A process for producing calcium oxide or ordinary Portland cement from calcium-containing rocks and minerals

Abstract

Aspects of the invention include a method of producing a cement material comprising a first reaction step in which a calcium-containing starting material is reacted with a first acid to produce a water-soluble first calcium salt, a second reaction step in which the water-soluble first calcium salt is reacted with a second acid to produce a solid second calcium salt, where the second acid is different from the first acid and the second calcium salt is different from the first calcium salt, and a heat-treating step in which the second calcium salt is heat-treated to produce a first cement material. Preferably, but not necessarily, during the second reaction step, the reaction between the first calcium salt and the second acid regenerates the first acid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62 / 886,137, filed August 13, 2019, U.S. Provisional Patent Application No. 62 / 913,620, filed October 10, 2019, U.S. Provisional Patent Application No. 62 / 932,200, filed November 7, 2019, and U.S. Provisional Patent Application No. 63 / 019,916, filed May 4, 2020, each of which is incorporated by reference in its entirety to the extent not inconsistent herewith. [Background technology]

[0002] Technologies for producing cementitious materials, including ordinary Portland cement, face many challenges, inefficiencies, and / or shortcomings. For example, traditional processes for producing cement are energy intensive, produce environmentally degrading by-products such as CO and / or SO, and use only a limited range of raw materials, primarily simple calcium-based materials such as calcium carbonate (limestone) or mined calcium sulfate (gypsum). The present application addresses these and other challenges in the art. Summary of the Invention

[0003] Provided herein are methods for producing cementitious materials having any combination of the following advantages or features: lower energy consumption than conventional approaches; in some embodiments, net energy neutral or even net energy production; regeneration of certain reagents characterized by a net reaction that does not include SO2 and / or CO2; reuse of certain by-products that does not include CO2 production and may utilize a wider range of feedstocks, including more composite materials; production of value-added by-products; and / or production of composite cementitious materials.

[0004] The methods described herein are methods for producing cementitious materials using a diacid approach, in which materials are reacted with two different acids and / or two different acid reaction steps. The advantages of these approaches include all or most of the advantages and features described above. For example, the disclosed diacid approach offers the ability to digest complex calcium-containing materials containing Ca and other metallic (including metalloid) elements, including Si, Al, and other species, and further form value-added by-products from these non-Ca metals while also regenerating reagent acid. Importantly, these methods are CO2-free and can include converting SO2 to reagent acid, thereby eliminating or dramatically reducing SO2 emissions for CaSO4-based approaches to cement production.

[0005] An embodiment of the present invention includes a method for producing a cement material, comprising: a first reaction step in which a calcium-containing starting material is reacted with a first acid to produce a water-soluble first calcium salt; a second reaction step in which the water-soluble first calcium salt is reacted with a second acid to produce a solid second calcium salt, where the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and a heat-treating step in which the one or more calcium salts are heat-treated to produce the first cement material. Preferably, but not necessarily, the one or more calcium salts are second calcium salts. Preferably, but not necessarily, during the second reaction step, the reaction between the first calcium salt and the second acid regenerates the first acid. Preferably, but not necessarily, the method is characterized by a net reaction that does not include acid-forming gas products. Preferably, but not necessarily, the method includes forming a solid second calcium salt characterized by a purity of 90% dry weight purity or greater. Preferably, but not necessarily, any of the methods disclosed herein includes a first separation step after the first reaction step and before the second reaction step, the first separation step including separating a first water-soluble fraction from a first solid fraction, wherein the first water-soluble fraction includes the water-soluble first calcium salt and the first solid fraction includes one or more solid by-products formed during the first reaction step. Preferably, but not necessarily, any of the methods disclosed herein includes a second separation step after the second reaction step and before the heat-treating step, the second separation step including separating a second solid fraction from a second water-soluble fraction, wherein the second solid fraction includes the solid second calcium salt and the second water-soluble fraction includes one or more water-soluble by-products formed during the second reaction step. Preferably, the solid fraction is characterized by a dry mass of which at least 90% by weight is the second calcium salt.

[0006] Preferably, but not necessarily, any of the methods disclosed herein include a second acid regeneration step, which involves converting one or more gas products of the thermal treatment step to a second acid. Optionally, the second acid regeneration step is a non-electrochemical process carried out according to the formula FX1A: SO + 1 / 2O + HO → HSO (FX1A), where SO in FX1A is a gas product of the thermal treatment step, and the HSO produced in FX1A is used as at least a portion of the second acid during the second reaction step. Optionally, the second acid regeneration step is a non-electrochemical process carried out according to the formula FX1B: SO + HO → HSO (FX1B), where SO in FX1B is a gas product of the thermal treatment step, and the HSO produced in FX1B is used as at least a portion of the second acid during the second reaction step. Optionally, the second acid regeneration step includes (i) electrochemically oxidizing sulfur dioxide to sulfuric acid and (ii) forming hydrogen gas via a reduction reaction, where the second acid regeneration step is carried out according to the equation FX2: SO2 + 2H2O → H2SO4 + H2(FX2), where SO2 in FX2 is a gas product of the thermal treatment step, and the H2SO4 produced in FX2 is used as at least a portion of the second acid during the second reaction step. Optionally, the thermal treatment step includes using energy generated from oxidizing the hydrogen gas formed as a result of the second acid regeneration. For example, the hydrogen gas produced via this method can be used to power the electrochemical step, such as via a fuel cell or turbine. Optionally, electrochemically oxidizing the sulfur dioxide includes using energy generated as a result of the second acid regeneration step. Note that when H2SO4 is added to a solution containing both MgCl2 and CaCl2, only CaSO4 precipitates. If H2SO3 is added to a solution of both MgCl2 and CaCl2, both MgSO3 and CaSO3 will precipitate.One thing to consider is that there are currently regulations against having Mg in cement, and as a result, it is preferred that the calcium-containing starting material have a low Mg content, thus minimizing the amount of precipitated Mg material.

[0007] Optionally, during the second reaction step, the reaction between the first calcium salt and the second acid is carried out to form a compound of formula FX3:CaCl 2(aq) +H2SO4 → CaSO 4(s) +2HCl (FX3), where the first calcium salt is CaCl2, the first acid is HCl, the second acid is H2SO4, and the second calcium salt is CaSO4.

[0008] The calcium-containing starting material comprises Ca. The calcium-containing starting material has a chemical composition comprising the element Ca. Preferably, the calcium-containing starting material has a chemical composition comprising the element Ca, wherein the weight percentage and / or mole percentage of Ca in the calcium-containing starting material is at least 0.001%, preferably at least 0.01%, preferably at least 0.1%, more preferably at least 1%, even more preferably at least 5%, even more preferably at least 10%, and even more preferably at least 20%. Optionally, in any of the methods disclosed herein, the calcium-containing starting material has a chemical composition comprising the element Ca, wherein the weight percentage and / or mole percentage of Ca in the calcium-containing starting material is selected from the range of 1% to 80%, optionally 1% to 60%, optionally 1% to 55%, and optionally 1% to 50%. Optionally, in any of the methods disclosed herein, the calcium-containing starting material comprises at least one multi-component metal oxide material having a composition comprising Ca and at least one other metallic element selected from the group consisting of Al, Si, Fe, Mn, and Mg. Optionally, the composition of the at least one multi-component metal oxide comprises 55% or less by weight of Ca. Optionally, the composition of the at least one multi-component metal oxide comprises 60% or less by weight of Ca. Optionally, in any of the methods disclosed herein, the at least one multi-component metal oxide material is at least one naturally occurring rock or mineral. Optionally, in any of the methods disclosed herein, the at least one naturally occurring rock or mineral comprises basalt, igneous apatite, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxene, magmatite, kamaphite, clinopyroxene, colemanite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheelite, skarn, limestone, natural gypsum, apatite, fluoroapatite, or any combination thereof. Optionally, in any of the methods disclosed herein, the calcium-containing starting material comprises cement, concrete, Portland cement, fly ash, slag, or any combination thereof.If the calcium-containing starting material includes CaCO, CO may be produced during the process. However, if CO is produced, it will be in high concentration and may be stored and / or utilized.

