Method for Producing a Hardened CO2 Sequestering Solid Composition, a System for Carrying Out the Same, and Hardened CO2 Sequestering Solid Compositions Producing Therefrom

Abstract

Methods for producing a hardened CO2 sequestration solid composition, such as a precipitate or aggregate composition, are provided. Method embodiments include preparing an initial CO2 sequestration solid composition and then contacting the initial composition with sufficient hardening liquid to produce the hardened CO2 sequestration solid composition. Also provided are systems for carrying out the methods, and hardened CO2 sequestration solid compositions produced therefrom.

Description

[Background technology]

[0001] Carbon dioxide (CO2) is a naturally occurring chemical compound that exists in the Earth's atmosphere as a gas. Sources of atmospheric CO2 are varied and include humans and other living organisms that produce CO2 during the breathing process, and other naturally occurring sources such as volcanoes, hot springs, and geysers.

[0002] Additional major sources of atmospheric CO2 include industrial plants. Many types of industrial plants (including cement plants, refineries, steel mills, and power plants) burn a variety of carbon-based fuels, such as fossil fuels and synthetic gas. The fossil fuels used include coal, natural gas, oil, petroleum coke, and biofuels. Fuels also come from coal gasification and biofuels produced using tar sands, oil shale, coal liquids, and synthetic gas.

[0003] The environmental impacts of CO2 are of considerable concern. CO2 is generally considered a greenhouse gas. Human activities since the Industrial Revolution have rapidly increased the concentration of CO2 in the atmosphere, and therefore anthropogenic CO2 has been implicated in global warming and climate change, as well as in the increase in bicarbonate concentrations in the oceans. Oceanic uptake of fossil fuel CO2 currently proceeds at approximately one million metric tons of CO2 per hour.

[0004] Concerns over anthropogenic climate change and ocean acidification have fueled the urgency to find scalable, cost-effective carbon capture and sequestration (CCS) methods. Typically, CCS methods involve separating pure CO2 from complex plumes, compressing the purified CO2, and finally injecting it into underground saline reservoirs for geological sequestration. These multiple steps are highly energy and capital intensive. Summary of the Invention

[0005] Methods for producing a hardened CO2 sequestration solid composition, such as a precipitate or aggregate composition, are provided. Method embodiments include preparing an initial CO2 sequestration solid composition and then contacting the initial composition with sufficient hardening liquid to produce the hardened CO2 sequestration solid composition. Also provided are systems for carrying out the methods, and hardened CO2 sequestration solid compositions produced therefrom. [Brief description of the drawings]

[0006] The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art, by reference to the accompanying drawings, in which: The figures depict various embodiments of the present invention for purposes of illustration only. Those skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods shown herein may be employed without departing from the principles of the present invention as described herein. The use of the same reference symbols in different drawings indicates similar or identical items.

[0007] [Figure 1] FIG. 1 illustrates a system for producing a durable CO sequestering solid composition, e.g., an aggregate composition, according to one embodiment of the present invention. [Diagram 2] FIG. 1 illustrates a method of hardening a CO sequestering solid composition, e.g., a precipitate composition, according to one embodiment of the present invention, where dashed lines indicate optional steps. [Figure 3A] FIG. 13 shows the effect of washing and hardening of CaCO3 aggregate. [Figure 3B] FIG. 13 shows the effect of washing and hardening of CaCO3-coated aggregate. [Figure 4] FIG. 1 shows SEM images of the original slurry (unwashed), the washed and agglomerated aggregate, and the final aggregate after hardening. [Figure 5A] FIG. 13 shows the effect of washing and curing on old slurry. [Figure 5B] FIG. 1 shows the effect of sodium and pH in the wash solution. [Figure 6]FIG. 1 illustrates an embodiment of a method for producing durable CaCO aggregate and sand by hardening slurry from a CO gas absorption process. [Figure 7] FIG. 13 illustrates the strength of aggregate made from a slurry curing where the slurry is cured without flocculation. [Figure 8A] FIG. 1 illustrates a closed steam treatment system for cleaning CO2 sequestration solids prior to hardening. [Figure 8B] FIG. 1 illustrates an open steam treatment system for cleaning CO2 sequestration solids prior to hardening. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Methods of producing a hardened CO2 sequestration solid composition, such as a precipitate or aggregate composition, are provided. Method embodiments include preparing an initial CO2 sequestration solid composition and then contacting the initial composition with sufficient hardening liquid to produce the hardened CO2 sequestration solid composition. Also provided are systems for carrying out the methods, and hardened CO2 sequestration solid compositions produced therefrom.

[0009] Before the present invention is described in more detail, it is to be understood that the invention is not limited to the particular embodiments described, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0010] Where a range of values ​​is provided, unless the context clearly indicates otherwise, it is understood that each intervening value, to the tenth of the unit of the lower limit between the upper and lower limits of that range, and any other stated or intervening value in the stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the invention, subject to any specific excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0011] Certain ranges are presented herein where the numerical values ​​are preceded by the term "about". The term "about" is used herein to provide literal support for the exact number it precedes, as well as a number that is close to or approximately the number it precedes. In determining whether a number is close to or approximately a specifically recited number, the number that is close to or approximately the unrecited number may be a number that provides substantial equivalence to the specifically recited number in the context provided.

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In addition, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, but representative exemplary methods and materials are described below.

[0013] All publications and patents cited herein are incorporated by reference as if each individual publication or patent was specifically and individually indicated to be incorporated by reference, and are incorporated by reference herein to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

[0014] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. It should be further noted that the claims may be drafted to exclude any optional element. Accordingly, this statement is intended to serve as a predicate for the use of exclusive terminology such as "solely," "solely," and the like, or the use of "negative" limitations in connection with the recitation of claim elements.

[0015] As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has distinct components and features which may be readily separated from or combined with the features of any of the other embodiments without departing from the scope or spirit of the invention. Any recited method may be carried out in the order of events recited or in any other order which is logically possible.

[0016] Although the apparatus and methods have been or will be described with functional descriptions for grammatical fluidity, it is expressly understood that unless expressly recited under 35 U.S.C. 35 U.S.C. 112, the claims should not necessarily be construed as limited by construction of "means" or "step" limitations, but should be accorded the full scope of meaning and equivalents of the definitions provided by the claims under the doctrine of legal equivalents, and where the claims are expressly recited under 35 U.S.C. 35 U.S.C. 112, they should be accorded the full legal equivalents under 35 U.S.C. 35 U.S.C.

