a concentration of aluminum less than 0.1 wt.% or less than 0.5 wt.% (e.g. a wt.% of aluminum less than 0.5, 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, or 0.005, optionally the wt.% is at least 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, or 0.005, such values ​​may be combined in any manner to form ranges such as 0.005-0.5 or 0.01-0.1); and / or a concentration of phosphorus ions less than 0.01 wt.% or less than 0.5 wt.% (optionally a wt.% of phosphorus less than 0.5, 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, or 0.001; optionally the wt.% is at least 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, 0.001, or 0.0005, such values ​​may be combined in any manner to form ranges such as 0.0005-0.5 or 0.001-0.01); and / or A manganese concentration of less than 1 wt.% or less than 0.5 wt.% (optionally a wt.% of manganese of less than 0.9, 0.8, 0.7, 0.6, 0.5, 0.2, 0.1, 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, or 0.001; optionally, the wt.% is at least 0.2, 0.1 , 0.08, 0.06, 0.05, 0.02, 0.01, 0.008, 0.006, 0.005, 0.002, 0.001, or 0.0005, and such values ​​may be combined in any manner to form ranges such as 0.0005 to 0.5 or 0.001 to 0.01.

[0475]

[0504] Embodiment C39: The method or system of any one of the preceding embodiments, wherein the first anolyte has a different composition than the first catholyte.

[0476]

[0505] Aspect C40: A system for producing iron, comprising: a dissolving subsystem having a first dissolving tank and a first electrochemical cell fluidly connected to the first dissolving tank; a dissolution subsystem, the first electrochemical cell comprising a first cathode chamber having a first anolyte in the presence of a first anode, a second anode chamber having the first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; an iron plating subsystem fluidly connected to the dissolving subsystem and having a second electrochemical cell; a first impurity removal subsystem; Equipped with a first dissolving tank receiving a feedstock having one or more iron-bearing ores and one or more impurities; The first dissolving tank dissolves at least a portion of the one or more iron-containing ores to produce a first Fe dissolved in an acidic iron salt solution. 3+ Contains an acidic iron salt solution to generate ions; First Fe 3+providing at least a portion of the acidic iron salt solution having at least a portion of the ions to a first cathode chamber; First Fe 3+ ions are electrochemically reduced at the first cathode to form Fe 2+ Forming ions; In the dissolution subsystem, an iron-rich solution is formed, and the iron-rich solution is dissolved in the Fe 2+ at least a portion of the ions and at least a portion of the one or more impurities; At least a portion of the iron-rich solution is fed to a first impurity removal subsystem to remove at least a portion of one or more impurities from the iron-rich solution, thereby forming Fe 2+ A treated iron-rich solution having at least a portion of the ions is formed; increasing the pH of the iron-rich solution from an initial pH to an adjusted pH in a first impurity removal subsystem to precipitate a removed portion of the one or more impurities; conveying at least a first portion of the treated iron-rich solution from the first impurity removal subsystem to an iron plating subsystem; A second electrochemical cell was used to measure the amount of transported Fe 2+ a second cathode for reducing at least a portion of the ions to Fe metal; The system wherein Fe metal is removed from the second electrochemical cell.

[0477]

[0506] Aspect D1a: A method for producing iron, comprising: In the first dissolving tank, the first iron-bearing ore is contacted with an acid to dissolve at least a portion of the first iron-bearing ore, thereby producing a dissolved first Fe 3+ forming an acidic iron salt solution having ions; circulating at least a portion of the acidic iron salt solution between the first dissolving tank and the first cathode chamber of the first electrochemical cell, thereby forming a first Fe 3+ providing at least a portion of the ions to a first catholyte in a first cathode chamber; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; First cathode, first Fe 3+ a first electrochemical reduction of at least a portion of the ions to produce Fe in the first catholyte; 2+ forming ions; Electrochemically generating protons in a first electrochemical cell; The circulating step is performed by circulating at least a portion of the electrochemically generated protons and the formed Fe 2+ providing at least a portion of the ions from the first catholyte to the acidic iron salt solution; Fe formed in the dissolution subsystem 2+ generating a first iron-rich solution having ions, the dissolving subsystem comprising a first dissolving tank and a first electrochemical cell; transferring at least a portion of the first iron-rich solution to an iron plating subsystem, the iron plating subsystem comprising a second electrochemical cell; The formed Fe 2+ a second electrochemical reduction of the first portion of the ions to Fe metal at a second cathode in a second electrochemical cell; a second electrochemical cell comprising a second cathode chamber having a second catholyte in the presence of a second cathode, a second anolyte chamber having a second anolyte in the presence of a second anode, and a second separator separating the first anolyte from the first catholyte; removing Fe metal from the second electrochemical cell, thereby producing iron; The method includes:

[0478]

