Methods for producing industrial gases and capturing carbon oxide using ferrous iron-containing materials

Abstract

Described are methods for producing industrial gases (e.g., hydrogen, ammonia, and / or methane) using ferrous iron-containing materials (e.g., olivine) while concurrently sequestering carbon dioxide. The process may involve mixing a ferrous iron-containing material with water and, in some examples, a reaction accelerant. The mixture may be heated to 100-300°C to initiate the oxidation of ferrous cations (Fe2+) to ferric cations (Fe3+) while reducing hydrogen (from water) and / or methane (from water and carbon dioxide, when carbon dioxide is introduced into the ferrous iron-containing mixture). In some examples, carbon dioxide may be added later (after recovering hydrogen) to form carbonates. Specifically, carbon dioxide may be injected at a high pressure (e.g., about 200 bar) post-oxidation to facilitate mineralization, using the exothermic reaction to maintain a favorable temperature. In some examples, metal complexing / chelating reagents are added to bind trace metals such as nickel, copper, cobalt, and platinum group metals for recovery.

Description

Methods for Producing Industrial Gases and Capturing Carbon Oxide Using Ferrous Iron-Containing MaterialsCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of US Provisional Patent Application 63 / 569,982, filed 2024-03-26 (Docket: STEPP002P) and US Provisional Patent Application 63682059, filed 2024-08-12 (Docket: STEPP003P), both of which are incorporated herein by reference in its entirety for all purposes.FIELD OF TECHNOLOGY

[0002] The present disclosure relates to methods for producing climatepositive industrial gases, such as hydrogen (H2), methane (CH4)from ferrous iron-containing materials, such as ultramafic minerals and industrial wastes, through material oxidation and carbonation, while recovering valuable trace metals and producing construction materials. The process disclosed yields multiple value streams while helping to mitigate the environmental challenges associated with reactive industrial wastes, such as metal slags and mine tailings. The methods are based on oxidizing ferrous cations (Fe2+) to ferric cations (Fe3+) (and potentially other cations) in the presence of water (H2O) and carbon dioxide (CO2).BACKGROUND

[0003] Hydrocarbon fuels have historically played a crucial role in global industrial development, providing essential energy for transportation, heating, and industrial processes. However, the environmental impact of fossil fuel emissions necessitates a transition to climate-neutral - or positive - energy sources. Hydrogen (H2) is a critical component of synthetic fuels, yet current production methods primarily rely on fossil fuels, resulting in significant carbon dioxide (CO2) emissions.

[0004] Geologic sources of hydrogen, produced through natural processes such as radiolysis and serpentinization, offer a promising alternative. These processes have been occurring for billions of years, resulting in trapped hydrogen (H2) that can be harvested. Accelerated serpentinization via the injection of water into iron-rich minerals, such as fayalite-rich olivine, or industrial wastes, such as copper slag, presents an opportunity to produce hydrogen on demand without carbon dioxide (CO2) emissions, or even with carbon dioxide sequestration (i.e., negative CO2emissions).SUMMARY

[0005] Described are methods for producing industrial gases (e.g., hydrogen and / or methane) using ferrous iron-containing materials (e.g., olivine, copper slag, steel slag) while sequestering carbon dioxide (CO2). The process may involve mixing a ferrous iron-containing material with water and, in some examples, reaction accelerants. The mixture may be mechanically and chemically deoxygenated and heated to 100-300°C to initiate material dissolution and the subsequent oxidation of ferrous cations (Fe2+) to ferric cations (Fe3+) while reducing and generating hydrogen (from water) and / or methane (from water and carbon dioxide if carbon dioxide is introduced into the ferrous iron-containing mixture). In some examples, carbon dioxide may be added after recovering hydrogen. Carbon dioxide may be injected at a high pressure (e.g., about 200 bar) post-oxidation to facilitate mineralization, using the exothermic reaction to maintain a favorable temperature (e.g., 100-300°C). In some examples, metal complexing / chelating reagents are added to bind trace metals such as nickel (Ni), copper (Cu), cobalt (Co), and platinum group metals (PGMs) for recovery.

[0006] Clause 1. A method for producing an industrial gas using a ferrous iron- containing material, the method comprising: combining the ferrous iron- containing material with water form a ferrous iron-containing mixture, wherein the ferrous iron-containing material and, subsequently, the ferrous iron- containing mixture comprise ferrous cations (Fe2+); maintaining the ferrousiron-containing mixture for an operating period at one or more processing conditions selected from the group consisting of an operating temperature range, an operating pressure range, an operating acidity (pH) level, and an operating catalyst concentration, wherein maintaining the ferrous iron- containing mixture for the operating period at the one or more processing conditions causes the ferrous cations (Fe2+) to oxidize into ferric cations (Fe3+) while releasing the industrial gas; and collecting the industrial gas from the ferrous iron-containing mixture thereby forming a ferric iron-containing mixture, wherein carbon dioxide is introduced to one or both of: (a) the ferrous iron-containing mixture, together with the water, such that the ferric iron- containing mixture contains mineral carbonates such as FeCO3, MgC03 or CaCO3, and (b) the ferric iron-containing mixture, after collecting the industrial gas, such that the ferric iron-containing mixture is converted into the carbonated mixture.

[0007] Clause 2. The method of clause 1, wherein combining the ferrous iron- containing material with water further comprising combining the ferrous iron- containing material with one or more salts selected from the group consistingof sodium chloride (NaCI), potassium chloride (KCI), copper chloride (CuCI2), and nickel chloride (NiCI2,).

[0008] Clause 3. The method of clause 1, wherein the ferrous iron-containing material also contains magnesium and calcium oxides such as forsterite (Mg2SiO4) and larnite (Ca2SiO4).

[0009] Clause 4. The method of clause 1, wherein the ferrous iron-containing material has a batch size of at least 1 metric ton.

[0010] Clause 5. The method of clause 1, wherein: combining the ferrous iron- containing material with the water further comprises introducing the carbon dioxide into the ferrous iron-containing material, the ferrous iron-containing mixture comprises both the water and the carbon dioxide, and the industrial gas comprises methane.

[0011] Clause 6. The method of clause 1, further comprising, after collecting the industrial gas from the ferrous iron-containing mixture and forming theferric iron-containing mixture, introducing carbon dioxide into the ferric iron- containing mixture thereby forming the carbonated mixture.

[0012] Clause 7. The method of clause 1, wherein the ferrous iron-containing material further comprises one or more elements selected from the group consisting of silicon, aluminum, calcium, and magnesium.

[0013] Clause 8. The method of clause 7, wherein the carbonated mixture further comprises one or more carbonates selected from the group consisting of calcium carbonate (CaCO3), manganese carbonate (MnCO3), and magnesium carbonate (MgCO3).

[0014] Clause 9. The method of clause 1, wherein the ferrous iron-containing material is formed from particles with an average diameter of less than 1 centimeter.

[0015] Clause 10. The method of clause 1, wherein the ferrous iron-containing material is industrial waste selected from the group consisting of ferrous-iron- rich metal slags and mine tailings.

