Process to make calcium oxide or ordinary Portland cement from calcium bearing rocks and minerals

Abstract

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.

Claims

1. A method comprising: first reacting a calcium-bearing starting material with a first acid to produce a first aqueous fraction comprising an aqueous first calcium salt and a first solid fraction comprising one or more solid byproducts; wherein: the calcium-bearing starting material has a chemical composition comprising a plurality of metal elements including at least Ca and Si; the one or more solid byproducts comprises a silicon compound; separating the first aqueous fraction from the first solid fraction; and treating the first calcium salt to produce a first cement material.

2. The method of claim 1, wherein the calcium-bearing starting material comprises at least one multinary 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.

3. The method of claim 1, wherein the calcium-bearing starting material comprises at least one natural rock or mineral comprising basalt, igneous appetites, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, mafurite, kamafurite, clinopyroxene, colemonite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheilite, skarn, limestone, natural gypsum, appetite, fluorapatite, or any combination of these.

4. The method of claim 3, wherein the calcium-bearing starting material comprises at least one natural rock or mineral comprising basalt, igneous appetites, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, mafurite, kamafurite, clinopyroxene, colemonite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheilite, skarn, natural gypsum, appetite, fluorapatite, or any combination of these.

5. The method of claim 1, wherein the calcium-bearing starting material is other than CaCO.sub.3 or comprises a material other than CaCO.sub.3.

6. The method of claim 1, wherein the first acid comprises hydrochloric acid.

7. The method of claim 6, further comprising regenerating the hydrochloric acid.

8. The method of claim 1, wherein the first reacting step is performed at a temperature of at least 50° C.

9. The method of claim 1, wherein the first calcium salt is calcium chloride.

10. The method of claim 1, wherein the silicon compound comprises SiO.sub.2.

11. The method of claim 1, wherein the silicon compound comprises >90 dry wt % purity SiO.sub.2.

12. The method of claim 1, wherein the silicon compound comprises silica fume.

13. The method of claim 1, further comprising: forming and isolating oxides of Al, oxides of Mg, and/or oxides of Fe.

14. The method of claim 1, wherein treating the first calcium salt to produce a first cement material comprises thermally treating the first calcium salt in the presence of water to produce the first cement material.

15. The method of claim 14, wherein thermally treating the first calcium salt in the presence of water regenerates the first acid.

16. The method of claim 1, wherein thermally treating the first calcium salt to produce a first cement material further comprises adding one or more additives to the first calcium salt prior to treating.

17. The method of claim 16, wherein the one or more additives comprise a byproduct of the first reacting step and/or are formed from the one or more byproducts of the first reacting step.

18. The method of claim 16, wherein the one or more additives comprise a silicon compound.

19. The method of claim 1, further comprising treating the first cement material to form a composite cement material.

20. The method of claim 19, wherein forming the composite cement material comprises thermally treating the first cement material in combination with one or more additives.

21. The method of claim 20, wherein the one or more additives comprise a byproduct of the first reacting step and/or are formed from the one or more byproducts of the first reacting step.

22. The method of claim 20, wherein the one or more additives comprise an aluminum and/or iron compound.

23. The method of claim 20, wherein thermally treating is performed at a temperature of 1100° C. to 1800° C.

24. The method of claim 19, wherein the composite cement material comprises Portland cement clinker.

25. The method of claim 1, further comprising producing one or more value-added side products.

26. The method of claim 25, wherein the value-added side products comprises a metal.

27. The method of claim 26, wherein the metal comprises Al, Mg, and/or Fe.

28. The method of claim 27, wherein the metal comprises oxide of Al, oxides of Mg, and/or oxides of Fe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. A plot showing methane production in a tube furnace in partial pressure of methane versus temperature. 0.3 lpm of forming gas (5% H.sub.2, 95% N.sub.2) flow rate.

(2) FIG. 2. A plot showing methane production in a tube furnace in mole methane versus time. 0.3 lpm of forming gas (5% H.sub.2, 95% N.sub.2) flow rate.

(3) FIG. 3. An XPS pattern of a product obtained from reacting CaCO.sub.3 in a reducing environment illustrating the pure CaO appears to be produced.

STATEMENTS REGARDING CHEMICAL COMPOUNDS AND NOMENCLATURE

(4) In general, the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal 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 invention.