[0507] Aspect D1b: A system for producing iron, comprising: a dissolving subsystem for producing an iron-rich solution, the dissolving subsystem comprising a first dissolving tank, a first electrochemical cell, and a first circulation subsystem; In the first dissolving tank, the iron-bearing ore is contacted with an acid to dissolve at least a portion of the iron-bearing ore, thereby producing dissolved Fe 3+ An acidic iron salt solution having ions is formed, A first circulation subsystem circulates at least a portion of the acidic iron salt solution between the first dissolving tank and the first cathode chamber of the first electrochemical cell, thereby producing a first Fe 3+ providing at least a portion of the ions to a first catholyte in a first cathode chamber; a first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte; A first electrochemical cell is connected to a first cathode and a first Fe 3+ Electrochemically reducing at least a portion of the ions to form Fe in the first catholyte. 2+ Forming ions, a first electrochemical cell electrochemically generates protons and supplies the electrochemically generated protons to a catholyte; a first circulation system supplies the electrochemically generated protons from the first catholyte to the acidic iron salt solution; The iron-rich solution generated in the first subsystem is converted into the Fe 2+ and a dissolved subsystem, including ions; a transition subsystem including a first inter-subsystem fluid connection for transferring at least a portion of the iron-rich solution to the iron plating subsystem; an iron plating subsystem comprising a second electrochemical cell; the second electrochemical cell includes a second cathode chamber having a second catholyte in the presence of a second cathode, a second anode chamber having a second anolyte in the presence of a second anode, and a second separator separating the first anolyte from the first catholyte having the second catholyte in the presence of the second cathode; Transported and formed Fe 2+ an iron plating subsystem, in which at least a first portion of the ions are electrochemically reduced to Fe metal at a second cathode; a subsystem for extracting Fe metal from the second electrochemical cell, thereby producing iron; A system comprising:

[0479]

[0508] Aspect D2: The method or system of Aspect D1a or D1b, or any of the preceding aspects, comprising: thermally reducing one or more non-magnetite iron oxide materials in the iron-bearing ore in the presence of a reducing agent to form magnetite, thereby forming a thermally reduced ore; the first iron-bearing ore in the first dissolving tank comprises the thermally reduced ore; and the dissolving step comprises using an acid to dissolve at least a portion of the thermally reduced ore to form an acidic iron salt solution.

[0480]

[0509] Aspect D3: The method or system of aspect D2 or any of the preceding aspects, comprising providing at least a portion of the catholyte having said electrochemically generated protons during the dissolving step from the electrochemical cell to an acidic iron salt solution, thereby providing electrochemically generated protons to the acidic iron salt solution in the presence of thermally reduced ore.

[0481]

[0510] Aspect D4: The method or system of aspect D3 or any of the preceding aspects, wherein the dissolving step occurs in a dissolving tank; the dissolving tank and the electrochemical cell are fluidly connected; and the acidic iron salt solution is circulated between the dissolving tank and the electrochemical cell.

[0482]

[0511] Aspect D5: The method or system of aspect D4 or any of the preceding aspects, wherein all of the acidic iron salt solution is circulated between the dissolving tank and the electrochemical cell during at least a portion of the dissolving step.

[0483]

[0512] Aspect D6: The method or system of any one of aspects D2-D5 or any of the preceding aspects, wherein the reaction between the thermally reduced ore being dissolved and the acidic iron salt solution produces water, thereby consuming protons of the acidic iron salt solution; and the supplied electrochemically generated protons replace at least a portion of the consumed protons in the acidic iron salt solution.

[0484]

[0513] Aspect D7: The method or system of any one of aspects D2-D6 or any of the preceding aspects, wherein electrochemically generated protons are continuously supplied to the acidic iron salt solution during at least a portion of the dissolving step.

[0485]

[0514] Aspect D8: The method or system of any one of aspects D2-D7 or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state concentration of free protons of at least 0.2 M (e.g., at least 0.2, 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, or 5 M, optionally the steady state free proton concentration is less than 0.3, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 2, 3, 4, 5, or 6 M, such values ​​may be combined in any manner to form a range, such as 0.2-6 M), during dissolution of the thermally reduced ore.

[0486]

[0515] Aspect D9: The method or system of aspect D8 or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state concentration of free protons selected from the range of 0.2M to 3M.

[0487]

[0516] Aspect D10: The method or system of aspect D8 or D9 or any of the preceding aspects, wherein the acidic iron salt solution is characterized by a steady state pH of less than 0.7 (e.g., less than or equal to 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, optionally the steady state pH is at least 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0, -0.1, -0.5, or -1, such values ​​may be combined in any manner to form ranges such as from -1 to 0.7 or from 0.1 to less than 0.7).

[0488]

[0517] Aspect D11: The method or system of any one of the preceding aspects, wherein the step of electrochemically generating electrochemically generated protons comprises electrochemically oxidizing water at the first anode.

[0489]

[0518] Aspect D12: The method or system of any one of the preceding aspects, wherein the step of supplying electrochemically generated protons includes transporting the electrochemically generated protons from the anolyte to the catholyte through a separator.