[0016] Clause 11. The method of clause 1, wherein the ferrous iron-containing material comprises Fayalite (Fe2SiO4).

[0017] Clause 12. The method of clause 11, wherein the Fayalite (Fe2SiO4) is a part of olivine.

[0018] Clause 13. The method of clause 1, wherein forming the ferrous iron- containing mixture comprises introducing an oxidation additive to the ferrous iron-containing material and the water while forming the ferrous iron- containing mixture, wherein the oxidation additive is selected from the group consisting of sodium chloride, aluminum, iron, nickel, magnetite, chromite, platinum group metals, and microorganisms.

[0019] Clause 14. The method of clause 1, wherein forming the ferrous iron- containing mixture comprises exposing the ferrous iron-containing mixture to electromagnetic radiation in a microwave-to-ultraviolet range.

[0020] Clause 15. The method of clause 1, wherein forming the ferrous iron- containing mixture comprises heating the ferrous iron-containing mixture to at least 100°C.

[0021] Clause 16. The method of clause 1, wherein the ferrous iron-containing material is a molten slag when combined with the water.

[0022] Clause 17. The method of clause 1, wherein forming the ferrous iron- containing mixture comprises adjusting the acidity (pH) of the ferrous iron- containing mixture to between 1 and 5.

[0023] Clause 18. The method of clause 17, wherein adjusting the acidity (pH) of the ferrous iron-containing mixture comprises adding, to the ferrous iron- containing mixture, one or acids selected from the group consisting of carbonic acid (H2CO3), hydrochloric acid (HCI), and sulfuric acid (H2SO4).

[0024] Clause 19. The method of clause 1, wherein collecting the industrial gas is performed for a duration of between 1 hour and 5 days.

[0025] Clause 20. The method of clause 1, wherein the carbon dioxide is introduced at a pressure of between 5 and 300 bar.

[0026] Clause 21. The method of clause 1, wherein a mass ratio of the water added to the ferrous iron-containing material to form a ferrous iron-containing mixture, is between 0.1 and 10.

[0027] Clause 22. The method of clause 1, wherein a mass ratio of the carbon dioxide added to the ferrous iron-containing material to form a ferrous iron- containing mixture, is between 0.1 and 10.

[0028] Clause 23. The method of clause 1, wherein the industrial gas comprises separating hydrogen from additional recovered gas.

[0029] Clause 24. The method of clause 23, wherein separating the hydrogen is performed using one or more techniques selected from the group consisting of a passive hydrogen-permeable membrane and an active electrochemical device.

[0030] Clause 25. The method of clause 1, further comprising: introducing a chelating agent to one or more mixtures of the ferrous iron-containing mixture, the ferric iron-containing mixture, and the carbonated mixture that the chelating agent binds to one or more metal components in the one or more mixture and forms a bound product, wherein the one or more metal components are selected from the group consisting of copper (Cu), cobalt (Cu), nickel (Ni), gold (Au), silver (Ag), rare earth elements (REEs), and platinumgroup metals (PGMs); and separating the bound product from the carbonated mixture.

[0031] Clause 26. The method of clause 25, wherein the chelating agent is selected from the group consisting of ammonia, ethylenediaminetetraacetic acid, sulfuric acid, cyanide, and an oxime-based extractant.

[0032] Clause 27. The method of clause 1 further comprising recovering heat from at least one of the ferric iron-containing mixture and the carbonated mixture and using that heat to raise the temperature of the ferrous iron- containing mixture.

[0033] Clause 28. The method of clause 1 further comprising drying the carbonated mixture to recover the carbonated mixture.

[0034] These and other embodiments are described further below with reference to the figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The included drawings are for illustrative purposes and serve only to provide examples of possible structures and operations for the disclosed inventive methods and systems. These drawings in no way limit any changes in form and detail that may be made by one skilled in the art without departing from the spirit and scope of the disclosed implementations.

[0036] FIG. 1 is a block diagram illustrating various materials (starting, intermediate, and resulting materials) that are involved in producing industrial gases and sequestering carbon dioxide using ferrous iron-containing materials, in accordance with some examples.

[0037] FIG. 2A is a schematic illustration of a system for producing industrial gases and sequestering carbon dioxide using a sequential introduction of water, nitrogen and / or carbon dioxide, in accordance with some examples.

[0038] FIG. 2B is a schematic illustration of a system for producing industrial gases and sequestering carbon dioxide using a simultaneous introduction ofwater and carbon dioxide to ferrous iron-containing materials, in accordance with some examples.

[0039] FIG. 2C is a schematic illustration of a system for underground production of industrial gases and sequestering carbon dioxide, in accordance with some examples.

[0040] FIG. 3 is a process flowchart of a method for producing industrial gases and sequestering carbon dioxide using ferrous iron-containing materials, in accordance with some examples.

[0041] FIG. 4A is a plot illustrating concentration profiles of various materials as a function of time during hydrogen production.

[0042] FIG. 4B is a plot illustrating the cumulative hydrogen output as a function of time during hydrogen production.

[0043] FIG. 4C is a plot illustrating concentration profiles of various materials as a function of time during carbon dioxide sequestration.

[0044] FIG. 4D is a plot illustrating the cumulative amount of carbon dioxide that is sequestered as a function of time during carbon dioxide sequestration.DETAILED DESCRIPTIONIntroduction

[0045] Low-cost and energy-dense fuels have been critical to the development of modern society. They have enabled the generation of the motive and electric power that are critical to our quality of life. Unfortunately, the accumulated carbon dioxide emissions associated with our consumption of fossil-derived fuels such as coal, petroleum, and natural gas now pose a significant threat to the stability of our climate and to our economy through the disruptions associated with our management of the implications associated with a warming world (e.g., extreme weather, sea level rise).

[0046] Our emerging transition to a more electrified society powered by carbon-neutral wind, solar, and / or nuclear-generated electric power will help tomitigate this challenge to some extent. Also, renewable / nuclear-charged battery storage will help us to manage short-duration (hours) transients in stationary generation applications as well as in short-range transportation applications (e.g., automobiles). However, cost-effective long-duration (days to months) stationary storage and long-range (e.g., trans-oceanic) transportation applications will continue to require energy dense-fuels.

[0047] However, to meet the world's climate goals (e.g., Net Zero by 2050), these fuels must be at least climate-neutral - meaning that their consumption results in no net emissions of carbon dioxide to the atmosphere. Green hydrogen produced from renewable / nuclear electric sources or from biological sources is offered as a potential fuel itself, or as a building block of other fuels, such as ammonia or hydrocarbon fuels that have been synthesized with carbon removed from the atmosphere. However, in order to produce climate-neutral fuels at the scales required to satisfy our forecast 2050 consumption rates, either trillions of dollars of investment in production technology is required (e.g., electrolyzers and associated solar / wind power systems and carbon dioxide capture systems) or significant fractions of our arable land must be dedicated to exclusively growing crops for fuel production purposes. Unfortunately, both of these options would come at significant economic cost.