(5) 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 thermal conversion of a chemical species is burning, though thermal conversion processes are not necessarily limited thereto. For example, thermal conversion of sulfur to sulfur dioxide may include burning of the sulfur, such as via a sulfur burner system. Thermal oxidation of a species is a form of thermal conversion of the species. For example, thermal conversion of sulfur to sulfur dioxide may be referred to as thermal oxidation of the sulfur to sulfur dioxide. In some embodiments, thermal conversion may be aided by a catalyst. In some embodiments, thermal conversion does not require a catalyst or is performed without a catalyst. It should be noted that thermal oxidation and electrochemical oxidation are different processes, where thermal oxidation is driven or activated thermally (via heat or burning) and electrochemical oxidation is driven electrochemically (e.g., via applying or withdrawing electrical energy, optionally with the aid of an electrochemical catalyst). The term “thermally treating” refers thermal treatment or exposure to heat, preferably in excess of room temperature heat, of one or more materials (such as a calcium salt, such as CaSO.sub.4) such that the one or more material may thermally convert, thermally decompose, or otherwise experience a heat-induced chemical change into another material (such as a cement material, such as CaO). For example, calcium sulfate (gypsum) may thermally convert/decompose into calcium oxide (CaO), along with formation of byproducts such as SO.sub.2 and oxygen. A thermal treatment may also cause a plurality of materials, such as a plurality of materials comprising calcium, aluminum, and silicon, to convert into or otherwise form a composite cement material, such as Ordinary Portland Cement (OPC).

(6) The term “calcium-bearing starting material” refers to one or more materials the chemical composition of which comprises Ca. A calcium-bearing 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 multinary metal oxide material. A calcium-bearing starting material can be a plurality of materials, such as one or more rocks, minerals, and/or industrially-processed material, wherein the chemical composition of the combination of said plurality of materials includes the element Ca, such as in the form of Ca cations of an ionic material, such as a multinary metal oxide material. Wherein a calcium-bearing starting material is a plurality of materials, any one or any combination of said plurality of materials can have a chemical composition comprising the element Ca in order for the chemical composition of the combination of said plurality of materials (which together are the calcium-bearing starting material) to include the element Ca. Preferably, a calcium-bearing starting material having a chemical composition comprising the element Ca refers to the weight percent and/or the molar percent of Ca in said calcium-bearing starting material being at least 0.001%, preferably at least 0.01%, preferably at least 0.1%, more preferably at least 1%, further more preferably at least 5%, still more preferably at least 10%, and yet more preferably at least 20%. On the other hand, the methods disclosed herein are compatible with a calcium-bearing starting material whose chemical composition has a low weight percent and/or molar percent, such as less than 60%, less than 55%, less than 50%, less than 45%, less than 40%, and less than 20%, at least because Ca, along with respective counterions, can be isolated.

(7) Generally, material or species having a chemical composition characterized as comprising an element X (wherein “X” is an element of the Periodic Table of Elements) refers to the weight percent and/or the molar percent of X in said material or species being at least 0.001%, preferably at least 0.01%, more preferably at least 0.1%, and still more preferably at least 1%.

(8) The term “calcium salt” refers to a salt whose chemical composition comprises the element Ca, for example in the form of Ca cations. A salt is a chemical compound comprising ionic species associated with each other at least in part via ionic bonding. For example, CaSO.sub.4 and CaCl.sub.2 are calcium salts wherein Ca is a cation and SO.sub.4 and Cl, respectively, are anions.

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

(10) The term “solid fraction” refers to solid species present in a mixture of solid(s) and liquid(s). The term “liquid fraction” refers to liquid species and species dissolved in the liquid species in a mixture of solid(s) and liquid(s). For example, a solid fraction can have the solid products of a chemical reaction and liquid fraction can have the liquid and dissolved products of the chemical reaction. Each of the solid fraction and the liquid fraction can optionally include unreacted reagents. The liquid fraction can include solvent(s) and ions dissolved in said solvent(s).

(11) A “dry mass” of one or more materials, such as a solid fraction, refers to the mass of the one or more materials being free of water, and optionally free of any liquid species.

(12) The term “metal oxide” generally refers to a material whose chemical composition comprises one or more metal elements and the element O. Optionally, a metal oxide material is an ionic material or at least partially an ionic material wherein at least a fraction of the chemical bonding is characterized as ionic bonding. A metal element is any metal element or metalloid element of the periodic table of elements. Generally, a metalloid element is selected from the group consisting of B, Si, Ge, As, Se, Sb, Te, Po, and At.

