WO2013106730A1

WO2013106730A1 - Carbon dioxide sequestration involving two-salt-based thermolytic processes

Info

Publication number: WO2013106730A1
Application number: PCT/US2013/021264
Authority: WO
Inventors: Joe David Jones; Al Yablonsky
Original assignee: Skyonic Corp
Current assignee: Skyonic Corp
Priority date: 2012-01-11
Filing date: 2013-01-11
Publication date: 2013-07-18
Anticipated expiration: 2014-07-11
Also published as: MX2014008491A; NZ628133A; AP2014007853A0; CN104284707A; HK1205039A1; JP2015508332A; IL233577A0; BR112014017019A8; EP2809427A4; AR090051A1; CL2014001842A1; PE20142384A1; AU2013203886A1; EP2809427A1; CA2863326A1; AU2013203886B2; BR112014017019A2; CO7020904A2; PH12014501606A1; SG11201404005SA

Description

DESCRIPTION

CARBON DIOXIDE SEQUESTRATION INVOLVING TWO-SALT-BASED

THERMOLYTIC PROCESSES

BACKGROUND OF THE INVENTION This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 61/585,597, filed January 1 1, 2012, hereby incorporated by reference in its entirety.

I. Field of the Invention

The present invention generally relates to the field of removing carbon dioxide from a source, such as the waste stream (e.g. flue gas) of a power plant, whereby Group 2 silicate minerals are converted into Group 2 chloride salts and Si0₂, Group 2 chloride salts are converted into Group 2 hydroxide and/or Group 2 hydroxychloride salts. These in turn may be reacted with carbon dioxide to form Group 2 carbonate salts, optionally in the presence of catalysts. These steps may be combined to form a cycle in which carbon dioxide is sequestered in the form of carbonate salts and byproducts from one or more steps, such as heat and chemicals, are re-used or recycled in one or more other steps.

II. Description of Related Art

Considerable domestic and international concern has been increasingly focused on the emission of C0₂ into the air. In particular, attention has been focused on the effect of this gas on the retention of solar heat in the atmosphere, producing the "greenhouse effect." Despite some debate regarding the magnitude of the effect, all would agree there is a benefit to removing C0₂ (and other chemicals) from point-emission sources, especially if the cost for doing so were sufficiently small.

Greenhouse gases are predominately made up of carbon dioxide and are produced by municipal power plants and large-scale industry in site-power-plants, though they are also produced in any normal carbon combustion (such as automobiles, rain-forest clearing, simple burning, etc.). Though their most concentrated point-emissions occur at power-plants across the planet, making reduction or removal from those fixed sites an attractive point to effect a removal-technology. Because energy production is a primary cause of greenhouse gas emissions, methods such as reducing carbon intensity, improving efficiency, and sequestering carbon from power-plant flue-gas by various means has been researched and studied intensively over the last thirty years.

Attempts at sequestration of carbon (in the initial form of gaseous C0₂) have produced many varied techniques, which can be generally classified as geologic, terrestrial, or ocean systems. An overview of such techniques is provided in the Proceedings of First National Conference on Carbon Sequestration, (2001). To date, many if not all of these techniques are too energy intensive and therefore not economically feasible, in many cases consuming more energy than the energy obtained by generating the carbon dioxide. Alternative processes that overcome one or more of these disadvantages would be advantageous.

The referenced shortcomings are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques for removing carbon dioxide from waste streams; however, those mentioned here are sufficient to demonstrate that the methodologies appearing in the art have not been altogether satisfactory and that a significant need exists for the techniques described and claimed in this disclosure.

SUMMARY OF THE INVENTION

Disclosed herein are methods and apparatuses for carbon dioxide sequestration, including removing carbon dioxide from waste streams.

In one aspect there are provided methods of sequestering carbon dioxide produced by a source, comprising:

(a) reacting MgCl₂ or a hydrate thereof with water in a first admixture under conditions suitable to form a first product mixture comprising a first step (a) product comprising Mg(OH)Cl and a second step (a) product comprising HC1;

(b) reacting some or all of the Mg(OH)Cl from step (a) with a quantity of water and a quantity of MgCi₂ in a second admixture under conditions suitable to form a second product mixture comprising a first step (b) product comprising Mg(OH)₂ and a second step (b) product comprising MgCl₂, wherein the quantity of water is sufficient to provide a molar ratio of water to MgCl₂ of greater than or equal to 6 to 1 in the second product mixture;

(c) admixing some or all of the Mg(OH)₂ from the first step (b) product with CaCl₂ or a hydrate thereof and carbon dioxide produced by the source in a third admixture under conditions suitable to form a third product mixture comprising a first step (c) product comprising MgCl₂ or a hydrate thereof, a second step (c) product comprising CaC0₃, and a third step (c) product comprising water; and

(d) separating some or all of the CaC0₃ from the third product mixture,

whereby some or all of the carbon dioxide is sequestered as CaC0₃. In certain embodiments, the MgCl₂ of step (a) is a MgCl₂ hydrate (e.g.,

MgCl₂-6(H₂0)). In some embodiments, the MgCl₂ of step (a) is greater than 90% by weight MgCl₂-6(H₂0). In still further embodiments, some or all of the MgCl₂ formed in step (b) and/or step (c) is the MgCl₂ used in step (a). Thus, in certain embodiments, some or all of the water in step (a) is present in the form of a hydrate of the MgCl₂ or is obtained from the water of step (c) or step (b). In certain embodiments, some or all of the water in step (a) is present in the form of steam or supercritical water. In some embodiments some or all of the hydrogen chloride of step (a) is admixed with water to form hydrochloric acid. In a further embodiment the first step (a) product comprises greater than 90% by weight Mg(OH)Cl. In certain embodiments step (a) occurs in one, two or three reactors. In some embodiments, a defined quantity of water is maintained in the second product mixture of step (b). For example, in some embodiments, the molar ratio of water to MgCl₂ in the second product mixture is between about 6 and about 10, between about 6 and 9, between about 6 and 8 , between about 6 and 7 or is about 6. In certain embodiments, a method comprises monitoring the concentration of MgCl₂ in the second product mixture, the quantity of water in the second product mixture or both. In still further embodiments, the amount MgCl₂ and/or water in step (b) (or the flow rates of MgCl₂ and/or water into the second admixture) is adjusted based on such monitoring.

In a further embodiment, a method comprises separating the step (b) products. For example, the Mg(OH)₂ product of step (b) can be a solid and separating the step (b) products can comprise separating some or all of the solid Mg(OH)₂ from the water and MgCl₂ solution. Thus, in some embodiments, the MgCl₂ product of step (b) is aqeous MgCl₂.

In yet a further embodiment step (b) comprises reacting some or all of the Mg(OH)Cl from step (a) with MgCl₂ and a quantity of water in a second admixture under conditions suitable to form a second product mixture comprising a first step (b) product comprising Mg(OH)₂ and a second step (b) product comprising MgCl₂, wherein the quantity of water is sufficient to provide a molar ratio of water to Mg of greater than or equal to 6 to 1 in said second admixture. In some embodiments, the some or all of the MgCl₂ for the reaction of step (b) is the MgCl₂ product of step (c).

In a further embodiment, step (c) further comprises admixing sodium hydroxide salt in the third admixture.

In still yet a further embodiment, a method comprises:

(e) admixing a calcium silicate mineral with HC1 under conditions suitable to form a third product mixture comprising CaCl₂, water, and silicon dioxide.

For example, in some cases, some or all of the HC1 in step (e) is obtained from step (a). In certain embodiments, step (e) further comprises agitating the calcium silicate mineral with HC1. In some embodiments, some or all of the heat generated in step (e) is recovered. In certain embodiments, some or all of the CaCl₂ of step (c) is the CaCl₂ of step (e). In further embodiments, a method comprises a separation step, wherein the silicon dioxide is removed from the CaCl₂ formed in step (e). In yet further embodiments, some or all of the water of step (a) and/or (b) is obtained from the water of step (e). Certain aspects of the embodiments comprise use of a calcium silicate mineral, such as a calcium inosilicate. In some embodiments, the calcium silicate mineral comprises diopside (CaMg[Si₂0₆]), tremolite Ca2Mg₅ { [OH]Si₄0i i }₂ or CaSi0₃. In some embodiments, the calcium silicate further comprises iron (e.g., fayalite (Fe₂[Si0₄])) and or manganese silicates.

In some embodiments, the carbon dioxide is in the form of flue gas, wherein the flue gas further comprises N₂ and H₂0.

In some embodiments, suitable reacting conditions of step (a) comprise a temperature from about 200 °C to about 500 °C. In some embodiments, the temperature is from about 230 °C to about 260 °C. In some embodiments, the temperature is about 250 °C. In some embodiments, the temperature is from about 200 °C to about 250 °C. In some embodiments, the temperature is about 240 °C.

In some embodiments, suitable reacting conditions of step (b) comprise a temperature from about 140 °C to about 240 °C.

In some embodiments, suitable reacting conditions of step (c) comprise a temperature from about 20 °C to about 100 °C. In some embodiments, the temperature is from about 25 °C to about 95 °C. In some embodiments, suitable reacting conditions of step (e) comprise a temperature from about 50 °C to about 200 °C. In some embodiments, the temperature is from about 90 °C to about 150 °C.

In further aspect there are provided methods of sequestering carbon dioxide produced by a source, comprising:

(a) reacting a first cation-based halide, sulfate or nitrate salt or hydrate thereof with water in a first admixture under conditions suitable to form a first product mixture comprising a first step (a) product comprising a first cation-based hydroxide salt, a first cation-based oxide salt and/or a first cation-based hydroxychloride salt and a second step (a) product comprising HCl, H₂SO₄ or HN0₃;

(b) admixing some or all of the first step (a) product with a second cation-based halide, sulfate or nitrate salt or hydrate thereof and carbon dioxide produced by the source in a second admixture under conditions suitable to form a second product mixture comprising a first step (b) product comprising a first cation-based halide, sulfate and/or nitrate salt or hydrate thereof, a second step (b) product comprising a second cation-based carbonate salt, and a third step (b) product comprising water; and

(c) separating some or all of the second cation-based carbonate salt from the second product mixture,

whereby the carbon dioxide is sequestered into a mineral product form.

In some embodiments, the first cation-based halide sulfate or nitrate salt or hydrate thereof of step (a) is a first cation-based chloride salt or hydrate thereof, and the second step (a) product is HCl. In some embodiments, the first cation-based halide, sulfate, or nitrate salt or hydrate thereof of step (b) is a first cation-based chloride salt or hydrate thereof.

In some embodiments, the first cation-based chloride salt or hydrate thereof of step (a) is MgCl₂. In some embodiments, the first cation-based chloride salt or hydrate thereof of step (a) is a hydrated form of MgCl₂. In some embodiments, the first cation-based chloride salt or hydrate thereof of step (a) is MgCl₂'6H₂0. In some embodiments, the first cation- based hydroxide salt of step (a) is Mg(OH)₂. In some embodiments, the first cation-based hydroxychloride salt of step (a) is Mg(OH)Cl. In some embodiments, the first step (a) product comprises predominantly Mg(OH)Cl. In some embodiments, the first step (a) product comprises greater than 90% by weight Mg(OH)Cl. In some embodiments, the first step (a) product is Mg(OH)Cl. In some embodiments, the first cation-based oxide salt of step (a) is MgO. In some embodiments, the second cation-based halide, sulfate or nitrate salt or hydrate thereof of step (b) is a second cation-based chloride salt or hydrate thereof, for example, CaCl₂. In some embodiments, the first cation-based chloride salt of step (b) is MgCl₂. In some embodiments, the first cation-based chloride salt of step (b) is a hydrated form of MgCl₂. In some embodiments, the first cation-based chloride salt of step (b) is MgCl₂-6H₂0.

In some embodiments, some or all of the water in step (a) is present in the form of steam or supercritical water. In some embodiments, some or all of the water of step (a) is obtained from the water of step (b). In some embodiments, step (b) further comprises admixing sodium hydroxide salt in the second admixture.

In some embodiments, the methods further comprise:

(d) admixing a Group 2 silicate mineral with HC1 under conditions suitable to form a third product mixture comprising a Group 2 chloride salt, water, and silicon dioxide.

In some embodiments, some or all of the HC1 in step (d) is obtained from step (a). In some embodiments, the methods of step (d) further comprises agitating the Group 2 silicate mineral with HC1. In some embodiments, some or all of the heat generated in step (d) is recovered. In some embodiments, some or all of the second cation-based chloride salt of step (b) is the Group 2 chloride salt of step (d). In some embodiments, the methods further comprise a separation step, wherein the silicon dioxide is removed from the Group 2 chloride salt formed in step (d). In some embodiments, some or all of the water of step (a) is obtained from the water of step (d).

In some embodiments, the Group 2 silicate mineral of step (d) comprises a Group 2 inosilicate. In some embodiments, the Group 2 silicate mineral of step (d) comprises CaSi0₃. In some embodiments, the Group 2 silicate mineral of step (d) comprises MgSi0₃. In some embodiments, the Group 2 silicate mineral of step (d) comprises olivine (Mg₂[Si0₄]). In some embodiments, the Group 2 silicate mineral of step (d) comprises serpentine (Mg6[OH]g[Si₄0io]). In some embodiments, the Group 2 silicate mineral of step (d) comprises sepiolite (Mg₄[(OH)₂Si₆Oi 5] -6H₂0), enstatite (Mg₂[Si₂0₆]), diopside (CaMg[Si₂0₆]), and/or tremolite Ca₂Mg₅{[OH]Si₄0n }₂. In some embodiments, the Group 2 silicate further comprises iron and or manganese silicates. In some embodiments, the iron silicate is fayalite (Fe₂[Si0₄]).

In some embodiments, some or all of the first cation-based chloride salt formed in step (b) is the first cation-based chloride salt used in step (a). In some embodiments, the carbon dioxide is in the form of flue gas, wherein the flue gas further comprises N₂ and H₂0.

In some embodiments, suitable reacting conditions of step (a) comprise a temperature from about 50 °C to about 200 °C. In some embodiments, the temperature is from about 90 °C to about 260 °C. In some embodiments, the temperature is from about 90 °C to about 230 °C. In some embodiments, the temperature is about 130 °C.

In some embodiments, suitable reacting conditions of step (a) comprise a temperature from about 400 °C to about 550 °C. In some embodiments, the temperature is from about 450 °C to about 500 °C.

In some embodiments, suitable reacting conditions of step (a) comprise a temperature from about 20 °C to about 100 °C. In some embodiments, the temperature is from about 25 °C to about 95 °C.

In some embodiments, suitable reacting conditions of step (a) comprise a temperature from about 50 °C to about 200 °C. In some embodiments, the temperature is from about 90 °C to about 150 °C.

In another aspect, the present invention provides methods of sequestering carbon dioxide produced by a source, comprising:

(a) admixing a magnesium chloride salt and water in a first admixture under conditions suitable to form (i) magnesium hydroxide, magnesium oxide and/or Mg(OH)Cl and (ii) hydrogen chloride;

(b) admixing (i) magnesium hydroxide, magnesium oxide and/or Mg(OH)Cl, (ii) CaCl₂ and (iii) carbon dioxide produced by the source in a second admixture under conditions suitable to form (iv) calcium carbonate, (v) a magnesium chloride salt, and (vi) water; and

(c) separating the calcium carbonate from the second admixture, whereby the carbon dioxide is sequestered into a mineral product form.

In some embodiments, some or all of the hydrogen chloride of step (a) is admixed with water to form hydrochloric acid. In some embodiments, some or all of the magnesium hydroxide, magnesium oxide and/or Mg(OH)Cl of step (b)(i) is obtained from step (a)(i). In some embodiments, some of all the water in step (a) is present in the form of a hydrate of the magnesium chloride salt. In some embodiments, step (a) occurs in one, two or three reactors. In some embodiments, step (a) occurs in one reactor. In some embodiments, the magnesium hydroxide, magnesium oxide and/or Mg(OH)Cl of step (a)(i) is greater than 90% by weight Mg(OH)Cl. In some embodiments, the magnesium chloride salt is greater than 90% by weight MgCl₂-6(H₂0).

In some embodiments, the methods further comprise:

(d) admixing a Group 2 silicate mineral with hydrogen chloride under conditions suitable to form a Group 2 chloride salt, water, and silicon dioxide.

In some embodiments, some or all of the hydrogen chloride in step (d) is obtained from step (a). In some embodiments, step (d) further comprises agitating the Group 2 silicate mineral with the hydrochloric acid. In some embodiments, some or all of the magnesium chloride salt in step (a) is obtained from step (d). In some embodiments, the methods further comprise a separation step, wherein the silicon dioxide is removed from the Group 2 chloride salt formed in step (d). In some embodiments, some or all of the water of step (a) is obtained from the water of step (d). In some embodiments, the Group 2 silicate mineral of step (d) comprises a Group 2 inosilicate.

In some embodiments, the Group 2 silicate mineral of step (d) comprises CaSi0₃. In some embodiments, the Group 2 silicate mineral of step (d) comprises MgSi0₃. In some embodiments, the Group 2 silicate mineral of step (d) comprises olivine. In some embodiments, the Group 2 silicate mineral of step (d) comprises serpentine. In some embodiments, the Group 2 silicate mineral of step (d) comprises sepiolite, enstatite, diopside, and/or tremolite. In some embodiments, the Group 2 silicate further comprises mineralized iron and or manganese.

In some embodiments, step (b) further comprises admixing CaCl₂ and water to the second admixture.

Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present disclosure. The invention may be better understood by reference to one of these drawings in combination with the detailed description of specific embodiments presented herein.

FIG. 1 is block diagram of a system for a Group 2 hydroxide-based process to sequester C0₂ as Group 2 carbonates according to some embodiments of the present invention.

2+

FIG. 2 is block diagram of a system in which Mg functions as a catalyst for the sequestration of C0₂ as calcium carbonate according to some embodiments of the present invention.