[0048] Fortunately, geologic sources of hydrogen have recently been identified as potential opportunities for the provision of (at least) climate-neutral hydrogen at globally-relevant scales. These opportunities include 1) the recovery of hydrogen that has been produced over geologic time-scales and trapped in naturally occurring reservoirs (i.e., white hydrogen), and 2) the production of hydrogen on-demand via the leveraging of the chemical potential of ferrous-iron rich (e.g., ultramafic) minerals (i.e., orange hydrogen).

[0049] However, despite the theoretical attractiveness of orange hydrogen, and the global availability of abundant ultramafic deposits, the economically attractive production of orange hydrogen will be a significant technical challenge - due in part to low yield (e.g., kg H2 / tonne of rock) and slow reaction kinetics (e.g., kg H2 / tonne of rock / hour). Fortunately, theseeconomic challenges can be mitigated via the pursuit of production economies of scope with both historical and concurrent processes and / or products. The historical scope economies include the leveraging of previous mining, comminution, and beneficiation work done in the extraction of metals (e.g., Cu, Ni) from natural minerals. The valuable metal-containing minerals also often contain substantial amounts of ferrous iron that is often a waste product and a major constituent of slags and tailings piles. Additionally, the substantial comminution and beneficiation work performed to extract the valuable metals yields a high-surface area (i.e., small particle) form that is supportive of cost- effective hydrogen (H2) yields and production rates.

[0050] The concurrent scope economies include the realization of multiple value streams from the same minerals via the concurrent sequestration of carbon dioxide, the recovery of remaining valuable metals, and the use of the resulting carbonate minerals as construction products.

[0051] The leveraging of the above-described historical and concurrent synergies / economies of scope is critical to the production of industrial gases such as hydrogen and methane at costs and scales that are relevant from global climate and economic perspectives.

[0052] Methods for producing industrial gases (e.g., hydrogen, ammonia, and / or methane) described herein use ferrous iron-containing materials (e.g., olivine, copper slag). Ferrous iron-containing materials and other like materials may be collectively referred to as reducing materials. When these materials are combined with water, hydrogen is produced (with varied reaction kinetics). Carbon dioxide may be added later, in a separate operation (after collecting hydrogen). In further examples, when these materials may be combined with water and carbon dioxide at the same time thereby causing the production of methane. In more specific examples, methane and hydrogen may both be produced, e.g., at the same time. The relative amounts of methane and hydrogen may depend on the relative amounts of water and carbon dioxide as well as process conditions (e.g., temperature, catalysts, composition of the ferrous iron-containing materials).

[0053] In general, various carbonates (e.g., ferrous carbonate) may be produced as end products (e.g., for subsequent use in construction and other applications). The types of carbonates may depend on the composition of the ferrous iron-containing materials. For example, these materials may comprise one or more of the following cations: manganese, calcium, and magnesium. These cations may also be converted into carbonates. Alternatively, some of the components in ferrous iron-containing materials, e.g., copper (Cu), cobalt (Cu), nickel (Ni), gold (Au), silver (Ag), the rare earth elements (REEs), and platinum group metals (PGMs), may be recovered. For example, various chelating agents may be used to facilitate the recovery of valuable trace metals adding significant economic benefits.

[0054] Overall, the process provides cost-effective hydrogen, ammonia, and / or methane production, carbon dioxide sequestration, resource recovery, and the like. More specifically, these methods and systems utilize abundant ferrous iron-containing waste and natural materials and leverage natural processes to produce hydrogen at low cost. The carbon dioxide sequestration enhances environmental benefits while producing valuable carbonate-based materials. Overall, this process addresses the need for climate-neutral hydrogen production and offers a sustainable pathway to mitigating the environmental impact of carbon emissions while providing economic benefits through resource recovery and industrial applications.

[0055] For example, a process may yield approximately 1 kg of hydrogen (H2) and sequester about 1 tonne of carbon dioxide (CO2) per tonne of natural olivine generating about 2 tonnes of mixed carbonates. This innovative approach leverages thermo-economic synergies to create lower overall economic and environmental costs for the total material value generated.

[0056] Additionally, in the context of the utilization of industrial wastes such as tailings or slag, the mineral carbonates resulting from the process are more chemically stable than the reactive raw materials. Such reactive stability may be attractive from an environmental standpoint, as they may be less likely to leach dangerous trace elements (e.g., arsenic - As) into the environment.Material Examples

[0057] FIG. 1 is a block diagram illustrating various materials (starting, intermediate, and resulting materials) that are involved in producing industrial gases and sequestering carbon dioxide using ferrous iron-containing materials, in accordance with some examples. A ferrous iron-containing material 250 is used as a reducing agent. In some examples, the ferrous iron-containing material 250 is combined with one or more non-iron salts 255, various examples of which are described below. It should be noted that these non-iron salts 255 may exist in the form or in addition to non-ferrous components 254, further described below.

[0058] Specifically, the ferrous iron-containing material 250 comprises at least ferrous cations 253 (that are later oxidized to ferric cations 265). In some examples, the ferrous iron-containing material 250 may also include nonferrous components 254, such as silicon, aluminum, calcium, and / or magnesium. In these examples, the carbonated mixture 266 (formed at the end of the overall process) further comprises one or more carbonates selected from the group iron carbonate (FeCO3), calcium carbonate (CaCO3), manganese carbonate (MnCO3), and magnesium carbonate (MgCO3).

[0059] In some examples, the ferrous iron-containing material 250 is formed from particles with an average diameter of less than 1 centimeter, less than 10 millimeters, or even less than 1 millimeter. Smaller particles have a larger surface-to-volume ratio and, therefore, help with improving reaction kinetics.

[0060] In some examples, the ferrous iron-containing material 250 is an industrial waste selected from the group consisting of ferrous-iron-rich metal slags and mine tailings. Metal slags are byproducts of high-temperature smelting / furnace processes. By nature of the metal purification process that produced them, they are not fully oxidized, and depending on the composition of the beneficiated ore supplied to them, they may include significant quantities of ferrous iron oxide (i.e., FeO), as well as valuable trace metals. Steel, copper, and nickel slags are of specific interest to the processes described herein. While there are commercial applications for slags, they are produced ata rate that exceeds demand, thereby creating a waste storage problem and often an environmental risk. The process described herein has the potential to convert environmental liabilities into useful assets. Lastly, depending on the metal purification and slag quenching process, the slags are frequently in granulated (i.e., high surface area) form. Such form offers the potential for high yields and fast reaction rates, which are both critical to the viability of the process. Mine tailings offer many of the same benefits as slags; however, the desirable reactive minerals and trace metals are often more dilute than they are in metal slags. In some examples, the ferrous iron-containing material 250 comprises a naturally occurring ferrous iron silicate (Fe2SiO4, Fayalite), e.g., as a part of olivine.

[0061] Ferrous iron-containing material 250 may be also referred to as ferrous iron-rich materials in which iron content is at least about 5% by weight, at least 10% by weight, or even at least 20% by weight.