(13) The term “natural rock or mineral” refers to one or more materials that is naturally found in and has been extracted from the Earth's crust. Natural rocks and minerals include, but are not limited to, basalt, igneous appetites, wollastonite, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, mafurite, kamafurite, clinopyroxene, colemonite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheilite, skarn, limestone, natural gypsum, appetite, fluorapatite, and any combination of these. In contrast, cement, concrete, Portland cements, fly ash, and slag are not natural rocks or mineral but may be referred to as industrially-derived materials.

(14) The term “bulk acid” refers to an acid or acid solution that does not require continuous input of energy (such as electrical energy) and/or exchange of electrons with an electrode surface to exist and function as required by a given process or step thereof. In contrast, a heterogeneous or local acidic solution, such as of hydronium ions or protons, near an electrode and formed as a result of and substantially only during exchange of electrons between the electrode and the solution is not a bulk acid. For example, a bulk acid is not a heterogeneous or local or acidic solution corresponding to a 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 on a time scale of at least 10 seconds, preferably at least 1 minute, in the absence of electrical energy input. In certain embodiments, the term “bulk acid” refers to an acid or acid solution that does exhibit or is capable of exhibiting thermodynamic, chemical, and/or kinetic stability on a time scale of at least 1 seconds and a length scale of at least 10 cm, preferably at least 10 cm from a surface of a bulk material, in the absence of electrical energy input.

(15) The term “electrochemical cell” refers to devices and/or device components that perform electrochemistry. Electrochemistry refers to conversion of chemical energy into electrical energy or electrical energy into chemical energy. Chemical energy can correspond to a chemical change or chemical reaction. Electrochemistry can thus refer to a chemical change (e.g., a chemical reaction of one or more chemical species into one or more other species) generating electrical energy and/or electrical energy being converted into or used to induce a chemical change. Electrical energy refers to electric potential energy, corresponding to a combination of electric current and electric potential in an electrical circuit. Electrochemical cells have two or more electrodes (e.g., positive and negative electrodes; e.g., cathode and anode) and one or more electrolytes. An electrolyte may include species that are oxidized and species that are reduced during charging or discharging of the electrochemical cell. Reactions occurring at the electrode, such as sorption and desorption of a chemical species or such as an oxidation or reduction reaction, contribute to charge transfer processes in the electrochemical cell. Electrochemical cells include, but are not limited to, electrolytic cells such as electrolysers and fuel cells. Electrochemical oxidation may occur at the positive electrode, for example, and electrochemical reduction may occur at the negative electrode, for example. Electrochemical oxidation refers to a chemical oxidation reaction accompanied by a transfer of electrical energy (e.g., electrical energy input driving the oxidation reaction) occurring in the context an electrochemical cell. Similarly, electrochemical reduction refers to a chemical reduction reaction accompanied by a transfer of electrical energy occurring in the context an electrochemical cell. A chemical species electrochemically oxidized during charging, for example, may be electrochemically reduced during discharging, and vice versa. The term “electrochemically” or “electrochemical” may describe a reaction, process, or a step thereof, as part of which chemical energy is converted into electrical energy or electrical energy is converted into chemical energy. For example, a product may be electrochemically formed when electrical energy is provided to help the chemical conversion of a reactant(s) to the product proceed. The term “non-electrochemical” refers to a reaction or process that does not include electrochemistry and/or does not require electrochemistry in order to be performed.

(16) A reacting step refers to a process step wherein a chemical reaction occurs, characterized by one or more chemical species experiencing a chemical change (such as via chemically reacting with each other) into another one or more chemical species.

(17) The term “elemental sulfur” refers to any one or combination of the allotropes of sulfur, such as, but not limited to, S.sub.7, S.sub.8, S.sub.6, S.sub.12, and S.sub.18, and including crystalline, polycrystalline, and/or amorphous sulfur.

(18) “RHE” refers to the reference electrode commonly referred to as the reversible hydrogen electrode. “SCE” refers to the reference electrode commonly referred to as the saturated calomel electrode.