[0490]

[0519] Embodiment D13: The method or system of any one of the preceding embodiments, wherein the electrochemical cell is characterized by a coulombic efficiency of greater than 80% (e.g., greater than 80%, 85%, 90%, 95%, or 99%, optionally the coulombic efficiency is less than 85%, 90%, 95%, 99%, or 100%, such values ​​may be combined in any manner to form a range, such as from 80 to 100%).

[0491]

[0520] Embodiment D14: The method or system of any one of the preceding embodiments, wherein the electrochemically generated protons at least partially form an acid in the first catholyte.

[0492]

[0521] Aspect D15: The method or system of any one of the preceding aspects, comprising providing water from the first catholyte to the first anolyte.

[0493]

[0522] Aspect D16: The method or system of any one of aspects D11-D15 or any of the preceding aspects, wherein the water oxidized at the first anode comprises water produced by dissolution of the iron-bearing ore during the dissolving step.

[0494]

[0523] Aspect D17: The method or system of any one of the preceding aspects, comprising supplying water from the catholyte to the anolyte by permeation through a first separator, membrane distillation, and / or flash distillation.

[0495]

[0524] Embodiment D18: The method or system of any one of the preceding embodiments, wherein the anolyte has a different composition than the catholyte.

[0496]

[0525] Embodiment D19: The method or system of any one of the preceding embodiments, wherein the first anolyte has a different pH than the first catholyte.

[0497]

[0526] Embodiment D20: The method or system of any one of the preceding embodiments, wherein the first catholyte has a lower pH than the first anolyte.

[0498]

[0527] Embodiment D21: The method or system of any one of the preceding embodiments, wherein the first anolyte comprises dissolved salts of a different composition than the composition in the first catholyte.

[0499]

[0528] Aspect D22: The method or system of any one of the preceding aspects, wherein the first anolyte contains one or more dissolved ferric salts, and wherein the first anolyte is characterized by a total concentration of the one or more dissolved ferric salts that is greater than or equal to a total iron ion concentration in the first catholyte.

[0500]

[0529] Embodiment D23: The method or system of any one of the preceding embodiments, wherein the first catholyte comprises one or more supporting salts.

[0501]

[0530] Aspect D24: The method or system of aspect D23 or any of the preceding aspects, wherein the first catholyte comprises one or more supporting salts at a concentration selected from the range of 0.1 to 1 M (e.g., 0.2 to 0.8 M, 0.4 to 0.6 M, 0.1 to 0.4 M, 0.4 to 0.8 M, or 0.8 to 1 M).

[0502]

[0531] Embodiment D25: The method or system of embodiment D23 or D24 or any of the preceding embodiments, wherein the one or more supporting salts comprise one or more metal sulfate compounds and / or one or more metal chloride compounds.

[0503]

[0532] Embodiment D26: The method or system of embodiment D25 or any of the preceding embodiments, wherein the one or more metal sulfate compounds comprise potassium sulfate, sodium sulfate, ammonium sulfate, lithium sulfate, potassium chloride, sodium chloride, ammonium chloride, lithium chloride, or a combination thereof.

[0504]

[0533] Embodiment D27: The method or system of any one of the preceding embodiments, wherein the first anolyte is characterized by at least one redox pair different from the first catholyte.

[0505]

[0534] Embodiment D28: The method or system of any one of the preceding embodiments, wherein the first anolyte comprises a higher total concentration of dissolved salts than the first catholyte.

[0506]

[0535] Embodiment D29: The method or system of any one of embodiments D1-D21 and D23-D27 or any of the preceding embodiments, wherein the first anolyte comprises a lower total concentration of dissolved salts than the first catholyte.

[0507]

[0536] Aspect D30: The anolyte comprises Fe 2+ and Fe 3+ The method or system of any one of embodiments D1-D21 and D23-D28 or any of the preceding embodiments, which is essentially free of ions.

[0508]

[0537] Embodiment D31: The method or system of any one of the preceding embodiments, wherein the catholyte is characterized by a maximum iron ion concentration selected from the range of 0.5-5M or 1-5M (e.g., 1-5M, 1-4M, 1-3M, 0.5-5M, 0.5-4M, 2-4M, 2-5M, 1-2M).

[0509]

[0538] Embodiment D32: The method or system of any one of the preceding embodiments, comprising electrochemically producing oxygen (O2) at the anode.

[0510]

[0539] Embodiment D33: The method or system of any one of the preceding embodiments, wherein the first anolyte is in ionically connected with the first catholyte through the first separator.

[0511]

[0540] Embodiment D34: The method or system of embodiment D33 or any of the preceding embodiments, wherein the first anolyte is fluidly separated from the first catholyte.

[0512]

[0541] Embodiment D35: The method or system of any one of the above embodiments, wherein the separator is an ion exchange membrane.

[0513]

[0542] Embodiment D36: The method or system of embodiment D35 or any of the preceding embodiments, wherein the separator is a proton exchange membrane (PEM).

[0514]

[0543] Aspect D37: The method or system of any one of the preceding aspects, wherein the produced iron-rich solution is characterized by a total iron ion concentration selected from the range of 0.5-5M or 1-5M (e.g., 1-5M, 1-4M, 1-3M, 0.5-5M, 0.5-4M, 2-4M, 2-5M, 1-2M).