FIG. 3 is a simplified process flow diagram according to some embodiments of the processes provided herein. Shown is a Group-II hydroxide-based process, which sequesters C0₂ as limestone (composed largely of the mineral calcite, CaC0₃). The term "road salt" in this figure refers to a Group II chloride, such as CaCl₂ and/or MgCl₂, either or both of which are optionally hydrated. In embodiments comprising MgCl₂, heat may be used to drive the reaction between road salt and water (including water of hydration) to form HC1 and magnesium hydroxide, Mg(OH)₂, and/or magnesium hydroxychloride, Mg(OH)Cl. In embodiments comprising CaCl₂, heat may be used to drive the reaction between road salt and water to form calcium hydroxide and HC1. The HC1 is reacted with, for example, calcium inosilicate rocks (optionally ground), to form additional road salt, e.g. , CaCl₂, and sand (Si0₂).

FIG. 4 is a simplified process-flow diagram corresponding to some embodiments of the present invention. Silicate rocks may be used in some embodiments of the present invention to sequester C0₂ as CaC0₃. The term "road salt" in this figure refers to a Group II chloride, such as CaCl₂ and/or MgCl₂, either or both of which are optionally hydrated. In the road salt boiler, heat may be used to drive the reaction between road salt, e.g. , MgCl₂-6H₂0, and water (including water of hydration) to form HC1 and Group II hydroxides, oxides, and/or mixed hydroxide-chlorides, including, for example, magnesium hydroxide, Mg(OH)₂, and/or magnesium hydroxychloride, Mg(OH)Cl. In embodiments comprising CaCl₂, heat may be used to drive the reaction between road salt and water to form calcium hydroxide and HC1. The HC1 may be sold or reacted with silicate rocks, e.g., inosilicates, to form additional road salt, e.g. , CaCl₂, and sand (Si0₂). Ion exchange reaction between Mg and Ca may used, in some of these embodiments, to allow, for example, the cycling of Mg²⁺ ions.

FIG. 5 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, a 35% MgCl₂, 65% H₂0 solution is heated to 536 °F (280 °C), then the stream leaves in the stream labeled "H₂0- MgOH," which comprises a solution of MgCl₂ and solid Mg(OH)₂. Typically, when Mg(OH)Cl dissolves in water it forms Mg(OH)₂ (solid) and MgCl₂ (dissolved). Here the MgCl₂ is not used to absorb C0₂ directly, rather it is recycled. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaC0₃. Results from the simulation suggest that it is efficient to recirculate a MgCl₂ stream and then to react it with H₂0 and heat to form Mg(OH)₂. One or more of the aforementioned compounds then reacts with a CaCl₂/H₂0 solution and C0₂ from the flue gas to ultimately form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to repeat the process.

FIG. 6 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaC0₃. In this embodiment, the hexahydrate is dehydrated in three separate chambers and decomposed in the fourth chamber where the HCl that is formed from the decomposition is recirculated back to the third chamber to prevent any side reactions. Reactions occurring in these chambers include the following:

1 ^st Chamber: MgCl₂-6H₂0→ MgCl₂-4H₂0 + 2H₂0 100 °C

2^nd Chamber: MgCl₂-4H₂0→ MgCl₂-2H₂0 + 2H₂0 125 °C

3^rd Chamber: MgCl₂-2H₂0→ MgCl₂-H₂0 + H₂0 160 °C

(HCl vapor present)

4^th Chamber: MgCl₂-H₂0→ Mg(OH)Cl + HCl 130 °C

HCl recirculates to the 3^r chamber.

4^th MgCl₂-H₂0→ Mg(OH)Cl + HCl 130°C 230°C- 260°C

* HCl Vapor Present

** HCl Vapor Recirculates to the 3^r Chamber

The first three reactions above may be characterized as dehydrations, while the fourth may be characterized as a decomposition. Results from this simulation, which is explained in greater detail in Example 2, indicate that at lower temperatures (130-250 °C) the decomposition of MgCl₂-6H₂0 results in the formation of Mg(OH)Cl instead of MgO. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)2, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again.

FIG. 7 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaC0₃. In this embodiment, the magnesium hexahydrate is dehydrated in two separate chambers and decomposed in a third chamber. Both dehydration and decomposition reactions occur in the third chamber. There is no recirculating HCl. Reactions occurring in these chambers include the following:

1 ^st Chamber: MgCl₂-6H₂0→ MgCl₂-4H₂0 + 2H₂0 100 °C

2^nd Chamber: MgCl₂ H₂0→ MgCl₂-2H₂0 + 2H₂0 125 °C

3^rd Chamber: MgCl₂-2H₂0→ Mg(OH)Cl + HCl + H₂0 130 °C

3^rd Chamber: MgCl₂-2H₂0→ MgCl₂-H₂0 + H₂0 130 °C

* No recirculating HCl

The first, second and fourth reactions above may be characterized as dehydrations, while the third may be characterized as a decomposition. As in the embodiment of FIG. 6, the temperatures used in this embodiment result in the formation of Mg(OH)Cl from the MgCl₂-6H₂0 rather than MgO. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂, which reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. Additional details regarding this simulation are provided in Example 3 below.

FIG. 8 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaC0₃. Results from this simulation indicate that it is efficient to heat MgCl₂-6H₂0 to form MgO. The MgO then reacts with H₂0 to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium hexahydrate is simultaneously dehydrated and decomposed in one chamber at 450 °C. This is the model termperature range. The preferred range in some emobodiments, is 450 °C - 500 °C. Thus the decomposition goes completely to MgO. The main reaction occurring in this chamber can be represented as follows:

MgCl₂-6H₂0→ MgO + 5H₂0 + 2HC1 450 °C

Additional details regarding this simulation are provided in Example 4 below.

FIG. 9 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software similar to the embodiment of FIG. 8 except that the MgCl₂-6H₂0 is decomposed into an intermediate compound, Mg(OH)Cl at a lower temperature of 250 °C in one chamber. The Mg(OH)Cl is then dissolved in water to form MgCl₂ and Mg(OH)₂, which follows through with the same reaction with CaCl₂ and C0₂ to form CaC0₃ and MgCl₂. The main reaction occurring in this chamber can be represented as follows:

MgCl₂-6H₂0→ Mg(OH)Cl + HC1 + 5H₂0 250 °C

The reaction was modeled at 250 °C. In some embodiments, the preferred range is from 230 °C to 260 °C. Additional details regarding this simulation are provided in Example 5 below.

FIG. 10 shows a graph of the mass percentage of a heated sample of MgCl₂-6H₂0. The sample's initial mass was approximately 70 mg and set at 100%. During the experiment, the sample's mass was measured while it was being thermally decomposed. The temperature was quickly ramped up to 150 °C, and then slowly increased by 0.5 °C per minute. At approximately 220 °C, the weight became constant, consistent with the formation of Mg(OH)Cl. FIG. 11 shows X-ray diffraction data corresponding to the product of Example 7.

FIG. 12 shows X-ray diffraction data corresponding to the product from the reaction using Mg(OH)2 of Example 8.

FIG. 13 shows X-ray diffraction data corresponding to the product from the reaction using Mg(OH)Cl of Example 8.

FIG. 14 shows the effect of temperature and pressure on the decomposition of MgCl₂-(H₂0).

FIG. 15 is a process flow diagram of an embodiment of the Ca Mg process described herein.

FIG. 16 is a process flow diagram of a variant of the process, whereby only magnesium compounds are used. In this embodiment the Ca²⁺ - Mg²⁺ switching reaction does not occur.

FIG. 17 is a process flow diagram of a different variant of the process which is in between the previous two embodiments. Half of the Mg is replaced by Ca , thereby making the resulting mineralized carbonate MgCa(C0₃)₂ or dolomite.

FIG. 18 - CaSi0₃-Mg(OH)Cl Process, Cases 10 & 11. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaSi0₃, C0₂ and water, to form Si0₂ and CaC0₃. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with CaSi0₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂-6H₂0 to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂-2H₂0 in the first chamber using heat from the HCl and CaSi0₃ reaction and decomposed in a second chamber at 250°C using heat from the flue gas. Thus the decomposition goes partially to Mg(OH)Cl. The main reactions occurring in this chamber can be represented as follows: ΔΗ** Reaction

Reaction

kJ/mole Temp. Range

230 °C -

MgCl₂-6H₂0→ Mg(OH)Cl + 5H₂0 + HC1 433

260 °C

2HCl(g) + CaSi0₃→ CaC\₂(aq) + H₂0 + Si0₂| -259 90 °C - 150 °C

2Mg(OH)Cl + C0₂ + CaCl₂→ 2MgCl₂ + CaC0₃| + H₂0 -266 25 °C - 95 °C

* * Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 10 and 1 1 below.

FIG. 19 - CaSi03-MgO Process, Cases 12 & 13. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaSi0₃, C0₂ and water, to form Si0₂ and CaC0₃. Results from this simulation indicate that it is efficient to use heat from the HC1 reacting with CaSi0₃ and heat from flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂-6H₂0 to form MgO. The MgO then reacts with H₂0 to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂-2H₂0 in the first chamber using heat from the HC1 and CaSi0₃ reaction and decomposed in a second chamber at 450°C using heat from the flue gas. Thus the decomposition goes completely to MgO. The main reactions occurring in this chamber can be represented as follows:

* * Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 12 and 13 below.

FIG. 20 - MgSi0₃-Mg(OH)Cl Process, Cases 14 & 15. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, MgSi0₃, C0₂ and water, to form Si0₂ and MgC0₃. Results from this simulation indicate that it is efficient to use heat from the HC1 reacting with MgSi0₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂-2H₂0 to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with C0₂ from the flue gas to form MgC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride remains in the dihydrate form MgCl₂-2H₂0 due to the heat from the HC1 and MgSi0₃ prior to decomposition at 250°C using heat from the flue gas. Thus the decomposition goes partially to Mg(OH)Cl. The main reactions occurring in this chamber can be represented as follows:

** Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 14 and 15 below.

FIG. 21 - MgSi0₃-MgO Process, Cases 16 & 17. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, MgSi0₃, C0₂ and water, to form Si0₂ and MgC0₃. Results from this simulation indicate that it is efficient to use heat from the HC1 reacting with MgSi0₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂-2H₂0 to form MgO. The MgO then reacts with H₂0 to form Mg(OH)₂, which then reacts with C0₂ from the flue gas to form MgC0₃, which is filtered out of the stream. In this embodiment, the magnesium chloride remains in the dihydrate form MgCl₂-2H₂0 due to the heat from the HC1 and MgSi0₃ prior to decomposition at 450°C using heat from the flue gas. Thus the decomposition goes completely to MgO. The main reactions occurring in this chamber can be represented as follows: Reaction ΔΗ kJ/mole Reaction Temp.

Range

MgCl₂-2H₂0→ MgO + H₂0(g) + 2HCl(g) 232.9 450 °C - 500°C

2HCl(g) + MgSi0₃→ MgCl₂(<¾ + H₂0(g) + Si0₂| -293.5 90 °C - 150 °C

MgO + C0₂ - MgC0₃| -100 25 °C - 95 °C

** Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 16 and 17 below.

FIG. 22 - Diopside-Mg(OH)Cl Process, Cases 18 & 19. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, diopside MgCa(Si03)₂, C0₂ and water, to form Si0₂ and dolomite MgCa(CC>3)₂. Results from this simulation indicate that it is efficient to use heat from the HC1 reacting with MgCa(Si03)₂ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂-6H₂0 to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form MgCa(C0₃)₂ which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂-2H₂0 in the first chamber using heat from the HC1 and CaSi0₃ reaction and decomposed to Mg(OH)Cl in a second chamber at 250°C using heat from the flue gas. The main reactions occurring in this chamber can be represented as follows:

** Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 1 8 and 19 below.

FIG. 23 - Diopside-MgO Process, Cases 20 & 21. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, diopside MgCa(Si0₃)₂, C0₂ and water, to form Si0₂ and dolomite MgCa(C0₃)₂. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with MgCa(Si0₃)₂ and heat from the flue gas emitted by a natural gas or coal fired power plant and/or other heat source to carry out the decomposition of MgCl₂-6H₂0 to form MgO. The MgO then reacts with H₂0 to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form MgCa(C0₃)₂ which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂-2H₂0 in the first chamber using heat from the HCl and CaSi0₃ reaction and decomposed to MgO in a second chamber at 450°C using heat from the flue gas. The main reactions occurring in this chamber can be represented as follows:

** Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 20 and 21 below.

FIG. 24 illustrates the percent C0₂ captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 10 through 13 of the CaSi0₃-Mg(OH)Cl and CaSi0₃-MgO processes. FIG. 25 illustrates the percent C0₂ captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 14 through 17 of the MgSi0₃-Mg(OH)Cl and MgSi0₃-MgO processes.

FIG. 26 illustrates the percent C0₂ captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 18 through 21 of the Diopside - Mg(OH)Cl and Diopside - MgO processes.

FIG. 27 is a simplified process-flow diagram corresponding to some embodiments of the present invention in which two different salts, e.g. , Ca²⁺ and Mg²⁺, are used for decomposition and carbonation.

FIGS. 28-29 show graphs of the mass percentages of heated samples of MgCl₂-6H₂0. The initial masses of the samples were approximately 70 mg each and were each set at 100%. During the experiment, the masses of the samples were measured while they was being thermally decomposed. The temperature was ramped up to 200 °C then further increased over the course of a 12 hour run. The identities of the decomposed materials can be confirmed by comparing against the theoretical plateaus provided. FIG. 28 is a superposition of two plots, the first one being the solid line, which is a plot of time (minutes) versus temperature (°C). The line illustrates the ramping of temperature over time; the second plot, being the dashed line is a plot of weight % (100% = original weight of sample) versus time, which illustrates the reduction of the sample's weight over time whether by dehydration or decomposition. FIG. 29 is also a superposition of two plots, the first (the solid line) is a plot of weighf% versus temperature (°C), illustrating the sample's weight decreasing as the temperature increases; the second plot (the dashed line) is a plot of the derivative of the weight% with respect to temperature (wt.%/°C) versus temperature °C. When this value is high it indicates a higher rate of weight loss for each change per degree. If this value is zero, the sample's weight remains the same although the temperature is increasing, indicating an absence of dehydration or decomposition. Note Figure 28 and 29 are of the same sample.

FIG. 30 - MgCl₂-6H₂0 Decomposition at 500°C after One Hour. This graph shows the normalized final and initial weights of four test runs of MgCl₂-6H₂0 after heating at 500 °C for one hour. The consistent final weight confirms that MgO is made by decomposition at this temperature.

FIG. 31 - Three-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from cold flue gas (chamber 1 ), heat from mineral dissolution reactor (chamber 2), and external natural gas (chamber 3) are used as heat sources. This process flow diagram illustrates a three chamber process for the decomposition to Mg(OH)Cl. The first chamber is heated by 200 °C flue gas to provide some initial heat about -8.2% of the total required heat, the second chamber which relies on heat recovered from the mineral dissolution reactor to provide 83% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 55% is from the condensation and formation of hydrochloric acid, and finally the third chamber, which uses natural gas as an external source of the remaining heat which is 8.5% of the total heat. The C0₂ is from a combined cycle power natural gas plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 32 - Four-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from cold flue gas (chamber 1), heat from additional steam (chamber 2), heat from mineral dissolution reactor (chamber 3), and external natural gas (chamber 4) are used as heat sources. This process flow diagram illustrates a four chamber process for the decomposition to Mg(OH)Cl, the first chamber provides 200 °C flue gas to provide some initial heat about -8.2% of the total required heat, the second chamber provides heat in the form of extra steam which is 0.8% of the total heat needed, the third chamber which relies on heat recovered from the mineral dissolution reactor to provide 83% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 55% is from the condensation and formation of hydrochloric acid, and finally the fourth chamber, which uses natural gas as an external source of the remaining heat which is 8.0% of the total heat. The C0₂ is from a combined cycle natural gas power plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 33 - Two-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from mineral dissolution reactor (chamber 1), and external natural gas (chamber 2) are used as heat sources. This process flow diagram illustrates a two chamber process for the decomposition to Mg(OH)Cl, the first chamber which relies on heat recovered from the mineral dissolution reactor to provide 87% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 59% is from the condensation and formation of hydrochloric acid, and the second chamber, which uses natural gas as an external source of the remaining heat which is 13% of the total heat. The C0₂ is from a combined cycle natural gas power plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 34 - Two-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from mineral dissolution reactor (chamber 1), and hot flue gas from open cycle natural gas plant (chamber 2) are used as heat sources. This process flow diagram illustrates a two chamber process for the decomposition to Mg(OH)Cl, the first chamber which relies on heat recovered from the mineral dissolution reactor to provide 87% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 59% is from the condensation and formation of hydrochloric acid, and the second chamber, which uses hot flue gas as an external source of the remaining heat which is 13%) of the total heat. The C0₂ is from an open cycle natural gas power plant, therefore substantial heat is available from the power plant in the form of 600 °C flue gas to power the decomposition reaction.

FIG. 35 shows a schematic diagram of a Auger reactor which may be used for the salt decomposition reaction, including the decomposition of MgCl₂-6H₂0 to M(OH)Cl or MgO. Such reactors may comprises internal heating for efficient heat utilization, external insulation for efficient heat utilization, a screw mechanism for adequate solid transport (when solid is present), adequate venting for HC1 removal. Such a reactors has been used to prepare ~1.8kg of -90% Mg(OH)Cl.

FIG. 36 shows the optimization index for two separate runs of making Mg(OH)Cl using an Auger reactor. The optimization index = % conversion ^χ % efficiency.

FIG. 37 shows a process flow diagram of an Aspen model that simulates an CaSi0₃- Mg(OH)Cl Process.