(19) The term “initial hours of operation” refers to the time during which the cell is operational starting from the very first/initial operation, or “turning on,” of the cell. Time during which the cell or system is not being operated (i.e., no electrochemical reduction or oxidation occurring therein, or no electrical energy input or output is occurring) is not included in the initial hours of operation determination.

(20) In some embodiments, the term “aqueous” refers to a solution where the solvent is water such that other species of the solution, or solutes, are substantially solvated by water. In some embodiments, the term “aqueous” may generally refer to a solution comprising water. Optionally, but not necessarily, an aqueous solution or an aqueous solvent includes 5 vol. % or less of non-aqueous solvent and/or solute species.

(21) The term “amending agricultural water” refers to changing or adding something, such as a solute, to agricultural water. For example, acidification of agricultural water by the addition of sulfuric acid, such as a solution including sulfuric acid, to agricultural water. Agricultural water refers to water used for an agricultural purpose, such as irrigation. The term “amending soil” refers to changing or adding something to soil. For example, acidification of soil by the addition of sulfuric acid, such as a solution including sulfuric acid, to soil.

(22) The term “cement” refers to hydraulic, non-hydraulic, or both hydraulic and non-hydraulic cement material. An exemplary cement is, but is not limited to, Portland cement. Generally, a cement is a binder material, which, for example, may be mixed with fine aggregate particles (such as to produce mortar for masonry) or with sand and gravel (to produce concrete). According to certain embodiments, cement comprises calcium oxide. Cement may optionally further comprise one or more other materials including, but not limited to, certain silicate(s), SiO.sub.2, certain oxide(s), Fe.sub.2O.sub.3, certain aluminate(s), Al.sub.2O.sub.3, belite, alite, tricalcium aluminate, brownmillerite, A “cement material” refers to a material that is or can be a constituent of cement. Preferably, a cement material has a chemical composition comprising Ca or CaO. For example, CaO is a cement material. For example, a cementitious material is a cement material. A composite cement material may include a plurality of materials, including at least one cement materials and optionally one or more additives. Exemplary composite cement materials are, but are not limited to, Portland cement clinker and Portland cement, such as Ordinary Portland Cement (OPC).

(23) The term “substantially” refers to a property or condition that is within 20%, optionally within 10%, optionally within 5%, optionally within 1%, or optionally is equivalent to a reference property or condition. The term “substantially equal,” “substantially equivalent,” or “substantially unchanged,” when used in conjunction with a reference value describing a property or condition, refers to a value or condition that is within 20%, optionally within 10%, optionally within 5%, optionally within 1%, optionally within 0.1%, or optionally is equivalent to the provided reference value or condition. 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,” when used in conjunction with a reference value or condition describing a property or condition, refers to a value 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 than, optionally at least 10% greater than, optionally at least 5% greater than, or optionally at least 1 greater than 500 mV. The term “substantially less,” 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% less than the provided reference value. For example, a voltage is substantially less than 500 mV if the voltage is at least 20% less than, optionally at least 10% less than, optionally at least 5% less than, or optionally at least 1% less than 500 mV.

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

(25) In an embodiment, a composition or compound of the invention, such as an alloy or precursor to an alloy, is isolated or substantially purified. In an embodiment, an isolated or purified compound is at least partially isolated or substantially purified as would be understood in the art. In an 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% pure.

DETAILED DESCRIPTION OF THE INVENTION

(26) 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. It will be apparent, however, to those of skill in the art that the invention can be practiced without these specific details.

(27) The invention can be further understood by the following non-limiting examples.

Example 1: A Process to Make Calcium Oxide or Ordinary Portland Cement From Calcium Bearing Rocks and Minerals

(28) Conventional cement is made by thermally decomposing CaCO.sub.3 into CaO and then mixing it with other materials including Al.sub.2Si.sub.2O.sub.5(OH).sub.4, Fe.sub.2O.sub.3, and CaSO.sub.4. Thermal decomposition occurs at ˜900 C and final OPC production occurs at ˜1450 C. Most of the energy required and CO.sub.2 emissions for cement making come from the thermal decomposition of limestone:
CaCO.sub.3.fwdarw.CaO+CO.sub.2 ΔH=178 (non spontaneous)  (FX5).

(29) Conventional cement requires 2.7-6 GJ/tonne OPC and produces 0.7-1.3 tonne CO.sub.2 per tonne of OPC (Ordinary Portland Cement). The normal cement process emits a lot of CO.sub.2 and take a lot of energy.