[0515]

[0544] Aspect D38: The step of thermally reducing the one or more non-magnetite iron oxide materials of the iron-containing ore is performed at a temperature between 200° C. and 600° C. (e.g., 200-550, 200-500, 200-450, 200-400, 200-350, 200-300, 200-250, 250-600, 250-550, 250-500, 250-400, 300-600, 300-550, 300-500, 300-450, 300-400, 350-6 300, 350-550, 350-500, 350-450, 400-600, 400-550, 400-500, 450-600, 450-550, or 500-600 temperatures (°C), thereby converting at least a portion of the one or more non-magnetite iron oxide materials to magnetite.

[0516]

[0545] Aspect D39: The method or system of any one of aspects D2-D38 or any of the preceding aspects, wherein the reducing agent comprises H2 gas; at least a portion of the H2 gas is generated chemically via a reaction between iron metal and an acid, and / or at least a portion of the H2 gas is generated electrochemically via a parasitic hydrogen evolution reaction of an iron electroplating process.

[0517]

[0546] Aspect D40: The method or system of aspect D38 or any of the preceding aspects, wherein the iron-bearing ore is exposed to an elevated temperature for a thermal treatment time during the thermal reducing step, and the iron-bearing ore is exposed to a reducing agent for the entire thermal treatment time.

[0518]

[0547] Aspect D41: The method or system of aspect D38 or any of the preceding aspects, wherein the iron-bearing ore is exposed to an elevated temperature for the heat treatment time during the thermally reducing step, and the iron-bearing ore is exposed to a reducing agent for a portion of the heat treatment time (e.g., air roasting can occur during the temperature ramp or during the initial portion of the period during which the iron-bearing ore is exposed to an elevated temperature of 200° C.-600° C. (e.g., or any temperature range specified elsewhere herein for this 200-600° C. range), followed by introduction of H gas to switch from air roasting to thermal reduction).

[0519]

[0548] Aspect D42: The method or system of aspect D41 or any of the preceding aspects, comprising air roasting the iron-bearing ore by exposing the iron-bearing ore to air during an initial portion of the heat treatment time.

[0520]

[0549] Aspect D43: In the presence of air, at least a portion of the iron-containing ore is heated to 200°C to 600°C (e.g., 200 to 550, 200 to 500, 200 to 450, 200 to 400, 200 to 350, 200 to 300, 200 to 250, 250 to 600, 250 to 550, 250 to 500, 250 to 400, 300 to 600, 300 to 550, 300 to 500, The method or system of any one of the above aspects, further comprising a step of air roasting at a temperature selected from the range of temperatures (°C) of 00 to 450, 300 to 400, 350 to 600, 350 to 550, 350 to 500, 350 to 450, 400 to 600, 400 to 550, 400 to 500, 450 to 600, 450 to 550, or 500 to 600.

[0521]

[0550] Aspect D44: The method or system of aspect D43 or any of the preceding aspects, wherein the air roasting step occurs prior to or separate from the thermal reduction step, and the air roasted ore is not thermally reduced prior to air roasting.

[0522]

[0551] Aspect D45: The method or system of aspect D43 or D44 or any of the preceding aspects, wherein the step of thermally reducing comprises thermally reducing the air roasted ore to form at least a portion of the thermally reduced ore; the air roasted ore comprises one or more non-magnetite iron oxide materials.

[0523]

[0552] Aspect D46: The method or system of aspect D43, D44, or D45 or any of the preceding aspects, wherein the melting step includes simultaneously and / or sequentially melting at least a portion of the air roasted ore and at least a portion of the thermally reduced ore.

[0524]

[0553] Aspect D47: The method or system of aspect D46 or any of the preceding aspects, wherein the melting step includes melting at least a portion of the air roasted ore in a melting tank separate from the thermally reduced ore during at least a portion of the melting step.

[0525]

[0554] Aspect D48: The method or system of any one of aspects D43-D47 or any of the preceding aspects, wherein the step of melting includes melting an ore mixture; the ore mixture including 0 wt.% to 100 wt.% thermally reduced ore, 5 wt.% to 100 wt.% roasted ore, and 0 wt.% to 90 wt.% roasted magnetite-containing ore (wherein the wt.% ranges for each of the ranges set forth in aspect A69 may be equally applied to the corresponding wt.% ranges in this aspect D48).

[0526]

[0555] Aspect D49: The method or system of any one of aspects D43-D48 or any of the preceding aspects, wherein the dissolving step includes circulating a dissolving solution between the first electrochemical cell and at least one of the first dissolving tank, the second dissolving tank, and the third dissolving tank; the first dissolving tank includes at least a portion of the thermally reduced ore, the second dissolving tank includes the air roasted ore, and the third dissolving tank includes the iron-bearing ore; and the ore is iron-bearing ore that has not been thermally reduced or air roasted.