[0017] method As mentioned above, aspects of the invention include methods of producing durable hardened CO2 sequestration solids. As used herein, "hardening" means changing the chemical composition of a compound. In one embodiment, hardening includes changing a compound in an initial CO2 sequestration solid composition (hereinafter also referred to as the "initial solid") from a first polymorph to a second polymorph. Thus, in some embodiments, the initial solid includes a first polymorph of calcium carbonate, and the hardening step converts some or all of the first polymorph of calcium carbonate to a second polymorph of calcium carbonate. The term "polymorphs" refers to compounds that have the same empirical formula but different crystal structures. "Empirical formula" refers to the ratio of atoms in a molecule, for example, the empirical formula of water is H2O. Calcite, aragonite, and vaterite are polymorphs of calcium carbonate (CaCO3) because they all have the same empirical formula of CaCO3, but they differ from each other in their crystal structures. The crystal structure space groups of calcite, aragonite, and vaterite are R3c, Pmcn, and P63 / mmc, respectively. In some cases, the polymorph is amorphous, i.e., the solid is not crystallized but instead lacks long-range order. For example, the solid may comprise amorphous calcium carbonate. In some cases, the first crystal structure is vaterite or amorphous calcium carbonate and the second crystal structure is aragonite or calcite. In other embodiments, hardening includes changing the first compound to a second compound, i.e., the empirical formula of the compound changes during hardening.

[0018] FIG. 1 illustrates an embodiment of a system 100 for producing durable CO2 sequestering solid compositions from an initial CO2 sequestering solid composition 110. The system 100 includes multiple modules, each of which may be independently configured for batch or continuous, i.e., flow, operation in some embodiments. In batch operation, a certain amount of compounds are mixed together in the module, the compounds are allowed to react for a certain amount of time without the addition of new compounds, and then the product is removed from the module. For example, if the hardening module is configured for batch operation, the initial CO2 sequestering solid composition and hardening liquid are added to the module, and the resulting hardened CO2 sequestering solid is removed from the module before additional initial CO2 sequestering solid composition is added. In continuous or flow operation, the input flows continuously into the module and the output flows continuously out of the module.

[0019] In some embodiments, the system 100 includes an initial CO2 sequestering solid composition preparation module 105. In some cases, the module 105 has an inlet for the CO2-containing gas 102, an inlet for the aqueous capture liquid 104, and an output for the initial CO2 sequestering solid composition 110. The module 105 is configured to contact the CO2-containing gas 102 with the aqueous capture liquid 104 and a cation source to generate the initial CO2 sequestering solid composition 110. In some cases, this generation includes a first section of the module 105 where the aqueous capture liquid contacts the gaseous CO2 source 102 to generate the aqueous liquid, and a second section of the module 105 where the aqueous liquid contacts the cation source to generate the initial CO2 sequestering solid composition 110. In other cases, the generation includes contacting the aqueous capture liquid 104 including the cation source with the gaseous CO2 source 102 to generate the initial CO2 sequestering solid composition 110. In such cases, the cation source is part of the capture liquid 104 before the capture liquid contacts the gaseous CO 2 source 102 .

[0020] In some embodiments, the initial CO sequestering solid composition 110 is a composition that stores a substantial amount of CO in a storage stable format such that CO gas is not readily generated from the material and released into the atmosphere. In some cases, the initial CO sequestering solid composition includes 5% or more CO by weight, e.g., 10% or more, 25% or more, 30% or more, 40% or more, or 45% or more CO by weight. For example, the solid composition 110 may include a mixture of carbonate ions (CO3 2- In other words, the solid composition 110 can include carbonate. The amount of carbonate in the initial CO2 sequestration solid composition 110 can be 10% or more, e.g., 25% or more, 50% or more, 60% or more, as determined, for example, by coulometry. In some cases, the CO2 is stored as an alkaline earth metal carbonate, e.g., calcium carbonate, magnesium carbonate, an alkaline earth metal carbonate, e.g., sodium carbonate, potassium carbonate, or a combination thereof.

[0021] The initial CO2 sequestration solid composition 110 provides long-term storage of CO2 in a manner such that the CO2 is sequestered (i.e., fixed) in the material, and the sequestered CO2 does not become part of the atmosphere. When the solid composition is maintained under conditions for its intended use, the solid composition 110 remains fixed for an extended period of time, such as 1 year or more, 5 years or more, 10 years or more, 25 years or more, or 50 years or more, with significant release of CO2 from the solid composition 110, if any. For example, when the solid composition 110 is maintained in a manner consistent with its intended use, the amount of CO2 gas released from the solid composition is 10% or less, such as 5% or less, or 1% or less of the total annual amount of CO2 in the solid composition when exposed to normal conditions of temperature and humidity, including precipitation at normal pH, for example, for the intended use. Any suitable surrogate marker or test that can reasonably predict such stability may be used. For example, accelerated testing including conditions of elevated temperature and / or moderate to more extreme pH conditions can reasonably indicate stability over extended periods of time. For example, depending on the intended use and environment of the composition, a sample of the initial CO2 sequestration solid composition 110 can be exposed to 50°C, 75°C, 90°C, 100°C, 120°C, or 150°C at 10%-50% relative humidity for 1 day, 2 days, 5 days, 25 days, 50 days, 100 days, 200 days, or 500 days, and a loss of less than 1%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, or 50% of its carbon can be considered sufficient evidence of stability of the solid composition for a given period of time (e.g., 1 year, 10 years, 100 years, 1000 years, or more than 1000 years). CO2 sequestration materials can have an isotopic profile that identifies whether the components are of fossil fuel origin or from modern plants, both of which fractionate CO2 during photosynthesis and are therefore CO2 sequestration. For example, in some embodiments, the carbon atoms in the CO2 material are labeled with the relative carbon isotopic composition (δ) of the fossil fuel (e.g., coal, oil, natural gas, tar sands, trees, grasses, agricultural plants) from which the CO2 from either fossil or modern plants used to make the material originates. 13In addition to or instead of carbon isotope profiling, oxygen (δ 18 O), nitrogen (δ 15 N), sulfur (δ 34 Other isotopic profiles, such as those of other trace elements, may be used to identify the fossil fuel source that was used to generate the industrial CO source from which the CO sequestration material was derived. For example, another marker of interest is (δ 18 Isotopic profiles that may be used as identifiers for the CO sequestration materials of the present invention are further described in U.S. Patent Application Serial No. 14 / 112,495, issued as U.S. Patent No. 9,714,406, the disclosure of which is incorporated herein by reference.