(30) Included in this discloses is a process to produce CaO from any calcium-bearing rock or mineral. In nature, acid (e.g. H.sub.2CO.sub.3 or H.sub.2SO.sub.4) weathers calcium bearing minerals to produce, typically, CaCO.sub.3 or CaSO.sub.4. The general weathering trend follows:
H.sub.2CO.sub.3+CaAl.sub.2Si.sub.2O.sub.8+H.sub.2O.fwdarw.CaCO.sub.3+Al.sub.2Si.sub.2O.sub.5(OH).sub.4  (FX6);
or
H.sub.2SO.sub.4+CaAl.sub.2Si.sub.2O.sub.8+H.sub.2O.fwdarw.CaSO.sub.4+Al.sub.2Si.sub.2O.sub.5(OH).sub.4  (FX7).

(31) In nature, these acids are very dilute and typically this weathering occurs over long periods of time (weeks to decades). Weathering can occur with a calcium bearing mineral or rock. Common examples are wollastinite, anorthocite, Ca-bentonite, montmorillonite, plagioclase and basalt. All calcium bearing rocks are possible including all mafic and ultra-mafic rocks.

(32) Methods disclosed herein can use an acid (e.g. H.sub.2SO.sub.4, HF, HCl, H.sub.2CO.sub.3) or a combination of acids plus a calcium bearing rock or mineral (e.g. anorthosite, montmorillonite, wollastonite) to produce a calcium salt (e.g. CaSO.sub.4, CaF.sub.2, CaCl.sub.2, CaCO.sub.3). It is then possible to hydrate or thermally decompose this salt to produce CaO. It may also be possible to achieve the correct ratios of starting materials to thermally decompose the calcium salt and byproducts into a cementitious material including Ordinary Portland Cement or calcium sulfoaluminate cement. The strength, concentration, or quality of the acid and the particle size of the mined calcium-bearing rock can change the kinetics of the removal of calcium salts from the calcium-bearing starting material and different acid concentrations and crushed rock sizes may be optimal for different versions of this process.

(33) The advantages of the processes disclosed herein can include that they can be CO.sub.2 free and energy neutral. For example:
H.sub.2SO.sub.4+CaAl.sub.2Si.sub.2O.sub.8+H.sub.2O.fwdarw.CaSO.sub.4+Al.sub.2Si.sub.2O.sub.5(OH).sub.4  (FX8);
CaSO.sub.4.fwdarw.CaO+SO.sub.2+½O.sub.2  (FX9);
SO.sub.2+H.sub.2O+½O.sub.2.fwdarw.H.sub.2SO.sub.4  (FX10);
Net: CaAl.sub.2Si.sub.2O.sub.8+2H.sub.2O.fwdarw.CaO+Al.sub.2Si.sub.2O.sub.5(OH).sub.4  (FX11);

(34) ΔH=˜0

(35) This process could also be used to make clean hydrogen if electrochemical cogeneration of H.sub.2 and H.sub.2SO.sub.4 are used:
H.sub.2SO.sub.4+CaAl.sub.2Si.sub.2O.sub.8+CaSO.sub.4+Al.sub.2Si.sub.2O.sub.5(OH).sub.4  (FX12);
CaSO.sub.4.fwdarw.CaO+SO.sub.2+½O.sub.2  (FX13);
SO.sub.2+2H.sub.2O.fwdarw.H.sub.2+H.sub.2SO.sub.4  (FX14);
Net: CaAl.sub.2Si.sub.2O.sub.8+2H.sub.2O.fwdarw.CaO+Al.sub.2Si.sub.2O.sub.5(OH).sub.4+½O.sub.2+H.sub.2  (FX15);

(36) ΔH=50 (slightly uphill)

Example 2: Reductive Thermal Decomposition of Limestone to Make Lime or Cement

(37) Lime is used directly as a commodity chemical as well as the primary constituent of cement which is the most consumed human made material on the planet. Lime is currently produced via the thermal decomposition of limestone in an air atmosphere (FX16).
CaCO.sub.3.fwdarw.CO.sub.2+CaO  (FX16);
This heat of decomposition of this reaction is 178 kJ/mol