[0527]

[0556] Aspect D50: The method or system of aspect D49 or any of the above aspects, wherein the circulating step includes circulating the dissolution solution for a total circulation time or total number of circulation cycles; the dissolution solution is circulated between the electrochemical cell and the third dissolution tank for 0-99% of the total circulation time or total number of circulation cycles; the dissolution solution is circulated between the electrochemical cell and the second dissolution tank for 0-99% of the total circulation time or total number of circulation cycles; the dissolution solution is circulated between the electrochemical cell and the first dissolution tank for 1-100% of the total circulation time or total number of circulation cycles (wherein the % circulation ranges for each of the ranges set forth in aspect A71 may be equally applied to the corresponding % circulation ranges in this aspect D50).

[0528]

[0557] Aspect D51: The method or system of aspect D49 or D50, or any of the preceding aspects, wherein during the circulating step, the dissolution solution is circulated between the electrochemical cell and any two or any three of the first, second and third dissolution tanks sequentially in any order and / or simultaneously.

[0529]

[0558] Aspect D52: The method or system of aspect D51 or any of the preceding aspects, wherein the circulating step includes first circulating the dissolving solution between the electrochemical cell and a third dissolving tank having the raw ore, then circulating the dissolving solution a second time between the electrochemical cell and a second dissolving tank having the air roasted ore, and then circulating the dissolving solution a third time between the electrochemical cell and the first dissolving tank having the thermally reduced ore.

[0530]

[0559] Embodiment D53: The method or system of any one of embodiments D49-D52 or any of the preceding embodiments, wherein the lysis solution is or comprises an acidic iron salt solution.

[0531]

[0560] Embodiment D54: The method or system of any one of embodiments D43-D53 or any of the preceding embodiments, wherein the first dissolving tank further contains air roasted ore, raw ore, or both during any portion of the dissolving step.

[0532]

[0561] Embodiment D55: The method or system of any one of embodiments D49-D54 or any of the preceding embodiments, wherein the second dissolving tank further contains thermally reduced ore, raw ore, or both during any portion of the dissolving step.

[0533]

[0562] Embodiment D56: The method or system of any one of embodiments D49-D55 or any of the preceding embodiments, wherein the third dissolving tank further contains air roasted ore, thermally reduced ore, or both during any portion of the dissolving step.

[0534]

[0563] Aspect D57: The method or system of any one of the preceding aspects, wherein the dissolving step occurs in at least one dissolving tank; and the dissolving step further comprises introducing the air roasted ore, the raw ore, or both into an acidic iron salt solution in the at least one dissolving tank in the presence of the thermally reduced ore.

[0535]

[0564] Embodiment D58: The method or system of any one of embodiments D2-D57 or any of the preceding embodiments, wherein the one or more non-magnetite iron oxide materials include hematite and / or goethite.

[0536]

[0565] Aspect D59: The method or system of any one of the preceding aspects, wherein the acidic iron salt solution comprises an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid, oxalic acid, boric acid, methanesulfonic acid, and any combination thereof.

[0537]

[0566] Aspect D60: Formed Fe 2+ 4. The method or system of any one of the preceding aspects, wherein the step of transporting ions includes removing at least a portion of the iron-rich solution from the dissolving subsystem and transporting the transported iron-rich solution to the iron plating subsystem; the transported iron-rich solution includes at least a portion of the removed iron-rich solution.

[0538]

[0567] Aspect D61: Formed Fe 2+ The method or system of embodiment D60 or any of the above embodiments, wherein the delivered iron-rich solution having ions is characterized by a pH of greater than 0.5 (e.g., greater than 0.5, 0.6, 0.7, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, optionally a pH less than 0.6, 0.7, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, such pHs may be combined in any manner to form a range such as 0.5 to 6).

[0539]

[0568] Aspect D62: The method or system of aspect D61 or any of the preceding aspects, wherein the delivered iron-rich solution is characterized by a pH of 1 or greater.

[0540]

[0569] Aspect D63: The method or system of aspect D62 or any of the preceding aspects, wherein the delivered iron-rich solution is characterized by a pH selected from the range of 2-6.

[0541]

[0570] Aspect D64: The transported iron-rich solution is 3+ Fe ions at higher concentrations 2+ The method or system of any one of embodiments D60-D63 or any of the preceding embodiments, comprising ions.

[0542]

[0571] Aspect D65: The transported iron-rich solution has an Fe content of 0.01 or less. 2+ Fe ions 3+ The method or system of any one of embodiments D60-D64 or any of the preceding embodiments, characterized by a ratio of concentrations of ions (e.g., less than or equal to 0.01, 0.0075, 0.005, 0.0025, or 0.001, optionally the ratio may be greater than or equal to 0.0075, 0.005, 0.0025, or 0.001, and such values ​​may be combined in any manner to form a range, such as from 0.001 to 0.01).

[0543]

[0572] Embodiment D66: The method or system of any one of embodiments D60-D65 or any of the preceding embodiments, wherein the conveyed iron-rich solution is conveyed directly or indirectly to a second cathode chamber; and the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode.