[0009] Optionally, in any of the methods disclosed herein, the first acid comprises hydrochloric acid (HCl). Optionally, in any of the methods disclosed herein, the first acid is hydrochloric acid. Optionally, in any of the methods disclosed herein, the second acid comprises sulfuric acid (H2SO4) and / or sulfurous acid (H2SO3). Optionally, in any of the methods disclosed herein, the second acid is sulfuric acid and / or sulfurous acid. Optionally, in any of the methods disclosed herein, the second acid is sulfuric acid. Optionally, in any of the methods disclosed herein, the second acid is sulfurous acid. Optionally, in any of the methods disclosed herein, the water-soluble first calcium salt is calcium chloride (CaCl2). Optionally, in any of the methods disclosed herein, the solid second calcium salt is calcium sulfate (CaSO4) and / or calcium sulfite (CaSO3). Optionally, in any of the methods disclosed herein, the solid second calcium salt is calcium sulfate. Optionally, in any of the methods disclosed herein, the solid second calcium salt is calcium sulfite (CaSO). Preferably, in any of the methods disclosed herein, the first cementitious material comprises CaO. Optionally, in any of the methods disclosed herein, the first cementitious material is calcium oxide (CaO). Optionally, in any of the methods disclosed herein, the first cementitious material is calcium oxide (CaO) or Portland cement clinker. Optionally, in any of the methods disclosed herein, the first cementitious material is Portland cement clinker. Optionally, in any of the methods disclosed herein, the acid-forming gas product is SO and / or CO. Optionally, in any of the methods disclosed herein, the acid-forming gas product is SO. Optionally, in any of the methods disclosed herein, the acid-forming gas product is CO.

[0010] Preferably, but not necessarily, in any of the methods disclosed herein, the first reaction step comprises reacting a calcium-containing starting material with hydrochloric acid to form at least water-soluble calcium chloride, water-soluble aluminum chloride, and solid silica. Preferably, but not necessarily, in any of the methods disclosed herein, the first separation step comprises separating a first water-soluble fraction comprising water-soluble calcium chloride and water-soluble aluminum chloride from a first solid fraction comprising solid silica. Preferably, but not necessarily, in any of the methods disclosed herein, the second reaction step comprises reacting at least water-soluble calcium chloride, water-soluble aluminum chloride, and sulfuric acid to form at least solid calcium sulfate, water-soluble aluminum sulfate, and hydrochloric acid. Preferably, but not necessarily, in any of the methods disclosed herein, the heat treatment step comprises heating calcium sulfate to form calcium oxide.

[0011] Preferably, but not necessarily, in any of the methods disclosed herein, the first reaction step involves reacting a calcium-containing starting material with hydrochloric acid to form at least water-soluble calcium chloride, water-soluble aluminum chloride, water-soluble iron chloride, water-soluble magnesium chloride, and solid silica. Preferably, but not necessarily, in any of the methods disclosed herein, the first separation step involves separating a first water-soluble fraction containing water-soluble calcium chloride and water-soluble aluminum chloride from a first solid fraction containing solid silica. Preferably, but not necessarily, in any of the methods disclosed herein, the second reaction step involves reacting at least water-soluble calcium chloride and sulfuric acid to form at least solid calcium sulfate, solid calcium sulfate, and hydrochloric acid. Preferably, but not necessarily, in any of the methods disclosed herein, the heat treatment step involves heating calcium sulfate to form calcium oxide.

[0012] Optionally, any of the methods disclosed herein includes an ion exchange step, wherein the ion exchange step includes exchanging one or more anions of the first calcium salt and / or the second calcium salt with one or more hydroxyl anions to form a third calcium salt. Optionally, the ion exchange step includes reacting the first calcium salt and / or the second calcium salt with a chelating agent to form a calcium chelating compound and reacting the calcium chelating compound with a base to form a third calcium salt. Optionally, the ion exchange step includes reacting the first calcium salt and / or the second calcium salt with a base to form a third calcium salt. Optionally, the ion exchange step includes using an ion exchange membrane to exchange one or more anions of the first calcium salt and / or the second calcium salt with one or more hydroxyl anions to form a third calcium salt. Optionally, the one or more calcium salts of the heat treatment step are third calcium salts. Optionally, the third calcium salt is Ca(OH). Optionally, any of the methods disclosed herein include a step of regenerating the chelating agent, where regenerating the chelating agent includes generating a third calcium salt. Optionally, any of the methods disclosed herein include a step of forming a first cement material from the third calcium salt. Optionally, forming the first cement material from the third calcium salt includes dehydrating the third calcium salt via a base or directly releasing the first cement material from the calcium chelating agent compound. For example, CaO can be formed by reacting CaCl, CaSO, or CaSO using a chelating agent or a base. For example, the chelating agent or base can then be regenerated in a manner that releases Ca(OH) which can be dehydrated to CaO, or CaO can be released directly from the chelating agent. For example, if CaSO precipitates, a chelating agent such as EDTA can be reacted with CaSO to make Ca-EDTA. For example, a base such as NaOH can then be used to directly generate Ca(OH) and regenerate EDTA.

[0013] Preferably, but not necessarily, any method disclosed herein includes forming a composite cement material, where (i) the heat-treating step includes forming a composite cement material and the first cement material is a composite cement material, or (ii) the step of forming the composite material is performed using a first cement material formed during the heat-treating step. For example, if the step of forming a composite material is performed using a first cement material formed during the heat-treating step, the formation of the composite material can occur simultaneously with the formation of the first cement material (e.g., CaO) or subsequently after the formation of the first cement material (e.g., CaO). Optionally, any method disclosed herein includes forming a composite cement material, where the heat-treating step includes forming a composite cement material and the first cement material is a composite cement material. Optionally, any method disclosed herein includes forming a composite cement material, where the step of forming the composite material is performed using a first cement material formed during the heat-treating step. Optionally, in any of the methods disclosed herein, the step of forming the composite cementitious material comprises heating the second calcium salt and / or the first cementitious material with one or more additives. Optionally, in any of the methods disclosed herein, the step of forming the composite cementitious material comprises heating the second calcium salt with one or more additives. Optionally, in any of the methods disclosed herein, the step of forming the composite cementitious material comprises heating the first cementitious material with one or more additives. Optionally, in any of the methods disclosed herein, the step of forming the composite cementitious material is performed simultaneously with the heat-treating step. Optionally, in any of the methods disclosed herein, it is performed after the heat-treating step. Optionally, in any of the methods disclosed herein, the composite cementitious material is Portland cement clinker. Optionally, in any of the methods disclosed herein, the composite cementitious material is ordinary Portland cement and / or the first cementitious material is calcium oxide.Optionally, in any of the methods disclosed herein, the first cement material is calcium oxide. Optionally, in any of the methods disclosed herein, the composite cement material is ordinary Portland cement. Optionally, any method disclosed herein includes forming one or more additives from a calcium-containing starting material. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the first reaction step, and / or formed from one or more by-products of the first reaction step, and / or are one or more by-products of the second reaction step, and / or are formed from one or more by-products of the second reaction step. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the first reaction step, and / or formed from one or more by-products of the first reaction step. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the second reaction step, and / or formed from one or more by-products of the second reaction step. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the first reaction step. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the second reaction step. Optionally, in any of the methods disclosed herein, the one or more additives are one or more by-products of the first reaction step and / or one or more by-products of the second reaction step. Optionally, in any of the methods disclosed herein, the combined chemical composition of the one or more additives includes Al and Si. Optionally, in any of the methods disclosed herein, the one or more additives are at least Al2O3 and SiO2.

[0014] An advantage of the methods disclosed herein is that they can form value-added by-products. For example, instead of using simple calcium sources such as limestone or gypsum as starting materials, complex minerals containing Ca and Si, and optionally other metals such as Al, Mg, and / or Fe, can be used. The methods disclosed herein can include steps to form and isolate valuable products with these special elements, such as oxides of Al, Mg, and / or Fe, instead of the undesirable elements that contaminate the cement product. These steps do not contribute significantly to additional operating costs.

[0015] Preferably, but not necessarily, any of the methods disclosed herein involve forming and isolating silica fume-grade silica, nanosilica and / or microsilica from a calcium-containing starting material. Preferably, but not necessarily, any of the methods disclosed herein involve forming and isolating alumina from a calcium-containing starting material.

[0016] Preferably, but not necessarily, in any method disclosed herein, the first reaction step comprises reacting a calcium-containing starting material with hydrochloric acid to form at least water-soluble aluminum chloride, wherein the method further comprises precipitating aluminum chloride in the presence of hydrochloric acid, optionally reacting the precipitated aluminum chloride with sulfuric acid to form solid aluminum sulfate, and heating the aluminum sulfate and / or aluminum chloride to form alumina. Preferably, but not necessarily, in any method disclosed herein, the hydrochloric acid is regenerated in these steps. Preferably, but not necessarily, in any method disclosed herein, the reaction of the precipitated aluminum chloride forms hydrochloric acid. Preferably, but not necessarily, in any method disclosed herein, the hydrochloric acid is regenerated in these steps. Preferably, but not necessarily, in any method disclosed herein, the second reaction step comprises reacting the precipitated aluminum chloride. Optionally, in any method disclosed herein, the heat-treating step comprises heating aluminum sulfate. Optionally, in any of the methods disclosed herein, the heat-treating step comprises heating aluminum chloride.