[0062] During processing, ferrous iron-containing material 250 is mixed with water 260 to form a ferrous iron-containing mixture 262. In some examples, carbon dioxide 280 is also added to the ferrous iron-containing mixture 262 (e.g., to form methane). Alternatively, carbon dioxide 280 is added later (to the ferric iron-containing mixture 264), e.g., when the ferrous iron-containing mixture 262 is used to form hydrogen.

[0063] In some examples, an additive 261 (e.g., an oxidation additive) and / or a dissolution agent may be added to the ferrous iron-containing mixture 262. For example, the dissolution agent may be an acid (e.g., carbonic acid (H2CO3), hydrochloric acid (HCI), sulfuric acid (H2SO4), nitric acid (HNO3)) for adjusting the acidity of the ferrous iron-containing mixture 262 as further described below. In the same or other examples, an additive 261 may be a deoxygenation additive. It has been found that controlling the reduction potential (e.g., oxygen fugacity (Eh)) of the mixture impacts the kinetics of hydrogen production. In general, various steps may be used to either remove oxygen (e.g., from the mixtures and / or environment) or prevent it from entering the system - including the reuse of a portion of the oxygen-poor solution (formingthe ferric iron-containing mixture 264) departing the oxidation reactor 210. In some examples, two separate water loops are used, e.g., (1) one oxygen-poor loop for the oxidation reactor 210 and (2) one carbon-dioxide rich loop for the carbonation reactor 234. A portion of the oxygen-poor water may be transferred into the carbonation reactor 234 to carry the solid reactants.However, the remaining portion of the oxygen-poor water (as large as possible) stays in the oxidation reactor 210. This oxygen-poor water will also contain dissolved salts that can be reused in the oxidation reactor 210 (e.g., helping to minimize the need for additional salt). In some examples, the salt concentration in the oxygen-poor water may be 5-200 g of salt per kg of water or more, specifically, 10- 100 g salt / kg water. For example, the reduction potential of the soluation (a measure of the concentration of oxygen) in reduction potential of the carbon-dioxide-rich water may be >0 mV.

[0064]

[0064] In the same or other examples, an additive 261 may be an accelerant, such as sodium chloride (NaCI), nickel chloride hexahydrate (NiCI2*6H2O), potassium chloride (KCI), copper chloride (CuCI2). In general, the amount of the additive 261 in either one of the ferrous iron-containing mixture 262, ferric iron-containing mixture 264, or carbonated mixture 266 is 0.1-20% by weight, or more specifically, 1-10% by weight.

[0065] Once the ferrous iron-containing mixture 262 is formed (and subjected to the processing conditions further described below), an industrial gas 272 is generated and collected. The industrial gas 272 may contain hydrogen (H2), ammonia (NH3), methane (CH ), and / or potentially higher hydrocarbons (such as propane and butane), including alcohols (such as methanol). The composition of the industrial gas 272 depends on the composition of the ferrous iron-containing mixture 262 and the processing conditions.

[0066] In some examples, a chelating agent 284 is added to one or more of the ferrous iron-containing mixture 262, ferric iron-containing mixture 264, and carbonated mixture 266 to recover one or more metal components, which may be selected from the group consisting of copper (Cu), cobalt (Cu), nickel (Ni), gold (Au), silver (Ag), the rare earth elements (REEs), and the platinum groupmetals (PGMs). Some examples of chelating agents 284 include but are not limited to ammonia (NH3), ethylenediaminetetraacetic acid (CIOHI6N2O8), sulfuric acid (H2SO4), sodium cyanide (NaCN), and oxime-based extractants. In the interest of facilitating high yields, the chelating agents 284 will most likely be added to the ferrous iron-containing mixture 262, when the solid materials are in their most reactive oxidation state. Chelating agents 284 can be separated from the carbonated mixture 266, after the completion of the hydrogen (H2) production and / or carbon dioxide (CO2) sequestration processes, e.g., while water is being recovered and recycled. For example, the chelating agents 284 may be able to robustly bond to their target metals through the sequential processes. Alternatively, the chelating agent 284 can be removed in the step after their introduction. In general, the amount of the chelating agents 284 in either one of the ferrous iron-containing mixture 262, ferric iron- containing mixture 264, or carbonated mixture 266 is 0.1-20% by weight, or more specifically, 1-10% by weight.

[0067] If carbon dioxide 280 is not added to the ferrous iron-containing mixture 262, then the ferric iron-containing mixture 264 is formed first (and hydrogen is recovered as a part of the industrial gas 272). In these examples, carbon dioxide 280 is added to the ferric iron-containing mixture 264 to form a carbonated mixture 266. Alternatively, when carbon dioxide 280 is added to the ferrous iron-containing mixture 262, the carbonated mixture 266 is formed directly from the ferrous iron-containing mixture 262 (and methane is recovered as a part of the industrial gas 272). In either case, the ferric iron-containing mixture264 (if one is formed) and the carbonated mixture 266 comprise ferric cations265 (e.g., as a part of ferric oxide (Fe2O3)). The ferric iron-containing mixture 264 and the carbonated mixture 266 comprise ferric cations 265 may also comprise ferrous cations 253 (e.g., in the form of iron carbonate (FeCO3) and magnetite (Fe3O4), which comprises both ferrous cations 253 and ferric cations 265).

[0068] The carbonated mixture 266 comprises carbonate minerals 290, e.g., iron carbonate (FeCO3). In some examples, carbonate minerals 290 furthercomprise one or more of calcium carbonate, and magnesium carbonate. The carbonated mixture 266 may also comprise trace metals 298, some of which may be recovered using chelating agents 284. Finally, the carbonated mixture 266 may comprise the remaining water 260 (unreacted water), which may be recovered (e.g., filtered) and reused.Systems Examples

[0069] FIGS. 2A-2B are schematic illustrations of various examples of a system for producing industrial gases and sequestering carbon dioxide. In each example, ferrous iron-containing material 250 is converted into a carbonated mixture 266. The ferrous iron-containing material 250 may have a batch size of at least 1 metric tons, at least 10 metric tons, or even at least 100 metric tons.

[0070] FIG. 2A is a schematic illustration of a system 200 for producing industrial gases 272 and sequestering carbon dioxide 280 using the sequential introduction of water 260 and carbon dioxide 280 to ferrous iron-containing materials 250, in accordance with some examples. In some examples, system 200 may comprise a mixing tank 208, an oxidation reactor 210, and a carbonization reactor 234. However, some of these components can be combined, e.g., a mixing tank 208 may be used as an oxidation reactor 210 and even as a carbonization reactor 234. The functionality may be provided by different reagents added to the tank.

[0071] Specifically, in a sequential process in FIG. 2A, water 260 (from a water supply 202), and ferrous iron-containing material 250 (from material storage 206) are first combined (e.g., in a mixing tank 208) forming a ferrous iron- containing mixture 262. In some examples, an oxidation additive / dissolution agent may be also added to the ferrous iron-containing mixture 262. The ferrous iron-containing mixture 262 may be passed through a heat exchanger 209 to recover heat from the carbonated mixture 266 and to bring the ferrous iron-containing mixture 262 to its operating temperature. In some examples, the ferrous iron-containing mixture 262 may be also passed through the heater. The heated ferrous iron-containing mixture 262 is provided to the oxidationreactor 210 where the ferrous iron-containing mixture 262 reacts releasing the industrial gas 272 (containing hydrogen) and producing the ferric iron- containing mixture 264. The industrial gas 272 may be then passed through a gas separator 220 to remove additional recovered gases 274 from hydrogen 270, which is stored in a gas storage 222.