[0544]

[0573] Embodiment D67: The method or system of embodiment D66 or any of the preceding embodiments, wherein at least 70% (e.g., at least 70%, 75%, 80%, 85%, 90%, 95%, 99%, or 100%, optionally such values ​​being less than 75%, 80%, 85%, 90%, 95%, 99%, or 100%, and may be combined in any manner to form ranges such as 70-99%) of the delivered iron-rich solution is delivered directly or indirectly to the second cathode chamber.

[0545]

[0574] Embodiment D68: The method or system of embodiment D67 or any of the preceding embodiments, wherein at least 90% of the delivered iron-rich solution is delivered directly or indirectly to the second cathode chamber.

[0546]

[0575] Aspect D69: The method or system of any one of aspects D60-D68 or any of the preceding aspects, wherein the second electrochemical reducing step forms a second spent catholyte, the second spent catholyte having a lower concentration of iron ions than the delivered iron-rich solution; at least a portion of the second spent catholyte is provided to the second anodic chamber; and the second electrochemical cell comprises a second anodic chamber having the second anolyte in the presence of a second anode.

[0547]

[0576] Aspect D70: The method or system of aspect D69 or any of the preceding aspects, wherein a spent second catholyte is formed when the second electrochemical reducing step is completed or stopped.

[0548]

[0577] Embodiment D71 The method or system of embodiment D68 or D69 or any of the preceding embodiments, wherein the spent second catholyte is characterized by a concentration of iron ions that is between 60% and 70% (e.g., 62-68%, 64-66%, 60-65%, or 65-70%) of the concentration of iron ions in the delivered iron-rich solution.

[0549]

[0578] Aspect D72: The method or system of aspect D69 or any of the preceding aspects, wherein the second electrochemical reducing step is completed or stopped when the concentration of iron ions in the second catholyte falls to between 60% and 70% (e.g., between 62 and 68%, between 64 and 66%, between 60 and 65%, or between 65 and 70%) of the concentration of iron ions in the delivered iron-rich solution.

[0550]

[0579] Embodiment D73: The method or system of any one of embodiments D60-D72 or any of the preceding embodiments, wherein a first portion of the delivered iron-rich solution is delivered directly or indirectly to a second cathode chamber; a second portion of the delivered iron-rich solution is delivered directly or indirectly to a second anodic chamber; the second electrochemical cell comprises a second cathode chamber having a second catholyte in the presence of a second cathode, and the second electrochemical cell comprises a second anodic chamber having a second anolyte in the presence of a second anode.

[0551]

[0580] Aspect D74: The method or system of aspect D73 or any of the preceding aspects, wherein the first portion is between 25 vol.% and 45 vol.% (e.g., between 30 and 40 vol.%, between 32 and 38 vol.%, between 25 and 35 vol.%, or between 35 and 45 vol.%) of the delivered iron-rich solution and the second portion is between 55 vol.% and 75 vol.% (e.g., between 60 and 70 vol.%, between 62 and 68 vol.%, between 55 and 65 vol.%, or between 65 and 75 vol.%) of the delivered iron-rich solution.

[0552]

[0581] Aspect D75: The first portion is Fe of the transported iron-rich solution 2+ and a second portion comprising 25 mol.% to 45 mol.% (e.g., 30-40 mol.%, 32-38 mol.%, 25-35 mol.%, or 35-45 mol.%) of the delivered iron-rich solution. 2+ The method or system of embodiment D73 or D74 or any of the preceding embodiments, comprising 55 mol.% to 75 mol.% (e.g. 60 to 70 mol.%, 62 to 68 mol.%, 55 to 65 mol.%, or 65 to 75 mol.%) of the

[0553]

[0582] Aspect D76: The method or system of any one of aspects D60-D75 or any of the preceding aspects, wherein the transferring step further comprises treating the removed portion of the iron-rich solution prior to the conveying step, thereby forming a treated iron-rich solution; and the conveyed iron-rich solution comprises at least a portion of the treated iron-rich solution.

[0554]

[0583] Aspect D77: The method or system of aspect D76 or any of the preceding aspects, wherein the treating step comprises increasing the pH of the removed portion of the iron-rich solution.

[0555]

[0584] Aspect D78: The method or system of aspect D76 or D77 or any of the preceding aspects, wherein the treating step includes increasing the pH of the removed portion of the iron-rich solution by providing metallic iron in the presence of the removed portion of the iron-rich sol...