[0017] Optionally, any of the methods disclosed herein include forming and isolating iron oxide from a calcium-containing starting material. Optionally, in any of the methods disclosed herein, forming and isolating the iron oxide includes forming an aqueous solution having water-soluble iron sulfate and / or iron chloride and optionally at least one other metal magnesium sulfate salt and / or chloride salt formed as a by-product during the second reaction step, where the aqueous solution is free of calcium salts and free of aluminum salts, drying the aqueous solution to form solid iron sulfate and / or solid iron chloride and optionally at least one other metal sulfate salt, heating the solid iron sulfate and optionally at least one other metal sulfate salt to form a water-insoluble iron oxide, and optionally dissolving the at least one other metal sulfate salt to isolate the water-insoluble iron oxide.

[0018] Optionally, any of the methods disclosed herein include forming and isolating iron oxide from a calcium-containing starting material. Optionally, in any of the methods disclosed herein, forming and isolating the iron oxide includes forming an aqueous solution having water-soluble iron sulfate or iron chloride and optionally at least one other metal magnesium sulfate or chloride salt formed as a by-product during the second reaction step, where the aqueous solution is free of calcium salts and free of aluminum salts, precipitating MgSO using SO, separating the water-soluble iron salt from the solid magnesium salt, drying the aqueous solution to form solid iron sulfate or iron chloride and optionally at least one other metal sulfate salt, heating the solid iron sulfate and optionally at least one other metal sulfate salt to form water-insoluble iron oxide, and optionally dissolving the at least one other metal sulfate salt to isolate the water-insoluble iron oxide.

[0019] Optionally, produce and sell iron chloride, iron sulfate, aluminum chloride and / or aluminum sulfate, and / or any other iron and / or aluminum salts, and / or combine with electrochemical procedures to make iron and aluminum metals from aluminum chloride, aluminum sulfate, and / or other salts. For example, aluminum chloride can be isolated, and aluminum can be electrowinning from the aluminum chloride with the co-production of chlorine gas. This chlorine gas can then be reacted with hydrogen, possibly from the co-production of sulfuric acid and hydrogen, to regenerate HCl. Another example is that iron can be electrowinning from iron sulfate to regenerate sulfuric acid.

[0020] The methods disclosed herein may include one or more acid-forming reactions. The acid-forming reactions may be reactions to regenerate acids consumed in various reactions of the methods. The acid-forming reactions may be reactions that provide an acid to a (first and / or second) reaction step in which the acid is consumed. For example, instead of providing an acid to a reaction step in which the acid is consumed to form a calcium salt, a reagent that forms the acid is provided to the reaction step, such that the reaction step includes both the formation of the acid and the respective acid-consuming (or salt-forming) reaction.

[0021] Preferably, but not necessarily, any method disclosed herein includes a step of forming a first acid, wherein (i) the first reacting step includes a step of forming a first acid, and the step of forming the first acid occurs simultaneously with the first reacting step, or (ii) the step of forming the first acid is performed separately from the first reacting step. Optionally, any method disclosed herein includes a step of forming a first acid, and wherein the first reacting step includes a step of forming a first acid, and the step of forming the first acid occurs simultaneously with the first reacting step. Optionally, any method disclosed herein includes a step of forming a first acid, and wherein the step of forming the first acid is performed separately from the first reacting step.

[0022] Preferably, but not necessarily, any method disclosed herein includes a step of forming a second acid, wherein (i) the second reaction step includes a step of forming a second acid, and the step of forming the second acid is carried out simultaneously with the second reaction step, or (ii) the step of forming the second acid is carried out separately from the second reaction step. Optionally, any method disclosed herein includes a step of forming a second acid, and wherein the second reaction step includes a step of forming a second acid, and the step of forming the second acid is carried out simultaneously with the second reaction step. Optionally, any method disclosed herein includes a step of forming a second acid, and wherein the step of forming the second acid is carried out separately from the second reaction step. Optionally, in any of the methods disclosed herein, the step of forming the second acid includes reacting SO with water to form HSO and / or HSO, and wherein the second acid is HSO and / or HSO. Optionally, in any of the methods disclosed herein, the second acid is H2SO3 and / or H2SO4, and wherein the second calcium salt is CaSO3 and / or CaSO4, respectively.

[0023] Optionally, in any of the methods disclosed herein, the first acid and / or the second acid is a bulk acid. Optionally, in any of the methods disclosed herein, the first acid is a bulk acid. Optionally, in any of the methods disclosed herein, the second acid is a bulk acid.

[0024] Optionally, in any of the methods disclosed herein, the step of forming a first acid comprises forming a pH gradient via electrolysis of water, wherein the first acid is formed via electrolysis of water. Optionally, in any of the methods disclosed herein, the step of forming a second acid comprises forming a pH gradient via electrolysis of water, wherein the second acid is formed via electrolysis of water.

[0025] Optionally, in any of the methods disclosed herein, the second acid regeneration step according to Equation FX1A is carried out at a temperature selected from the range of 400°C to 1800°C. Optionally, in any of the methods disclosed herein, the second acid regeneration step according to Equation FX1A is carried out at a temperature selected from the range of 400°C to 600°C. Optionally, in any of the methods disclosed herein, the second acid regeneration step according to Equation FX1A is carried out at a temperature selected from the range of 400°C to 600°C, is exothermic, and is carried out in the presence of a catalyst. Optionally, the catalyst comprises vanadium oxide. Optionally, in any of the methods disclosed herein, the method is characterized by a net energy selected from the range of -2 to +2 GJ per metric ton of produced cementitious material (e.g., the produced first cementitious material or the produced composite cementitious material, such as OPC). Optionally, in any of the methods disclosed herein, the method is characterized by a net energy selected from the range of -10 to +10 GJ / t, optionally -5 to +5 GJ / t, optionally -5 to +4 GJ / t, optionally -5 to +3 GJ / t, optionally -5 to +2 GJ / t, optionally -5 to +1 GJ / t, optionally -5 to +0.5 GJ / t, optionally -5 to +0.2 GJ / t, optionally -5 to +0.1 GJ / t, optionally -5 to 0 GJ / t, optionally -2 to 1 GJ / t, optionally -2 to -1.5 GJ / t, optionally -2 to +1.0 GJ / t, optionally -2 to +0.5 GJ / t, optionally -2 to +0.3 GJ / t, optionally -2 to +0.2 GJ / t, optionally -2 to +0.1 GJ / t, optionally -2 to +0 GJ / t. Optionally, in any of the methods disclosed herein, the first reaction step is exothermic. Optionally, in any of the methods disclosed herein, the second acid regeneration step is exothermic. Optionally, in any of the methods disclosed herein, the first reaction step is carried out at a temperature of at least 50°C. Optionally, in any of the methods disclosed herein, the first reaction step is carried out at a temperature selected from the range of 80°C to 100°C, preferably 90±5°C.Optionally, in any of the methods disclosed herein, the heat-treating step is carried out at a temperature selected from the range of 1100°C to 1800°C. Optionally, in any of the methods disclosed herein, the heat-treating step includes heat-treating the second calcium salt in the presence of a chemical reducing agent, and is carried out at a temperature selected from the range of 800°C to 1200°C. Optionally, the chemical reducing agent is water, carbon (or carbon, hydrogen gas, methane, any allotrope or combination of allotropes of gases, or any combination thereof). Optionally, the chemical reducing agent is water, carbon (or carbon, methane, any allotrope or combination of allotropes of gases, or any combination thereof). If desired, the heat treatment step can be carried out according to any one or combination of the formulas FX4A, FX4B, FX4C, and FX4D, i.e., CaSO4 + H2O → CaO + H2SO4 (FX4A), CaSO4 + 2C → CaS + 2CO2 (FX4B), CaSO4 + CH4 → CaS + CO2 + 2H2O (FX4C), CaS + 3CaSO4 → 4CaO (FX4D).

[0026] Any of the methods disclosed herein may be carried out as a batch process, a plug flow process, a semi-continuous process, a stepwise process, a continuous process, or any combination thereof. Any step of any of the methods disclosed herein may be carried out as a batch process, a plug flow process, a semi-continuous process, a stepwise process, a continuous process, or any combination thereof.