[0072] The ferric iron-containing mixture 264 may be transferred to the carbonization reactor 234 where the ferric iron-containing mixture 264 is combined with carbon dioxide 280 (from a carbon dioxide storage 232) to form the carbonated mixture 266. Various processing conditions and compositions of each mixture are described in this disclosure. The carbonation reaction (as well as other reactions) may be exothermic. The carbonated mixture 266 may pass through the heat exchanger 209 to transfer some of this generated heat to the ferrous iron-containing mixture 262. The carbonated mixture 266 may then be passed through a water separator 240 to recover the carbonate minerals 290. Water 260 or, more specifically, water solution 292 may be further processed to recover various additional materials 294 from water solution 292 (while the remaining water 260 may be recycled).

[0073] FIG. 2B is a schematic illustration of another example of a system 200 for producing industrial gases 272 and sequestering carbon dioxide 280 using the simultaneous introduction of water 260 and carbon dioxide 280 to ferrous iron- containing materials 250, in accordance with some examples. Specifically, a mixing tank 208 may be used to combine water 260, carbon dioxide 280, and ferrous iron-containing materials 250 and remove the industrial gas 272 (into the gas storage 222). In this example, the industrial gas 272 may comprise methane. The carbonated mixture 266 may be produced directly from the ferrous iron-containing mixture 262. Water 260 and / or various additional materials 294 may be recovered from the carbonated mixture 266 in a manner similar to the one described above with reference to FIG. 2A.

[0074] FIG. 2C is a schematic illustration of a system 200 for underground production of industrial gases 272 and sequestering carbon dioxide 280, in accordance with some examples. Specifically, water 260 and carbon dioxide 280are pumped underground (e.g., using an injection well) to an underground area containing the ferrous iron-containing material 250. In some examples, additional materials (e.g., catalysts) are pumped to the ferrous iron-containing material 250 as well. Water 260 and carbon dioxide 280 react with the ferrous iron-containing material 250 and form a carbonated mixture 266 while releasing industrial gas 272, which is carried (e.g. using a production well) to gas storage 222. As is the case for the ex-situ processes, the in situ underground industrial gas 272 production and carbon dioxide 280 processes may be performed either sequentially or concurrently. If performed sequentially, the industrial gas 272 will be comprised of hydrogen, and if performed concurrently, the industrial gas 272 will be comprised of methane and potentially higher hydrocarbons.Method Examples

[0075] FIG. 3 is a process flowchart of method 300 for producing industrial gases 272 and sequestering carbon dioxide 280 using ferrous iron-containing materials 250, in accordance with some examples. Various examples of ferrous iron-containing materials 250 and systems 200 for processing these materials are described above.

[0076] Method 300 comprises (block 310) combining the ferrous iron- containing material 250 with water 260 to form a ferrous iron-containing mixture 262. In some examples, carbon dioxide 280 is introduced (block 311) into the ferrous iron-containing mixture 262 (e.g., to generate methane) and form a carbonated mixture 266 directly from the ferrous iron-containing mixture 262.8FeO + 2H2O + 3CO2- 3FeCO3+ Fe3O4+ Fe2O3+ CH4

[0077] Alternatively, the ferrous iron-containing mixture 262 is substantially free from carbon dioxide 280 (e.g., to generate hydrogen). For purposes of this disclosure, the term "substantially free" is defined as a concentration of less than 5% by weight. In this alternative example, carbon dioxide 280 is introduced later (after collecting hydrogen) into a ferric iron-containing mixture264 (formed from the ferrous iron-containing mixture 262) thereby forming a carbonated mixture 266 (as further described below).3FeO + H2O -> Fe3O4+ H2

[0078] In some examples, the ferrous iron-containing mixture 262 is maintained for an operating period at one or more processing conditions selected from the group consisting of an operating temperature range, an operating pressure range, an operating acidity (pH) level, and an operating catalyst concentration. This maintaining operation causes the ferrous cations (Fe2+) to oxidize into ferric cations (Fe3+) while releasing the industrial gas. Various conditions are further described below.

[0079] In some examples, a ferrous iron-containing material 250 may contain other non-iron species that can provide further opportunities for carbon dioxide sequestration and / or valuable metal recovery, including non-iron orthosilicates 257. For example, magnesium (Mg) is the predominant cation in olivine, while calcium (Ca) is also present in olivine and in many metal slags. In some examples, these non-iron ortho-silicates 257 and / or other non-iron materials do not participate in reactions (e.g., present as substantially inert materials). In some examples, a ferrous iron-containing material 250 may be refine to reduce the amount / concentration of non-iron materials. Examples of additional non-iron-containing reactive species includeinclude but are not limited to magnesium ortho-silicate / forsterite (Mg2SiO4) and calcium ortho- silicate / la mite (Ca2SiO4). Magnesium and / or calcium-containing materials have some carbon dioxide (CO2) sequestration value as will now be explained in more detail.

[0080] A specific example of hydrogen production reactions involving a ferrous iron-containing material that also contains magnesium ortho-silicate / forsterite (Mg2SiO4) is presented below.0.11Fe3O4 + 0.15H2+ ~10H2O & Minor SpeciesIn the above reaction, olivine (a mixture of fayalite and forsterite) is reacted with water at a water to rock mass ratio of 1 at a temperature of 220 °C. The reaction products on the right hand side of the expression represent the equilibrium products, which include brucite (Mg(OH)2), chrysotile (Mg3Si2O5(OH)4), magnetite (Fe3O4), hydrogen (H2), residual water, and tens of minor species that are not listed. A portion of the reactant water is consumed in the production of hydrogen and in the formation of chrysotile - and other hydrated minerals. After the gaseous produced hydrogen is removed from the system, the remaining reactants - and additional water - may be reacted with carbon dioxide to form mineral carbonates for carbon dioxide sequestration purposes. An example sequestration reaction is presented below.0.2Mg(OH)2+ 0.4Mg3Si2O5(OH)4+ 0.11Fe3O4+ 5.2CO2+ 13H2O & Minor Species 0.93SiO2+ 0.22FeOOH + 2MgCO3+ 0.12FeCO3+ 14H2O + 3CO2+ Minor SpeciesIn the above reaction, the brucite, chrysotile, and magnetite react with CO2to yield carbonated minerals, including magnesite (MgCO3) and siderite (FeCO3). If calcium were presented in the original ferrous iron-containing materials used for hydrogen production, calcite (CaCO3) would also be a carbonated mineral product.