FIG. 38A-I shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaSi0₃, C0₂ and water, to form Si0₂ and CaC0₃. Heat is used to carry out the decomposition of MgCl₂-6H₂0 to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂. The quantity of H₂0 is regulated to favor formation of solid Mg(OH)₂ and aqueous MgCl₂ (which is recycled to the first reactor to begin the process again) The Mg(OH)₂ then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. A, is an overview diagram of the process. B-I, are overlapping enlargements of the overview diagram shown in A.

FIG. 39A-I shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of C0₂ from flue gas using inexpensive raw materials, CaSi0₃, C0₂ and water, to form Si0₂ and CaC0₃. Heat is used to carry out the decomposition of MgCl₂-6H₂0 to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂0 to form MgCl₂ and Mg(OH)₂. The quantity of H₂0 is regulated to favor formation of solid Mg(OH)₂ and aqueous MgCl₂ (which is recycled to the first reactor to begin the process again). The Mg(OH)₂ then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. A, is an overview diagram of the process. B-I, are overlapping enlargements of the overview diagram shown in A.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The present invention relates to carbon dioxide sequestration, including energy- efficient processes in which Group 2 chlorides are converted to Group 2 hydroxides and hydrogen chloride, which are then used to remove carbon dioxide from waste streams. In some embodiments, hydrogen chloride may be further reacted with Group 2 silicates to produce additional Group 2 chloride starting materials and silica.

In some embodiments, the methods and apparatuses of the invention comprise one or more of the following general components: (1) the conversion of Group 2 silicate minerals with hydrogen chloride into Group 2 chlorides and silicon dioxide, (2) conversion of Group 2 chlorides into Group 2 hydroxides and hydrogen chloride, (3) an aqueous decarbonation whereby gaseous C0₂ is absorbed into an aqueous caustic mixture comprising Group 2 hydroxides to form Group 2 carbonate and/or bicarbonate products and water, (4) a separation process whereby the carbonate and/or bicarbonate products are separated from the liquid mixture, (5) the reuse or cycling of by-products, including energy, from one or more of the steps or process streams into another one or more steps or process streams. Each of these general components is explained in further detail below.

While many embodiments of the present invention consume some energy to accomplish the absorption of C0₂ and other chemicals from flue-gas streams and to accomplish the other objectives of embodiments of the present invention as described herein, one advantage of certain embodiments of the present invention is that they provide ecological efficiencies that are superior to those of the prior art, while absorbing most or all of the emitted C0₂ from a given source, such as a power plant.

Another additional benefit of certain embodiments of the present invention that distinguishes them from other C0₂-removal processes is that in some market conditions, the products are worth considerably more than the reactants required or the net-power or plant- depreciation costs. In other words, certain embodiments are industrial methods of producing chloro-hydro-carbonate products at a profit, while accomplishing considerable removal of C0₂ and incidental pollutants of concern. I. Definitions

As used herein, the terms "carbonates" or "carbonate products" are generally defined as mineral components containing the carbonate group, [C0₃] . Thus, the terms encompass both carbonate/bicarbonate mixtures and species containing solely the carbonate ion. The terms "bicarbonates" and "bicarbonate products" are generally defined as mineral components containing the bicarbonate group, [HC0₃]'^~. Thus, the terms encompass both carbonate/bicarbonate mixtures and species containing solely the bicarbonate ion.

As used herein "Ca/Mg" signifies either Ca alone, Mg alone or a mixture of both Ca and Mg. The ratio of Ca to Mg may range from 0: 100 to 100:0, including, e.g., 1 :99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90: 10, 95:5, and 99: 1. The symbols "Ca/Mg", "MgxCa(l-x)" and CaxMg(l-x)" are synonymous. In contrast, "CaMg" or "MgCa" refers to a 1 : 1 ratio of these two ions.

As used herein, the term "ecological efficiency" is used synonymously with the term "thermodynamic efficiency" and is defined as the amount of C0₂ sequestered by certain embodiments of the present invention per energy consumed (represented by the equation "3C0₂/<9E"), appropriate units for this value are kWh/ton C0₂. C0₂ sequestration is denominated in terms of percent of total plant C0₂; energy consumption is similarly denominated in terms of total plant power consumption.

The terms "Group II" and "Group 2" are used interchangeably.

"Hexahydrate" refers to MgCl₂-6H₂0.

In the formation of bicarbonates and carbonates using some embodiments of the present invention, the term "ion ratio" refers to the ratio of cations in the product divided by the number of carbons present in that product. Hence, a product stream formed of calcium bicarbonate (Ca(HC0₃)₂) may be said to have an "ion ratio" of 0.5 (Ca/C), whereas a product stream formed of pure calcium carbonate (CaC0₃) may be said to have an "ion ratio" of 1.0 (Ca/C). By extension, an infinite number of continuous mixtures of carbonate and bicarbonate of mono-, di- and trivalent cations may be said to have ion ratios varying between 0.5 and 3.0.

Based on the context, the abbreviation "MW" either means molecular weight or megawatts.

The abbreviation "PFD" is process flow diagram.

The abbreviation "Q" is heat (or heat duty), and heat is a type of energy. This does not include any other types of energy.

As used herein, the term "sequestration" is used to refer generally to techniques or practices whose partial or whole effect is to remove C0₂ from point emissions sources and to store that C0₂ in some form so as to prevent its return to the atmosphere. Use of this term does not exclude any form of the described embodiments from being considered "sequestration" techniques.

In the context of a chemical formula, the abbreviation "W" refers to H₂0.

The pyroxenes are a group of silicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems. Pyroxenes have the general formula XY(Si,Al)₂0₆, where X represents calcium, sodium, iron (II) and magnesium and more rarely zinc, manganese and lithium and Y represents ions of smaller size, such as chromium, aluminium, iron(III), magnesium, manganese, scandium, titanium, vanadium and even iron (II).

In addition, atoms making up the compounds of the present invention are intended to include all isotopic forms of such atoms. Isotopes, as used herein, include those atoms having the same atomic number but different mass numbers. By way of general example and without limitation, isotopes of hydrogen include tritium and deuterium, and isotopes of carbon include ¹³C and ¹⁴C.

The use of the word "a" or "an," when used in conjunction with the term "comprising" in the claims and/or the specification may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one."

Throughout this application, the term "about" is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects. The terms "comprise," "have" and "include" are open-ended linking verbs. Any forms or tenses of one or more of these verbs, such as "comprises," "comprising," "has," "having," "includes" and "including," are also open-ended. For example, any method that "comprises," "has" or "includes" one or more steps is not limited to possessing only those one or more steps and also covers other unlisted steps.

The term "effective," as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

The above definitions supersede any conflicting definition in any of the reference that is incorporated by reference herein. The fact that certain terms are defined, however, should not be considered as indicative that any term that is undefined is indefinite. Rather, all terms used are believed to describe the invention in terms such that one of ordinary skill can appreciate the scope and practice the present invention.

II. Sequestration of Carbon Dioxide Using Salts of Group II Metals

FIG. 1 depicts a simplified process-flow diagram illustrating general, exemplary embodiments of the apparatuses and methods of the present disclosure. This diagram is offered for illustrative purposes only, and thus it merely depicts specific embodiments of the present invention and is not intended to limit the scope of the claims in any way.

In the embodiment shown in FIG. 1, reactor 10 (e.g., a road salt boiler) uses power, such as external power and/or recaptured power (e.g., heat from hot flue gas or an external source of heat such as solar concentration or combustion), to drive a reaction represented by equation 1.

(Ca/Mg)Cl₂ + 2 H₂0→ (Ca/Mg)(OH)₂ + 2 HC1 ( 1 )

The water used in this reaction may be in the form of liquid, steam, a crystalline hydrate, e.g. , MgCl₂-6H₂0, CaCl₂-2H₂0, or it may be supercritical. In some embodiments, the reaction uses MgCl₂ to form Mg(OH)₂ and/or Mg(OH)Cl (see, e.g., FIG. 2). In some embodiments, the reaction uses CaCl₂ to form Ca(OH)₂. Some or all of the Group 2 hydroxide or hydroxychloride (not shown) from equation 1 may be delivered to reactor 20. In some embodiments, some or all of the Group 2 hydroxide and/or Group 2 hydroxychloride is delivered to reactor 20 as an aqueous solution. In some embodiments, some or all of the Group 2 hydroxide is delivered to reactor 20 in an aqueous suspension. In some embodiments, some or all of the Group 2 hydroxide is delivered to reactor 20 as a solid. In some embodiments, some or all of the hydrogen chloride (e.g. , in the form of vapor or in the form of hydrochloric acid) may be delivered to reactor 30 (e.g. , a rock melter). In some embodiments, the resulting Group 2 hydroxides are further heated to remove water and form corresponding Group 2 oxides. In some variants, some or all of these Group 2 oxides may then be delivered to reactor 20.

Carbon dioxide from a source, e.g. , flue-gas, enters the process at reactor 20 (e.g. , a fluidized bed reactor, a spray-tower decarbonator or a decarbonation bubbler), potentially after initially exchanging waste-heat with a waste-heat/DC generation system. In some embodiments the temperature of the flue gas is at least 125 °C. The Group 2 hydroxide, some or all of which may be obtained from reactor 10, reacts with carbon dioxide in reactor 20 according to the reaction represented by equation 2.

(Ca/Mg)(OH)₂ + C0₂→ (Ca/Mg)C0₃ + H₂0 (2)

The water produced from this reaction may be delivered back to reactor 10. The Group 2 carbonate is typically separated from the reaction mixture. Group 2 carbonates have a very low ^_Sp (solubility product constant). So they be separated as solids from other, more soluble compounds that can be kept in solution. In some embodiments, the reaction proceeds through Group 2 bicarbonate salts. In some embodiments, Group 2 bicarbonate salts are generated and optionally then separated from the reaction mixture. In some embodiments, Group 2 oxides, optionally together with or separately from the Group 2 hydroxides, are reacted with carbon dioxide to also form Group 2 carbonate salts. In some embodiments, the flue gas, from which C0₂ and/or other pollutants have been removed, is released to the air.

Group 2 silicates (e.g. , CaSi0₃, MgSi0₃, MgOFeOSi0₂, etc.) enter the process at reactor 30 (e.g. , a rock melter or a mineral dissociation reactor). In some embodiments, these Group 2 silicates are ground in a prior step. In some embodiments, the Group 2 silicates are inosilicates. These minerals may be reacted with hydrochloric acid, either as a gas or in the form of hydrochloric acid, some or all of which may be obtained from reactor 10, to form the corresponding Group 2 metal chlorides (CaCl₂ and/or MgCl₂), water and sand (Si0₂). The reaction can be represented by equation 3.

2 HC1 + (Ca/Mg)Si0₃→ (Ca/Mg)Cl₂ + H₂0 + Si0₂ (3) Some or all of the water produced from this reaction may be delivered to reactor 10. Some or all of the Group 2 chlorides from equation 3 may be delivered to reactor 20. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 as an aqueous solution. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 in an aqueous suspension. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 as a solid. The net reaction capturing the summation of equations 1 -3 is shown here as equation

4:

C0₂ + (Ca/Mg)Si0₃→ (Ca/Mg)C0₃ + Si0₂ (4)

In another embodiment, the resulting Mg_xCa₍]-_X)C0₃ sequestrant is reacted with HC1 in a manner to regenerate and concentrate the C0₂. The Ca/MgCl₂ thus formed is returned to the decomposition reactor to produce C0₂ absorbing hydroxides or hydroxyhalides.

Through the process shown in FIG. 1 and described herein, Group 2 carbonates are generated as end-sequestrant material from the captured C0₂. Some or all of the water, hydrogen chloride and/or reaction energy may be cycled. In some embodiments, only some or none of these are cycled. In some embodiments, the water, hydrogen chloride and reaction energy made be used for other purposes.

In some embodiments, and depending on the concentration of C0₂ in the flue gas stream of a given plant, the methods disclosed herein may be used to capture 33-66% of the plant's C0₂ using heat-only as the driver (no electrical penalty). In some embodiments, the efficiencies of the methods disclosed herein improve with lower C0₂-concentrations, and increase with higher (unscrubbed) flue-gas temperatures. For example, at 320 °C and 7% C0₂ concentration, 33% of flue-gas C0₂ can be mineralized from waste-heat alone. In other embodiments, e.g. , at the exit temperatures of natural gas turbines approximately 100% mineralization can be achieved.

These methods and devices can be further modified, e.g. , with modular components, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Patent 7,727,374, U.S. Patent Application Publications 2006/0185985 and 2009/0127127, U.S. Patent Application No. 1 1/233,509, filed September 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed September 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed January 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed September 23, 2004, U.S. Patent Application No. 12/235,482, filed September 22, 2008, U.S. Provisional Application No. 60/973,948, filed September 20, 2007, U.S. Provisional Application No. 61/032,802, filed February 29, 2008, U.S. Provisional Application No. 61/033,298, filed March 3, 2008, U.S. Provisional Application No. 61/288,242, filed January 20, 2010, U.S. Provisional Application No. 61/362,607, filed July 8, 2010, and International Application No. PCT/US08/77122, filed September 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

The above examples were included to demonstrate particular embodiments of the invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

III. Sequestration of Carbon Dioxide Using Mg²⁺ as Catalyst

FIG. 2 depicts a simplified process-flow diagram illustrating general, exemplary embodiments of the apparatuses and methods of the present disclosure. This diagram is offered for illustrative purposes only, and thus it merely depicts specific embodiments of the present invention and is not intended to limit the scope of the claims in any way.

In the embodiment shown in FIG. 2, reactor 100 uses power, such as external power and/or recaptured power (e.g., heat from hot flue gas), to drive a decomposition -type reaction represented by equation 5.

MgCl₂-x(H₂0) + y¾0→

z'[Mg(OH)₂] + z"[MgO] + z"'[MgCl(OH)] + (2ζ' + 2z" + z"')[HCl] (5) The water used in this reaction may be in the form of a hydrate of magnesium chloride, liquid, steam and/or it may be supercritical. In some embodiments, the reaction may occur in one, two, three or more reactors. In some embodiments, the reaction may occur as a batch, semi-batch of continuous process. In some embodiments, some or all of the magnesium salt product may be delivered to reactor 200. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 as an aqueous solution. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 in an aqueous suspension. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 as a solid. In some embodiments, some or all of the hydrogen chloride (e.g. , in the form of vapor or in the form of hydrochloric acid) may be delivered to reactor 300 (e.g. , a rock melter). In some embodiments, the Mg(OH)2 is further heated to remove water and form MgO. In some embodiments, the MgCl(OH) is further heated to remove HC1 and form MgO. In some variants, one or more of Mg(OH)2, MgCl(OH) and MgO may then be delivered to reactor 200.

Carbon dioxide from a source, e.g., flue-gas, enters the process at reactor 200 (e.g. , a fluidized bed reactor, a spray-tower decarbonator or a decarbonation bubbler), potentially after initially exchanging waste-heat with a waste-heat/DC generation system. In some embodiments the temperature of the flue gas is at least 125 °C. Admixed with the carbon dioxide is the magnesium salt product from reactor 100 and CaCl₂ {e.g. , rock salt). The carbon dioxide reacts with the magnesium salt product and CaCl₂ in reactor 200 according to the reaction represented by equation 6.

C0₂ + CaCl₂ + z'[Mg(OH)₂] + z"[MgO] + z"'[MgCl(OH)]→

(z' + z" + z"')MgCl₂ + (z' + ½z'")H₂0 + CaC0₃ (6)

In some embodiments, the water produced from this reaction may be delivered back to reactor 100. The calcium carbonate product (e.g., limestone, calcite) is typically separated {e.g., through precipitation) from the reaction mixture. In some embodiments, the reaction proceeds through magnesium carbonate and bicarbonate salts. In some embodiments, the reaction proceeds through calcium bicarbonate salts. In some embodiments, various Group 2 bicarbonate salts are generated and optionally then separated from the reaction mixture. In some embodiments, the flue gas, from which C0₂ and/or other pollutants have been removed, is released to the air, optionally after one or more further purification and/or treatment steps. In some embodiments, the MgCl₂ product, optionally hydrated, is returned to reactor 100. In some embodiments, the MgCl₂ product is subjected to one or more isolation, purification and/or hydration steps before being returned to reactor 100.

Calcium silicate {e.g. , 3CaOSi0₂, Ca₃Si0₅; 2CaOSi0₂, Ca₂Si0₄; 3CaO2Si0₂, Ca₃Si₂0₇ and CaOSi0₂, CaSi0₃ enters the process at reactor 300 {e.g. , a rock melter). In some embodiments, these Group 2 silicates are ground in a prior step. In some embodiments, the Group 2 silicates are inosilicates. In the embodiment of FIG. 2, the inosilicate is CaSi0₃ {e.g., wollastonite, which may itself, in some embodiments, contain small amounts of iron, magnesium and/or manganese substituting for iron). The CaSi0₃ is reacted with hydrogen chloride, either gas or in the form of hydrochloric acid, some or all of which may be obtained from reactor 100, to form CaCl₂, water and sand (Si0₂). The reaction can be represented by equation 7.

2 HC1 + (Ca/Mg)Si0₃→ (Ca/Mg)Cl₂ + H₂0 + Si0₂

** Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Some or all of the water produced from this reaction may be delivered to reactor 100. Some or all of the CaCl₂ from equation 7 may be delivered to reactor 200. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 as an aqueous solution. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 in an aqueous suspension. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 as a solid.

The net reaction capturing the summation of equations 5-7 is shown here as equation

8: C0₂ + CaSi0₃→ CaC0₃ + Si0₂ (8)

** Measured at standard temperature and pressure (STP). Through the process shown in FIG. 2 and described herein, calcium carbonates are generated as end-sequestrant material from C0₂ and calcium inosilicate. Some or all of the various magnesium salts, water, hydrogen chloride and reaction energy may be cycled. In some embodiments, only some or none of these are cycled. In some embodiments, the water, hydrogen chloride and/or reaction energy made be used for other purposes.