(38) Included in this invention is a process to produce cement from limestone via reductive thermal decomposition with hydrogen. The first step in the process may follow the following reactions:
CaCO.sub.3+4H.sub.2.fwdarw.CH.sub.4+2H.sub.2O  (FX17A);
or
CaCO.sub.3+2H.sub.2.fwdarw.CH.sub.4+O.sub.2  (FX17B);

(39) Water content of the reacting gas influences whether the reaction proceeds according to FX17A, FX17B, or both. CaCO.sub.3 can react with H.sub.2 to either make CaO+CH.sub.4+O.sub.2 or CaO+CH.sub.4+2H.sub.2O. If H.sub.2O is formed, 4 H.sub.2s are consumed. If O.sub.2 is formed, only 2 H.sub.2s are consumed. This reaction can be driven to only consume 2 H.sub.2s if there is a water atmosphere, for example.

(40) The reaction may stop there or the second step may be methane pyrolysis to regenerate the hydrogen, or any methane involving chemical reaction:
CH.sub.4.fwdarw.2H.sub.2+C  (FX18);

(41) One benefit of this reaction is that we can make solid carbon instead of CO.sub.2 and therefore will not pollute the atmosphere. Another benefit of reaction FX17A is that it is a lower energy requirement than traditional thermal decomposition of limestone (13.1 kJ/mol). A benefit of reaction FX17B is that 100% of the necessary hydrogen can be regenerated from methane pyrolysis.

(42) In certain embodiments, reaction FX17A occurs under reducing conditions above 700 C for example in an H.sub.2, an H.sub.2/N.sub.2 atmosphere or any other combination. Reaction FX17B may occur above 700 C with H.sub.2 under a water atmosphere. For example, we put 2.011 g of CaCO.sub.3 powder into a tube furnace and heated it at 7 C per minute. For example, we flowed forming gas at 0.3 liters per minute (lpm). For example, we attached a gas analyzer to the back of the furnace to measure the methane concentration. Data is found in FIGS. 1 and 2. XPS is to determine that the resulting thermal decomposition yielded >99% lime (FIG. 3).

(43) By integrating under these curves, we determine that we achieved ˜100% decarbonization.

Example 3: Production of Gypsum and Cement Materials

(44) Exemplary aspect 1: The production of ordinary portland cement (OPC) from any calcium containing starting material without the net production of acid-forming gases (e.g. SO.sub.2 and CO.sub.2). Examples of calcium containing starting materials include: basalt, igneous appetites, wollastonite, slag, fly ash, anorthosite, montmorillonite, bentonite, calcium-containing feldspar, anorthite, diopside, pyroxene, pyroxenite, mafurite, kamafurite, clinopyroxene, colemonite, grossular, augite, pigeonite, margarite, calcium serpentine, garnet, scheilite, OPC, concrete, any rock that has any Ca or CaO by mass especially rocks with >5%, >10%, or >15% CaO, any skarns, limestone, gypsum, appetite, or fluorapatite.

(45) In certain embodiments, we do this by first producing >90% pure synthetic gypsum from the above calcium containing rocks (details in claim 2) and then thermally decomposing this gypsum to make CaO and then mixing it with the proper ratios of other materials to form OPC. The produced SO.sub.2 is then reformed into sulfuric acid (via the contact process or via a sulfur depolarization electrolyzer) which can then be recycled to make synthetic gypsum. The general chemistry is below:
1. CaAl.sub.2Si.sub.2O.sub.8+H.sub.2SO.sub.4.fwdarw.CaSO.sub.4(>90 dry wt. % pure)+Al.sub.2O.sub.3+SiO.sub.2  (FX19);
2. CaSO.sub.4+heat.fwdarw.CaO+½O.sub.2+SO.sub.2  (FX20);
3. CaO+xAl.sub.2O.sub.3+ySiO.sub.2.fwdarw.OPC  (FX21);
4. SO.sub.2+½O.sub.2+H.sub.2O.fwdarw.H.sub.2SO.sub.4  (FX22);

(46) Ordinary Portland Cement (OPC) is made in industry today exclusively from limestone (primarily CaCO.sub.3). The production of OPC involves first producing CaO by thermally decomposing CaCO.sub.3 (e.g. CaCO.sub.3+heat.fwdarw.CaO+CO.sub.2) and then heating the CaO with silica and alumina to form OPC which is ˜60% CaO by mass. The production of CO.sub.2 from cement manufacturing is responsible for >5% of global CO.sub.2 emissions.