[0027] Additional aspects of the invention disclosed herein include methods for producing cementitious materials via reductive pyrolysis, the methods comprising reacting a calcium-containing material with a chemical reducing gas to produce methane and cementitious materials. Preferably, but not necessarily, in any method for producing cementitious materials via reductive pyrolysis, the calcium-containing material comprises CaCO3, CaSO4, CaS, a calcium salt, or any combination thereof. Preferably, but not necessarily, in any method for producing cementitious materials via reductive pyrolysis, the calcium-containing material is CaCO3, CaSO4, CaS, or any combination thereof. Preferably, but not necessarily, in any method for producing cementitious materials via reductive pyrolysis, the calcium-containing material is CaCO3. Preferably, but not necessarily, in any method for producing cementitious materials via reductive pyrolysis, the calcium-containing material comprises CaCO3. Preferably, but not necessarily, in any method for producing cementitious materials via reductive pyrolysis, the chemical reducing gas is hydrogen gas or a gas containing hydrogen gas, such as forming gas. Preferably, but not necessarily, in any method for producing a cementitious material via reductive pyrolysis, the cementitious material comprises CaO. Preferably, but not necessarily, in any method for producing a cementitious material via reductive pyrolysis, the cementitious material is CaO. Preferably, but not necessarily, in any method for producing a cementitious material via reductive pyrolysis, the molar ratio of the calcium-containing material reacted with the chemical reducing gas is 1:4 or 1:2. Optionally, in any method for producing a cementitious material via reductive pyrolysis, the reaction is carried out in the presence of water. Optionally, in any method for producing a cementitious material via reductive pyrolysis, the reaction is carried out in the absence of water. Optionally, in any method for producing a cementitious material via reductive pyrolysis, the molar ratio of CaCO3 reacts with hydrogen gas at a molar ratio of 1:4 during the reacting step.Optionally, in any method for producing cementitious materials via reductive pyrolysis, a molar ratio of CaCO3 reacts with hydrogen gas at a 1:2 molar ratio during the reacting step. Generally, a 1:4 molar ratio reaction has lower energy but higher OpEx because more H2 needs to be produced but a lower temperature can be used. Generally, a 1:2 molar ratio reaction has higher energy but lower OpEx. Optionally, in any method for producing cementitious materials via reductive pyrolysis, oxygen gas, water, or a combination of oxygen gas and water is produced during the reacting step. Optionally, in any method for producing cementitious materials via reductive pyrolysis, the method includes decomposing methane to produce hydrogen gas and one or more carbonaceous materials. Optionally, in any method for producing cementitious materials via reductive pyrolysis, the method does not include forming CO2. Optionally, in any method for producing a cementitious material via reductive pyrolysis, the reacting step is characterized by a lower heating value (LHV) of 720 kJ / mol or less and a higher heating value (HHV) of 800 kJ / mol or less. Optionally, in any method for producing a cementitious material via reductive pyrolysis, the reacting step is carried out at a temperature of at least 700°C.

[0028] Additional aspects of the invention disclosed herein include methods for producing cement materials according to a single-acid approach, where only one acid or only one acid reaction step is required. In one aspect, the method for producing a cement material includes a first reaction step of reacting a calcium-containing starting material with a first acid to produce a first water-soluble fraction including a water-soluble first calcium salt and a first solid fraction including one or more solid by-products, where the calcium-containing starting material has a chemical composition including multiple metal elements including at least Ca and Si, and the one or more solid by-products include silicon salts; a first separation step of separating the first water-soluble fraction from the first solid fraction; and a step of treating the first calcium salt to produce a first cement material. Optionally, the treatment step includes thermally treating (or pyrolyzing) the first calcium salt in the presence of water to produce the first cement material. Optionally, the first acid is regenerated by thermally treating (or pyrolyzing) the first calcium salt. Optionally, the processing step includes an ion exchange step, where the ion exchange step includes exchanging one or more anions of the first calcium salt with one or more hydroxyl anions to form a third calcium salt. Optionally, the ion exchange step includes reacting the first calcium salt with a chelating agent to form a calcium chelating compound and reacting the calcium chelating compound with a base to form a third calcium salt. Optionally, the ion exchange step includes reacting the first calcium salt with a base to form a third calcium salt. Optionally, the ion exchange step includes using an ion exchange membrane to exchange one or more anions of the first calcium salt with hydroxyl anions to form the third calcium salt. Preferably, the third calcium salt is Ca(OH). Optionally, the processing step includes thermally treating (or pyrolyzing) the third calcium salt to produce the first cement material. Optionally, the base is a hydroxide compound. Optionally, the first calcium salt is CaCl.Optionally, for example, the treating step includes thermally decomposing CaCl in the presence of air according to the formula: CaCl + O → CaO + Cl + 1 / 2O. Optionally, for example, the treating step includes thermally treating CaCl in the presence of water according to the formula: CaCl + H O → CaO + 2HCl. Optionally, for example, the treating step includes ion exchange using an ion exchange membrane to exchange Cl ions for OH ions, thereby forming Ca(OH). Optionally, for example, the treating step further includes dehydrating the Ca(OH) to create the first cementitious material. Optionally, for example, the treating step includes reacting the first calcium salt with a chelating agent to form a calcium chelating agent compound. Optionally, for example, the treating step includes reacting a base, such as NaOH, Mg(OH) or MgCl(OH), with the first calcium salt, such as CaCl, to form Ca(OH). Optionally, for example, the treating step further comprises pyrolyzing Ca(OH) to produce a first cement material. The first cement material optionally is or optionally includes CaO. Optionally, the first acid is hydrogen chloride. Optionally, the one or more solid by-products include SiO. Optionally, the at least one multi-metal oxide material is at least one naturally occurring rock or mineral.

[0029] Optionally, in any of the methods disclosed herein, the first calcium salt and / or the second calcium salt is other than Ca(OH) or comprises a salt other than Ca(OH). Optionally, in any of the methods disclosed herein, the first reaction step is not an electrochemical step. Optionally, in any of the methods disclosed herein, the second reaction step is not an electrochemical step. Optionally, in any of the methods disclosed herein, the calcium-containing starting material is other than CaCO or comprises a material other than CaCO.

[0030] While not wishing to be bound by any particular theory, there may be discussion herein of beliefs or understandings of the underlying principles related to the devices and methods disclosed herein, and it is recognized that whether or not the mechanistic explanations and hypotheses are fundamentally correct, embodiments of the present invention will be operable and useful regardless. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a plot of methane production in a tube furnace as methane partial pressure versus temperature. The flow rate of forming gas (5% H2, 95% N2) is 0.3 lpm. [Figure 2] 1 is a plot of methane production in a tube furnace as moles of methane versus time. The forming gas (5% H2, 95% N2) flow rate is 0.3 lpm. [Figure 3] 1 is an XPS pattern of the product obtained by reacting CaCO3 in a reducing environment, showing pure CaO produced. DETAILED DESCRIPTION OF THE INVENTION

[0032] (Compound and nomenclature description) Generally, the terms and phrases used herein have meanings recognized by those skilled in the art, which can be found by reference to standard texts, references, and contexts known to those skilled in the art. The following definitions are provided to clarify their specific use in the context of the present invention.

[0033] The terms "thermal conversion" and "thermally converting" refer to the conversion of a first chemical species to a second chemical species via a thermally activated or thermally driven process, which may also be referred to as a thermochemical process. An exemplary process for the thermal conversion of a chemical species is combustion, but thermal conversion processes are not necessarily limited thereto. For example, the thermal conversion of sulfur to sulfur dioxide may include the combustion of sulfur, such as via a sulfur burner system. The thermal oxidation of a species is a form of thermal conversion of a species. For example, the thermal conversion of sulfur to sulfur dioxide may be referred to as the thermal oxidation of sulfur to sulfur dioxide. In some embodiments, the thermal conversion may be facilitated by a catalyst. In some embodiments, the thermal conversion does not require a catalyst or is carried out without a catalyst. Note that thermal oxidation and electrochemical oxidation are distinct processes, with thermal oxidation being thermally driven or activated (via heating or combustion) and electrochemical oxidation being electrochemically driven (e.g., via the application or withdrawal of electrical energy, optionally with the assistance of an electrochemical catalyst). The term "thermal treatment" refers to the thermal treatment or exposure of one or more materials (such as calcium salts such as CaSO) to heat, preferably above room temperature, such that the one or more materials may thermally transform, thermally decompose, or otherwise undergo a heat-induced chemical change to another material (such as a cementitious material such as CaO). For example, calcium sulfate (gypsum) may thermally transform / decompose to calcium oxide (CaO), with the formation of by-products such as SO and oxygen. Heat treatment may also convert or otherwise form multiple materials, such as materials containing calcium, aluminum, and silicon, into composite cementitious materials such as ordinary Portland cement (OPC).

[0034] The term "calcium-containing starting material" refers to one or more materials whose chemical composition includes Ca. The calcium-containing starting material can be a single material, such as a mineral, whose chemical composition includes the element Ca, such as in the form of Ca cations as part of an ionic material, such as a multi-component metal oxide material. The calcium-containing starting material can be multiple materials, such as one or more rocks, minerals, and / or industrially processed materials, where the chemical composition of the combination of the multiple materials includes the element Ca, such as in the form of Ca cations in an ionic material, such as a multi-component metal oxide material. When the calcium-containing starting material is multiple materials, any one or any combination of the multiple materials can have a chemical composition that includes the element Ca, such that the chemical composition of the combination of the multiple materials (together a calcium-containing starting material) includes the element Ca. Preferably, a calcium-containing starting material having a chemical composition that includes the element Ca refers to a weight percent and / or mole percent of Ca in the calcium-containing starting material that is at least 0.001%, preferably at least 0.01%, preferably at least 0.1%, more preferably at least 1%, even more preferably at least 5%, even more preferably at least 10%, and even more preferably at least 20%. On the other hand, the methods disclosed herein are compatible with calcium-containing starting materials whose chemical composition has a low weight and / or molar percentage, such as less than 60%, less than 55%, less than 50%, less than 45%, less than 40%, and less than 20%, since at least Ca can be isolated along with its respective counterion.