[0022] The term "solid composition" in "initial CO2 sequestering solid composition" refers to the presence of one or more compounds in the solid state of matter. In other words, at least a portion (but not all) of the initial CO2 sequestering solid composition 110 is in a solid state. In some cases, the solid composition includes solids and liquids. In some cases, the solid composition includes solids but not liquids, i.e., the solid composition includes dry solids. In some cases, the initial CO2 sequestering solid composition includes solids that store a significant amount of CO2 in a storage stable form, such that CO2 gas is not readily produced from the material and released into the atmosphere, as described above. In some cases, the solids of the solid composition include "precipitates," which are solids formed by chemical reactions. For example, the precipitates may be CO2 sequestering precipitates and may include, for example, carbonate compounds. For example, when gaseous CO2 is contacted with an aqueous solution that includes a cation source, one possible product is solid particles that include carbonate compounds formed by a chemical reaction between the cation source and the gaseous CO2. Because the particles are formed by a chemical reaction between the CO2 and the cation source, they are referred to herein as precipitates. If the precipitate is subjected to a physical operation that changes the size, shape, or both of the solid, the resulting solid is referred to as an "aggregate." In some cases, an aggregate is a solid resulting from an operation that has increased the size of the precipitate solid, e.g., an aggregate having a greater length, width, height, diameter, or combination thereof, as compared to the precipitate. In some cases, forming the precipitate into an aggregate involves the removal of components, such as separating water from the precipitate by filtration. In some cases, forming the precipitate into an aggregate involves the addition of components, such as adding a binding compound. For example, the precipitate can be combined with cement to form a concrete aggregate. In some cases, the precipitate is formed into an aggregate before hardening, in some cases the precipitate is formed into an aggregate after hardening, and in some cases an aggregate is not formed and the resulting hardened solid is a precipitate.

[0023] The initial CO sequestering solid composition 110 may be prepared using any convenient protocol. In an embodiment, the protocol involves using a source of CO, such as artificial CO, in the process of producing the initial CO sequestering solid composition. For example, the CO 102 may be a carbonate compound, i.e., carbonate ions (CO 2- ). Carbonate compounds can include many different cations, including, but not limited to, ionic species of calcium, magnesium, sodium, potassium, sulfur, boron, silicon, strontium, and combinations thereof. Of interest are carbonate compounds of divalent metal cations, such as calcium and magnesium carbonate compounds. Particular carbonate compounds of interest include, but are not limited to, calcium carbonate minerals, magnesium carbonate minerals, and calcium magnesium carbonate minerals. Calcium carbonate minerals of interest include, but are not limited to, calcite (CaCO3), aragonite (CaCO3), vaterite (CaCO3), ikaite (CaCO3·6H2O), and amorphous calcium carbonate (CaCO3). Magnesium carbonate minerals of interest include, but are not limited to, magnesite (MgCO3), baringtonite (MgCO3·2H2O), nesquonite (MgCO3·3H2O), rhamfordite (MgCO3·5H2O), hydromagnesite, and amorphous calcium magnesium carbonate (MgCO3). Calcium magnesium carbonate minerals of interest include, but are not limited to, dolomite (CaMg(CO3)2), haunchite (Mg3Ca(CO3)4), and sergievite (CaMg 11 (CO3) 13HO). The carbonate compound of the product may contain one or more waters of hydration or may be anhydrous. In some cases, the amount of magnesium carbonate compound in the precipitate exceeds the amount of calcium carbonate compound in the precipitate. For example, the weight of magnesium carbonate compound in the precipitate may exceed the weight of calcium carbonate compound in the precipitate by 5% by weight or more, e.g., 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more. In some cases, the weight ratio of magnesium carbonate compound to calcium carbonate compound in the precipitate is in the range of 1.5 to 5:1, e.g., 2 to 4:1, including 2 to 3:1. In some cases, the precipitation product may include hydroxides, e.g., divalent metal ion hydroxides, e.g., calcium hydroxide and / or magnesium hydroxide.

[0024] Exemplary carbonate compounds include compounds of the formula MCO3, where M is a divalent cation, e.g., Ca 2+ or Mg 2+ In other cases, the carbonate compound has the formula M2CO3, where each M is independently a monovalent positive ion, e.g., Na + Or K + or ammonium cation (NH4 + In some cases, CO2 102 is a bicarbonate compound, i.e., bicarbonate ion (HCO3 - For example, a bicarbonate compound can have the formula MHCO3, where M is a monovalent positive ion, e.g., Na + Or K + or ammonium cation (NH4 + ). In some cases, the CO2 102 is converted to a mixture of carbonate and bicarbonate ions. In other words, the initial CO2 sequestering solid composition 110 includes a mixture of one or more carbonate compounds and one or more bicarbonate compounds.

[0025] The CO2 102 undergoing the chemical reaction can be in any suitable state of matter, for example, gaseous CO2 or CO2 dissolved in a liquid, such as water (CO2(aq)). In some embodiments, the source of CO2 102 can be pure CO2 or a multi-component gas (i.e., a multi-component gas stream) that includes CO2. For example, the gas source can be a combustion module that provides CO2 102 as part of a combustion by-product gas. In some cases, the multi-component gas is a flue gas. The waste stream of interest is an industrial plant exhaust gas, for example, a flue gas. By "flue gas" is meant a gas obtained from a combustion product from the combustion of a fossil fuel or a biomass fuel, which is then sent to a chimney, also known as a flue, of an industrial plant. In certain embodiments, the CO2-containing gas 102 is obtained from an industrial plant, for example, where the CO2-containing gas 102 is a waste feed from the industrial plant. The industrial plants from which the CO2-containing gas 102 can be obtained, for example, as a waste feed from the industrial plant, can vary. Industrial plants of interest include, but are not limited to, power plants and industrial manufacturing plants, such as, but not limited to, chemical and mechanical processing plants, refineries, cement plants, steel plants, etc., as well as other industrial plants that produce CO2 as a by-product of fuel combustion or other processing steps (such as calcination by cement plants). Waste feeds of interest include, for example, gas streams produced by industrial plants as secondary or incidental products of processes performed by the industrial plants.

[0026] In some cases, the generation of the initial CO2 sequestering solid composition 110 is mediated through a carbonate intermediate. For example, in some cases, the CO2 gas 102 is contacted with the capture liquid such that the majority of the CO2 becomes carbonate as opposed to bicarbonate. For example, a preference for carbonate can be achieved by having a higher pH. A cationic intermediate can then be added to convert the aqueous carbonate solution to a solid carbonate. Further details regarding carbonate mediated generation protocols are described in U.S. Pat. Nos. 7,744,761, 7,771,684, 7,829,053, 7,914,685, 7,922,809, 7,931,809, 7,939,336, 8,006,446, 8,062,418, 8,114,214, 8,137,455, and 8,177,909, the disclosures of which are incorporated herein by reference.

[0027] In some cases, the CO2 gas 102 contacts the capture liquid 104 to produce a bicarbonate containing liquid, where the majority of the CO2 becomes bicarbonate as opposed to carbonate. The capture liquid is then contacted with a cation source such that two moles of bicarbonate form one mole of carbonate solid and one mole of CO2 gas. This allows for the sequestration of CO2 without the need to convert the bicarbonate to carbonate, for example, by increasing the pH, prior to adding the cation source. The bicarbonate-mediated process can also be carried out when the cation source is already part of the capture liquid when it contacts the CO2 gas 102. Additional details regarding such bicarbonate mediated generation methods can be found in U.S. Pat. Nos. 7,815,880, 8,177,909, 8,333,944, 9,707,513, 9,714,406, 9,993,799, 10,197,747, 10,711,236, 10,322,371, and 10,766,015, and PCT Patent Publication Nos. 2016 / 160612, 2018 / 160888, and 2020 / 047243, the disclosures of which are hereby incorporated by reference.