(47) Besides limestone, OPC may also be made from gypsum (CaSO.sub.4). Mined gypsum (CaSO.sub.4) can be used by some methods for producing OPC. In this process CaSO.sub.4 is thermally decomposed to produce CaO (e.g. CaSO.sub.4+heat.fwdarw.CaO+½O.sub.2+SO.sub.2). This process can also be accomplished with carbo or hydro thermic reduction in which case CaS is produced by reacting CaSO.sub.4 with a reductant (e.g. coal) and then CaS is co-thermally-decomposed with CaSO.sub.4 to make CaO. This process is known as the Mueller-Kuehne Process. Neither of these processes are practiced commercially today because SO.sub.2 cannot be released into the atmosphere and the global demand for SO.sub.2 is far lower than the demand for OPC.

(48) OPC can be produced from “phosphogypsum” (CaSO.sub.4 produced by reacting phosphate rock with H.sub.2SO.sub.4 to make phosphoric acid and gypsum). The fertilizer industry produces waste CaSO.sub.4 by reacting sulfuric acid with phosphate rock (primarily Ca.sub.5(PO.sub.4).sub.3OH) to make phosphoric acid. This synthetic gypsum can be thermally decomposed to make CaO and then OPC as in the process above.

(49) Methods disclosed herein dramatically expand the starting materials from which OPC can be made compared to conventional methods.

(50) Exemplary Aspect 2: The production of >90% purity CaSO.sub.4 from any calcium containing rock. For example, HCl is first reacted with the rock to dissolve the calcium chloride, precipitates out >90 dry wt % purity SiO.sub.2, and other byproducts. For example, we then react the dissolved solution with sulfuric acid which selectively precipitates out CaSO.sub.4 as this is the only sulfate salt among the common sulfate salts (MgSO.sub.4, Al.sub.2(SO.sub.4).sub.3, Fe.sub.2(SO.sub.4).sub.3) that does not dissolve in water. This also regenerates the HCl. Sample chemistry is below:
1. CaAl.sub.2Si.sub.2O.sub.8+8HCl.fwdarw.CaCl.sub.2(aq)+2AlCl.sub.3(aq)+SiO.sub.2(s)  (FX23);
2. Separate the solid and the aqueous fraction  (FX24);
3. CaCl.sub.2(aq)+2AlCl.sub.3(aq)+4H.sub.2SO.sub.4.fwdarw.CaSO.sub.4(s)+Al.sub.2(SO.sub.4).sub.3(aq)+8HCl  (FX25);

(51) Methods disclosed herein include production of >90 dry wt. % purity CaSO.sub.4, which is make the process less expensive, less complicated, more controllable of necessary materials ratios for accurate production of OPC.

(52) 90 dry wt. % calcium sulfate can also be produced as a byproduct of reacting sulfuric acid with either limestone (CaCO.sub.3) and phosphate rock (Ca.sub.5(PO.sub.4).sub.3OH or Ca.sub.5(PO.sub.4).sub.3F). The products of these reactions are either water soluble (HF, H.sub.2PO.sub.4), liquid (H.sub.2O) or gaseous (CO.sub.2).

(53) Advantageously, methods disclosed herein can yield highly pure synthetic gypsum from any rock even if the byproducts are not soluble in sulfuric acid.

Example 4: Generation of Valuable Co-Products

(54) Exemplary aspect 3: The production of alumina from any calcium containing rock. This can be done by first leaching with HCl and then saturating the leach solution with HCl, the high HCl concentration causes AlCl.sub.3 to precipitate. AlCl.sub.3 can then be mixed with H.sub.2SO.sub.4 to make Al.sub.2(SO.sub.4).sub.3 and regenerate the HCl. Al.sub.2(SO.sub.4).sub.3 can be thermally decomposed to make Al.sub.2O.sub.3 and make SO.sub.2 in order to regenerate the sulfuric acid. Exemplary chemistry below:
1. CaAl.sub.2Si.sub.2O.sub.8+8HCl.fwdarw.CaCl.sub.2(aq)+2AlCl.sub.3(aq)+SiO.sub.2(s)  (FX26);
2. AlCl.sub.3(aq)+HCl.sub.(aq).fwdarw.AlCl.sub.3(s)+HCl.sub.(aq)  (FX27);
3. 2AlCl.sub.3(s)+H.sub.2SO.sub.4.fwdarw.Al.sub.2(SO.sub.4).sub.3  (FX28);
4. Al.sub.2(SO.sub.4).sub.3+heat.fwdarw.3SO.sub.2+Al.sub.2O.sub.3+3/2O.sub.2  (FX29);
5. SO.sub.2+½O.sub.2+H.sub.2O.fwdarw.H.sub.2SO.sub.4  (FX30);