These methods and devices can be further modified, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Patent 7,727,374, U.S. Patent Application Publications 2006/0185985 and 2009/0127127, U.S. Patent Application No. 1 1/233,509, filed September 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed September 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed January 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed September 23, 2004, U.S. Patent Application No. 12/235,482, filed September 22, 2008, U.S. Provisional Application No. 60/973,948, filed September 20, 2007, U.S. Provisional Application No. 61/032,802, filed February 29, 2008, U.S. Provisional Application No. 61/033,298, filed March 3, 2008, U.S. Provisional Application No. 61/288,242, filed January 20, 2010, U.S. Provisional Application No. 61/362,607, filed July 8, 2010, and International Application No. PCT/US08/77122, filed September 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

IV. Conversion of Group 2 Chlorides into Group 2 Hydroxides or Group II Hydroxy Chlorides

Disclosed herein are processes that react a Group 2 chloride, e.g. , CaCl₂ or MgCl₂, with water to form a Group 2 hydroxide, a Group 2 oxide, and/or a mixed salt such as a Group 2 hydroxide chloride. Such reactions are typically referred to as decompositions. In some embodiments, the water may be in the form of liquid, steam, from a hydrate of the Group 2 chloride, and/or it may be supercritical. The steam may come from a heat exchanger whereby heat from an immensely combustible reaction, i.e. natural gas and oxygen or hydrogen and chlorine heats a stream of water. In some embodiments, steam may also be generated through the use of plant or factory waste heat. In some embodiments, the chloride salt, anhydrous or hydrated, is also heated.

In the case of Mg²⁺ and Ca²⁺, the reactions may be represented by equations 9 and 10, respectively:

MgCl₂ + 2 H₂0→ Mg(OH)₂ + 2 HCl(g) ΔΗ = 263 kJ/mole** (9)

CaCl₂ + 2 H₂0→ Ca(OH)₂ + 2 HCl(g) ΔΗ = 284 kJ/mole** (10)

**Measured at 100 °C. The reactions are endothermic meaning energy, e.g., heat has to be applied to make these reactions occur. Such energy may be obtained from the waste-heat generated from one or more of the exothermic process steps disclosed herein. The above reactions may occur according to one of more of the following steps:

CaCl₂ + (x + y + z) H₂0→ Ca²⁺-xH₂0 + CPyH₂0 + CPzH₂0 (1 1)

Ca⁺²-xH₂0 + CPyH₂0 + CPzH₂0→

[Ca²⁺-(x-l)(H₂0)OH^~]⁺ + CP(yIi₂0) + CP(z-l )H₂0 + H₃0⁺ (12) [Ca²⁺-(x-l)(H₂0)OH^"]⁺ + CP(yH₂0) + CP(z-l)H₂0 + H₃0⁺→

[Ca²⁺-(x-l)(H₂0)OH ⁺ + CP(yH₂0)^~ + zH₂0 + HCl(g)† (13)

2+

[Ca²⁺-(x^~l)(H₂0)OH ⁺ + CP(yH₂0)

[Ca²⁺-(x-2)(H₂0) (OH^~)₂] + CP(y-l)H₂0 + H₃<X (14) [Ca²⁺-(x-2)(H₂0) (OH^")₂] + CP(y-l)H₂0 + H₃0⁺→

Ca(OH)₂i + (x-2)H₂0 + yH₂0 + HCl† (15)

The reaction enthalpy (ΔΗ) for CaCl₂ + 2 ¾0→ Ca(OH)₂ + 2 HCl(g) is 284 kJ/mole at 100 °C. In some variants, the salt MgCl₂-6H₂0, magnesium hexahydrate, is used. Since water is incorporated into the molecular structure of the salt, direct heating without any additional steam or water may be used to initiate the decomposition. Typical reactions temperatures for the following reactions are shown here:

From 95-1 10 °C:

MgCl₂-6H₂0→ MgCl₂-4H₂0 + 2 H₂0 (16)

MgCl₂-4H₂0→ MgCl₂-2H₂0 + 2 H₂0 (17) From 135-180 °C:

MgCl₂-4H₂0→ Mg(OH)Cl + HCl + 3 H₂0 (18)

MgCl₂-2H₂0→ MgCl₂-H₂0 + H₂0 (19)

From 185-230 °C:

MgCl₂-2H₂0→ Mg(OH)Cl + HCl +H₂0 (20) From >230 °C:

MgCl₂-H₂0→ MgCl₂ + H₂0 (21 )

MgCl₂-H₂0→ Mg(OH)Cl + HCl (22)

Mg(OH)Cl→ MgO + HCl (23) Referenced

ΔΗ Temp.

Reaction Temp.

kJ/mole** Reaction Range

95 °C -

MgCl₂-6H₂0 - MgCl₂-4H₂0 + 2 H₂0(g) 1 15.7 100°C

1 10 °C

95 °C -

MgCl₂-4H₂0→ MgCl₂-2H₂0 + 2 H₂0(g) 134.4 100°C

1 10 °C

MgCl₂-4H₂0→ Mg(OH)Cl + HCl(g) + 3 135 °C -

275 160°C H₂0(g) 180 °C

135 °C -

MgCl₂-2H₂0→ MgCl₂-H₂0 + H₂0(g) 70.1 160°C

180 °C

MgCl₂-2H₂0→ Mg(OH)Cl + HCl(g) 185 °C -

141 210°C +H₂0(g) 230 °C

MgCl₂-H₂0 -> MgCl₂ + H₂0(g) >230 °C 76.6 240°C

MgCl₂-H₂0→ Mg(OH)Cl + HCl(g) >230 °C 70.9 240°C

Mg(OH)Cl→ MgO + HCl(g) >230 °C 99.2 450°C

** ΔΗ values were calculated at the temperature of reaction (column "Temp. Reaction"). See the chemical reference Kirk Othmer 4^th ed. Vol. 15 p. 343 1998 John Wiley and Sons, which is incorporated herein by reference. See example 1 , below, providing results from a simulation that demonstrating the ability to capture C0₂ from flue gas using an inexpensive raw material, CaCl₂, to form CaC0₃. See also Energy Requirements and Equilibrium in the dehydration, hydrolysis and decomposition of Magnesium Chloride - K.K. Kelley, Bureau of Mines 1941 and Kinetic Analysis of Thermal Dehydration and Hydrolysis of MgCl₂.6H₂0 by DTA and TG - Y. Kirsh, S. Yariv and S. Shoval - Journal of Thermal Analysis, Vol. 32 (1987), both of which are incorporated herein by reference in their entireties.

In certain aspects, Mg(OH)₂ can be more efficiently generated from MgCl₂ (via Mg(OH)Cl) by adjusting the proportion of MgCl₂ and water in the presence of Mg(OH)Cl. In order to optimize production of Mg(OH)₂, the amount of water in the chamber is adjusted to favor Mg(OH)₂ precipitation, while preventing formation of MgCl₂-6(H₂0) hydrates. Specifically, the amount of water in a Mg(OH)Cl solution is maintained at a water to MgCl₂ molar ratio of greater than or equal to 6, such as a ratio of of between about 6 and 7. Under these conditions Mg(OH)₂, which is virtually insoluble, whereas the magnesium chloride remains in an aqueous solution. See, for example page 52 of de Bakker 201 1 , the entire disclosure of which is incorporated herein by reference. Thus, to reach a product mixture of MgCl₂-6H₂0 and Mg(OH)₂ Mg(OH)Cl is reacted with an aqueous MgCl₂ solution, such as that from the bubble column. That reaction would be:

CaCl₂(aq) + C0₂ + Mg(OH)₂ => MgCl₂(aq) + CaC0₃ |+ H₂0

MgCl₂(aq) ~ MgCl₂- 13-16H₂0(liquid)

Boiling the mixture MgCl₂- 13-16H₂0(liquid) + ΔΗ => MgCl₂-6H₂0(solid) + 7- 9H₂0(gas)† would require significant energy usage. Thus, a solution more dilute than MgCl₂-6H₂0 shall cause the disproportionation of Mg(OH)Cl, a solution of MgCl₂.xH₂0(liquid) where x > 12 should also be able to cause the disproportionation of Mg(OH)Cl. The equation is written as follows:

Mg(OH)Cl + ½ MgCl₂-13-16H₂0(liquid) => ½ Mg(OH)₂ + MgCl₂-6.5-8H₂0

Such as: Mg(OH)Cl + ½ MgCl₂- 12H₂0(liquid) => ½ Mg(OH)₂ + MgCl₂-6H₂0 The MgCl₂(aq) is being reconstituted to half of the original MgCl₂-6H₂0 by water removal and the remaining half of the MgCl₂-6H₂0 forms from the disproportionation of Mg(OH)Cl by addition of water.

An example of a system that utilizes Mg(OH)₂ generated as detailed above is shown in FIG. 38A-I. The Aspen diagram is below, and has a red rectangle around the defined "water disproportionator". At the top of the red rectangle, Mg(OH)Cl, stream SOLIDS- 1 , is leaving the decomposition reactor labeled "DECOMP". Then in the module labeled MGOH2, the Mg(OH)Cl is mixed the aqueous MgC12 from the absorption column, stream RECYCLE2. They leave as a slurry from the unit as stream "4", pass through a heat exchanger and send heat to the decomposition chamber. The stream is then named "13" which passes through a separation unit which separates the stream into stream MGCLSLRY (MgCl₂.6H₂0 almost) and stream SOLIDS-2, which is the Mg(OH)₂ heading to the absorption column.

V. Reaction of Group 2 Hydroxides and C0₂ to Form Group 2 Carbonates

In another aspect of the present disclosure, there are provided apparatuses and methods for the decarbonation of carbon dioxide sources using Group 2 hydroxides, Group 2 oxides, and/or Group 2 hydroxide chlorides as C0₂ adsorbents. In some embodiments, C0₂ is absorbed into an aqueous caustic mixture and/or solution where it reacts with the hydroxide and/or oxide salts to form carbonate and bicarbonate products. Sodium hydroxide, calcium hydroxide and magnesium hydroxide, in various concentrations, are known to readily absorb C0₂. Thus, in embodiments of the present invention, Group 2 hydroxides, Group 2 oxides (such as CaO and/or MgO) and/or other hydroxides and oxides, e.g. , sodium hydroxide may be used as the absorbing reagent.

For example, a Group 2 hydroxide, e.g. , obtained from a Group 2 chloride, may be used in an adsorption tower to react with and thereby capture C0₂ based on one or both of the following reactions:

Ca(OH)₂ + C0₂→ CaCOs + H₂0 (24)

ΔΗ = -1 17.92 kJ/mol**

AG = -79.91 kJ/mol** Mg(OH)₂ + C0₂→ MgC0₃ + H₂0 (25)

ΔΗ = -58.85 kJ/mol**

AG = -16.57 kJ/mol**

** Calculated at STP.

In some embodiments of the present invention, most or nearly all of the carbon dioxide is reacted in this manner. In some embodiments, the reaction may be driven to completion, for example, through the removal of water, whether through continuous or discontinous processes, and/or by means of the precipitation of bicarbonate, carbonate, or a mixture of both types of salts. See example 1, below, providing a simulation demonstrating the ability to capture C0₂ from flue gas using an inexpensive raw material, Ca(CO)₂ derived from CaCl₂, to form CaC0₃.

In some embodiments, an initially formed Group 2 may undergo an salt exchange reaction with a second Group 2 hydroxide to transfer the carbonate anion. For example:

CaCl₂ + MgC0₃ +→ MgCl₂ + CaC0₃ (25a)

These methods and devices can be further modified, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Patent 7,727,374, U.S. Patent Application No. 1 1/233,509, filed September 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed September 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed January 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed September 23, 2004, U.S. Patent Application No. 12/235,482, filed September 22, 2008, U.S. Provisional Application No. 60/973,948, filed September 20, 2007, U.S. Provisional Application No. 61/032,802, filed February 29, 2008, U.S. Provisional Application No. 61/033,298, filed March 3, 2008, U.S. Provisional Application No. 61/288,242, filed January 20, 2010, U.S. Provisional Application No. 61/362,607, filed July 8, 2010, and International Application No. PCT/US08/77122, filed September 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

VI. Silicate Minerals for the Sequestration of Carbon Dioxide

In aspects of the present invention there are provided methods of sequestering carbon dioxide using silicate minerals. The silicate minerals make up one of the largest and most important classes of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group. Silicate minerals all contain silicon and oxygen. In some aspects of the present invention, Group 2 silicates may be used to accomplish the energy efficient sequestration of carbon dioxide.

In some embodiments, compositions comprising Group 2 inosilicates may be used. Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedra with either Si0₃, 1 :3 ratio, for single chains or Si₄Oi i, 4: 1 1 ratio, for double chains.

In some embodiments, the methods disclosed herein use compositions comprising Group 2 inosilicates from the pyroxene group. For example, enstatite (MgSi0₃) may be used.

In some embodiments, compositions comprising Group 2 inosilicates from the pyroxenoid group are used. For example, wollastonite (CaSi0₃) may be used. In some embodiments, compositions comprising mixtures of Group 2 inosilicates may be employed, for example, mixtures of enstatite and wollastonite. In some embodiments, compositions comprising mixed-metal Group 2 inosilicates may be used, for example, diopside (CaMgSi₂0₆).

Wollastonite usually occurs as a common constituent of a thermally metamorphosed impure limestone. Typically wollastonite results from the following reaction (equation 26) between calcite and silica with the loss of carbon dioxide:

CaC0₃ + Si0₂→ CaSi0₃ + C0₂ (26) In some embodiments, the present invention has the result of effectively reversing this natural process. Wollastonite may also be produced in a diffusion reaction in skarn. It develops when limestone within a sandstone is metamorphosed by a dyke, which results in the formation of wollastonite in the sandstone as a result of outward migration of calcium ions. In some embodiments, the purity of the Group 2 inosilicate compositions may vary. For example, it is contemplated that the Group 2 inosilicate compositions used in the disclosed processes may contain varying amounts of other compounds or minerals, including non-Group 2 metal ions. For example, wollastonite may itself contain small amounts of iron, magnesium, and manganese substituting for calcium.

In some embodiments, compositions comprising olivine and/or serpentine may be used. CO₂ mineral sequestration processes utilizing these minerals have been attempted. The techniques of Goldberg et al. (2001) are incorporated herein by reference.

The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)₂SiC>4. When in gem-quality, it is called peridot. Olivine occurs in both mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks. Mg-rich olivine is known to crystallize from magma that is rich in magnesium and low in silica. Upon crystallization, the magna forms mafic rocks such as gabbro and basalt. Ultramafic rocks, such as peridotite and dunite, can be residues left after extraction of magmas and typically are more enriched in olivine after extraction of partial melts. Olivine and high pressure structural variants constitute over 50% of the Earth's upper mantle, and olivine is one of the Earth's most common minerals by volume. The metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite. VII. Generation of Group 2 Chlorides from Group 2 Silicates

Group 2 silicates, e.g., CaSi0₃, MgSi0₃, and/or other silicates disclosed herein, may be reacted with hydrochloric acid, either as a gas or in the form of aqueous hydrochloric acid, to form the corresponding Group 2 metal chlorides (CaCl₂ and/or MgCl₂), water and sand. In some embodiments the HCl produced in equation 1 is used to regenerate the MgCl₂ and/or CaCl₂ in equation 3. A process loop is thereby created. Table 1 below depicts some of the common calcium/magnesium containing silicate minerals that may be used, either alone or in combination. Initial tests by reacting olivine and serpentine with HCl have been successful. Si0₂ was observed to precipitate out and MgCl₂ and CaCl₂ were collected. Table 1. Calcium/Magnesium Minerals.

See "Handbook of Rocks, Minerals & Gemstones by Walter Schumann Published 1993, Houghton Mifflin Co., Boston, New Yor which is incorporated herein by reference.

VIII. Further Embodiments

In some embodiments, the conversion of carbon dioxide to mineral carbonates may be defined by two salts. The first salt is one that may be heated to decomposition until it becomes converted to a base (hydroxide and/or oxide) and emits an acid, for example, as a gas. This same base reacts with carbon dioxide to form a carbonate, bicarbonate or basic carbonate salt.

For example, in some embodiments, the present disclosure provides processes that react one or more salts from Tables A-C below with water to form a hydroxides, oxides, and/or a mixed hydroxide halides. Such reactions are typically referred to as decompositions. In some embodiments, the water may be in the form of liquid, steam, and/or from a hydrate of the selected salt. The steam may come from a heat exchanger whereby heat from an immensely combustible reaction, i.e. natural gas and oxygen or hydrogen and chlorine heats a stream of water. In some embodiments, steam may also be generated through the use of plant or factory waste heat. In some embodiments, the halide salt, anhydrous or hydrated, is also heated.

Table A. Decomposition Salts

Table B. Decomposition Salts (cont.)

^Subsequent tests have proven the heat of reaction within 1.5-4% of the fhermodynamically derived value using TGA (thermogravinometric analysis) of heated samples and temperature ramp settings. Table C. Decomposition Salts (cont.)

5

Table D. Decomposition Salts (cont.)

kWh/tonne, NC = did not converge, and NA = data not available.

This same carbonate, bicarbonate or basic carbonate of the first salt reacts with a second salt to do a carbonate/bicarbonate exchange, such that the anion of second salt combines with the cation of the first salt and the cation of the second salt combines with the carbonate/bicarbonate ion of the first salt, which forms the final carbonate/bicarbonate.

In some cases the hydroxide derived from the first salt is reacted with carbon dioxide and the second salt directly to form a carbonate/bicarbonate derived from (combined with the cation of) the second salt. In other cases the carbonate/bicarbonate/basic carbonate derived from (combined with the cation of) the first salt is removed from the reactor chamber and placed in a second chamber to react with the second salt. FIG. 27 shows an embodiment of this 2-salt process.