Claims

1. 1. A method for producing iron, comprising: providing a solid feedstock having iron-bearing ore and one or more non-ferrous impurities to a smelting subsystem; Dissolving at least a portion of the iron-containing ore using an acid to obtain a dissolved first Fe ３＋ forming an acidic iron salt solution having ions; The first Fe ３＋ The ions are reduced to Fe ２＋ forming ions; generating an iron-rich solution in the dissolution subsystem, the iron-rich solution being comprised of the formed Fe ２＋ at least a portion of the ions and at least a portion of the one or more non-ferrous impurities; treating at least a first portion of the iron-rich solution to remove at least a portion of the one or more non-ferrous impurities from the iron-rich solution, thereby forming a Fe ２＋ forming a treated iron-rich solution having at least a portion of the ions; a treating step comprising increasing the pH of the iron-rich solution from an initial pH to an adjusted pH, thereby precipitating at least a portion of the one or more non-ferrous impurities from the treated iron-rich solution; conveying at least a first portion of the treated iron-rich solution to an iron plating subsystem having an electrochemical plating cell; The transported formed Fe ２＋ electroplating iron by electrochemically reducing at least a first portion of the ions to Fe metal at a plating cathode of said electrochemical plating cell; removing the Fe metal from the electrochemical plating cell, thereby producing iron; The method includes:

2. 10. The method of claim 1, wherein dissolving at least a portion of the iron-bearing ore produces insoluble impurities; and the method further comprises separating and removing at least a portion of the insoluble impurities.

3. 3. The method of claim 2, wherein removing at least a portion of the insoluble impurities is by filtering and / or separating the insoluble impurities.

4. 3. The method of claim 2, wherein the insoluble impurities include quartz, gypsum, and any combination thereof.

5. The adjusted pH is equal to or greater than the precipitation pH of the one or more non-ferrous impurities, and ２＋ 2. The method of claim 1, wherein the pH is less than the precipitation pH of the ions, thereby precipitating at least a portion of the one or more non-ferrous impurities.

6. The adjusted pH is equal to or greater than the precipitation pH of aluminum, titanium, and phosphate ions, and equal to or greater than the precipitation pH of Fe. ２＋ 6. The method of claim 5, wherein the pH of the treated iron-rich solution is less than said precipitation pH of ions, thereby precipitating at least a portion of aluminum, titanium, and / or phosphorus-containing ions from the treated iron-rich solution.

7. 7. The method of claim 6, comprising precipitating titanium hydroxide, aluminum hydroxide, aluminum phosphate, and / or iron phosphate.

8. The method of claim 5 including the step of removing at least a portion of the precipitated impurities.

9. 2. The method of claim 1, wherein the adjusted pH is selected from the range of 3 to 7.

10. 10. The method of claim 9, wherein the adjusted pH is selected from the range of 4 to less than 7.

11. 10. The method of claim 1, wherein the adjusted pH also results in coagulation of colloidal silica along with precipitation of the one or more non-ferrous impurities; the method further comprising removing at least a portion of the coagulated silica.

12. 2. The method of claim 1, wherein the step of increasing the pH comprises providing metallic iron in the presence of the first portion of the iron-rich solution; and wherein a reaction between the first portion of the iron-rich solution and the provided metallic iron consumes protons in the iron-rich solution, thereby increasing its pH.

13. The method of claim 12, wherein the metallic iron is part of the Fe metal formed during the step of electroplating the iron.

14. The method of claim 12 , wherein the metallic iron is part of the Fe metal formed during the electroplating step.

15. said treated ferrous iron product solution A concentration of aluminum ions less than 1 mM; and / or Concentration of phosphorus-containing ions less than 1 mM The method of claim 1 , characterized by:

16. 2. The method of claim 1, wherein the electrochemical plating cell comprises a plating cathode chamber having a plating catholyte in the presence of the plating cathode, a plating anode chamber having a plating anolyte in the presence of a plating anode, and a plating separator separating the plating catholyte from the plating anolyte.

17. 17. The method of claim 16, wherein the treated iron-rich solution is conveyed directly or indirectly to the plating cathode chamber.

18. 20. The method of claim 17, wherein the treated iron-rich solution is not conveyed to the plating anode chamber.

19. 18. The method of claim 17, comprising the step of conveying, directly or indirectly, a second portion of the produced iron-rich solution to the plating anode chamber, wherein the second portion of the iron-rich solution is untreated or is subjected to a different treatment than the first portion of the iron-rich solution.

20. 2. The method of claim 1, wherein the iron-rich solution comprises colloidal silica; and the step of treating comprises removing at least a portion of the colloidal silica.

21. 21. The method of claim 20, wherein removing colloidal silica comprises agglomerating at least a portion of the colloidal silica to form aggregated colloidal silica.

22. 21. The method of claim 20, wherein the step of removing colloidal silica comprises adding polyethylene oxide to the iron-rich solution to promote aggregation of the colloidal silica, thereby producing aggregated colloidal silica.

23. 21. The method of claim 20, wherein removing the colloidal silica is by filtration, sedimentation, and / or any solid-liquid separation process.

24. 2. The method of claim 1, wherein the treated iron-rich solution has a colloidal silica content of 10 mM or less.

25. 2. The method of claim 1, wherein the initial pH is in the range of 0.5 to 1.

5.

26. The iron-rich solution is characterized by the initial pH, Fe ３＋ Fe at a higher concentration than the ion ２＋ The method of claim 1 further comprising ions.

27. The iron-rich solution has an Fe content of 0.1 or less. ２＋ Fe ions ３＋ The method of claim 1 characterized by a ratio of concentrations of ions.