[0028] In some embodiments, the aqueous capture liquid 104 includes aqueous captured ammonia to produce an aqueous ammonium carbonate solution. The aqueous ammonium carbonate may vary, and in some cases, the aqueous ammonium carbonate includes at least one of ammonium carbonate and ammonium bicarbonate, and in some cases, includes both ammonium carbonate and ammonium bicarbonate. When the aqueous capture liquid 104 includes aqueous captured ammonia, contacting the liquid 104 with a cation source produces the initial CO2 sequestration solid composition 110. Further details regarding such ammonia-mediated production protocols can be found in U.S. Pat. No. 10,322,371, the disclosure of which is incorporated herein by reference.

[0029] In some embodiments, the temperature of the capture liquid 104 in contact with the CO2-containing gas 102 may vary. In some cases, the temperature may range from -1.4 to 100°C, such as 20 to 80°C, including 40 to 70°C. In some cases, the temperature may range from -1.4 to 50°C or higher, such as -1.1 to 45°C or higher. In some cases, lower temperatures are used, such temperatures may range from -1.4 to 4°C, such as -1.1 to 0°C. In some cases, higher temperatures are used. For example, in some cases, the temperature of the capture liquid 104 may be 25°C or higher, such as 30°C or higher, and in some embodiments, may range from 25 to 50°C, such as 30 to 40°C.

[0030] In some embodiments, the CO2-containing gas 102 and capture liquid 104 are contacted at a pressure suitable for producing the desired CO2-charged liquid. In some cases, the pressure of the contacting conditions is selected to provide optimal CO2 absorption, and such pressure may range from 1 to 100 atmospheres, such as 1 to 50 atmospheres, e.g., 20 to 30 atmospheres, or 1 to 10 atmospheres. If the contacting occurs at a location that is naturally at 1 atmosphere, the pressure may be increased to the desired pressure using any convenient protocol. In some cases, the contacting occurs where an optimal pressure exists, e.g., at a location below the surface of a body of water, such as an ocean or sea. In some cases, the contacting of the CO2-containing gas 102 with the alkaline aqueous medium 104 occurs at a depth below the surface of the water (e.g., the surface of the ocean), and the depth may range from 10 to 1000 meters, e.g., 10 to 100 meters, in some cases. In some cases, the CO2-containing gas 102 and the CO2 capture liquid 104 are contacted at a pressure that provides selective absorption of CO2 from the gas relative to other gases in the CO2-containing gas, such as N2. In these examples, the pressure at which the CO2-containing gas 102 and the capture liquid 104 are contacted can vary from 1 to 100 atmospheres (atm), including, for example, 1 to 10 atm, and 20 to 50 atm.

[0031] After formation of the intermediate, one or more reagents are reacted with the intermediate, thereby producing the CO2-sequestering solid of the initial CO2-sequestering solid composition 110. In some embodiments, the reagents that cause sequestration of CO2 can be dissolved in any suitable state of matter, e.g., water, gas, solid, or liquid, such as liquid. In some cases, these reagents provide cations that convert the intermediate to a CO2-sequestering compound. For example, the reagents can interact with the intermediate that includes a divalent cation, e.g., bicarbonate or carbonate ion, to form a CO2-sequestering compound, e.g., a divalent cation carbonate compound, such as calcium carbonate or magnesium carbonate, Ca. 2+ or Mg 2+In some cases, the reagent modifies the pH of the liquid in contact with the intermediate. For example, the reagent can increase the pH of the capture liquid, which can cause conversion of the intermediate compound, e.g., a bicarbonate compound, to a carbonate compound, which is a CO2 sequestering compound.

[0032] In some cases, the reagent provides a divalent cation and also increases the pH of the capture solution. In some cases, the reagent provides a divalent alkaline earth metal cation, e.g., Ca 2+ and Mg 2+ For example, the reagents can include calcium hydroxide (Ca(OH)2) or magnesium hydroxide (Mg(OH)2), either as solid Ca(OH)2(s) and MgCl2(s), or aqueous liquids Ca(OH)2(aq) and MgCl2(aq), which can raise the pH of the capture solution, thereby favoring carbonate ions, and can interact with carbonate to form CO2-sequestering carbonate compounds.

[0033] In some cases, the reagent includes a transition metal cation, e.g., a fourth-period transition metal cation, such as Mn, Fe, Ni, Cu, Co, or Zn. In some embodiments, the transition metal cation becomes part of a transition metal carbonate in the CO2-sequestering solid, e.g., as MnCO3, FeCO3, NiCO3, CuCO3, CoCO3, ZnCO3. In some cases, the transition metal is part of a pigment, i.e., a color-imparting compound that gives the CO2-sequestering solid a different color than a reference solid that does not have the transition metal carbonate. The solid with the transition metal compound can have any color, e.g., red, orange, brown, yellow, green, blue, blue, purple, magenta, black, gray, or white. For example, further details regarding the use of transition metal cations in the production of pigment products are provided in U.S. Pat. No. 10,287,439, the disclosure of which is incorporated herein by reference.

[0034] As an example, in module 105, the capture liquid 104 and gaseous CO2 102 contact a liquid-gas contactor to form a solid precipitate identified as calcium carbonate (CaCO3).

[0035] The system 100 includes a rinsing station 120 for dewatering the initial CO2 sequestration solid composition 110 and washing or rinsing with a rinsing liquid 115 to produce a dewatered and washed solid composition 125. The rinsing liquid 115 may vary as desired, and in some embodiments, the rinsing liquid 115 is the same as the setting liquid 145 or the rinsing liquid 165. Washing may be accomplished using any convenient protocol, such as a solid / liquid contacting protocol as described below.

[0036] The system 100 includes an aggregate generation module 130 for shaping and forming the washed solid composition 125 into aggregate 135. In some embodiments, shaping the washed solid composition 125 in the aggregate generation module 130 may use mechanical methods to form aggregate 135. In other embodiments, shaping the washed solid composition 125 in the aggregate generation module 130 may use a combination of mechanical methods and applied heat to form aggregate 135. For example, in one embodiment, the aggregate generation module 130 is configured such that the washed solid composition 125 is first shaped by a pin mixer and then fed into a rotating drum where it is tumbled for a short period in the presence of heat to obtain aggregate 135 and then enters the hardening module 140.

[0037] The hardening module 140 can be configured to contact the solid composition 125, which can be solidified (e.g., as described above) with a hardening liquid 145, thereby producing a hardened CO2 sequestering solid 150. Hardening refers to bringing two elements into physical proximity to one another such that they can chemically interact and harden the solid composition.

[0038] In some cases, the curing module 140 has a nozzle for spraying the curing liquid onto the solid composition 125. In some cases, the curing module 140 is configured to submerge the solid composition 125 in the curing liquid 145. In some cases, the curing module 140 includes a curing liquid 145 disposed in a reservoir of the curing module 140. The curing liquid 145 disposed in the reservoir of the curing module 140 can have any of the characteristics described above.