This reaction may be beneficial when making a carbonate/bicarbonate when a salt of the second metal is desired, and this second metal is not as capable of decomposing to form a C0₂ absorbing hydroxide, and if the carbonate/bicarbonate compound of the second salt is insoluble, i.e. it precipitates from solution. Below is a non-exhaustive list of examples of such reactions that may be used either alone or in combination, including in combination with one or more either reactions discussed herein. Examples for a Decomposition of a Salt-1 :

2NaI + H₂0→ Na₂0 + 2HI and/or Na₂0 + H₂0→ 2NaOH

MgCl₂-6H₂0→ MgO + 5H₂0 + 2HC1 and/or MgO + H₂0→ Mg(OH)₂ Examples of a Decarbonation:

2NaOH + C0₂→ Na₂C0₃+ H₂0 and/or Na₂C0₃ + C0₂ + H₂0→ 2NaHC0₃

Mg(OH)₂ + C0₂→ MgC0₃ + H₂0 and/or Mg(OH)₂ + 2C0₂→ Mg(HC0₃)₂ Examples of a Carbonate exchange with a Salt-2:

Na₂C0₃ + CaCl₂→ CaC0₃| + 2NaCl

Na₂C0₃ + 2AgN0₃→ Ag₂C0₃|+ 2NaN0₃

Ca(OH) ₂ + Na₂C0₃→ CaC0₃i + 2NaOH*

* In this instance the carbonate, Na₂C0₃ is Salt-2, and the salt decomposed to form Ca(OH)₂, i.e. CaCl₂ is the Salt-1. This is the reverse of some of the previous examples in that the carbonate ion remains with Salt-1.

Known carbonate compounds include H₂C0₃, Li₂C0₃, Na₂C0₃, K₂C0₃, Rb₂C0₃, Cs₂C0₃, BeC0₃, MgC0₃, CaC0₃, MgC0₃, SrC0₃, BaC0₃, MnC0₃, FeC0₃, CoC0₃, CuC0₃, ZnC0₃, Ag₂C0₃, CdC0₃, A1₂(C0₃)₃, T1₂C0₃, PbC0₃, and La₂(C0₃)₃. Group IA elements are known to be stable bicarbonates, e.g., LiHC0₃, NaHC0₃, RbHC0₃, and CsHC0₃. Group IIA and some other elements can also form bicarbonates, but in some cases, they may only be stable in solution. Typically rock-forming elements are H, C, O, F, Na, Mg, Al, Si, P, S, CI, K, Ca, Ti, Mg and Fe. Salts of these that can be thermally decomposed into corresponding hydroxides by the least amount of energy per mole of C0₂ absorbing hydroxide may therefore be considered potential Salt-1 candidates.

Based on the energies calculated in Tables A-D, several salts have lower energies than MgCl₂ 6H₂0. Table E below, summarizes these salts and the percent penalty reduction through their use relative to MgCl₂.6H₂0.

Table E: Section Lower Energy Alternative Salts

CaBr₂ 2743 64%

MnF₂ 3318 36%

FeF₂ 2102 114%

FeCI₂.4H₂0 3860 17%

Fel₂.4H₂0 3055 47%

CoCl₂.6H₂0 3860 17%

Col₂.6H₂0 4123 9%

CoS0₄.4H₂0 3351 34%

ZnF₂.2H₂0 3285 37%

ZnBr₂.4H₂0 4418 2%

Znl₂.4H₂0 4271 5%

CdF₂ 3137 43%

AgF 2168 108%

The following salts specify a decomposition reaction through their respective available MSDS information.

Table F.

CoS0₄.4H₂0 http://www.chemicalbook.com/ProductMSDSDetailCB0323842_EN.htm

CdCI₂-2.5H20 http://www.espimetals.com/index.php/msds/460-cadmium-chloride

Ca(N0₃) 4H20 http://avogadro.chem.iastate.edu/MSDS/Ca%28N03%292-4H20.htm

IX. Limestone Generation and Uses

In aspects of the present invention there are provided methods of sequestering carbon dioxide in the form of limestone. Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaC0₃). This mineral has many uses, some of which are identified below.

Limestone in powder or pulverized form, as formed in some embodiments of the present invention, may be used as a soil conditioner (agricultural lime) to neutralize acidic soil conditions, thereby, for example, neutralizing the effects of acid rain in ecosystems. Upstream applications include using limestone as a reagent in desulfurizations.

Limestone is an important stone for masonry and architecture. One of its advantages is that it is relatively easy to cut into blocks or more elaborate carving. It is also long-lasting and stands up well to exposure. Limestone is a key ingredient of quicklime, mortar, cement, and concrete.

Calcium carbonate is also used as an additive for paper, plastics, paint, tiles, and other materials as both white pigment and an inexpensive filler. Purified forms of calcium carbonate may be used in toothpaste and added to bread and cereals as a source of calcium. CaC0₃ is also commonly used medicinally as an antacid.

Currently, the majority of calcium carbonate used in industry is extracted by mining or quarrying. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides a non-extractive source of this important product.

X. Magnesium Carbonate Generation and Uses

In aspects of the present invention there are provided methods of sequestering carbon dioxide in the form of magnesium carbonate. Magnesium carbonate, MgC0₃, is a white solid that occurs in nature as a mineral. The most common magnesium carbonate forms are the anhydrous salt called magnesite (MgC0₃) and the di, tri, and pentahydrates known as barringtonite (MgC0₃ -2H₂0), nesquehonite (MgC0₃ -3H₂0), and lansfordite (MgC0₃ -5H₂0), respectively. Magnesium carbonate has a variety of uses; some of these are briefly discussed below. Magnesium carbonate may be used to produce magnesium metal and basic refractory bricks. MgC0₃ is also used in flooring, fireproofing, fire extinguishing compositions, cosmetics, dusting powder, and toothpaste. Other applications are as filler material, smoke suppressant in plastics, a reinforcing agent in neoprene rubber, a drying agent, a laxative, and for color retention in foods. In addition, high purity magnesium carbonate is used as antacid and as an additive in table salt to keep it free flowing.

Currently magnesium carbonate is typically obtained by mining the mineral magnesite. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides a non-extractive source of this important product. XL Silicon Dioxide Generation and Uses

In aspects of the present invention there are provided methods of sequestering carbon dioxide that produce silicon dioxide as a byproduct. Silicon dioxide, also known as silica, is an oxide of silicon with a chemical formula of Si0₂ and is known for its hardness. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms. Silica is the most abundant mineral in the Earth's crust. This compound has many uses; some of these are briefly discussed below.

Silica is used primarily in the production of window glass, drinking glasses and bottled beverages. The majority of optical fibers for telecommunications are also made from silica. It is a primary raw material for many whiteware ceramics such as earthenware, stoneware and porcelain, as well as industrial Portland cement.

Silica is a common additive in the production of foods, where it is used primarily as a flow agent in powdered foods, or to absorb water in hygroscopic applications. In hydrated form, silica is used in toothpaste as a hard abrasive to remove tooth plaque. Silica is the primary component of diatomaceous earth which has many uses ranging from filtration to insect control. It is also the primary component of rice husk ash which is used, for example, in filtration and cement manufacturing.

Thin films of silica grown on silicon wafers via thermal oxidation methods can be quite beneficial in microelectronics, where they act as electric insulators with high chemical stability. In electrical applications, it can protect the silicon, store charge, block current, and even act as a controlled pathway to limit current flow.

Silica is typically manufactured in several forms including glass, crystal, gel, aerogel, fumed silica, and colloidal silica. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides another source of this important product.

XII. Separation of Products

Separation processes may be employed to separate carbonate and bicarbonate products from the liquid solution and/or reaction mixture. By manipulating the basic concentration, temperature, pressure, reactor size, fluid depth, and degree of carbonation, precipitates of one or more carbonate and/or bicarbonate salts may be caused to occur. Alternatively, carbonate/bicarbonate products may be separated from solution by the exchange of heat energy with incoming flue-gases.

The exit liquid streams, depending upon reactor design, may include water, CaC0₃,

MgC0₃, Ca(HC0₃)₂, Mg(HC0₃)₂, Ca(OH)₂, Ca(OH)₂, NaOH, NaHC0₃, Na₂C0₃, and other dissolved gases in various equilibria. Dissolved trace emission components such as H₂S0₄, HN0₃, and Hg may also be found. In one embodiment, removing/separating the water from the carbonate product involves adding heat energy to evaporate water from the mixture, for example, using a reboiler. Alternatively, retaining a partial basic solution and subsequently heating the solution in a separating chamber may be used to cause relatively pure carbonate salts to precipitate into a holding tank and the remaining hydroxide salts to recirculate back to the reactor. In some embodiments, pure carbonate, pure bicarbonate, and mixtures of the two in equilibrium concentrations and/or in a slurry or concentrated form may then be periodically transported to a truck/tank-car. In some embodiments, the liquid streams may be displaced to evaporation tanks/fields where the liquid, such as water, may be carried off by evaporation.

The release of gaseous products includes a concern whether hydroxide or oxide salts will be released safely, i.e., emitting "basic rain." Emission of such aerosolized caustic salts may be prevented in some embodiments by using a simple and inexpensive condenser/reflux unit.

In some embodiments, the carbonate salt may be precipitated using methods that are used separately or together with a water removal process. Various carbonate salt equilibria have characteristic ranges where, when the temperature is raised, a given carbonate salt, e.g. , CaC0₃ will naturally precipitate and collect, which makes it amenable to be withdrawn as a slurry, with some fractional NaOH drawn off in the slurry. XIII. Recovery of Waste-Heat

Because certain embodiments of the present invention are employed in the context of large emission of C0₂ in the form of flue-gas or other hot gases from combustion processes, such as those which occur at a power plant, there is ample opportunity to utilize this 'waste' heat, for example, for the conversion of Group 2 chlorides salts into Group 2 hydroxides. For instance, a typical incoming flue-gas temperature (after electro-static precipitation treatment, for instance) is approximately 300 °C. Heat exchangers can lower that flue-gas to a point less than 300°C, while warming the water and/or Group 2 chloride salt to facilitate this conversion.

Generally, since the flue-gas that is available at power-plant exits at temperatures between 100°C (scrubbed typical), 300°C (after precipitation processing), and 900°C (precipitation entrance), or other such temperatures, considerable waste-heat processing can be extracted by cooling the incoming flue-gas through heat-exchange with a power-recovery cycle, for example an ammonia-water cycle (e.g. , a "Kalina" cycle), a steam cycle, or any such cycle that accomplishes the same thermodynamic means. Since some embodiments of the present invention rely upon DC power to accomplish the manufacture of the reagent/absorbent, the process can be directly powered, partially or wholly, by waste-heat recovery that is accomplished without the normal transformer losses associated with converting that DC power to AC power for other uses. Further, through the use of waste- heat-to-work engines, significant efficiencies can be accomplished without an electricity generation step being employed at all. In some conditions, these waste-heat recovery energy quantities may be found to entirely power embodiments of the present invention.

XIV. Alternative Processes

As noted above, some embodiments of the apparatuses and methods of the present disclosure produce a number of useful intermediates, by-products, and final products from the various reaction steps, including hydrogen chloride, Group 2 carbonate salts, Group 2 hydroxide salts, etc. In some embodiments, some or all of these may be used in one or more of the methods described below. In some embodiments, some or all of one of the starting materials or intermediates employed in one or more of the steps described above are obtained using one or more of the methods outlined below. A. Use of Chlorine for the Chlorination of Group 2 Silicates

In some embodiments the chlorine gas may be liquefied to hydrochloric acid that is then used to chlorinate Group 2 silicate minerals. Liquefaction of chlorine and subsequent use of the hydrochloric acid is particularly attractive especially in situations where the chlorine market is saturated. Liquefaction of chlorine may be accomplished according to equation 27:

Ch(g) + 2 H₂0 (/) + hv (363 nm)→ 2 HC1 (/) + ½ 0₂ (g) (27) In some embodiments, the oxygen so produced may be returned to the air-inlet of the power plant itself, where it has been demonstrated throughout the course of power-industry investigations that enriched oxygen-inlet plants have (a) higher Carnot-efficiencies, (b) more concentrated C0₂ exit streams, (c) lower heat-exchange to warm inlet air, and (d) other advantages over non-oxygen-enhanced plants. In some embodiments, the oxygen may be utilized in a hydrogen/oxygen fuel cell. In some embodiments, the oxygen may serve as part of the oxidant in a turbine designed for natural gas power generation, for example, using a mixture of hydrogen and natural gas.

B. Use of Chlorine for the Chlorination of Group 2 Hydroxides

In some embodiments the chlorine gas may be reacted with a Group 2 hydroxide salts to yield a mixture of a chloride and a hypochlorite salts (equation 28). For example, HC1 may be sold as a product and the Group 2 hydroxide salt may be used to remove excess chlorine.

Ca/Mg(OH)₂ + Cl₂→ ½ Ca/Mg(OCl)₂ + ½ Ca/MgCl₂ + H₂0 (28) The Group 2 hypochlorites may then be decomposed using a cobalt or nickel catalyst to form oxygen and the corresponding chloride (equation 29).

Ca/Mg(OCl)₂→ Ca/MgCl₂ + 0₂ (29)

The calcium chloride and/or the magnesium chloride may then be recovered.

XV. Removal of other Pollutants from Source

In addition to removing C0₂ from the source, in some embodiments of the invention, the decarbonation conditions will also remove SOx and ΝΟχ and, to a lesser extent, mercury. In some embodiments of the present invention, the incidental scrubbing of ΝΟχ, SOx, and mercury compounds can assume greater economic importance; i.e., by employing embodiments of the present invention, coals that contain large amounts of these compounds can be combusted in the power plant with, in some embodiments, less resulting pollution than with higher-grade coals processed without the benefit of the C0₂ absorption process. Such principles and techniques are taught, for example, in U.S. Patent 7,727,374, U.S. Patent Application No. 1 1/233,509, filed September 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed September 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed January 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed September 23, 2004, U.S. Patent Application No. 12/235,482, filed September 22, 2008, U.S. Provisional Application No. 60/973,948, filed September 20, 2007, U.S. Provisional Application No. 61/032,802, filed February 29, 2008, U.S. Provisional Application No. 61/033,298, filed March 3, 2008, U.S. Provisional Application No. 61/288,242, filed January 20, 2010, U.S. Provisional Application No. 61/362,607, filed July 8, 2010, and International Application No. PCT/US08/77122, filed September 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

XVI. Examples

The following examples are included to demonstrate some embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention. Example 1 - Process Simulation of Capture C0₂ from Flue Gas Using

CaCl₂ to form CaC0₃.

One embodiment of the present invention was simulated using Aspen Plus v. 7.1 software using known reaction enthalpies, reaction free energies and defined parameters to determine mass and energy balances and suitable conditions for capturing C0₂ from a flue gas stream utilizing CaCl₂ and heat to form CaC0₃ product. These results show that it is possible to capture C0₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaC0₃. Part of the defined parameters includes the process flow diagram shown in FIG. 5. Results from the simulation suggest that it is efficient to recirculate an MgCl₂ stream to react with H₂0 and heat to form Mg(OH)₂. This Mg(OH)₂ then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HQ to yield CaCl₂.

Constraints and parameters specified for this simulation include:

• The reactions were run at 100% efficiencies with no losses. The simulations can be modified when pilot runs determine the reaction efficiencies.

• Simulations did not account for impurities in the CaCl₂ feed stock or in any make-up MgCl₂ required due to losses from the system.

The results of this simulation indicate a preliminary net energy consumption of approximately 130 MM Btu/hr. Tables 2a and 2b provide mass and energy accounting for the various streams (the columns in the table) of the simulated process. Each stream corresponds to the stream of FIG. 5.

The process consists of two primary reaction sections and one solids filtration section. The first reactor heats MgCl₂/water solution causing it to break down into a HC1/H₂0 vapor stream and a liquid stream of Mg(OH)₂. The HC1/H₂0 vapor stream is sent to the HC1 absorber column. The Mg(OH)₂ solution is sent to reactor 2 for further processing. The chemical reaction for this reactor can be represented by the following equation:

MgCl₂ + 2 H₂0→ Mg(OH)₂ + 2HC1 (30)

A CaCl₂ solution and a flue gas stream are added to the MgCl₂ in reactor 2. This reaction forms CaC0₃, MgCl₂ and water. The CaC0₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. The chemical reaction for this reactor can be represented by the following equation:

Mg(OH)₂ + CaCl₂ + C0₂→ CaC0₃ (s) + MgCl₂ + H₂0 (31 )

The primary feeds to this process are CaCl₂, flue gas (C0₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaC0₃ product, and small amounts that leave with the HCl/water product. This process is a net energy user. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams. Significant heat recovery may be obtained by reacting the concentrated HCl thus formed with silicate minerals.

Table 2a. Mass and Energy Accounting for Simulation of Capture C0₂ from Flue Gas Using CaCl₂ to form CaC0₃.

Table 2b. Mass and Energy Accounting for Simulation of Capture C0₂ from Flue Gas Using CaCI₂ to form CaC0₃.

Example 2 (Case 1)- Process Simulation of Magnesium Ion Catalyzed

Capture C0₂ from Flue Gas Using CaCl₂ to form CaC0₃.

Results from the simulation suggest that it is efficient to heat a MgCl₂-6H₂0 stream in three separate dehydration reactions, each in its own chamber, followed by a decomposition reaction, also in its own chamber, to form Mg(OH)Cl and HC1, i.e. total of four chambers. The Mg(OH)Cl is reacted with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂-6H₂0 formed is recycled along with the earlier product to the first reactor to begin the process again.

This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HC1 to yield CaCl₂.

Constraints and parameters specified for this simulation include:

· Simulations did not account for impurities in the CaCl₂ feed stock or in any make-up MgCl₂ required due to losses from the system.

• Part of the defined parameters include the process flow diagram shown in FIG.

6.