[0035] Generally, a material or species having a chemical composition characterized as including an element X (where "X" is an element in the periodic table of the elements) refers to a weight percent and / or mole percent of X in that material or species that is at least 0.001%, preferably at least 0.01%, more preferably at least 0.1%, and even more preferably at least 1%.

[0036] The term "calcium salt" refers to a salt whose chemical composition includes the element Ca, for example, in the form of the Ca cation. A salt is a compound containing ionic species at least partially bonded to one another through ionic bonds. For example, CaSO4 and CaCl2 are calcium salts, where Ca is the cation and SO4 and Cl are the anions, respectively.

[0037] A regeneration step refers to a step in a process for producing a species or material using the product of a different step that consumes (e.g., is converted to another species or material via a chemical change) that species or material in question. For example, a reaction characterized by (A+B→C+D) consumes species A and B to form species C and D. A reaction characterized by (C+E→A+F) can be referred to as a regeneration reaction for regenerating species A using the product (species C) of the reaction that consumed species A.

[0038] The term "solid fraction" refers to solid species present in a mixture of solids and liquids. The term "liquid fraction" refers to liquid species and species dissolved in liquid species in a mixture of solids and liquids. For example, the solid fraction can have solid products of a chemical reaction, and the liquid fraction can have liquid and dissolved products of a chemical reaction. Each of the solid and liquid fractions can optionally contain unreacted reagents. The liquid fraction can include a solvent and ions dissolved in the solvent.

[0039] The "dry mass" of one or more ingredients, such as the solid fraction, refers to the mass of one or more ingredients, excluding water and, optionally, excluding liquid species.

[0040] The term "metal oxide" generally refers to a material whose chemical composition includes one or more metal elements and the element O. Optionally, the metal oxide material is an ionic or at least partially ionic material, where at least some of the chemical bonds are characterized as ionic bonds. The metal element is any metal or metalloid element of the periodic table of the elements. Generally, the metalloid element is selected from the group consisting of B, Si, Ge, As, Se, Sb, Te, Po, and At.

[0041] The term "natural rock or mineral" refers to one or more substances naturally occurring in or extracted from the Earth's crust. Natural rocks and minerals include, but are not limited to, basalt, igneous apatite, wollastonite, anorthosite, montmorillonite, bentonite, calcium-bearing feldspar, anorthite, diopside, pyroxene, pyroxenite, magmatite, kamaphite, clinopyroxene, colemanite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheelite, skarn, limestone, natural gypsum, apatite, fluorapatite, and any combination thereof. In contrast, cement, concrete, Portland cement, fly ash, and slag are not naturally occurring rocks or minerals but may be referred to as industrially derived materials.

[0042] The term "bulk acid" refers to an acid or acid solution that exists and functions as required by a given process or step without requiring a continuous input of energy (such as electrical energy) and / or the exchange of electrons with an electrode surface. In contrast, a heterogeneous or localized acidic solution, such as hydronium ions or protons, that is near an electrode and forms substantially only as a result of and during the exchange of electrons between the electrode and the solution is not a bulk acid. For example, a bulk acid is not a heterogeneous or localized acidic solution that corresponds to the pH gradient formed at an electrode during water electrolysis. In certain embodiments, the term "bulk acid" refers to an acid or acid solution that exhibits thermodynamic, chemical, and / or kinetic stability in the absence of electrical energy input over a time scale of at least 10 seconds, preferably at least 1 minute. In certain embodiments, the term "bulk acid" refers to an acid or acid solution that exhibits or is capable of exhibiting thermodynamic, chemical, and / or kinetic stability in the absence of electrical energy input over a time scale of at least 1 second and a length scale of at least 10 cm, preferably at least 10 cm from the surface of the bulk material.

[0043] The term "electrochemical cell" refers to devices and / or device components that perform electrochemistry. Electrochemistry refers to the conversion of chemical energy to electrical energy or electrical energy to chemical energy. Chemical energy can correspond to a chemical change or reaction. Thus, electrochemistry can refer to a chemical change (e.g., a chemical reaction of one or more chemical species to one or more other species) that produces electrical energy and / or electrical energy that is converted or used to induce a chemical change. Electrical energy refers to potential energy, which corresponds to the combination of current and potential in an electric circuit. Electrochemical cells have two or more electrodes (e.g., positive and negative electrodes, e.g., a cathode and an anode) and one or more electrolytes. The electrolyte can contain species that are oxidized and species that are reduced during charging or discharging of the electrochemical cell. Reactions occurring at the electrodes, such as sorption and desorption of chemical species or oxidation or reduction reactions, contribute to the charge transfer process of the electrochemical cell. Electrochemical cells include, but are not limited to, electrolytic cells, such as electrolyzers and fuel cells. Electrochemical oxidation can occur, for example, at an anode, and electrochemical reduction can occur, for example, at a cathode. Electrochemical oxidation refers to a chemical oxidation reaction involving the transfer of electrical energy (e.g., an electrical energy input that drives an oxidation reaction) that occurs in the context of an electrochemical cell. Similarly, electrochemical reduction refers to a chemical reduction reaction involving the transfer of electrical energy that occurs in the context of an electrochemical cell. For example, a chemical species electrochemically oxidized during charging can be electrochemically reduced during discharging, and vice versa. The terms "electrochemically" or "electrochemical" can refer to a reaction, process, or steps thereof in which chemical energy is converted to electrical energy or electrical energy is converted to chemical energy. For example, when electrical energy is provided to help drive the chemical conversion of reactants to products, products can be formed electrochemically. The term "non-electrochemical" refers to a reaction or process that does not involve and / or require electrochemistry to perform.

[0044] A reaction step refers to a process step in which a chemical reaction occurs and is characterized by one or more chemical species undergoing a chemical change to one or more other chemical species (e.g., via chemical reaction with each other).

[0045] The term "elemental sulfur" includes S7, S8, S6, and S 12 and S 18 "Sulfur" refers to any one or combination of allotropes of sulfur, including, but not limited to, crystalline, polycrystalline and / or amorphous sulfur.

[0046] "RHE" refers to a reference electrode commonly called a reversible hydrogen electrode. "SCE" refers to a reference electrode commonly called a saturated calomel electrode.

[0047] The term "initial operating time" refers to the time the cell is operating, starting from the first / initial operation or "power-on" of the cell. Time during which the cell or system is not operating (i.e., time during which no electrochemical reduction or oxidation is occurring, or no input or output of electrical energy is occurring) is not included in the initial time for operational determinations.

[0048] In some embodiments, the term "aqueous" refers to a solution in which the solvent is water, such that other species or solutes are substantially solvated by the water. In some embodiments, the term "aqueous" may generally refer to a solution that includes water. Optionally, but not necessarily, the aqueous solution or solvent contains 5% or less by volume of non-aqueous solvent and / or solute species.

[0049] The term "agricultural water improvement" refers to changing agricultural water or adding something, such as a solute, to agricultural water. For example, acidifying agricultural water by adding sulfuric acid, such as a solution containing sulfuric acid, to agricultural water. Agricultural water refers to water used for agricultural purposes, such as irrigation. The term "soil improvement" refers to changing soil or adding something to soil. For example, acidifying soil by adding sulfuric acid, such as a solution containing sulfuric acid, to soil.

[0050] The term "cement" refers to hydraulic, non-hydraulic, or both hydraulic and non-hydraulic cementitious materials. An exemplary cement is, but is not limited to, Portland cement. Generally, cement is a binding material and may be mixed with, for example, finely aggregated particles (such as when producing masonry mortar) or sand or gravel (when producing concrete). According to certain embodiments, cement includes calcium oxide. Cement may optionally further include one or more other materials, including, but not limited to, certain silicates, SiO2, certain oxides, Fe2O3, certain aluminates, Al2O3, belite, alite, tricalcium aluminate, and brownmillerite. "Cementitious material" refers to a material that is or can be a component of cement. Preferably, the cementitious material has a chemical composition that includes Ca or CaO. For example, CaO is a cementitious material. For example, a cementitious material is a cementitious material. A composite cementitious material may include multiple materials, including at least one cementitious material and, optionally, one or more additives. Exemplary composite cement materials are, but are not limited to, Portland cements such as Portland cement clinker and ordinary Portland cement (OPC).