[0039] In some cases, the curing module 140 is configured to cure the solid composition 125 for a period ranging from 1 minute to 50 days, e.g., 1 hour to 40 days, e.g., 1 day to 30 days, or 7 days to 21 days. In some cases, the curing module 140 includes a heater to raise the temperature of the curing liquid 145, e.g., to 30° C. to 50° C. or higher, e.g., to 80° C. In some cases, the curing module 140 is configured such that the curing liquid 145 is at a temperature in the range of 15° C. to 80° C., e.g., 17° C. to 50° C., e.g., 20° C. to 50° C., including 30° C. to 50° C., and in some cases, the range is 17° C. to 25° C. during at least a portion of the curing, e.g., the entire duration of the curing. Thus, the curing module 140 can include a heater configured to heat the curing liquid 145 and the aggregate 135.

[0040] In some embodiments, the hardening liquid 145 is a composition that can be contacted with the solid composition 125, thereby hardening it to produce the hardened CO2 sequestering solid composition 150. In some embodiments, the hardening module 140 includes a single hardening step, or two or more different hardening steps, as desired. When multiple hardening steps are used, the hardening liquid 145 used in each of the multiple steps can be the same or different. Thus, in some cases, the solid composition 125 is subjected to multiple hardening steps with the same hardening liquid 145. In other instances, the solid composition 125 is subjected to multiple hardening steps with different hardening liquids 145.

[0041] The term "liquid" in "curing liquid" 145 means that the curing composition includes compounds that are in a liquid state of matter, e.g., water. For example, curing liquid 145 can be an aqueous liquid, such that water is the most abundant compound present in the curing liquid. In some cases, curing liquid 145 is substantially free or completely free of any compounds dissolved in the water of the aqueous curing liquid. In other embodiments, curing liquid 145 includes water and compounds dissolved in the water, i.e., the curing liquid is a solution that includes solutes dissolved in a solvent. In some cases, curing liquid 145 also includes compounds in a solid state, i.e., solid compounds that are not dissolved in a liquid. In some embodiments, curing liquid 145 is an emulsion, i.e., it is a mixture of two or more liquids that would normally form two immiscible layers, but the addition of an emulsifier causes the two layers to fuse together to form a single layer.

[0042] In some cases, the setting liquid 145 has a sufficient concentration of dissolved inorganic carbon to produce a desired setting composition. Dissolved inorganic carbon (DIC) refers to the amount of carbonate ions (CO 2- ), bicarbonate ion (HCO3 - ), and CO2 dissolved in the liquid. In some cases, the hardening liquid 145 has a DIC in the range of 0.01M to 10M, e.g., 0.05M to 5M, 0.1M to 4M, or 0.5M to 3M. For example, if the hardening liquid 145 contains 1M carbonate ions, 0.2M bicarbonate ions, and 0.1M dissolved CO2, the dissolved inorganic carbon concentration will be 1.3M. In some cases, the hardening liquid 145 has a concentration of positive ions in the range of 0.01M to 10M, e.g., 0.05M to 5M, 0.1M to 4M, or 0.5M to 3M, e.g., the positive ions may be Na + , K + , and NH4 + For example, in some cases, the hardening liquid 145 is selected from the group consisting of Na in the range of 0.5M to 5M. + It has a concentration of ions.

[0043] In some cases, the hardening liquid 145 allows for the temporary dissolution of solid compounds into the hardening liquid 145, followed by returning these compounds to a solid state but transitioning them into a second crystal structure. In some cases, the hardening liquid 145 favors the formation of the second crystal structure over the formation of the first crystal structure. In some embodiments, the hardening liquid 145 includes an ion, e.g., carbonate, that is also present in the initial CO2 sequestration composition. Due to solubility limitations, the presence of this ion in the hardening liquid 145 can help prevent an undesirably large amount of the initial CO2 sequestration composition 110 from dissolving in and remaining in the hardening liquid 145. In other words, the presence of this common ion can favor returning the compounds to a solid state but transitioning them into a second crystal structure. In other cases, the hardening liquid 145 can directly interact with the solid in the first crystal structure and change it to the second crystal structure without dissolving in the hardening liquid.

[0044] "Hardening" refers to altering the chemical composition of a compound. In some cases, the hardening module 140 provides the solid composition 125 with an increase in a desired property compared to the composition prior to hardening, e.g., due to a change in crystal structure. For example, in some cases, the solid composition 125 may be hardened, e.g., due to the cation source used in the method being Ca. 2+ When ionic, it includes calcium carbonate (CaCO3). Calcium carbonate has many known polymorphs, including amorphous calcium carbonate, aragonite, calcite, and vaterite. In some cases, the hardened solid composition 150 has a crystalline structure, i.e., it is not amorphous. In some cases, the hardened solid composition 150 includes calcium carbonate in the form of aragonite, calcite, or a combination thereof.

[0045] In other embodiments, hardening occurs because the hardening liquid 145 changes the pH of the initial CO2 sequestering solid composition 110. In other words, the hardening liquid 145 can have a pH that causes protonation or deprotonation of compounds in the initial CO2 sequestering solid composition 110. In some cases, the hardening process occurs because some solid compounds of the initial CO2 sequestering solid composition 110 dissolve in the hardening liquid 145, thereby separating them from the sequestering solid. The hardening liquid 145 can also contain compounds that transition from being dissolved in the hardening liquid 145 to a solid state, thereby becoming part of the sequestering solid.

[0046] Hardening Liquid 145 is Na + Alkali metal ions such as HCO3 - and CO3 2- The setting liquid 145 may also be described by the molar ratio of ammonium ions to dissolved inorganic carbon, such as 1M sodium carbonate, 2M sodium ions, 1M carbonate ions, and 2M dissolved inorganic carbon. For example, if the setting liquid 145 has 1M sodium carbonate, the concentration of sodium ions is 2M, the concentration of carbonate ions is 1M, and the molar ratio is 2. In a different example, if the setting liquid 145 has 1M sodium bicarbonate, the concentration of sodium ions is 1M, the concentration of bicarbonate is 1M, and the molar ratio is 1. In addition, in some cases, the setting liquid 145 has a combination of carbonate and bicarbonate compounds, such as 1M sodium bicarbonate and 1M sodium carbonate. In such a case, the setting liquid 145 has 3M sodium ions and 2M dissolved inorganic carbon, and the molar ratio is 1.5. Thus, in some cases, the molar ratio of alkali metal cations and ammonium ions to dissolved inorganic carbon ranges from 1 to 3, such as 1.25 to 2.75, 1.5 to 2.5, or 1.75 to 2.25. Molar ratios greater than 2 can be induced by the addition of non-dissolved inorganic carbon compounds. For example, 1 M sodium carbonate and 1 M potassium hydroxide (KOH) results in a molar ratio of alkali metal ions to dissolved inorganic carbon of 3.