The results of this simulation indicate a preliminary net energy consumption of 5946 kwh/tonne C0₂. Table 3 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 6.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂-6H₂0 causing it to break down into a HC1/H₂0 vapor stream and a solid stream of Mg(OH)Cl. The HC1/H₂0 vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following:

MgCl₂-6H₂0 + Δ→ Mg(OH)Cl + 5 H₂0† + HCl† (32)

2 Mg(OH)Cl(a )→ Mg(OH)₂ + MgCl₂ (33)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaC0₃, MgCl₂ and water. The CaC0₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following:

Mg(OH)₂ + CaCl₂ + C0₂→ CaC0₃ 0) + MgCl₂ + H₂0 (34)

The primary feeds to this process are CaCl₂, flue gas (C0₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaC0₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. The amount of energy is under investigation and optimization. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams.

The steps for this process (Case 1 ) are summarized below:

Table 3a. Mass and Energy Accounting for Case 1 Simulation.

Table 3b. Mass and Energy Accounting for Case 1 Simulation.

Example 3 - Process Simulation of Magnesium Ion Catalyzed Capture

C0₂ from Flue Gas Using CaCl₂ to form CaC0₃.

Part of the defined parameters includes the process flow diagram shown in FIG. 7. Results from the simulation suggest that it is efficient to heat a MgCl₂'6H₂0 stream to form Mg(OH)Cl in two separate dehydration reactions, each in their own chambers followed by a decomposition reaction, also in its own chamber to form Mg(OH)Cl and HC1, i.e. a total of three chambers. The Mg(OH)Cl is reacted with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂.6H₂0 formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HC1 to yield CaCl₂.

Constraints and parameters specified for this simulation include:

The results of this simulation indicate a preliminary net energy consumption of 4862 kwh/tonne C0₂. Table 4 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream in FIG. 7.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂0 causing it to break down into a HC1/H₂0 vapor stream and a solid stream of Mg(OH)Cl. The HC1/H₂0 vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following:

MgCl₂-6H₂0 + Δ→ Mg(OH)Cl + 5 H₂0† + HCl† (35)

2 Mg(OH)Cl(a )→ Mg(OH)₂ + MgCl₂ (36)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaC0₃, MgCl₂ and water. The CaC0₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following: Mg(OH)₂ + CaCl₂ + C0₂→ CaC0₃ 0) + MgCl₂ + H₂0 (37)

The steps for this process (Case 2) are summarized below:

CASE 2

2 STEP Dehydration then Decomposition

Hexahydrate is dehydrated in 2 separate chambers. Step 1 hex to tetra, Step 2 tetra to di. Di-hydrate is decomposed into 100% Mg(OH)CI.

C0₂ Absorbed 53333 MTPY

CaCI₂ 134574 MTPY

HCI Dry 88368 MTPY

CaC0₃ 105989 MTPY

Hexahydrate recycled 492737 MTPY

HEX TO TETRA (100 °C) 1445 kWh/tonne C0₂

TETRA TO DI (125 °C) 1774 kWh/tonne C0₂

DI-HYDRATE

DEHYDRATION & DECOMPOSITION 1790 kWh/tonne C0₂

TO 100% Mg(OH)CI (130 °C)

YEILDS 66% HCI VAPOR

NO CARRIER MgCI₂ = BETTER OVERALL EFFICIENCY

NO USE OF HCI PP

0.9

Heat Recovery 148 kWh/tonne C0₂

from 28% HCI vapor

TOTAL 4862 kWh/tonne C0₂ Table 4a. Mass and Energy Accounting for Case 2 Simulation.

Table 4b. Mass and Energy Accounting for Case 2 Simulation.

Example 4 - Process Simulation of Magnesium Ion Catalyzed Capture

C0₂ from Flue Gas Using CaCl₂ to Form CaC0₃.

Part of the defined parameters include the process flow diagram shown in FIG. 8. Results from the simulation suggest that it is efficient to heat a MgCl₂-6H₂0 stream to form MgO in a single chamber. The MgO is reacted with H₂0 to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂0 solution and C0₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂-6H₂0 formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HC1 to yield CaCl₂.

Constraints and parameters specified for this simulation include:

The results of this simulation indicate a preliminary net energy consumption of 3285 kwh/tonne C0₂. Table 5 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 8.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂-6H₂0 causing it to break down into a HC1/H₂0 vapor stream and a solid stream of MgO. The HC1/H₂0 vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the MgO is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following:

MgCl₂-6H₂0 + Δ→ MgO + 5 H₂0† + 2 HCl† (38)

MgO + H₂0→ Mg(OH)₂ (39)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaC0₃, MgCl₂ and water. The CaC0₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following::

Mg(OH)₂ + CaCl₂ + C0₂→ CaC0₃ J_/(s) + MgCl₂ + H₂0 (40)

The primary feeds to this process are CaCl₂, flue gas (C0₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaC0₃ product, and small amounts that leave with the

HCl/water product.

The steps for this process (Case 3) are summarized below:

CASE 3

Combined Dehydration/Decomposition to MgO

Hexahydrate is dehydrated and decomposed simultaneously at 450C. Reactor yeilds 100% MgO.

C0₂ Absorbed 53333 MTPY

CaCI₂ 134574 MTPY

HCI Dry 88368 MTPY

CaC0₃ 105989 MTPY

Hexahydrate recycled 246368 MTPY

HEXAHYDRATE

DEHYDRATION & DECOMPOSITION 3778 kWh/tonne C02

TO 100% MgO (450 °C)

YIELDS 44.7% HCI VAPOR

RECYCLES HALF AS MUCH HEXAHYDRATE

BUT NEEDS HIGH QUALITY HEAT

Heat Recovery 493 kWh/tonne C02

from 45% HCI vapor

TOTAL 3285 kWh/tonne C02

fable 5a. Mass and Energy Accounting for Case 3 Simulation.

Table 5b. Mass and Energy Accounting for Case 3 Simulation.

Example 5 - Process Simulation of Magnesium Ion Catalyzed Capture

C0₂ from Flue Gas Using CaCl₂ to form CaC0₃.

Part of the defined parameters include the process flow diagram shown in FIG. 9. Results from the simulation suggest that it is efficient to heat a MgCl₂'6H₂0 stream to form Mg(OH)Cl in a single chamber. The Mg(OH)Cl is reacted with H₂0 to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCb/FbO solution and CO₂ from the flue gas to form CaC0₃, which is filtered out of the stream. The resulting MgCl₂-6H₂0 formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaC^. For example, it may be obtained from reacting calcium silicate with HC1 to yield CaCl₂.

Constraints and parameters specified for this simulation include:

• Simulations did not account for impurities in the CaC^ feed stock or in any make-up MgC required due to losses from the system.

The results of this simulation indicate a preliminary net energy consumption of 4681 kwh/tonne CO₂. Table 6 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 9.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂0 causing it to break down into a HCI/H₂O vapor stream and a solid stream of Mg(OH)Cl. The HCI/H₂O vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following:

MgCl₂.6H₂0 + Δ→ Mg(OH)Cl + 5 H₂0† + HCl† (41) 2 Mg(OH)Cl(a^)→ Mg(OH)₂ + MgCl₂ (42)

A CaCh solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaC0₃, MgCl₂ and water. The CaC0₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following:

Mg(OH)₂ + CaCl₂ + C0₂→ CaC0₃ + MgCl₂ + H₂0 (43) The primary feeds to this process are CaCl₂, flue gas (C0₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaC0₃ product, and small amounts that leave with the HCl/water product.

The steps for this process (Case 4) are summarized below:

CASE 4

Combined Dehydration/Decomposition to Mg(OH)CI

Hexahydrate is dehydrated and decomposed simultaneously at 250 °C. Reactor yields 100%

Mg(OH)CI.

C0₂ Absorbed 53333 MTPY

CaCI₂ 134574 MTPY

HCI Dry 88368 MTPY

CaC0₃ 105989 MTPY

Hexahydrate recycled 492737 MTPY

DEHYDRATION & DECOMPOSITION 5043 kWh/tonne C02

TO 100% Mg(OH)CI (250 °C)

YEILDS 28.8% HCI VAPOR

2.2 MW

Heat Recovery 361 kWh/tonne C02

from 28% HCI vapor

TOTAL 4681 kWh/tonne C02

fable 6a. Mass and Energy Accounting for Case 4 Simulation.

Table 6b. Mass and Energy Accounting for Case 4 Simulation.

Example 6 - Road Salt Boiler: Decomposition of Mg0 -6H₂0

FIG. 10 shows a graph of the mass percentage of a heated sample of MgCl₂-6H₂0. The sample's initial mass was approximately 70 mg and set at 100%. During the experiment, the sample's mass was measured while it was being thermally decomposed. The temperature was quickly ramped up to 150 °C, and then slowly increased by 0.5 °C per minute. At approximately 220 °C, the weight became constant, consistent with the formation of Mg(OH)Cl. The absence of further weight decrease indicated that almost all the water has been removed. Two different detailed decompositional mass analyses are shown in FIGS. 28 and 29, with the theoretical plateaus of different final materials shown. FIG. 30 confirms that MgO can be made by higher temperatures (here, 500 °C) than those which produce Mg(OH)Cl.

Example 7 - Dissolution of Mg(OH)Cl in H₂0

A sample of Mg(OH)Cl, produced by the heated decomposition of MgCl₂-6H₂0, was dissolved in water and stirred for a period of time. Afterwards, the remaining precipitate was dried, collected and analyzed. By the formula of decomposition, the amount of Mg(OH)₂ could be compared to the expected amount and analyzed. The chemical reaction can be represented as follows:

2 Mg(OH)Cl (aq)→ Mg(OH)₂ + MgCl₂ (44)

The solubility data for Mg(OH)₂ and MgCl₂ is as follows:

MgCl₂ 52.8 gm in 100 gm. H₂0 (very soluble)

Mg(OH)₂ 0.0009 gm in 100 gm. H₂0 (virtually insoluble)

Theoretical weight of recovered Mg(OH)₂:

Given weight of sample: 3.0136 gm.

MW Mg(OH)Cl 76.764

MW Mg(OH)₂ 58.32

Moles Mg(OH)₂ formed per mole Mg(OH)Cl

Expected amount of Mg(OH)₂

2 Mg(OH)Cl (aq)→ Mg(OH)₂ + MgCl₂

3.016gm * (MW Mg(OH)₂ ÷ (MW Mg(OH)Cl * ½ = 1.1447 gm

Precipitate collected = 1.1245 gm

% of theoretical collected - ( 1.1447 ÷ 1.1245) * 100 = 98.24%

Analytical data: Next the sample of Mg(OH)₂ was sent for analysis, XRD (X-ray -diffraction) and EDS. Results are shown in FIG. 1 1. The top row of peaks is that of the sample, the spikes in the middle row are the signature of Mg(OH)2 while the spikes at the bottom are those of MgO. Thus verifying that the recovered precipitate from the dissolution of Mg(OH)Cl has a signal resembling that of Mg(OH)2.

Element k-ratio ZAF Atom % Element Wt % Err.

(calc. ) Wt % (1-Sigma)

Mg-K 0.9472 1.014 96.88 96.02 +/- 0.23

Si-K 0.0073 2.737 1.74 1.99 +/- 0.17

Cl-K 0.0127 1.570 1.38 2.00 +/- 0.16

Total 100.00 100.00

Note: Results do not include elements with Z<11 (Na) .

The EDS analysis reveals that very little chlorine [CI] was incorporated into the precipitate. Note, this analysis cannot detect oxygen or hydrogen.

Example 8 - Decarbonation Bubbler Experiment: Production of CaCC>3

by reacting C0₂ with Mg(OH)₂ {or Mg(OH)Cl} and CaCl₂

Approximately 20 grams of Mg(OH)₂ was placed in a bubble column with two liters of water and C0₂ was bubbled though it for x minutes period of time. Afterwards some of the liquid was collected to which a solution of CaCl₂ was added. A precipitate immediately formed and was sent through the XRD and EDS. The chemical reaction can be represented as follows:

Mg(OH)₂ + C0₂ + CaCl₂→ CaC0₃ + H₂0 (45) The XRD analysis (FIG. 12) coincides with the CaC0₃ signature.

EDS

Element k-ratio ZAF Atom % Element Wt % Err .

( calc . ) Wt % ( 1-Sigma )

Mg-K 0.0070 2.211 2.52 1.55 +/- 0.10

Al-K 0.0013 1.750 0.33 0.22 +/- 0.04

Si-K 0.0006 1.382 0.12 0.09 +/- 0.03

Cl-K 0.0033 1.027 0.38 0.34 +/- 0.03

Ca-K 0.9731 1.005 96.64 97.80 +/- 0.30

Total 100.00 100.00

Note: Results do not include elements with Z<11 (Na)

The EDS analysis indicates almost pure CaC0₃ with only a 1.55% by weight magnesium impurity and almost no Chlorine from the CaCl₂. The same test was performed, except that Mg(OH)Cl from the decomposition of MgCl₂-6H₂0 was used instead of Mg(OH)₂. Although Mg(OH)Cl has half the hydroxide [OH-], as Mg(OH)₂ it is expected to absorb C0₂ and form precipitated CaC0₃ (PCC).

The X D analysis (FIG. 13) coincides with the CaC0₃ signature.

EDS

Chi-sqd = 5.83 Livetime = 300.0 Sec.

Standardless Analysis

PROZA Correction Acc.Volt.= 20 kV Take-off Angle=35.00 deg Number of Iterations = 3

Element k-ratio ZAF Atom % Element Wt % Err.

(calc. ) Wt % (1-Sigma)

Mg-K 0.0041 2.224 1.48 0.90 +/- 0.09

S -K 0.0011 1.071 0.14 0.11 +/- 0.04

Ca-K 0.9874 1.003 98.38 98.98 +/- 0.34

Total 100.00 100.00

Note : Result s do not include element s with Z<11 ( Na ) .

Again the results indicate almost pure CaC0₃, almost no Mg or CI compounds.

Example 9A - Rock Melter Experiment: Reaction of Olivine and

Serpentine with HCl

Samples of olivine (Mg,Fe)₂Si0₄ and serpentine Mg₃Si₂C>₅(OH)₄were crushed and reacted with 6.1 molar HCl over a period of approximately 72 hours. Two sets of tests were run, the first at room temperature and the second at 70 °C. These minerals have variable formulae and often contain iron. After the samples were filtered, the resulting filtrand and filtrate were dried in an oven overnight. The samples then went through XRD and EDS analysis. The filtrates should have MgCl₂ present and the filtrand should be primarily Si0₂. Olivine Filtrate Reacted with HCl at Room Temperature

Element k-ratio ZAF Atom % Element Wt % Err .

(calc . . ) Wt % ( 1-Sigma )

Mg-K 0.1960 1.451 37.06 28 , .45 +/- 0.18

Si-K 0.0103 1.512 1.75 1 , .56 +/- 0.11

Cl-K 0.5643 1.169 58.89 65 , .94 +/- 0.31

Fe-K 0.0350 1.161 2.30 4 , .06 +/- 0.22

Total 100.00 100.00

Olivine Filtrate Reacted with HCl at 70 °C

Note: Results do not include elements with Z<11 (Na)

Element k-ratio ZAF Atom % Element wt % Err .

( calc . ) Wt % ( 1-Sigma )

Mg-K 0.1172 1.684 27.39 19. .74 +/- 0.12

Si-K 0.0101 1.459 1.77 1. ,48 +/- 0.07

Cl-K 0.5864 1.142 63.70 66. , 94 +/- 0.24 Fe-K 0.0990 1.144 6.84 11.33 +/- 0.21 Ni-K 0.0045 1.128 0.29 0.51 +/- 0.09

Total 100.00 100.00

Serpentine Filtrate Reacted with HCl at Room Temperature

Note: Results do not include elements with Z<11 (Na) .

Element k-ratio ZAF Atom % Element Wt % Err.

(calc . . ) Wt % (1 -Sigma )

Mg-K 0 .1674 1 .466 32. .47 24. .53 +/- 0. .15

Al-K 0 .0025 1 .863 0. .55 0. .46 +/- 0. .06

Si-K 0 .0033 1 .456 0. .55 0. .48 +/- 0. .04

Cl-K 0 .6203 1 .141 64. .22 70. .77 +/- 0. .27

Ca-K 0 .0016 1 .334 0. .17 0. .21 +/- 0. .05

Cr-K 0 .0026 1 .200 0. .19 0. .31 +/- 0. .07

Mn-K 0 .0011 1 .200 0. .08 0. .14 +/- 0. .08

Fe-K 0 .0226 1 .160 1. .51 2. .62 +/- 0. .10

Ni-K 0 .0042 1 .128 0. .26 0. .48 +/- 0. .10

Total 100 .00 100. 00

Serpentine Filtrate Reacted with HCl at 70°C

Note: Results do not include elements with Z<11 (Na) .

Element k-ratio ZAF Atom % Element

(calc. ) Wt % (1-Sigma)

Mg-K 0. .1759 1. .455 33. .67 25, .59 +/- 0. .14

Al-K 0. , 0017 1. ,886 0. .39 0. .33 +/- 0. .06

Si-K 0. .0087 1. .468 1. .46 1. .28 +/- 0. .04

Cl-K 0. , 6014 1. , 152 62. .46 69. .27 +/- 0. .25

Cr-K 0. .0016 1. .199 0. .12 0. .19 +/- 0. .06

Fe-K 0. .0268 1. .161 1. .78 3. .11 +/- 0. .17

Ni-K 0. .0020 1. .130 0. .12 0. .22 +/- 0. .08

Total 100.00 100.00

Note: Results do not include elements with Z<11 (Na) .

The filtrate clearly for both minerals serpentine and olivine at ambient conditions and 70 °C all illustrate the presence of MgC^, and a small amount of FeCl₂ in the case of olivine. Olivine Filtrand Reacted with HCl at Room Temperature

Element k-ratio ZAF Atom % Element Wt % Err.