[0051] The term "substantially" refers to a property or condition that is within 20%, optionally within 10%, optionally within 5%, optionally within 1%, of a reference property or condition, or is equivalent to the reference property or condition, as appropriate. The terms "substantially equal," "substantially equivalent," or "substantially unchanged," when used in conjunction with a reference value describing a property or condition, refer to a value or condition that is within 20%, optionally within 10%, optionally within 5%, optionally within 1%, optionally within 0.1% of the reference value or condition, or is equivalent to the provided reference value or condition, as appropriate. For example, a voltage that is substantially 500 mV (or substantially equivalent to 500 mV) is within 20%, optionally within 10%, optionally within 5%, optionally within 1%, or optionally equal to 500 mV. The term "substantially greater than," when used in conjunction with a reference value or condition describing a property or condition, refers to a value or condition that is at least 2%, optionally at least 5%, optionally at least 10%, or optionally at least 20% greater than the provided reference value or condition. For example, a voltage is substantially greater than 500 mV if the voltage is at least 20% greater, optionally at least 10% greater, optionally at least 5% greater, or optionally at least 1% greater than 500 mV. The term "substantially lower," when used in conjunction with a reference value or condition describing a property or condition, refers to a value or condition that is at least 2%, optionally at least 5%, optionally at least 10%, or optionally at least 20% lower than the provided reference value. For example, a voltage is substantially less than 500 mV if the voltage is at least 20% lower, optionally at least 10% lower, optionally at least 5% lower, or optionally at least 1% lower than 500 mV.

[0052] Additionally, to the extent not inconsistent herewith, incorporated by reference herein is U.S. Patent Publication No. 2019 / 0376191 (Finke; U.S. Patent Application No. 16 / 415,275), which may contain additional useful terms, descriptions, and embodiments.

[0053] In one embodiment, a composition or compound of the invention, such as an alloy or a precursor to an alloy, is isolated or substantially purified. In one embodiment, an isolated or purified compound is at least partially isolated or substantially purified, as understood in the art. In one embodiment, a substantially purified composition, compound, or formulation of the invention has a chemical purity of 95%, optionally for some applications 99%, optionally for some applications 99.9%, optionally for some applications 99.99%, and optionally for some applications 99.999% purity.

[0054] (Detailed Description of the Invention) In the following description, numerous specific details of the devices, device components, and methods of the present invention are set forth in order to provide a thorough explanation of the precise nature of the invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

[0055] The present invention can be further understood by the following non-limiting examples.

[0056] Example 1: Process for making calcium oxide or ordinary Portland cement from calcium-containing rocks and minerals

[0057] Conventional cement is made by pyrolyzing CaCO3 to CaO, which is then mixed with other materials including Al2Si2O5(OH)4, Fe2O3, and CaSO4. Pyrolysis occurs at approximately 900°C, and the final OPC formation occurs at approximately 1450°C. Most of the energy required and CO2 emissions for cement production come from the pyrolysis of limestone. CaCO3 → CaO + CO2 ΔH = 178 (non-spontaneous reaction) (FX5) Conventional cement requires 2.7 to 6 GJ / ton of OPC and produces 0.7 to 1.3 tons of CO2 per ton of OPC (ordinary portland cement). The conventional cement process emits large amounts of CO2 and consumes large amounts of energy.

[0058] Included in this disclosure is a process for producing CaO from calcium-containing rocks or minerals. In nature, acids (e.g., H2CO3 or H2SO4) weather calcium-containing minerals, typically producing CaCO3 or CaSO4. The general weathering trend is: H2CO3+CaAl2Si2O8+H2O→CaCO3+Al2Si2O5(OH)4(FX6), or H2SO4+CaAl2Si2O8+H2O→CaSO4+Al2Si2O5(OH)4(FX7), Follow.

[0059] In nature, these acids are very dilute, and this weathering usually occurs over long periods of time (weeks to decades). Weathering can occur on calcium-bearing minerals or rocks. Common examples are wollastonite, anorthosite, Ca-bentonite, montmorillonite, plagioclase, and basalt. All calcium-bearing rocks are possible, including all mafic and ultramafic rocks.

[0060] The methods disclosed herein may use acids (e.g., H2SO4, HF, HCl, H2CO3) or combinations of acids with calcium-containing rocks or minerals (e.g., anorthosite, montmorillonite, wollastonite) to produce calcium salts (e.g., CaSO4, CaF2, CaCl2, CaCO3). This salt can then be hydrated or pyrolyzed to produce CaO. This may also enable suitable ratios of starting materials to pyrolyze the calcium salts and by-products into cementitious materials, including ordinary Portland cement or calcium sulfoaluminate cement. The strength, concentration, or quality of the acid and the particle size of the mined calcium-containing rock may alter the kinetics of calcium salt removal from the calcium-containing starting material, and different acid concentrations and crushed rock sizes may be optimal for different types of this process.

[0061] Advantages of the processes disclosed herein may include that they are CO2-free and energy-neutral. H2SO4+CaAl2Si2O8+H2O→CaSO4+Al2Si2O5(OH)4(FX8), CaSO4 → CaO + SO2 + 1 / 2O2 (FX9), SO2+H2O+1 / 2O2→H2SO4(FX10), Net value: CaAl2Si2O8 + 2H2O → CaO + Al2Si2O5(OH)4(FX11), ΔH≒0 is.

[0062] This process can also be used to make clean hydrogen when using electrochemical co-generation of H2 and H2SO4. H2SO4+CaAl2Si2O8+H2O→CaSO4+Al2Si2O5(OH)4(FX12), CaSO4→CaO+SO2+1 / 2O2(FX13), SO2 + 2H2O → H2 + H2SO4 (FX14), Net value: CaAl2Si2O8 + 2H2O → CaO + Al2Si2O5(OH)4 + 1 / 2O2 + H2(FX15), ΔH=50 (slight increase) is.

[0063] Example 2: Reductive pyrolysis of limestone to produce lime or cement

[0064] Lime is used directly as a commodity chemical as well as the main component of cement, the most consumed man-made material on Earth. Lime is currently produced via the thermal decomposition of limestone in the atmosphere (FX16). CaCO3 → CO2 + CaO (FX16). The heat of decomposition for this reaction is 178 kJ / mol.

[0065] Included in this invention is a process for producing cement from limestone via reductive pyrolysis with hydrogen. The first step in the process is CaCO3+4H2→CH4+2H2O (FX17A), or CaCO3 + 2H2 → CH4 + O2 (FX17B), The reaction can be followed by:

[0066] The water content of the reactant gas affects whether the reaction proceeds according to FX17A, FX17B, or both. CaCO3 reacts with H2 to make either CaO + CH4 + O2 or CaO + CH4 + 2H2O. If H2O is formed, 4 H2 are consumed. If O2 is formed, only 2 H2 are consumed. This reaction can be driven to consume only 2H2, for example, if a water atmosphere is present.

[0067] The reaction may stop there, or a second step may be a chemical reaction, i.e. CH4→2H2+C (FX18), methane pyrolysis to regenerate hydrogen or optionally methane.

[0068] One advantage of this reaction is that it produces solid carbon instead of CO2, so it does not pollute the atmosphere. Another advantage of reaction FX17A is that it requires less energy than conventional limestone pyrolysis (13.1 kJ / mol). An advantage of reaction FX17B is that 100% of the required hydrogen can be regenerated from methane pyrolysis.

[0069] In certain embodiments, reaction FX17A occurs under reducing conditions, e.g., above 700°C, in an H2, H2 / N2 atmosphere, or any other combination. Reaction FX17B can occur above 700°C using H2 under a water atmosphere. For example, 2.011 g of CaCO3 powder was placed in a tube furnace and heated at 7°C / min. For example, forming gas was flowed at 0.3 liters per minute (lpm). For example, a gas analyzer was attached to the back of the furnace to measure methane concentration. The data can be seen in Figures 1 and 2. XPS determines that the pyrolysis resulted in greater than 99% lime (Figure 3).

[0070] By integrating under these curves, we determine that we have achieved approximately 100% decarbonization.

[0071] Example 3: Production of gypsum and cementitious materials

[0072] Exemplary Embodiment 1: Production of Ordinary Portland Cement (OPC) from any calcium-containing starting material without net production of acid-forming gases (e.g., SO and CO). Examples of calcium-containing starting materials include basalt, igneous apatite, wollastonite, slag, fly ash, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, magmatite, kamaphite, clinopyroxene, colemanite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheelite, OPC, concrete, any rock having Ca or CaO, particularly rock having more than 5%, more than 10%, or more than 15% CaO by weight, any skarn, limestone, gypsum, apatite, or fluoroapatite.