[0081] In some examples, methane (CH4) production and carbon dioxide (CO2) sequestration may be performed in a single step using ferrous iron-containing materials. A specific example of such a reaction between olivine (a mixture of fayalite and forsterite), water, and carbon dioxide is presented below.0.25Mg3Si2O5(OH)4+ 0.14MgSiO3+ 0.015FeSiO3+ 0.049 FeO + 0.054Mg2SiO4+ 0.12FeOOH + 0.06Fe203+ 0.84MgCO3+ 0.034FeC03+ 0.049Mg3Si4Oio(OH)2+ 3.3H2O + 0.22CO2+ 0.044CH4+ Minor SpeciesIn the above equilibrium reaction at 220 °C, fayalite (Fe2SiO4) and forsterite (Mg2SO4) (i.e., olivine) react with water and carbon dioxide to a yield mixture contaiing the carbonated minerals magnesite (MgCO3) and siderite (FeCO3) in addition to methane (CH4). In the above reaction, more carbon dioxide issequestered than would be generated in the combustion of the produced methane. Also, if calcium oxides were contained within the initial ferrous iron- contain mixture, calcium carbonate (CaCCh) would also be a reaction product.

[0082] In some examples, the mass ratio of the water 260 added to the ferrous iron-containing material 250 to form the ferrous iron-containing mixture 262, is between 0.1 and 10 or, more specifically, between 0.25 and 2 (relative to the total weight of the ferrous iron-containing mixture 262). The amount of water needs to be sufficient to dissolve the ferrous iron-containing minerals and oxidize most of the resulting ferrous cations 253 (Fe2+).

[0083] In the same or other examples, the mass ratio of the carbon dioxide 280 added to the ferrous iron-containing material 250 to form ferrous iron- containing mixture 262, is between 0.1 and 10 or, more specifically, between 0.25 and 2.

[0084] As noted above, the ferrous iron-containing material 250 and, subsequently, the ferrous iron-containing mixture 262 comprise ferrous cations 253 (Fe2+). These ferrous cations (Fe2+) 253 are used as reducing agents to recover hydrogen (from water) and / or methane (from a combination of water and carbon dioxide), e.g., by oxidizing the ferrous cations 253 (Fe2+) to ferric cations 265 (Fe2+).

[0085] In some examples, (block 310) forming the ferrous iron-containing mixture 262 comprises (block 312) introducing an additive 261 to the ferrous iron-containing material 250 and water 260 (while forming the ferrous iron- containing mixture 262). In other words, the ferrous iron-containing mixture 262 may comprise a catalytic oxidation-enhancing additive. Various examples of additives 261 are within the scope, e.g., sodium-containing additive, aluminum- containing additive, iron-containing additive, copper-containing additive, nickel- containing additive, magnetite, chromite, platinum group metals, and potentially microorganisms.

[0086] In some examples, (block 310) forming the ferrous iron-containing mixture 262 comprises (block 313) adjusting the acidity (pH) of the ferrous iron- containing mixture 262 to between 1 and 5 pH or, more specifically, to 2 to 4pH. The acidic pH levels will help to accelerate the dissolution of the ferrous- iron containing material 250 into the ferrous iron-containing mixture 262, thereby accelerating the production of industrial gases 272. For example, adjusting the acidity (pH) of the ferrous iron-containing mixture 262 may comprise adding, to the ferrous iron-containing mixture 262, one or acids selected from the group consisting of carbonic acid (H2CO3), hydrochloric acid (HCI), nitric acid (HNO3), and sulfuric acid (H2SO4). Furthermore, in some examples, it may be advantageous to adjust the acidity (pH) to between 9 and 13 pH, or more specifically to between 10 and 12 pH. The basic pH levels will help to accelerate the production of industrial gases from the ferrous iron containing mixture 262. For example, adjusting the acidity (pH) of the ferrous- iron containing mixture 262 may comprise adding, to the ferrous iron- containing mixture, one or more bases selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide Ca(OH)2, and magnesium hydroxide Mg(OH)2. Without being restricted to any particular theory, it is belived that acidic pHs are effective for mineral dissolution. Basic pHs are effective for hydrogen production. Overall, a change from acidic to basic pHs through the process may be beneficial in some examples,

[0087] In some examples, (block 310) forming the ferrous iron-containing mixture 262 comprises (block 314) heating the ferrous iron-containing mixture 262 to at least 100°C or, more specifically, to at least 200°C, e.g., 100-300°C. Heating increases the reaction kinetics thereby speeding up the process of generating the industrial gas 272. However, at the same time, higher temperature decreases the hydrogen yield and the degree of reaction exothermicity.

[0088] The ferrous iron containing mixture 262 will be contained in an oxidation reactor 210 and maintained at approximately the saturation pressure of water for the reaction temperature. However, the pressure may increase (~10%) as the industrial gases 272 are being generated, if they are notimmediately removed from the oxidation reactor 210. Hence, during the reaction, most of the water will remain in liquid form.

[0089] The heating may be achieved by heating a mixing tank 208 and / or by heating incoming reagents (e.g., water 260, ferrous iron-containing material 250, and / or carbon dioxide 280). For example, the ferrous iron-containing material 250 may be supplied as a ~1100 °C molten slag when combined with the water 260, as the molten slag leaves the furnace / smelter. When the slag is in molten form, the reaction kinetics are extremely fast, preheating the water and carbon dioxide may not be necessary, and the achievement of complete mixing and full reaction will be more achievable. Also, the industrial gas 272 can be generated in close proximity to the furnace / smelter, thereby enabling the use of the produced gas as a supplement to the fuel being supplied to the furnace or smelter and reducing the amount of fresh fuel consumed.

[0090] In some examples, (block 310) forming the ferrous iron-containing mixture 262 comprises (block 315) exposing the ferrous iron-containing mixture 262 to electromagnetic radiation. Without being restricted to any particular theory, it is believed that radiation in a microwave-to-ultraviolet range also increases the reaction kinetics thereby speeding up the process of generating the industrial gas 272 without requiring the entire ferrous iron-containing mixture 262 to be heated to the reaction temperature.

[0091] Method 300 may proceed with (block 340) collecting the industrial gas 272 from the ferrous iron-containing mixture 262 thereby forming a ferric iron- containing mixture 264. As noted above, the industrial gas 272 may comprise hydrogen and / or methane. In some examples, industrial gas 272 may comprise additional recovered gases 274 that may be later separated (block 344) from hydrogen and methane. The industrial gas 272 is generated by reducing hydrogen (from water) and / or carbon (from carbon dioxide).

[0092] Depending on the reaction kinetics, collecting the industrial gas 272 is performed for a duration of between 1 hour and 30 days such as between 12 hours and 7 days.

[0093] In the methane-producing example, (block 310) combining the ferrous iron-containing material 250 with the water 260 further comprises (block 311) introducing carbon dioxide 280 into the ferrous iron-containing mixture 262 (i.e., combining the ferrous iron-containing material 250 with the carbon dioxide 280). As such, in this example, the ferrous iron-containing mixture 262 comprises both the water 260 and the carbon dioxide 280.