( calc . , ) Wt % (1 -Sigma )

Mg-K 0.2239 1 .431 37 , .68 32. .04 +/- 0. .14

Si-K 0.3269 1 .622 53 , .96 53. .02 +/- 0. .19

Cl-K 0.0140 1 .658 1. .87 2. .32 +/- 0. .06

Cr-K 0.0090 1 .160 0, .58 1. .05 + /- 0. .08

Mn-K 0.0013 1 .195 0. .08 0. .16 +/- 0. .09

Fe-K 0.0933 1 .167 5. .57 10. .89 +/- 0. .26

Ni-K 0.0045 1 .160 0. .25 0. .52 +/- 0. .11

Total 100.00 100. 00

Note: Results do not include elements with Z<11 (Na) ,

Olivine Filtrand Reacted with HCl at 70 °C

Element k-ratio ZAF Atom % Element Wt % Err.

(calc. ) Wt % (1-Sigma)

Mg-K 0.2249 1.461 38.87 32.86 +/- 0.16 Si-K 0..3030 1.649 51..12 49..94 +/- 0..21

Cl-K 0. .0223 1 .638 2. .96 3. .65 +/- 0. .14

Ca-K 0. , 0033 1 .220 0. .29 0. .41 +/- 0. .05

Cr-K 0. .0066 1 .158 0. .42 0. .76 +/- 0. .08

Mn-K 0. .0023 1 .193 0. .15 0. .28 +/- 0. .10

Fe-K 0. .0937 1 .163 5. .61 10. .89 +/- 0. .29

Ni-K 0. .0074 1 .158 0. .42 0. .86 +/- 0. .13

Cu-K 0. .0029 1 .211 0. .16 0. .35 +/- 0. .16

Total 100. .00 100. 00

Note: Results do not include elements with Z<11 (Na) .

Given that the formula for olivine is (Mg,Fe)₂Si0 , and this is a magnesium rich olivine. The raw compound has a Mg:Si ratio of 2: 1. However the filtrand, that which does not pass through the filter has a (Mg + Fe:Si) ratio of (37+5.5:52) or 0.817:1. (Atom % on the chart), evidently more than 50% of the magnesium passed through the filter.

Serpentine Filtrand Reacted with HCI at Room Temperature

Element k-ratio ZAF Atom % Element Wt % Err .

(calc . . ) Wt % ( 1-Sigma )

Mg-K 0.1930 1.595 37.32 30. .78 +/- 0.15

Si-K 0.2965 1.670 51.94 49. .50 +/- 0.20

Cl-K 0.0065 1.633 0.88 1. .06 +/- 0.06

Cr-K 0.0056 1.130 0.36 0. .63 +/- 0.08

Fe-K 0.1532 1.155 9.33 17. .69 +/- 0.31

Ni-K 0.0029 1.159 0.17 0. .34 +/- 0.12

Total 100.00 100.00

Note: Results do not include elements with Z<11 (Na)

Serpentine Filtrand Reacted with HCI at 70 °C

Element k-ratio ZAF Atom % Element Wt % Err .

(calc . . ) Wt % ( 1-Sigma)

Mg-K 0.1812 1.536 33.53 27 , .83 +/- 0.13

Si-K 0.3401 1.593 56.49 54 , .18 +/- 0.18

Cl-K 0.0106 1.651 1.45 1. .75 +/- 0.11

Cr-K 0.0037 1.142 0.24 0, .43 +/- 0.07

Mn-K 0.0009 1.188 0.05 0. .10 +/- 0.08

Fe-K 0.1324 1.159 8.05 15. .35 +/- 0.26

Ni-K 0.0032 1.160 0.18 0, .37 +/- 0.11

Total 100.00 100.00

Note: Results do not include elements with Z<11 (Na)

Given that the formula of serpentine is (Mg,Fe)3Si₂0₅(OH)4 the initial 1.5: 1 ratio of (Mg + Fe) to Si has been whittled down to (37 + 9.3:56.5) = 0.898: 1. Example 9B - Temperature/Pressure Simulation for Decomposition of

MgC12-6(H20) Pressure and temperature was varied, as shown below (Table 7) and in FIG. 14, to determine the effect this has on the equilibrium of the decomposition of MgCl₂-6(H₂0). Inputs are:

1 ) MgCl₂-6H₂0

2) CaCl₂

3) The temperature of the hot stream leaving the heat exchanger (HX) labeled Mg(OH)Cl (see FIGS. 7-8).

4) Percentage of Solids separated in decanter.

5) Water needed labeled H₂0

6) Flue Gas.

Table 7.

VARY 1 VARY 2 INPUT Mg(OH)CI MgO Q

REACTOR1 REACTOR1

PARAM PARAM

TEMP PRES

°C PSIA MOL/SEC MOL/SEC MOL/SEC MW kWh/tonne C02

410 13 76.854 76.854 0 31.41 5159

420 13 76.854 76.854 0 31.44515 5165

430 13 55.59535 34.3367 21.25865 25.07026 4118

440 13 38.427 0 38.427 19.9123 3271

450 13 38.427 0 38.427 19.93111 3274

400 15 76.854 76.854 0 31.37484 5153

410 15 76.854 76.854 0 31.41 5159

420 15 76.854 76.854 0 31.44515 5165

430 15 66.51322 56.17244 10.34078 28.36229 4659

440 15 46.41875 15.98351 30.43525 22.32544 3667

450 15 38.427 0 38.427 19.93111 3274

200 5 127 76.854 0 47.51946 7805

210 5 85 76.854 0 33.34109 5476

220 5 77 76.854 0 30.74184 5049

230 5 77 76.854 0 30.77702 5055

240 5 77 76.854 0 30.8122 5061

250 5 77 76.854 0 30.84739 5067

200 7 184 76.854 0 66.57309 10935

210 7 125 76.854 0 46.75184 7679

220 7 85 76.854 0 33.32609 5474

230 7 77 76.854 0 30.777 5055

240 7 77 76.854 0 30.81218 5061

250 7 77 76.854 0 30.84737 5067

200 9 297 76.854 0 89.51079 14702

210 9 165 76.854 0 60.16258 9882

220 9 113 76.854 0 42.92123 7050

230 9 78 76.854 0 31.04401 5099

240 9 77 76.854 0 30.81217 5061

250 9 77 76.854 0 30.84735 5067

200 11 473 76.854 0 136.5784 22433

210 11 205 76.854 0 73.57332 12084

220 11 142 76.854 0 52.51638 8626

230 11 98 76.854 0 38.01558 6244

240 11 77 76.854 0 30.81216 5061

250 11 77 76.854 0 30.84734 5067

200 13 684 76.854 0 192.9858 31698

210 13 303 76.854 0 91.43505 15018

220 13 170 76.854 0 62.11152 10202

230 13 119 76.854 0 44.98715 7389 VARY 1 VARY 2 INPUT Mg(OH)CI MgO Q

REACTOR1 REACTOR1

PARAM PARAM

TEMP PRES

°C PSIA MOL/SEC MOL/SEC MOL/SEC MW kWh/tonne C02

240 13 83.3323 76.854 0 33.00459 5421

250 13 76.854 76.854 0 30.84733 5067

200 15 930.5287 76.854 0 258.7607 42502

210 15 422.9236 76.854 0 123.7223 20322

220 15 198.7291 76.854 0 71.70666 11778

230 15 139.6567 76.854 0 51.95871 8534

240 15 98.51739 76.854 0 38.14363 6265

250 15 76.854 76.854 0 30.84733 5067

Examples 10 - 21

The following remaining examples are concerned with obtaining the necessary heat to perform the decomposition reaction using waste heat emissions from either coal or natural gas power plants. In order to obtain the necessary heat from coal flue gas emissions, the heat source may be located prior to the baghouse where the temperature ranges from 320-480 °C in lieu of the air pre-heater. See Reference: pages 1 1-15 of "The structural design of air and gas ducts for power stations and industrial Boiler Applications," Publisher: American Society of Civil Engineers (August 1995), which is incorporated by reference herein in its entirety. Open cycle natural gas plants have much higher exhaust temperatures of 600 °C. See Reference: pages 1 1 -15 of "The structural design of air and gas ducts for power stations and industrial Boiler Applications," Publisher: American Society of Civil Engineers (August 1995), which is incorporated by reference herein in its entirety. Additionally, the decomposition reaction of MgCi₂-6H₂0 may also run in two different modes, complete decomposition to MgO or a partial decomposition to Mg(OH)Cl. The partial decomposition to Mg(OH)Cl requires in some embodiments a temperature greater than 180 °C whereas the total decomposition to MgO requires in some embodiments a temperature of 440 °C or greater.

Additionally the incoming feed to the process can be represented as a continuum between 100% Calcium Silicate (CaSi0₃) and 100% Magnesium Silicate (MgSi0₃) with Diopside (MgCa(Si0₃)2) (or a mixture of CaSi0₃ and MgSi0₃ in a 1 : 1 molar ratio) representing an intermediate 50% case. For each of these cases the resulting output will range in some embodiments from calcium carbonate (CaC0₃) to magnesium carbonate (MgC0₃) with Dolomite CaMg(C0₃)2 representing the intermediate case. The process using 100% calcium silicate is the Ca-Mg process used in all of the previously modeled embodiments. It is also important to note that the 100% magnesium silicate process uses no calcium compounds; whereas the 100% calcium silicate incoming feed process does use magnesium compounds, but in a recycle loop, only makeup magnesium compounds are required.

Further details regarding the Ca-Mg, Mg only, Diopside processes, for example, using complete and partial decomposition of hydrated MgCl₂ to MgO and Mg(OH)Cl, respectively, are depicted below.

I) Ca-Mg Process

Overall reaction CaSi0₃ + C0₂→ CaC0₃ + Si0₂

a) Full decomposition ("the CaSi0₃-MgO process"):

1 ) MgCl₂.6FI₂0 + A -> MgO + 5H₂0† + 2FIC1†

A thermal decomposition reaction.

2) 2HCl(aq) + CaSi0₃ - Ca£\₂{aq) + Si0₂| + H₂0

A rock melting reaction.

Note 5 H₂0 will be present per 2 moles of HC1 during the reaction.

3) MgO + Ca.C\₂(aq) + C0₂→ CaC0₃| + MgCl₂(fl_¾

Some versions of this equation use Mg(OH)₂ which is formed from MgO and H₂0.

4) MgC\₂(aq) + 6H₂0→ MgCl₂-6H₂0

Regeneration of MgCl₂.6H₂0, return to #1.

b) Partial decomposition ("the CaSi0₃-Mg(OH)Cl process"):

1 ) 2 [MgCl₂-6H₂0 + Δ→ Mg(OH)Cl + 5H₂0† + HCl† ]

Thermal decomposition.

Twice as much MgCl₂-6FI₂0 is needed to trap the same amount of

C0₂.

2) 2HC\(aq) + CaSi0₃→ CaC\₂( q) + Si0₂ j + H₂0

Rock melting reaction.

3) 2Mg(OH)Cl + CaCl₂(£^) + C0₂→ CaC0₃ I + 2MgC\₂(aq) + H₂0

C0₂ capture reaction

2 MgCl₂ + 12H₂0→ 2MgCl₂-6H₂0

Regeneration of MgCl₂.6H₂0, return to #1 . II) Mg Only Process

Overall reaction MgSi0₃ + C0₂→ MgC0₃ + Si0₂

c) Full decomposition ("the MgSi0₃-MgO process")

1 ) 2HCl(a^) + MgSi0₃ + (x-l )H₂0→ MgCl₂ + Si0₂| + x¾0

Rock melting reaction.

2) MgCl₂-xH₂0 + Δ→ MgO + (x-l)H₂0† + 2HC1†

Thermal decomposition reaction.

Note "x-1" moles H₂0 will be produced per 2 moles of HC1.

3) MgO + C0₂ - MgC0₃

C0₂ capture reaction.

Note, in this embodiment no recycle of MgCl₂ is required. The value of x, the number of waters of hydration is much lower than 6 because the MgCl₂ from the rock melting reaction is hot enough to drive much of the water into the vapor phase. Therefore the path from the rock melting runs at steady state with "x" as modeled with a value of approximately 2.

d) Partial decomposition ("the MgSi0₃-Mg(OH)Cl process")

1) 2UCl(aq) + MgSi0₃→ MgCl₂ + Si0₂| + H₂0

Rock melting reaction.

Note "x-1 " H₂0 will be present per mole of HC1 during the reaction.

2) 2 [MgCl₂.xH₂0 + Δ→ Mg(OH)Cl + (x-1) H₂0† + HCl†]

Decomposition.

Twice as much MgCl₂-(x-l)H₂0 is needed to trap the same amount of C0₂.

3) 2Mg(OH)Cl + C0₂→ MgC0₃| + MgCl₂ + H₂0

C0₂ capture reaction.

4) MgC (aq) + 6H₂0→ MgCl₂-6H₂0

Regenerate MgCl₂-6H₂0, Return to #1.

Note, in this embodiment half of the MgCl₂ is recycled. The value of x, the number of waters of hydration is somewhat lower than 6 because half of the MgCl₂ is from the rock melting reaction which is hot enough to drive much of the water into the vapor phase and the remaining half is recycled from the absorption column. Therefore the number of hydrations for the total amount of MgCl₂ at steady state will have a value of approximately 4, being the average between the MgCl₂-6H₂0 and MgCl₂-2H₂0. III) Diopside or Mixed process:

Note diopside is a mixed calcium and magnesium silicate and dolomite is a mixed calcium and magnesium carbonate.

Overall reaction: ½ CaMg(Si0₃)₂ + C0₂→ ½ CaMg(C0₃)₂ + Si0₂

e) Full decomposition ("the Diopside-MgO process"):

1) MgCl₂.6H₂0 + Δ→ MgO + 5H₂0† + 2HC1†

Thermal decomposition.

2) HCl + ½ CaMg(Si0₃)₂→ ½ CaCl₂ + ½ MgSi0₃| + ½ Si0₂| + ½ H₂0 First rock melting reaction.

3) HCl + ½ MgSi0₃→ ½MgCl₂ + ½ Si0₂| + ½ H₂0

Second rock melting reaction. The MgCl₂ returns to #1.

4) MgO + ½ CaCl₂ + C0₂→ ½ CaMg(C0₃) ₂| + ½ MgCl₂

5) ½ MgCl₂ + 3H₂0→ ½ MgCl₂.6H20

Regenerate MgCl₂.6H₂0, return to #1.

f) Partial decomposition ("the Diopside-Mg(OH)Cl process"):

1) 2 [MgCl₂-6H₂0 + Δ→ Mg(OH)Cl + 5H₂0† + HCl† ]

Thermal decomposition.

Twice as much MgCl₂-6H₂0 is needed to trap the same amount of C0₂.

3) HCl + ½ MgSi0₃→ ½MgCl₂ + ½ Si0₂I + ½ H₂0

Second rock melting reaction. Here the MgCl₂ returns to #1.

4) 2Mg(OH)Cl + ½ CaCl₂ + C0₂→ ½ CaMg(C0₃) ₂| + 3/2 MgCl₂ + H₂0

5) 3/2 MgCl₂ + 9H₂0→ 3/2 MgCl₂-6H₂0

Regenerate MgCl₂-6H₂0, return to #1 Table 9. Summary of Processes

1 - The temperature range of 320-550 °C includes models run at 320, 360, 400, 440 and 550 °C respectively.

2 - The C0₂ percentage of flue gas 7.2% - 18%) includes models run at 7.2%, 10%, 14% and 18%) respectively.

Calcium Silicate process:

The CaSi0₃-MgO and CaSi0₃-Mg(OH)Cl decomposition processes are further divided into two stages, the first step consists of a dehydration reaction where MgCl₂-6H₂0 is converted to MgCl₂-2H₂0 + 4 H₂0 and the second step in which the MgCl₂-2H₂0 is converted to Mg(OH)Cl + HQ + H₂0 if partial decomposition is desired or required and MgO + 2HC1 + H₂0 if total decomposition is desired or required. FIG. 15 describes a layout of this process.

Magnesium Silicate process:

The MgSi0₃-MgO and MgSi0₃-Mg(OH)Cl processes consists of a one chamber decomposition step in which the HC1 from the decomposition chamber reacts with MgSi0₃ in the rock-melting reactor and the ensuing heat of reaction leaves the MgCl₂ in the dihydrate form MgCl₂-2H₂0 as it leaves the rock-melting chamber in approach to the decomposition reactor where it is converted to either MgO or Mg(OH)Cl as described earlier. This process may be preferred if calcium silicates are unavailable. The HC1 emitted from the decomposition reacts with MgSi0₃ to form more MgCl₂. The magnesium silicate process follows a different path from the calcium. The process starts from the "rock melting reaction HC1 + silicate", and then moves to the "decomposition reaction (MgCl₂ + heat)," and lastly the absorption column. In the calcium silicate process, all the magnesium compounds rotate between the decomposition reaction and the absorption reaction. FIG. 16 describes the layout of this process.

Mixed Magnesium and Calcium Silicate "Diopside" process:

The intermediate process Diopside-MgO and Diopside-Mg(OH)Cl also involve a two stage decomposition consisting of the dehydration reaction MgCl₂-6H₂0 + Δ— > MgCl₂-2H₂0 + 4 H₂0 followed by the decomposition reaction MgCl₂-2H₂0 + Δ→ MgO + 2HC1 + H₂0 (full decomposition) or MgCl₂-2H₂0 + Δ→ Mg(OFI)Cl + HC1 + FI₂0 partial decomposition. FIG. 17 describes a layout of this process.