[0047] In some cases, the hardening liquid 145 includes a carbonate hardening liquid, i.e., the liquid contains carbonate ions (CO 2-), bicarbonate compounds containing the bicarbonate ion (HCO3 2- ), or both. In some cases, the carbonate compound has the formula M2CO3, where M is a monovalent positive ion, such as an alkali metal cation. For example, the carbonate compound can be sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3), or potassium carbonate (K2CO3). In some cases, the setting liquid 145 includes a bicarbonate compound, for example, of formula MHCO3, where M is an ion in the monovalent position, such as an alkali metal cation. Examples of bicarbonate compounds include sodium bicarbonate (NaHCO3), ammonium bicarbonate (NH4HCO3), and potassium bicarbonate (K2HCO3).

[0048] In some cases, the hardening liquid 145 may be a phosphate hardening liquid, i.e., include a phosphate compound. As used herein, "phosphate" refers to a compound that includes four oxygen atoms bonded to a phosphorus atom, i.e., a compound that includes a phosphate group. In some cases, the phosphate compound has the formula PO4R 1 R 2 R 3 wherein R 1 , R 2 , and R 3 are each independently hydrogen or a negative charge. 1 , R 2 , and R 3 When R is all hydrogen atoms, the compound is H3PO4, which is referred to herein as phosphoric acid. 1 and R 2 is hydrogen and R 3 is negatively charged, the resulting compound is H2PO4 - which is referred to herein as the dihydrogen phosphate ion, and the hardening liquid contains an alkali metal cation, e.g., Na + Or K + and the corresponding positive ions such as R 1 is hydrogen and R 2 and R 3 is negatively charged, the resulting compound is HPO4 2-which is referred to herein as the hydrogen phosphate ion, and the hardening liquid has the corresponding positive ion or ions. R 1 , R 2 , and R 3 are all negatively charged, the compound is PO4 3- which is referred to herein as a phosphate ion, and the setting liquid has the corresponding positive ion or ions. Phosphate setting liquids can also include polyphosphate groups, i.e., groups having two or more phosphorus atoms, each bonded to four oxygen atoms, with one of the oxygen atoms bonded to two phosphorus atoms. An exemplary polyphosphate compound has the formula HO-(POH) n -H, where n is an integer equal to or greater than 2, e.g., 2 to 10,000. In some cases, the polyphosphate is deprotonated, i.e., one or more of the hydrogen atoms are replaced with a negative charge, and the hardening liquid 145 contains the corresponding positive ion, e.g., Na + and K + In some cases, the phosphate compound is an organophosphate compound, i.e., a compound having the formula PO4R 1 R 2 R 3 wherein R 1 , R 2 , and R 3 are each independently a hydrogen atom, a hydrocarbon group, or a negative charge; R 1 , R 2 , and R 3 At least one of the groups is a hydrocarbon group.

[0049] In some cases, the setting liquid 145 is a divalent alkaline earth metal, such as calcium, magnesium, etc., a setting liquid such as a calcium setting liquid, i.e., it does not contain divalent alkaline earth metal ions, such as calcium ions (Ca 2+ ) Magnesium ion (Mg 2+), and the like. In some cases, the divalent alkaline earth metal, e.g., calcium, setting liquid has an ion concentration of the divalent alkaline earth metal, e.g., calcium, in the range of 0.01M to 1.0M, such as 0.02M to 0.2M, or 0.09M to 0.9M. Such setting liquids may vary as desired so long as they provide a source of divalent alkaline earth ions, and examples of such setting liquids include, but are not limited to, CaCl2, MgCl2, and the like. In some cases where the setting liquid 145 is a calcium setting liquid, the calcium setting liquid may include, but is not limited to, CaCl2, MgCl2, and the like. 2+ and DIC to form additional CO2 sequestering solids 110.

[0050] In some cases, the setting liquid 145 includes tap water, i.e., the setting liquid includes water obtained from a municipal water supply. The term "municipal water supply" refers to potable water (i.e., drinking water) that is deemed safe for humans to drink and that is delivered by pipe to two or more businesses or homes, such as 100 or more businesses or homes. For example, a municipal water supply may obtain water from a body of water, such as a lake or river, optionally treat the water, and then distribute it to homes and businesses. The water is sometimes treated to kill microorganisms, remove solid particulates, add compounds that inhibit corrosion of pipes, add compounds that inhibit tooth decay in humans who drink the water, or combinations thereof. The setting liquid 145 can include exclusively tap water, or the setting liquid can include tap water mixed with other compounds, such as the bicarbonate compounds, carbonate compounds, or phosphate compounds described above, or combinations thereof. In some cases, tap water has a salinity, i.e., the amount of salt dissolved in the water, ranging from 0 parts per thousand (ppt) to 5 ppt (mass per volume), e.g., 0 ppt to 2 ppt, or 0 ppt to 1 ppt. In some cases, tap water meets the requirements for acceptable drinking water established by the government that has jurisdiction over the distribution of tap water. For example, the United States Environmental Protection Agency (EPA) has published the National Primary Drinking Water Regulations, which list maximum allowable levels for approximately 90 contaminants. For example, in the 2016 version of the regulations, maximum contaminant levels (MCLs) are set at 0.005 mg / L for benzene, 4.0 mg / L for fluoride, 4 millirem per year for "beta photon emitters," and 0.005 mg / L for cadmium. As another example, the European Union issued the Drinking Water Directive (Directive 98 / 83 / EC) in 1998, which lists maximum permissible levels for various contaminants, e.g., 0.001 mg / L for benzene and 1.5 mg / L for fluoride.

[0051] In some cases, the setting liquid 145 includes any combination of the setting liquids mentioned above, i.e., bicarbonate setting liquid, carbonate setting liquid, phosphate setting liquid, alkaline earth metal, e.g., calcium, setting liquid and tap water, or a composite setting liquid made up of any combination thereof.

[0052] In some cases, the pH of the hardening liquid 145 influences the hardening process. In other words, the hardening liquid 145 can have a pH that causes protonation or deprotonation of compounds in the initial CO2 sequestering solid composition. In some cases, the pH of the hardening liquid 145 is increased by the addition of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, an alkaline earth metal hydroxide, such as calcium hydroxide or magnesium hydroxide, or a combination thereof. In some cases, the hardening liquid 145 has a pH in the range of 5-14, e.g., 6-14, 7-14, 8-14, 9-14, or 10-14.

[0053] In some embodiments, the curing module 140 includes a chamber (not shown), such as a bubble or bag, to maintain a certain amount of humidity to prevent the solid composition 125 from drying out.