28. 10. The method of claim 1, wherein the pH of the treated iron-rich solution is decreased during plating.

29. The method of claim 28, wherein the pH during plating is in the range of 2 to 6.

30. 10. The method of claim 1, wherein the feedstock comprises magnetite, hematite, goethite, and any combination thereof.

31. 10. The method of claim 1, wherein the one or more impurities comprise aluminum compounds, titanium compounds, phosphate compounds, silicon compounds, or any combination thereof.

32. 10. The method of claim 1, wherein the feedstock comprises the one or more impurities at a concentration selected from the range of 1 to 50 wt.

33. 10. The method of claim 1, further comprising a step of second treating the plating anolyte and / or the plating catholyte from the second electrochemical cell to adjust pH, change composition and / or remove impurities.

34. 34. The method of claim 33, wherein the second treating step occurs after the electroplating reducing step is completed or stopped.

35. The extracted Fe metal is 10. The method of claim 1, characterized by an aluminum concentration of less than 0.1 wt.%; and / or a phosphorus ion concentration of less than 0.01 wt.%.

36. The method of claim 1 , wherein the first anolyte has a different composition than the first catholyte.

37. 1. A system for producing iron, comprising: a dissolving subsystem having a first dissolving tank; an iron plating subsystem fluidly connected to the dissolving subsystem and having an electrochemical plating cell; a first impurity removal subsystem; and Equipped with the first dissolving tank receives a solid feedstock having one or more iron-bearing ores and one or more non-ferrous impurities; The first dissolving tank dissolves at least a portion of the one or more iron-containing ores to produce a first Fe dissolved in an acidic iron salt solution. ３＋ said acidic iron salt solution for generating ions; The first Fe ３＋ The ion is reduced to Fe ２＋ forming ions; An iron-rich solution is formed in the dissolution subsystem, and the iron-rich solution is mixed with the formed Fe ２＋ ions and at least a portion of the one or more non-ferrous impurities; At least a portion of the iron-rich solution is fed to the first impurity removal subsystem to remove at least a portion of the one or more non-ferrous impurities from the iron-rich solution, thereby forming a first impurity removal subsystem. ２＋ forming a treated iron-rich solution having at least a portion of the ions; increasing a pH of the iron-rich solution from an initial pH to an adjusted pH in the first impurity removal subsystem to precipitate the removed portion of one or more non-ferrous impurities; conveying at least a first portion of the treated iron-rich solution from the first impurity removal subsystem to the iron plating subsystem; The electrochemical plating cell is ２＋ a plating cathode for reducing at least a portion of the ions to Fe metal; The Fe metal is removed from the electrochemical plating cell.

38. The method of claim 1, wherein the reducing step includes contacting metallic iron with the acidic iron salt solution to chemically convert at least a portion of the first Fe 3+ ions to at least a portion of the formed Fe 2+ ions.

39. The method of claim 39, comprising providing at least a portion of the acidic iron salt solution having at least a portion of the first Fe ions to a first cathode chamber of a first electrochemical cell; the first electrochemical cell comprising a first anode chamber having a first anolyte in the presence of a first anode, a first cathode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte and the first catholyte; 2. The method of claim 1, wherein the reducing step comprises electrochemically reducing the first Fe3+ ions in the first catholyte to at least a portion of the formed Fe2+ ions in the first catholyte.

40. The method of claim 1, wherein the step of electroplating iron includes electrochemically oxidizing ferrous ions to ferric ions at an anode of the electrochemical plating cell.

41. The method of claim 1, wherein the step of electroplating iron includes an oxygen evolution reaction at the anode of the electrochemical plating cell.

42. The system described in claim 37, wherein the first impurity removal subsystem is configured to contact metallic iron with the acidic iron salt solution to chemically convert at least a portion of the first Fe3+ ions to at least a portion of the formed Fe2+ ions.

43. The system described in claim 37, wherein the first impurity removal subsystem comprises a reactor for contacting a portion of the Fe metal removed from the electrochemical plating cell with the iron-rich solution.

44. The system of claim 37, wherein the first impurity removal subsystem comprises a solid / liquid separation system for separating precipitated solids from the treated iron-rich solution.

45. The system of claim 37, wherein the dissolution subsystem further comprises a first electrochemical cell fluidly connected to the first dissolution tank; the first electrochemical cell comprises a first cathode chamber having a first anolyte in the presence of a first anode, a second anode chamber having a first catholyte in the presence of a first cathode, and a first separator separating the first anolyte from the first catholyte, wherein at least a portion of the acidic iron salt solution having at least a portion of the first Fe3+ ions is supplied to the first cathode chamber, and at least a portion of the first Fe3+ ions are electrochemically reduced at the first cathode to form Fe2+ ions in the first catholyte.

46. ​​The system of claim 37, wherein the electrochemical plating cell is configured to electrochemically oxidize ferrous ions to ferric ions at an anode of the electrochemical plating cell.

47. The system described in claim 37, wherein the electrochemical plating cell is configured to perform an oxygen evolution reaction at the anode of the electrochemical plating cell.

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