The ensuing HC1 from the decomposition then reacts with the Diopside CaMg(Si0₃)₂ in a two step "rock melting reaction." The first reaction creates CaCl₂ through the reaction 2HC1 + CaMg(Si0₃)₂→ CaC\₂(aq) + MgSi0₃|+ Si0₂j + H₂0. The solids from the previous reaction are then reacted with HC1 a second time to produce MgCl₂ through the reaction MgSi0₃ + 2HC1→ MgCl₂ + Si0₂J +H₂0. The CaCl₂ from the first rock melter is transported to the absorption column and the MgCl₂ from the second rock melter is transported to the decomposition reactor to make Mg(OH)Cl or MgO. Basis of the reaction:

All of these examples assume 50% C0₂ absorption of a reference flue gas from a known coal fired plant of interest. This was done to enable a comparison between each example. The emission flow rate of flue gas from this plant is 136,903,680 tons per year and the C0₂ content of this gas is 10% by weight. This amount of C0₂ is the basis for examples 10 through 21 which is:

Amount of C0₂ present in the flue gas per year:

136,903,680 tons per year * 10% = 13,690,368 tons per year

Amount of C0₂ absorbed per year.

13,690,368 tons per year * 50% = 6,845, 184 tons per year of C0₂.

Since the amount of C0₂ absorbed is a constant, the consumption of reactants and generation of products is also a constant depending on the reaction stoichiometry and molecular weight for each compound.

For all the examples of both the CaSi0₃-MgO and the CaSi0₃-Mg(OH)Cl process (examples 10-13) the overall reaction is:

CaSi0₃ + C0₂→ CaC0₃ + Si0₂

For all the examples of both the MgSi0₃-MgO and the MgSi0₃-Mg(OH)Cl process (examples 14-17) the overall reaction is:

MgSi0₃ + C0₂→ MgC0₃ + Si0₂

For all the examples of both the Diopside-MgO and the Diopside-Mg(OH)Cl process

(examples 18-21) the overall reaction is:

½ CaMg(Si0₃)₂+ C0₂→ ½ CaMg(C0₃)₂+ Si0₂

The Aspen model enters the required inputs for the process and calculates the required flue gas to provide the heat needed for the decomposition reaction to produce the carbon dioxide absorbing compounds MgO, Mg(OH)₂ or Mg(OH)Cl. This flue gas may be from a natural gas or a coal plant and in the case of coal was tested at a range of temperatures from 320 °C to 550 °C. This flue gas should not be confused with the reference flue gas which was used a standard to provide a specific amount of C0₂ removal for each example. A process with a higher temperature flue gas would typically require a lesser amount of flue gas to capture the same amount of carbon dioxide from the basis. Also a flue gas with a greater carbon dioxide concentration would typically result in greater amount of flue gas needed to capture the carbon dioxide because there is a greater amount of carbon dioxide that needs to be captured. The consumption of reactants and generation of products can be determined from the basis of C0₂ captured and the molecular weights of each input and each output for each example.

Table 10. Molecular Masses of Inputs and Outputs (all embodiments).

* Number of moles must be divided by 2 to measure comparable C0₂ absorption with the other processes,

For Examples 10-13:

The CaSi0₃ consumption is:

6,845,184 tons per year * (1 16.16 / 44.01) = 18,066,577 tons per year.

The CaC0₃ production is:

6,845,184 tons per year * (100.09 / 44.01) = 15,559,282 tons per year.

The Si0₂ production is:

6,845,184 tons per year * (60.08 / 44.01 ) = 9,344,884 tons per year

The same type of calculations may be done for the remaining examples. This following table contains the inputs and outputs for examples 10 through 21. Basis: 6,845,184 tons C0₂ absorbed per year.

Table 11. Mass Flows of Inputs and Outputs for Examples 10-21.

All measurements are in tons per year (TPY)

Examples

10-13 14-17 18-21

INPUTS

Flue Gas for C0₂ Capture 136,903,680 136,903,680 136,903,680

10% CO₂ 13,690,368 13,690,368 13,690,368

CaSi0₃ 18,066,577

MgSi0₃ 15,613,410

Diopside 16,839,993

OUTPUTS

Si0₂ 9,344,884 9,344,884 9,344,884

CaC0₃ 15,559,282

MgC0₃ 13,1 1 1 ,817

Dolomite 14,319,845

Running the Aspen models generated the following results for the heat duty for each step of the decomposition reaction, dehydration and decomposition. The results for each example are summarized in the table below.

Table 12. Power (Rate of Energy for each process at the particular basis of C0₂ absorption).

D&D equals dehydration and decomposition

Table 13. Percentage C0₂ captured as a function of flue gas temperature and C0₂ concentration. Examples 10 through 13.

A value of over 100% means that excess heat is available to produce more Mg(OH)Cl or MgO. FIG. 24 illustrates the percent C captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and al whether the process relied on full or partial decomposition for examples 10 through 13 of the CaSi0₃-Mg(OH)Cl and CaSi0₃-MgO processes.

fable 14. Percentage C0₂ captured as a function of flue gas temperature and C0₂ concentration. Examples 14 through 17.

FIG. 25 illustrates the percent C0₂ captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas w originated from coal or natural gas, and also whether the process relied on full or partial decomposition for examples 14 through 17 of t MgSi0₃-Mg(OH)Cl and MgSi0₃-MgO processes.

Table 15. Percentage C0₂ captured as a function of flue gas temperature and C0₂ concentration. Examples 18 through 21.

* Note Diop equals Diopside

FIG. 26 illustrates the percent C0₂ captured for varying C0₂ flue gas concentrations, varying temperatures, whether the flue gas w originated from coal or natural gas, and also whether the process relied on full or partial decomposition for examples 18 through 21 of t Diopside - Mg(OH)Cl and Diopside - MgO processes.

Table 16a. Mass and Energy Accounting for Examples 10 and 11 Simulation.

Table 16b. Mass and Energy Accounting for Examples 10 and 11 Simulation.

Table 17a. Mass and Energy Accounting for Examples 12 and 13 Simulation.

Table 17b. Mass and Energy Accounting for Examples 12 and 13 Simulation.

Table 18a. Mass and Energy Accounting for Examples 14 and 15 Simulation.

fable 18b. Mass and Energy Accounting for Examples 14 and 15 Simulation.

Table 19a. Mass and Energy Accounting for Examples 16 and 17 Simulation.

Table 19b. Mass and Energy Accounting for Examples 16 and 17 Simulation.

Table 20a. Mass and Energy Accounting for Examples 18 and 19 Simulation.

Table 20b. Mass and Energy Accounting for Examples 18 and 19 Simulation.

Table 21a. Mass and Energy Accounting for Examples 20 and 21 Simulation.

Table 21b. Mass and Energy Accounting for Examples 20 and 21 Simulation.

Example 22: Decomposition of other salts.

The thermal decomposition of other salts has been measured in lab. A summary of some test results are shown in the table below.

Table 22. Decomposition of other salts.

Example 22: Two, Three and Four-Chamber Decomposition Models

Table 23 (see below) is a comparison of the four configurations corresponding to FIGS. 31-34. Depicted are the number and description of the chambers, the heat consumed in MW (Megawatts), the percentage of heat from that particular source and the reduction of required external heat in kW-H/tonne of C0₂ because of available heat from other reactions in the process, namely the hydrochloric acid reaction with mineral silicates and the condensation of hydrochloric acid. In the FIG. 34 example, the hot flue gas from the open- cycle natural gas plant also qualifies.

Example 23: Output Mineral Compared with Input Minerals— Coal

In this case study involving flue gas from a coal-based power plant, Table 24 illustrates that the volume of mineral outputs (limestone and sand) are 83% of the volume of input minerals (coal and inosilicate). The results summarized in Table 24 are based on a 600 MWe coal plant; total 4.66 E6 tonne C0₂, includes C0₂ for process-required heat. Example 24: Output Mineral Compared with Input Minerals— atural

Gas

In this case study summarized in Table 25 (below) involving flue gas from a natural gas-based power plant, the "rail-back volume" of minerals is 92% of the "rail-in volume" of minerals. The results summarized in Table 25 are (based on a 600 MWe CC natural gas plant; total 2.41 E6 tonne C0₂, which includes C0₂ for process-required heat.

fable 23. Two, Three and Four-Chamber Decomposition Results

fable 24. Coal Scenario— Volume of Mineral Outputs Compared with Volume of Mineral Inputs

fable 25. Natural Gas Scenario— Volume of Mineral Outputs Compared with Volume of Mineral Inputs

Example 25: Selective production of magnesium hydroxide by disproportionation of water and magnesium chloride

Mg(OH)₂ can be used in the following reaction to produce limestone from C0₂ gas. CaCl₂(aq) + C0₂ + Mg(OH)₂ => MgCl₂(aq) + CaC0₃l+ H₂0

In order to optimize production of Mg(OH)₂, upon conversion of MgCl₂ to Mg(OH)Cl, the amount of water in the reaction chamber will be adjusted to favor Mg(OH)₂ precipitation. Specifically, when Mg(OH)Cl and MgCl₂ is provided in a large enough volume of water, the magnesium hydroxide precipitates, as it is virtually insoluble, whereas the magnesium chloride forms an aqueous solution. Thus the two compounds may be efficiently separated. Note the water (H₂0) in the reaction below, does not become part of the products, it merely solvates the Mg and CI^" so they become an ionic solution.

Mg(OH)Cl (H₂0) => ½ Mg(OH)₂j+ ½ MgCl₂(aq)

If the amount of water is reduced until the a ratio of about 6 to 1 relative to magnesium, it would be possible to form MgCl₂-6H₂0 instead of MgCl₂(aq). The equation would be as follows:

Mg(OH)Cl + 3H₂0 => ½ Mg(OH)₂l+ ½ MgCl₂.6H₂0

Thus, by maintaining a MgCl₂ to water ratio of greater than or equal to 6 to 1, production of aqueous MgCl₂ and solid Mg(OH)₂ is favored. Thus, an example set of C0₂ capture reactions can be represented as:

i) MgCl₂-H₂0 => Mg(OH)CL + H₂0 + HC1

ii) HCl + CaSi0₃ => CaCl₂ + H₂0 + Si0₂

iii) Mg(OH)Cl + MgCl₂ + H₂0 => Mg(OH)₂ + MgCl₂ + H₂0

iv) H₂0 + Mg(OH)₂ + C0₂ + CaCl₂ => MgCl₂ + CaC0₃ + H₂0

With an overall reaction of: CaSi0₃ C0₂ => CaC0₃ + Si0₂.

This system is shown in the the Aspen diagram of FIG. 38A-I and FIG. 39A-I. The outlined rectangle in the center of the diagram is around the defined "water disproportionator". At the top of the rectangle, Mg(OH)Cl, stream SOLIDS- 1, is leaving the decomposition reactor labeled "DECOMP". Then in the module labeled MGOH2, the Mg(OH)Cl is mixed the aqueous MgCl₂ from the absorption column, stream RECYCLE2. They leave as a slurry from the unit as stream "4", pass through a heat exchanger and send heat to the decomposition chamber. The stream is then named "13" which passes through a separation unit which separates the stream into stream MGCLSLRY (MgCl₂.6FI₂0 almost) and stream SOLIDS-2, which is the Mg(OH)₂ heading to the absorption column. All of the methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

REFERENCES

The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference.

U.S. Prov. Appln. 60/612,355

U.S. Prov. Appln. 60/642,698

U.S. Prov. Appln. 60/718,906

U.S. Prov. Appln. 60/973,948

U.S. Prov. Appln. 61/032,802

U.S. Prov. Appln. 61/033,298

U.S. Prov. Appln. 61/288,242

U.S. Prov. Appln. 61/362,607

U.S. Patent Appln. 1 1/233,509

U.S. Patent Appln. 12/235,482

U.S. Patent Pubn. 2006/0185985

U.S. Patent Pubn. 2009/0127127

U.S. Patent 7,727,374

PCT Appln. PCT/US08/77122

Goldberg et al, Proceedings of First National Conference on Carbon Sequestration, 14-17 May 2001, Washington, DC. , section 6c,United States Department of Energy, National Energy Technology Laboratory, available at:

http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/6cl .pdf.

Proceedings of First National Conference on Carbon Sequestration, 14-17 May 2001, Washington, DC. United States Department of Energy, National Energy Technology Laboratory. CD-ROM USDOE/NETL-2001/1 144; also available at http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/carbon__seq01.html. de Bakker, The Recovery of Magnesium Oxide and Hydrogen Chloride from Magnesium Chloride Brines and Molten Salt Hydrates, March 201 1 , Queens University, Kingston, Ontario, Canada. Thesis by Jan Simon Christiaan de Bakker; also available on the internet at qspace.library.queensu.ca/bitstream/1974/6337/l/de%20Bakker_Jan_S_C_201 103_P hD.pdf.

Claims

WHAT IS CLAIMED IS:

1. A method of sequestering carbon dioxide produced by a source, comprising:

(b) reacting some or all of the Mg(OH)Cl from step (a) with a quantity of water and a quantity of MgCl₂ in a second admixture under conditions suitable to form a second product mixture comprising a first step (b) product comprising Mg(OH)₂ and a second step (b) product comprising MgCl₂, wherein the quantity of water is sufficient to provide a molar ratio of water to MgCl₂ of greater than or equal to 6 to 1 in the second product mixture;

(d) separating some or all of the CaC0₃ from the third product mixture, whereby some or all of the carbon dioxide is sequestered as CaC0₃.

2. The method of claim 1 , wherein some or all of the water in step (a) is present in the form of a hydrate of the MgCl₂.

3. The method according to either claims 1 or 2, wherein the molar ratio of water to MgC in the second product mixture is between 6 and 10.

4. The method of claim 3, wherein the molar ratio of water to MgCl₂ in the second product mixture is between about 6 and about 7.

5. The method according to any one of claims 1-4, further comprising monitoring the concentration of Mg in the second admixture.

6. The method of claim 5, wherein the amount of Mg(OH)Cl or the quantity of water in a second admixture is adjusted based on said monitoring.

7. The method according to any one of claims 1 -6, wherein the MgCl₂ of step (a) is a MgCl₂ hydrate.

8. The method of claim 7, wherein the MgCl₂ hydrate of step (a) is MgCl₂-6H₂0.

9. The method according to any one of claims 1 -8, wherein the MgCl₂ of step (a) is greater than 90% by weight MgCl₂-6(H₂0).

10. The method according to any one of claims 1-9, wherein the first step (a) product comprises greater than 90% by weight Mg(OH)Cl.

1 1. The method according to any one of claims 1 -10, further comprising separating the step (b) products.

12. The method of claim 1 1 , wherein the Mg(OH)₂ product of step (b) is a solid and wherein separating the step (b) products comprises separating some or all of the solid Mg(OH)₂ from the water and the MgCl₂.

13. The method according to any one of claims 1-12, wherein the MgCl₂ product of step (b) is aqueous MgCl₂.

14. The method according to any one of claims 1-13, wherein some or all of the MgCl₂ formed in step (b) or step (c) is the MgCl₂ used in step (a).

15. The method according to any one of claims 1-13, where some or all of the water in step (a) is present in the form of steam or supercritical water.

16. The method according to any one of claims 1-15, where some or all of the water of step (a) is obtained from the water of step (c).

17. The method of any one of claims 1-16, further comprising:

(e) admixing a calcium silicate mineral with HQ under conditions suitable to form a third product mixture comprising CaCl₂, water, and silicon dioxide.

18. The method of claim 17, where some or all of the HC1 in step (e) is obtained from step (a).

19. The method of claim 17, wherein step (e) further comprises agitating the calcium silicate mineral with HC1.

20. The method according to any one of claims 17-19, wherein some or all of the heat generated in step (e) is recovered.

21. The method according to any one of claims 17-20, where some or all of the CaCl₂ of step (c) is the CaCl₂ of step (e).

22. The method according to any one of claims 17-21 , further comprising a separation step, wherein the silicon dioxide is removed from the CaCl₂ formed in step (e).

23. The method according to any one of claims 17-22, where some or all of the water of step (a) is obtained from the water of step (e).

24. The method according to any one of claims 17-22, wherein the calcium silicate mineral of step (e) comprises a calcium inosilicate.

25. The method according to any one of claims 17-22, wherein the calcium silicate mineral of step (e) comprises CaSi0₃.

26. The method according to any one of claims 17-22, wherein the calcium silicate mineral of step (e) comprises diopside (CaMg[Si₂0₆]) or tremolite Ca₂M_g5{[OH]Si₄On }₂.

27. The method according to any one of claims 17-22, wherein the calcium silicate further comprises iron and or manganese silicates.

28. The method of claim 27, wherein the iron silicate is fayalite (Fe₂[Si0₄]).

29. The method according to any one of claims 1-28, wherein the carbon dioxide is in the form of flue gas, wherein the flue gas further comprises N₂ and H₂0.

30. The method according to any one of claims 1 -29, wherein suitable reacting conditions of step (a) comprise a temperature from about 200 °C to about 500 °C.

31. The method of claim 30, wherein the temperature is from about 230 °C to about 260 °C.

32. The method of claim 30, wherein the temperature is about 250 °C.

33. The method of claim 30, wherein the temperature is from about 200 °C to about 250 °C.

34. The method of claim 30, wherein the temperature is about 240 °C.

35. The method according to any one of claims 1-34, wherein the suitable reacting conditions of step (b) comprise a temperature from about 140 °C to about 240 °C.

36. The method according to any one of claims 1-35, wherein suitable reacting conditions of step (c) comprise a temperature from about 20 °C to about 100 °C.

37. The method of claim 36, wherein the temperature is from about 25 °C to about 95 °C.

38. The method according to any one of claims 17-37, wherein suitable reacting conditions of step (e) comprise a temperature from about 50 °C to about 200 °C.

39. The method of claim 38, wherein the temperature is from about 90 °C to about 150 °C.

40. The method according to any one of claims 1 -39, wherein some or all of the hydrogen chloride of step (a) is admixed with water to form hydrochloric acid.

41. The method of claim 1, wherein step (a) occurs in one, two or three reactors.

42. The method of claim 1 , wherein step (a) occurs in one reactor.