[0094] In the hydrogen-producing example, method 300 further comprises (block 350) introducing carbon dioxide 280 into the ferric iron-containing mixture 264 thereby forming the carbonated mixture 266. More specifically, carbon dioxide 280 is introduced into the ferric iron-containing mixture 264 after collecting the industrial gas 272 from the ferrous iron-containing mixture 262 (and forming the ferric iron-containing mixture 264).

[0095] In either example, carbon dioxide 280 may be introduced at a pressure of 500 - 30,000 kPa (5-300 bar) or, more specifically, at 1000 - 10,000 kPa (10- 200 bar). A higher pressure may be harder to achieve and contain but allows using higher temperatures (resulting in faster kinetics) while forming carbonates. Specifically, the pressure may be at or higher than the saturation pressure of water at the reaction temperature while producing the hydrogen gas (e.g., lOOkPA at 100°C or 1,530 kPa at 200°C).

[0096] In some examples, (block 340) collecting the industrial gas 272 comprises (block 342) separating hydrogen and / or methane from additional recovered gas 274. For example, this separation process is performed using one or more techniques selected from the group consisting of a passive hydrogen- permeable membrane and an active electrochemical device.

[0097] In some examples, method 300 further comprises (block 360) introducing a chelating agent to one or more mixtures (of the ferrous iron- containing mixture 262, the ferric iron-containing mixture 264, and the carbonated mixture 266) such that the chelating agent binds to one or more metal components in the one or more mixture and forms a bound product. Method 300 also comprises separating the bound product from one or more mixtures.

[0098] In some examples, method 300 further comprises (block 370) recovering heat from at least one of the ferric iron-containing mixture 264 and the carbonated mixture 266 and using that heat to raise the temperature of the ferrous iron-containing mixture 262 before it is introduced into the oxidation reactor 210.

[0099] In some examples, method 300 further comprises (block 380) drying the carbonated mixture 266 to recover the carbonated mineral mixture.Operating Examples

[0100] A batch system may comprise a single reactor that is sequentially used to produce fuel and then sequester carbon dioxide. As a reference, the weight of ferrous iron-containing material is 500 weight units, which can be scaled / adapted based on the operating scales of actual systems. Weight units are used here to illustrate the proportions of different materials. For each of 500 weight units of ferrous iron-containing material, the amount of water may be 500-1000 weight units. Water may be in a deoxygenated form (e.g., water processed using thermal degassing, vacuum degassing, and / or nitrogen purging). 20-40 weight units of additives (e.g., sodium chloride (NaCI)) and 0-10 weight units of Ni, Cu, or Al-containing salts may be added. Depending on the material being converted, either an acid (e.g., H2SO4) or a base (e.g., sodium hydroxide NaOH) may be added to achieve a non-neutral pH. Without being restricted to any particular theory, an acidic pH is believed to be helpful from a waste / mineral dissolution (kinetic) standpoint, while a basic pH is believed to be helpful from a hydrogen production (yield) standpoint.

[0101] After the reactants are loaded, the reactor may be closed and any air trapped in the reactor is evacuated with a vacuum pump in an effort to remove as much reactive oxygen as possible to facilitate the production of hydrogen. The sealed reactor may be then heated to between 200 and 300 °C. The pressure increases with the increasing water saturation pressure. The sealed reactor is stirred periodically (e.g., for 1-10 minutes each hour) and may be maintained at a constant temperature for durations of between severalhours and several days. During this time, the ferrous iron-containing material dissolves into the aqueous solution, releasing ferrous (Fe+2) iron. If most dissolved and gaseous oxygen has been removed from the system, the dissolved ferrous iron will react with water (instead of oxygen). In doing so, ferrous (Fe+2) iron oxidizes to ferric (Fe+3) iron in the form of magnetite (Fe3O4) and / or hematite (Fe2O3), while the hydrogen cations (H+) from water are reduced to hydrogen gas (H2). At the end of the reaction period, the reactor is cooled down to ambient temperature, and the produced gas is removed.

[0102] After the removal of the produced gas, and if not enough carbon dioxide was added in the fuel production step to fully carbonate the reactive (e.g., Ca+2, Mg+2) minerals, carbon dioxide may be added to the reactor for purposes of mineralization. After its addition, the reactor may be reheated to a temperature of between 150 and 300 °C and maintained at this temperature for durations of several hours to several days. During this time, the gaseous CO2will dissolve into the water and react with Ca+2and Mg+2to yield CaCO3and MgCO3, which will precipitate out of the solution. At the end of the reaction period, any unreacted CO2would be removed along with the carbonated solid material and aqueous solution.

[0103] A variety of this batch processing may be implemented in a continuous flow system comprising two reactors, e.g., one for fuel production and one for carbon dioxide sequestration / mineralization. To start the process, a slurry of waste material / natural minerals and water is pumped into the system. This mixture is heated to the first reactor temperature using the enthalpy of the stream departing the second mineralization reactor. Required additives in the form of salt solutions will be mixed into the inflowing stream after the heat exchanger, as the heated stream flows into the first reactor. The water and salt-to-solid material ratios and reaction conditions will be similar to those used in the example above.

[0104] The first reactor will be sized such that the slurry stream entering at the specified flow rate has a residence time of the desired duration (i.e., minutes to hours) before departing to ensure that an adequate amount of thesolid material reacts with the aqueous solution. The gaseous fuel products will be removed from the reactor as they are produced.

[0105] The solid products - and some aqueous solution - will be removed from the first reactor before being mixed with a portion of the solution leaving the recuperator that was used to heat the slurry flowing into the first reactor. Carbon dioxide will be added to this mixture as it flows into the second reactor. The second reactor will be sized such that the carbon dioxide-rich mixture flowing through it has adequate time to react (i.e., minutes to hours) and form solid carbonates. The solid carbonates (with some residual solution) are removed from the reactor and pumped to a storage facility, where they may be dried and sold as building / construction products. The remaining solution will be cycled through the recuperator to use the exotherm from the carbonation reactions to heat the reactants flowing into the fuel production reactor.

[0106] Lastly, if the waste material is rich in valuable metals such as copper and nickel, the salt mixture added to the slurry prior to the first reactor may be supplemented with chelating agents such as ethylenediaminetetraacetic acid (EDTA) to bind with the metals to facilitate their removal from the solution leaving the first reactor via a gravity-based separation system.Experimental Results

[0107] FIG. 4A is a plot illustrating concentration profiles of various materials as a function of time during hydrogen production. The process involved combining forsterite (about 0.6 moles) and fayalite (0.08 moles) with water (2.1 moles). Forsterite (Mg2SiO4) comprising Mg2+cations is a magnesium-rich olivine constituent. Fayalite (Fe2SiO ) comprising ferrous cations (Fe2+) is an iron-rich olivine constinuent. During the simulation, the reactor was maintained at a temperature of 200 °C by removing the heat of the reaction from the adiabatic reactor, and the pressure increased from ~15 bar to ~16 bar as the industrial gas 272 (hydrogen in this case) was produced. In abouta day, the amount of forsterite and fayalite remaining was less than 0.02-0.03 moles, while the amount of lizardite (Mg3Si2O5(OH)4) produced was over 0.3 moles. Likewise, the amount of brucite (Mg(OH)2) produced was over 0.2 moles. Additionally, ~0.04 moles of magnetite (Fe3O4) were produced. The following is a representation of the reactions (presented in the unbalanced form):

[0108] FIG. 4B is a plot illustrating hydrogen output as a function of time during hydrogen production, presented in the above-referenced test. About 50% of recoverable hydrogen was recovered in half a day, while more than 70% of the recoverable hydrogen was recovered in the first full day.