[0073] In certain embodiments, this is done by first producing synthetic gypsum of greater than 90% purity from the calcium-bearing rocks described above (more details in claim 2), then pyrolyzing the gypsum to make CaO, which is then mixed with appropriate ratios of other materials to form OPC. The SO2 produced can be upgraded to sulfuric acid (via a catalytic process or sulfur-depolarized electrolyzer) and recycled to make synthetic gypsum. The general chemical reaction is:

[0074] 1.CaAl2Si2O8+H2SO4→CaSO4(purity over 90 dry weight%)+Al2O3+SiO2(FX19),

[0075] 2.CaSO4+heating→CaO+1 / 2O2+SO2(FX20),

[0076] 3.CaO+xAl2O3+ySiO2→OPC (FX21),

[0077] 4.SO2+1 / 2O2+H2O→H2SO4(FX22).

[0078] Ordinary Portland cement (OPC) is currently made industrially exclusively from limestone (primarily CaCO3). The production of OPC involves first producing CaO by thermal decomposition of CaCO3 (e.g., CaCO3 + heat → CaO + CO2), and then heating the CaO with silica and alumina to form OPC, which is about 60% CaO by mass. CO2 production from cement production accounts for over 5% of global CO2 emissions.

[0079] In addition to limestone, OPC can also be made from gypsum (CaSO4). Mined gypsum (CaSO4) can be used in several ways to produce OPC. In this process, CaSO4 is thermally decomposed to produce CaO (e.g., CaSO4 + heat → CaO + 1 / 2O2 + SO2). This process can also be achieved by carbothermal or hydrothermal reduction, in which CaS is produced by reacting CaSO4 with a reducing agent (such as coal), which is then co-pyrolyzed with CaSO4 to produce CaO. This process is known as the Mueller-Kühne process. Neither of these processes is currently commercially practiced because SO2 cannot be released into the atmosphere and the global demand for SO2 is much lower than that for OPC.

[0080] OPC can be produced from "phosphogypsum" (CaSO4, produced by reacting phosphate rock with H2SO4 to make phosphoric acid and gypsum). The fertilizer industry produces waste CaSO4 by reacting sulfuric acid with phosphate rock (mainly Ca5(PO4)3OH) to make phosphoric acid. This synthetic gypsum can be pyrolyzed to make CaO, which can then produce OPC, as in the process described above.

[0081] The methods disclosed herein dramatically expand the starting materials from which OPCs can be made compared to conventional methods.

[0082] Exemplary Embodiment 2: Production of >90% pure CaSO4 from calcium-bearing rock. For example, HCl first reacts with the rock to dissolve calcium chloride and precipitate >90% dry weight pure SiO2 and other by-products. The dissolved solution is reacted with, for example, sulfuric acid, which selectively precipitates CaSO4 because it is the only sulfate among common sulfates (MgSO4, Al2(SO4)3, Fe2(SO4)3) that is insoluble in water. This also regenerates HCl. The sample chemical reaction is as follows:

[0083] 1. CaAl2Si2O8+8HCl → CaCl 2(aq) +2AlCl3 (aq) +SiO 2(s) (FX23),

[0084] 2. Separation of solid and water-soluble fractions (FX24),

[0085] 3. CaCl 2(aq) +2AlCl 3(aq) +4H2SO4 → CaSO 4(s) +Al2(SO4) 3(aq) +8HCl (FX25).

[0086] The methods disclosed herein involve the production of CaSO4 with purity greater than 90% by dry weight, making the process cheaper, less complex, and more controllable for the ratios of materials required for the precise production of OPC.

[0087] Calcium sulfate, 90% dry weight, can also be produced as a by-product of reacting sulfuric acid with either limestone (CaCO3) and rock phosphate (Ca5(PO4)3OH or Ca5(PO4)3F). The products of these reactions are either water soluble (HF, H2PO4), liquid (H2O) or gaseous (CO2).

[0088] Advantageously, the methods disclosed herein can obtain high purity synthetic gypsum from any rock, even if the by-products are not soluble in sulfuric acid.

[0089] Example 4: Co-production of valuable by-products

[0090] Exemplary Embodiment 3: Production of alumina from any calcium-bearing rock. This can be done by first leaching with HCl and then saturating the leachate with HCl. The high concentration of HCl causes precipitation of AlCl. The AlCl is then mixed with HSO to make Al(SO) and regenerate HCl. Al(SO) can be thermally decomposed to make AlO, which can make SO to regenerate sulfuric acid. An exemplary chemical reaction is as follows:

[0091] 1. CaAl2Si2O8+8HCl → CaCl 2(aq) +2AlCl 3(aq) +SiO 2(s) (FX26),

[0092] 2. AlCl 3(aq) +HCl (aq) →AlCl 3(s) +HCl (aq) (FX27),

[0093] 3.2AlCl 3(s) +H2SO4 → Al2(SO4)3(FX28),

[0094] 4.Al2(SO4)3+ heating → 3SO2+Al2O3+3 / 2O2(FX29),

[0095] 5.SO2+1 / 2O2+H2O→H2SO4(FX30).

[0096] Exemplary Embodiment 4: Iron oxide production from any calcium-bearing rock. Once Al, Ca, and Si are removed via the process described above, only water-soluble iron sulfate and magnesium sulfate remain in solution. When the water is evaporated and the salt is heated to 500-700°C, the iron sulfate decomposes into insoluble iron oxide, and the remaining magnesium sulfate can dissolve in water, leaving only the iron oxide.

[0097] Exemplary Embodiment 5: Production of secondary cementitious materials including silica fume from calcium-bearing rocks. A secondary benefit of our process is that it dissolves everything except the silica, so all particle sizes are very small and synthetic silica fume can be created.

[0098] The co-production of value-added by-products is a key advantage of the methods disclosed herein. An unexpected additional benefit of the "first reaction" step, or the leaching step corresponding to the reaction of the calcium-containing starting material with the first acid, is that it can co-produce numerous by-products, including Al2O3, SiO2, silica fume-grade silica, Fe2O3, and MgO. These products can also be of high purity due to the use of chemical separation. As disclosed herein, according to certain embodiments with the advantages of higher thermal decomposition efficiency and valuable HCl regeneration, the use of HCl concentrations to precipitate aluminum was used to make AlCl3 from aluminum-bearing rocks, but not to make Al2(SO4)3.

[0099] The methods disclosed herein include the advantages of expanding the starting materials from which these products can be made and often achieving superior process efficiency, product purity and quality over conventional processes.

[0100] INCORPORATION-BY-REFERENCE AND VARIATIONS THEREOF All references throughout this application, e.g., patent documents, patent applications, including issued or issued patents or equivalents, and non-patent literature or other materials, are incorporated herein in their entirety, as if individually incorporated by reference, to the extent that each reference does not at least partially contradict the disclosure of this application (e.g., a partially contradictory reference is incorporated by reference except for the partially contradictory portion).

[0101] The terms and expressions used herein are used as terms of description and not of limitation. The use of such terms and expressions is not intended to exclude the features shown and described therein or equivalents thereof, but it is recognized that various modifications are possible within the scope of the claimed invention. Thus, while the present invention is specifically disclosed by preferred embodiments, exemplary embodiments, and optional features, it should be understood that modifications and variations of the concepts disclosed herein may be utilized by those skilled in the art, and such modifications and variations may be considered within the scope of the present invention, as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention, and it will be apparent to those skilled in the art that the present invention can be implemented using numerous variations of the devices, device components, and method steps described in this description. As will be apparent to those skilled in the art, the methods and devices useful in the methods of the present invention may include numerous optional compounds and processing elements and steps.

[0102] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a cell" includes a plurality of such cells and equivalents thereof known to those of skill in the art. Similarly, the terms "a" (or "an"), "one or more," and "at least one" may be used interchangeably herein. It should also be noted that the terms "comprising," "including," and "having" may be used interchangeably. The phrase "any of claims XX-YY" (where XX and YY refer to claim numbers) is intended to provide multiple dependent claims in an alternative format and, in some embodiments, is interchangeable with the phrase "any one of claims XX-YY."

[0103] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, including any isomers, enantiomers, and diastereomers of the group members, are separately disclosed. When Markush groups or other groups are used herein, all individual members of the group and all possible combinations and subcombinations of the group are intended to be individually included in the disclosure. When a compound is described herein such that a specific isomer, enantiomer, or diastereomer of the compound is not specified, for example, by formula or chemical name, the description is intended to include each isomer and enantiomer of the compound described individually or in any combination. In addition, unless otherwise specified, all isotopic variations of the compounds disclosed herein are intended to be included in the disclosure. For example, it is understood that any one or more hydrogen atoms in the disclosed molecules can be replaced with deuterium or tritium. Isotopic variations of molecules are generally useful as standards for assays of molecules and chemical and biological studies related to the molecules or their uses. Methods for making such isotopic variations are known in the art. The particular names of the compounds are intended to be exemplary, as one of ordinary skill in the art will recognize that the same compound may have different names.