[0054] The hardening module 140 may contact the solid composition 125 with the hardening liquid 145 using any convenient protocol. For example, one of the elements may be stationary and the other element may move in proximity to the first element. For example, the hardening module 140 may include a reservoir in which the hardening liquid 145 may be located such that the solid composition 125 may be placed in the reservoir, thereby causing the solid composition 125 to be submerged in the hardening liquid 145. Thus, some or all of the solid composition 125 is located below the upper surface of the hardening liquid 145. The solid composition 125 may remain submerged in the hardening liquid 145 for any suitable period of time, such as 1 minute to 30 days, 1 hour to 10 days, and 12 hours to 5 days. As another example, the solid composition 125 may be stationary and the hardening liquid 145 may be sprayed onto it, i.e., the hardening liquid 145 may move to contact the surface of the solid composition 125. In some cases, spraying includes moving the hardening liquid 145 through one or more openings to form two or more separate droplets of hardening liquid before contacting the surface of the solid composition 125. Forcing the hardening liquid 145 through the one or more openings can include exerting a mechanical force on the hardening liquid 145, for example, via a pump, which can include gravity pushing the hardening liquid 145 through one or more openings, or both. After the hardening liquid 145 is sprayed onto the solid composition 125, for example, when the solid composition 125 is positioned on a filtration membrane and a suction force is applied that moves the hardening liquid 145 through the filtration membrane, the hardening liquid 145 can continue to move such that it is no longer in contact with the solid composition 125, or the hardening liquid 145 can stop moving and remain in contact with the solid composition 125 for a suitable period of time, such as 1 minute to 30 days, 1 hour to 10 days, and 12 hours to 5 days. In some cases, contacting includes moving both the hardening liquid 145 and the solid composition 125 as they come into contact with each other. For example, the solid composition 125 can be placed on a moving surface, such as a conveyor belt, and the moving surface can move the aggregate 135, for example through the openings of a sprayer, to where the hardening liquid 145 is moving, thereby causing the solid composition 125 and the hardening liquid 145 to contact each other.In some embodiments, the hardening liquid 145 is recycled after contacting the solid composition 125 on the moving surface such that the solid composition 125 can contact a second solid composition. In some cases, the hardening liquid 145 is at a temperature in the range of 5° C. to 80° C., e.g., 5° C. to 60° C., such as 10° C. to 50° C., e.g., 17° C. to 50° C., e.g., 20° C. to 50° C., during at least a portion of the contacting, e.g., the entire time of the contacting.

[0055] The hardened solid composition 150 can provide long-term storage of CO in a manner such that the CO is sequestered (i.e., fixed) in the material, and the sequestered CO does not become part of the atmosphere. When the hardened aggregate 150 is maintained under conditions for its intended use, the solids will remain fixed with the sequestered CO for extended periods of time, such as 1 year or more, 5 years or more, 10 years or more, 25 years or more, or 50 years or more, with significant release of CO from the solids, if any. For example, when the hardened aggregate 150 is maintained in a manner consistent with its intended use, the amount of CO gas released from the solids is 10% or less, such as 5% or less, or 1% or less of the total annual amount of CO in the solids when exposed to normal conditions of temperature and moisture, including precipitation at normal pH, for example, for the intended use. Any suitable surrogate marker or test that can reasonably predict such stability can be used. For example, accelerated testing including conditions of elevated temperature and / or moderate to more extreme pH conditions can reasonably indicate stability over extended periods of time. For example, depending on the intended use and environment of the solid, a sample of the hardened CO2 sequestration solid can be exposed to 50, 75, 90, 100, 120, or 150°C at 10%-50% relative humidity for 1, 2, 5, 25, 50, 100, 200, or 500 days, and a loss of less than 1%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, or 50% of its carbon can be considered sufficient evidence of stability of the solid for a given period of time (e.g., 1, 10, 100, 1000, or more than 1000 years).

[0056] In some cases, hardening causes compounds of the initial CO2 sequestration composition 110 to change from a first crystal structure to a second crystal structure, and the hardened compounds enable or increase the rate of this change. In some cases, hardening causes carbonate compounds to change from a first crystal structure in the initial CO2 sequestration solid composition 110 to a second crystal structure in the hardened CO2 sequestration aggregate 150. For example, in some cases, the first crystal structure is vaterite or amorphous calcium carbonate and the second crystal structure is aragonite or calcite. In some cases, the hardened CO2 sequestration solid composition 150 has a crystalline structure, i.e., it is not amorphous.

[0057] In some cases, the hardened CO2 sequestration solid composition 150 has different properties than the initial CO2 sequestration solid composition 110. For example, the hardened CO2 sequestration solid composition 150 may have a higher resistance to fracture than the initial CO2 sequestration solid composition 110. For example, this increased resistance to fracture may be caused by a change in crystal structure. The fracture resistance may be described in various manners. For example, in some cases, fracture resistance is the resistance of a single piece of material to break into multiple pieces upon mechanical agitation. In some cases, fracture resistance is the resistance of a single piece of material to break into multiple pieces when compressed by an external force. In some embodiments, the hardened CO2 sequestration solid composition 150 has a Mohs scratch hardness of 2 or greater according to the Mohs hardness scale. In some cases, concrete specimens containing the hardened CO2 sequestration solid composition have a Mohs scratch hardness of 2,500 psi to 4,000 psi and 100 lb / ft, respectively, according to ASTM C330. 3 ~115lb / ft 3 The specimens have average 28-day compressive strengths and calculated equilibrium densities in the range of 0.1 to 1.0 mm / s.

[0058] As an example, to perform durability testing of finished aggregates, the dried aggregate can be placed in a sieve shaker along with granite boulders to provide abrasion. For example, approximately 6 g of aggregate (3 granules) can be placed in a sieve along with 155.0 g of granite boulders. The same set of granite boulders can be used for all durability tests. In some tests, durable aggregates have been found to have a weight loss of less than 4.0%.

[0059] As an example, Figure 3B shows the results of a durability test. As shown, curing caused a decrease in the average weight loss after the durability test, such that the durability of the aggregates cured in warm 1 M Na2CO3 for 1 month is much better compared to the uncured aggregates.

[0060] The effect of spraying hardening liquids on aggregates at different temperatures is one embodiment of the present invention. Without any hardening liquid sprayed, the mass loss of the aggregates during durability testing was about 10%, while the mass loss when sprayed with 1 M sodium carbonate at 25°C and 40°C was about 6% in both cases. Thus, spraying increased durability, but spraying at 25°C or 40°C seemed to increase durability approximately equally. In other words, the temperature difference of 25°C compared to 40°C did not seem to affect the durability of the aggregates.

[0061] System 100 may optionally include a washing station 160 for treating hardened solid composition 150 to remove one or more ions / compounds associated therewith to produce a washed hardened CO2 sequestering solid composition 170. For example, washing station 160 may be used to wash hardened CO2 sequestering solid composition 150 to remove one or more compounds, e.g., compounds or ions, associated therewith using a rinsing liquid 165. For example, if a given production protocol results in the presence of chloride ions or compounds, the hardened solid may be washed to remove chloride ions or compounds. Similarly, if a given production protocol results in the presence of ammonia ions / compounds, the hardened solid composition 150 may be washed to remove such ions / compounds. In some embodiments, washing station 160 is the same as rinsing station 120, depending, for example, on the type of liquid used.