[0109] FIG. 4C is a plot illustrating concentration profiles of various materials as a function of time during carbon dioxide sequestration. FIG. 4D is a plot illustrating the cumulative amount of carbon dioxide that has been sequestered as a function of time. In this simulation, the reactor was maintained at a temperature of 150 °C by removing the heat of the reaction from the adiabatic reactor. The initial reactor pressure was 200 bar. The pressure was decreased to ~172 bar as a portion of the initial carbon dioxide was mineralized.Conclusion

[0110] Although the foregoing concepts have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing processes, systems, and apparatuses. Accordingly, the present embodiments are to be considered illustrative and not restrictive.

Claims

CLAIMS1. A method for producing an industrial gas using a ferrous iron-containing material, the method comprising: combining the ferrous iron-containing material with water form a ferrous iron-containing mixture, wherein the ferrous iron-containing material and, subsequently, the ferrous iron-containing mixture comprise ferrous cations (Fe2+); maintaining the ferrous iron-containing mixture for an operating period at one or more processing conditions selected from the group consisting of an operating temperature range, an operating pressure range, an operating acidity (pH) level, and an operating catalyst concentration, wherein maintaining the ferrous iron-containing mixture for the operating period at the one or more processing conditions causes the ferrous cations (Fe2+) to oxidize into ferric cations (Fe3+) while releasing the industrial gas; and collecting the industrial gas from the ferrous iron-containing mixture thereby forming a ferric iron-containing mixture, wherein carbon dioxide is introduced to one or both of:(a) the ferrous iron-containing mixture, together with the water, such that the ferric iron-containing mixture contains mineral carbonates such as FeCOs, MgCCh or CaCOs, and(b) the ferric iron-containing mixture, after collecting the industrial gas, such that the ferric iron-containing mixture is converted into the carbonated mixture.

2. The method of claim 1, wherein combining the ferrous iron-containing material with water further comprising combining the ferrous iron-containing material with one or more salts selected from the group consisting of sodium chloride (NaCI), potassium chloride (KCI), copper chloride (CUCI2), and nickel chloride (NiCl2,).

3. The method of claim 1, wherein the ferrous iron-containing material also contains magnesium and calcium oxides such as forsterite (Mg2SiO4) and larnite (Ca2SiO4).

4. The method of claim 1, wherein the ferrous iron-containing material has a batch size of at least 1 metric ton.

5. The method of claim 1, wherein: combining the ferrous iron-containing material with the water further comprises introducing the carbon dioxide into the ferrous iron-containing material, the ferrous iron-containing mixture comprises both the water and the carbon dioxide, and the industrial gas comprises methane.

6. The method of claim 1, further comprising, after collecting the industrial gas from the ferrous iron-containing mixture and forming the ferric iron-containing mixture, introducing carbon dioxide into the ferric iron-containing mixture thereby forming the carbonated mixture.

7. The method of claim 1, wherein the ferrous iron-containing material further comprises one or more elements selected from the group consisting of silicon, aluminum, calcium, and magnesium.

8. The method of claim 7, wherein the carbonated mixture further comprises one or more carbonates selected from the group consisting of calcium carbonate (CaCO3), manganese carbonate (MnCO3), and magnesium carbonate (MgCO3).

9. The method of claim 1, wherein the ferrous iron-containing material is formed from particles with an average diameter of less than 1 centimeter.

10. The method of claim 1, wherein the ferrous iron-containing material is industrial waste selected from the group consisting of ferrous-iron-rich metal slags and mine tailings.

11. The method of claim 1, wherein the ferrous iron-containing material comprises Fayalite (Fe2SiO^).

12. The method of claim 11, wherein the Fayalite (FezSiO4) is a part of olivine.

13. The method of claim 1, wherein forming the ferrous iron-containing mixture comprises introducing an oxidation additive to the ferrous iron-containing material and the water while forming the ferrous iron-containing mixture, wherein the oxidation additive is selected from the group consisting of sodium chloride, aluminum, iron, nickel, magnetite, chromite, platinum group metals, and microorganisms.

14. The method of claim 1, wherein forming the ferrous iron-containing mixture comprises exposing the ferrous iron-containing mixture to electromagnetic radiation in a microwave-to-ultraviolet range.

15. The method of claim 1, wherein forming the ferrous iron-containing mixture comprises heating the ferrous iron-containing mixture to at least 100°C.

16. The method of claim 1, wherein the ferrous iron-containing material is a molten slag when combined with the water.

17. The method of claim 1, wherein forming the ferrous iron-containing mixture comprises adjusting the acidity (pH) of the ferrous iron-containing mixture to between 1 and 5.

18. The method of claim 17, wherein adjusting the acidity (pH) of the ferrous iron-containing mixture comprises adding, to the ferrous iron-containingmixture, one or acids selected from the group consisting of carbonic acid (H2CO3), hydrochloric acid ( HCI), and sulfuric acid (H2SO4).

19. The method of claim 1, wherein collecting the industrial gas is performed for a duration of between 1 hour and 5 days.

20. The method of claim 1, wherein the carbon dioxide is introduced at a pressure of between 5 and 300 bar.

21. The method of claim 1, wherein a mass ratio of the water added to the ferrous iron-containing material to form a ferrous iron-containing mixture, is between 0.1 and 10.

22. The method of claim 1, wherein a mass ratio of the carbon dioxide added to the ferrous iron-containing material to form a ferrous iron-containing mixture, is between 0.1 and 10.

23. The method of claim 1, wherein the industrial gas comprises separating hydrogen from additional recovered gas.

24. The method of claim 23, wherein separating the hydrogen is performed using one or more techniques selected from the group consisting of a passive hydrogen-permeable membrane and an active electrochemical device.

25. The method of claim 1, further comprising: introducing a chelating agent to one or more mixtures of the ferrous iron-containing mixture, the ferric iron-containing mixture, and the carbonated mixture that the chelating agent binds to one or more metal components in the one or more mixture and forms a bound product, wherein the one or more metal components are selected from the group consisting of copper (Cu), cobalt (Cu), nickel (Ni), gold (Au), silver (Ag), rare earth elements (REEs), and platinum group metals (PGMs); andseparating the bound product from the carbonated mixture.

26. The method of claim 25, wherein the chelating agent is selected from the group consisting of ammonia, ethylenediaminetetraacetic acid, sulfuric acid, cyanide, and an oxime-based extractant.

27. The method of claim 1 further comprising recovering heat from at least one of the ferric iron-containing mixture and the carbonated mixture and using that heat to raise the temperature of the ferrous iron-containing mixture.

28. The method of claim 1 further comprising drying the carbonated mixture to recover the carbonated mixture.

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