[0104] Certain molecules disclosed herein may contain one or more ionizable groups (groups from which a proton can be removed (e.g., -COOH) or added (e.g., amine), or quaternized (e.g., amine)). All possible ionic forms of such molecules and their salts are intended to be individually included in the disclosure herein. With respect to salts of the compounds herein, those skilled in the art can select from a wide variety of available counterions appropriate for preparing salts of the present invention for a given application. In certain applications, the selection of a given anion or cation for preparing a salt may result in an increase or decrease in the solubility of the salt.

[0105] All devices, systems, formulations, compositions, combinations of components, or methods or steps thereof described or exemplified herein can be used to practice the invention unless otherwise specified.

[0106] Whenever a range is specified, such as, for example, a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values ​​included in the specified range, are intended to be included in the disclosure. It is understood that any subrange or individual value within a range or subrange included in the description herein may be excluded from the claims herein.

[0107] All patents and literature cited herein are indicative of the level of skill of those skilled in the art to which this invention pertains. The references cited herein are incorporated by reference in their entirety to indicate the state of the art as of the publication date or filing date, and it is intended that this information may be incorporated herein, if necessary, to exclude certain embodiments that are in the prior art. For example, when a composition of matter is claimed, it should be understood that compounds known and available in the art prior to the applicant's invention, including compounds for which the references cited herein provide useful disclosures, are not intended to be included in the composition of the substance claims herein.

[0108] As used herein, "comprising" is synonymous with "including," "containing," or "characterized by," and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, "consisting of" excludes elements, steps, or ingredients not specified in the claim element. As used herein, "consisting essentially of" does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein, any of the terms "comprising," "essentially consisting of," and "consisting of" may be replaced with either of the other two terms. The invention illustratively described herein may be practiced in the absence of one or more elements, limitation, or limitations not specifically disclosed herein.

[0109] It will be understood by those skilled in the art that starting materials, biological materials, reagents, synthetic methods, purification methods, analytical methods, assay methods, and biological methods other than those specifically exemplified may be used in the practice of the present invention without resort to undue experimentation. All art-known equivalents of such materials and methods are intended to be encompassed by this invention. The terms and expressions used are used as terms of description and not of limitation. The use of such terms and expressions is not intended to exclude equivalents of the features shown and described therein or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed invention. Thus, while the present invention has been specifically disclosed by preferred embodiments and optional features, it will be understood that modifications and variations of the concepts disclosed herein may be utilized by those skilled in the art, and that such modifications and variations may be considered within the scope of the present invention, as defined by the appended claims.

Claims

1. (A) reacting a calcium-containing starting material with a first acid to produce a first water-soluble fraction comprising a water-soluble first calcium salt and a first solid fraction comprising one or more solid by-products; the calcium-containing starting material has a chemical composition including a plurality of metal elements including at least Ca and Si; the one or more solid by-products comprise a silicon compound; (B) separating the first water-soluble fraction from the first solid fraction; (C) treating the first calcium salt in the first water-soluble fraction separated from the first solid fraction to produce a first cementitious material; Including, The first cement material is CaSO ４ and CaCO ３ Not including, the first acid is a bulk acid; The method, wherein the bulk acid is an acid or acid solution that exhibits thermodynamic, chemical and / or kinetic stability on a time scale of at least 10 seconds in the absence of electrical energy input.

2. The method of claim 1 , wherein the plurality of metallic elements comprises Al, Fe, and / or Mg.

3. 3. The method of claim 1, wherein the calcium-containing starting material comprises at least one multi-component metal oxide material having a composition comprising Ca and at least one other metal element selected from the group consisting of Al, Si, Fe, Mn, and Mg.

4. The method of claim 3 , wherein the multi-component metal oxide material comprises up to 60% Ca.

5. 5. The method of any one of claims 1 to 4, wherein the calcium-containing starting material comprises at least one naturally occurring rock or mineral comprising basalt, igneous apatite, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, magmatite, kamaphite, clinopyroxene, colemanite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheelite, skarn, limestone, natural gypsum, apatite, fluoroapatite, or any combination thereof.

6. 6. The method of any one of claims 1 to 5, wherein the calcium-containing starting material comprises at least one naturally occurring rock or mineral comprising basalt, igneous apatite, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, magmatite, kamaphite, clinopyroxene, colemanite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheelite, skarn, natural gypsum, apatite, fluoroapatite, or any combination thereof.

7. The calcium-containing starting material is CaCO ３ Other than CaCO ３ The method of any one of claims 1 to 6, comprising materials other than

8. 8. The method of claim 7, wherein the calcium salt is not a calcium carbonate salt.

9. The method of any one of claims 1 to 8, wherein the first acid comprises hydrochloric acid.

10. 10. The method of claim 9, further comprising regenerating the hydrochloric acid.

11. The method of any one of claims 1 to 10, wherein the reaction in (A) is carried out at a temperature of at least 50°C.

12. 12. The method of any one of claims 1 to 11, wherein the first calcium salt is calcium chloride.

13. The silicon compound is SiO ２ The method according to any one of claims 1 to 12, comprising:

14. The silicon compound is SiO having a purity of more than 90% by dry weight. ２ The method according to any one of claims 1 to 13, comprising:

15. The method of any one of claims 1 to 14, wherein the silicon compound comprises silica fume.

16. The method of any one of claims 1 to 15, further comprising forming and separating oxides of Al, Mg and / or Fe.

17. 17. The method of any one of claims 1 to 16, wherein treating the first calcium salt to produce a first cementitious material comprises heat-treating the first calcium salt in the presence of water to produce the first cementitious material.

18. 18. The method of any one of claims 1 to 17, wherein heat treating the first calcium salt in the presence of water regenerates the first acid.

19. 19. The method of any one of claims 1 to 18, wherein heat-treating the first calcium salt to produce a first cementitious material further comprises adding one or more additives to the first calcium salt prior to treating.

20. 20. The method of claim 19, wherein the one or more additives comprise a by-product of the reaction in (A) and / or are formed from the one or more solid by-products of the reaction in (A).

21. 21. The method of claim 19 or 20, wherein the one or more additives comprise a silicon compound.

22. The method of any one of claims 1 to 21, further comprising processing the first cementitious material to form a composite cementitious material.

23. 23. The method of claim 22, wherein forming the composite cementitious material comprises combining the first cementitious material with one or more additives and heat treating.

24. 24. The method of claim 23, wherein the one or more additives comprise a by-product of the reaction in (A) and / or are formed from the one or more solid by-products of the reaction in (A).

25. 25. The method of claim 23 or 24, wherein the one or more additives comprise aluminum and / or iron compounds.

26. The method of any one of claims 23 to 25, wherein the heat treating is carried out at a temperature of from 1100°C to 1800°C.

27. 27. The method of any one of claims 22 to 26, wherein the composite cementitious material comprises Portland cement clinker.

28. (i) a system configured to react a calcium-containing starting material with a first acid to produce a first water-soluble fraction comprising a water-soluble first calcium salt and a first solid fraction comprising one or more solid by-products, wherein the first acid is a bulk acid, and the bulk acid is an acid or acid solution that exhibits thermodynamic, chemical, and / or kinetic stability on a time scale of at least 10 seconds in the absence of electrical energy input; (ii) a system configured to separate the first water-soluble fraction from the first solid fraction; (iii) processing the first calcium salt in the first water-soluble fraction separated from the first solid fraction, optionally with one or more additives, to produce a first cementitious material, the first cementitious material comprising: CaSO ４ and CaCO ３ a system that does not include (iv) a system configured to process the first cementitious material, optionally in the presence of one or more additives, to produce a composite cementitious material; Including, A device in which (i) to (iv) are operatively connected.

29. 30. The apparatus of claim 28, wherein the system for processing the first calcium salt to produce a first cementitious material is further configured to regenerate the first acid.

30. 1. A method for producing cement materials and secondary cementitious materials (SCM), comprising: (A) reacting a calcium-containing starting material with a first acid to produce a first water-soluble fraction comprising a water-soluble first calcium salt and a first solid fraction comprising one or more solid by-products comprising a silicon compound, wherein the first acid is a bulk acid, the bulk acid being an acid or acid solution that exhibits thermodynamic, chemical, and / or kinetic stability on a time scale of at least 10 seconds in the absence of electrical energy input; (B) separating the first water-soluble fraction from the first solid fraction; (C) producing the SCM from the first solid fraction containing the silicon compound; (D) treating the first calcium salt in the first water-soluble fraction separated from the first solid fraction to produce CaSO ４ and CaCO ３ producing a first cementitious material that is free of 1. A method for producing cementitious materials and secondary cementitious materials (SCM), comprising:

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