(55) Exemplary aspect 4: The production of iron oxide from any calcium containing rock. Once Al, Ca, and Si are removed via the process described above, only aqueous iron sulfate and magnesium sulfate are left in solution. If the water is evaporated and the salts are raised to 500-700 C iron sulfate will decompose into insoluble iron oxide and the remaining magnesium sulfate can be dissolved away in water leaving only iron oxide.

(56) Exemplary aspect 5: The production of supplementary cementitious materials including silica fume from calcium-containing rocks. A side benefit of our process is that because it dissolves everything except the silica, the particle size of everything is very small and therefore we can make synthetic silica fume.

(57) The production of value added co-products is a significant advantage of methods disclosed herein. An unexpected added benefit of the leach step(s), corresponding to the “first reacting” step, or the reaction of a calcium-bearing starting material with a first acid, is it can produce numerous co-products including Al.sub.2O.sub.3, SiO.sub.2, silica-fume grade silica, Fe.sub.2O.sub.3, and MgO. These products also may be highly pure because a chemical separation is used. The use of HCl concentration to precipitate aluminum had been used to make AlCl.sub.3 from aluminum containing rocks but not to make Al.sub.2(SO.sub.4).sub.3, as disclosed herein, according to certain embodiments, which has the benefit of higher thermal decomposition efficiencies and the regeneration of valuable HCl.

(58) Methods disclosed herein include benefits of expanding the starting materials that are capable of making these products, and, in many cases, achieving better processes efficiencies, product purities, and qualities than conventional processes.

Statements Regarding Incorporation by Reference and Variations

(59) All references throughout this application, for example patent documents including issued or granted patents or equivalents; patent application publications; and non-patent literature documents or other source material; are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application (for example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference).

(60) The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this 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 one skilled in the art that the present invention may be carried out using a large number of variations of the devices, device components, methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional composition and processing elements and steps.

(61) As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a cell” includes a plurality of such cells and equivalents thereof known to those skilled in the art. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. The expression “of any of claims XX-YY” (wherein XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form, and in some embodiments is interchangeable with the expression “as in any one of claims XX-YY.”

(62) 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 disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. When a compound is described herein such that a particular isomer, enantiomer or diastereomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomers and enantiomer of the compound described individual or in any combination. Additionally, unless otherwise specified, all isotopic variants of compounds disclosed herein are intended to be encompassed by the disclosure. For example, it will be understood that any one or more hydrogens in a molecule disclosed can be replaced with deuterium or tritium. Isotopic variants of a molecule are generally useful as standards in assays for the molecule and in chemical and biological research related to the molecule or its use. Methods for making such isotopic variants are known in the art. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently.

(63) Certain molecules disclosed herein may contain one or more ionizable groups [groups from which a proton can be removed (e.g., —COON) or added (e.g., amines) or which can be quaternized (e.g., amines)]. All possible ionic forms of such molecules and salts thereof are intended to be included individually in the disclosure herein. With regard to salts of the compounds herein, one of ordinary skill in the art can select from among a wide variety of available counterions those that are appropriate for preparation of salts of this invention for a given application. In specific applications, the selection of a given anion or cation for preparation of a salt may result in increased or decreased solubility of that salt.

(64) Every device, system, formulation, composition, combination of components, or method, or step thereof, described or exemplified herein can be used to practice the invention, unless otherwise stated.

(65) Whenever a range is given in the specification, 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 ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

(66) All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information can be employed herein, if needed, to exclude specific embodiments that are in the prior art. For example, when composition of matter are claimed, it should be understood that compounds known and available in the art prior to Applicant's invention, including compounds for which an enabling disclosure is provided in the references cited herein, are not intended to be included in the composition of matter claims herein.

(67) 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 any element, step, or ingredient 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”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

(68) One of ordinary skill in the art will appreciate that starting materials, biological materials, reagents, synthetic methods, purification methods, analytical methods, assay methods, and biological methods other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.