[0062] FIG. 2 illustrates an embodiment of a method 200 of operation of the system 100 for producing durable CaC03 aggregate and sand by hardening aggregate from a CO2 gas absorption process. The method 200 begins at block 210 where the module 105 prepares an initial CO2 sequestration solid composition 110 as an aggregate or coated aggregate. At block 220, the initial CO2 sequestration aggregate or coated aggregate composition is dewatered at a rinsing station 120 and washed with a suitable rinsing liquid 115 to produce a washed aggregate 125. In some embodiments, block 225 is optional and the rinsing liquid is the same as the hardening liquid. By way of example, the precipitated CaC03 slurry is washed with water 1-5 times. In some samples, the slurry is mixed with a mixing solution and dewatered. The mixed solution may be used as one solution or in combination with Na2CO3, NaHCO3, SrCl2, MgCl2, Na-silicate, silica gel, NaH2PO3, Na2HPO3, and Na3PO4 solutions. As a result, a dewatered wet CaCO3 cake with a solid content of about 50-80% is produced. The slurry can be used to make the following products: pure CaCO3 coarse aggregate and CaCO3 coated aggregate (coarse or fine). In block 230, the CaCO3 slurry is formed into aggregate. As an example, the CaCO3 slurry with a solid content of 50-80% is placed in a rotating drum for 15-40 minutes to further compress, dry and mature the unstable CaCO3 phase. The slurry is agglomerated to form aggregate.

[0063] In some embodiments, the method further includes, at block 235, optionally solidifying the aggregate if wet. As discussed above, the initial CO2 sequestration solid composition 110 can include compounds in a liquid state, such as liquid water, as well as compounds in a solid state. "Solidifying" is used interchangeably with "air drying" and includes placing the washed aggregate 125 in an environment such that liquid evaporates from the solid composition. Removing liquid from the solid composition can change the chemical composition and thereby the physical properties of the solid composition, e.g., the reduced volume of liquid can transition solutes dissolved in the liquid to a solid state. For example, the washed aggregate 125 can be placed on a solid surface so that it does not come into contact with another liquid, e.g., liquid from the solid composition evaporates and the solid composition does not gain liquid from another liquid. In some cases, step 220 includes methods to increase the evaporation rate, such as flowing a gas through the solid composition, applying a reduced gas pressure to the solid composition, increasing the temperature of the solid composition, or a combination thereof. Flowing the gas through the solid composition can be performed, for example, using a fan. A pump, for example, a vacuum pump, can be used to reduce the gas pressure and thereby increase the evaporation rate. The temperature of the washed aggregate 125 can be raised, for example, to a temperature in the range of 25° C. to 95° C., for example, 35° C. to 80° C., using, for example, an electric heater or a natural gas heater. In an embodiment, solidification can be performed by simply air drying for 1 to 30 days, or by drying at elevated temperature (30 to 200° C. for several minutes to several hours). By way of example, the aggregate can be solidified by leaving it in the open air or by placing it in a moist environment for several hours. This process can be accelerated by application of heat for 10 minutes to 2 hours depending on the temperature.

[0064] The solidification time affects the hardening of the CO2 sequestration aggregate. As discussed, in block 220, the aggregate can be allowed to "solidify" for a period of time prior to the hardening step 230. In one embodiment, the CO2 sequestration aggregate was "solidified" by leaving it in room temperature air for 1, 3, or 7 days, and then hardened by submerging in 1M sodium carbonate. Without solidification, the mass loss during durability testing was about 21%, but solidifying the aggregate for about 1 day before hardening reduced that amount to about 15%. Thus, solidification appears to be able to increase the durability of the aggregate. Increasing the solidification time to 3 or 7 days reduced the mass loss during durability testing by about 6% or about 3%, respectively. Thus, increasing the solidification time (e.g., to at least a 7-day solidification time) appears to significantly increase durability and significantly reduce mass loss from about 21% to about 3%.

[0065] At block 240, the aggregate 135 contacts the hardening liquid 145 in the hardening module 140. Contacting the aggregate 135 with the hardening liquid 145 results in the production of hardened CO2 sequestering aggregate 150. By way of example, the aggregate 135 is submerged (hardened) in or sprayed with any of the following hardening solutions at 4C to 100C for minutes to months: water, 0.1-1M Na2CO3, 0.1-1M NaHCO3, 10mM-1M Na3PO4, Na2HPO4, Na3PO4 solutions. By way of example, the solidified aggregate may be submerged in or sprayed with any of the following hardening solutions at 4C to 100C for periods ranging from 30 minutes to several months: water, 0.1-1M Na2CO3, 0.1-1M NaHCO3, 10mM-1M Na3PO4, Na2HPO4, Na3PO4 solutions.

[0066] At block 240, in some embodiments, the set aggregate 235 can be hardened by simply slowing the drying rate. For example, in one embodiment of the method, the set aggregate 235 is hardened to form the hardened aggregate 250 by being placed in an enclosed space or cavity with temperature and humidity control. In some cases, the set aggregate 235 is exposed to a temperature controlled environment whereby the humidity consists of the rinse liquid 115 in the enclosed space or cavity. In other examples, the set aggregate 235 is exposed to a temperature controlled environment whereby the humidity consists of the rinse liquid 165 in the enclosed space or cavity, and in still other examples, the set aggregate 235 is exposed to a temperature controlled environment whereby the humidity consists of the hardening liquid 145 in the enclosed space or cavity. In some of the above embodiments, or in any combination of the above embodiments, the set aggregate 235 results in the hardened aggregate 250, all of which are suitable for use as a building material, for example, as an aggregate in concrete.

[0067] In other embodiments at block 240, the temperature and humidity may be controlled to have a desired relative humidity to slow or increase the rate of hardening of the solidified aggregate 235 into hardened aggregate 250.

[0068] At block 245, in some embodiments, the method optionally further includes treating the hardened aggregate 150 to remove one or more ions / compounds associated therewith. For example, the method may include washing the hardened CO2 sequestration aggregate 150 at washing station 160 to remove one or more compounds, e.g., compounds or ions, associated therewith. For example, if a given production protocol results in the presence of chloride ions or compounds, the hardened solid may be washed to remove chloride ions or compounds. Similarly, if a given production protocol results in the presence of ammonia ions / compounds, the hardened aggregate 150 may be washed to remove such ions / compounds. Washing may be accomplished using any convenient protocol. For example, the hardened aggregate 150 may be contacted with a washing solution 165, e.g., tap water, under conditions sufficient to separate the desired ions / compounds from the hardened product (e.g., as described above). For example, the hardened aggregate 150 may be submerged in the washing liquid 165, the washing liquid 165 may flow over the hardened solids, the washing liquid 165 may contact the hardened aggregate 150 under pressure, etc. If desired, the ions / compounds removed from the hardened aggregate 150 may be recovered from the washing liquid 165, e.g., for reuse. By way of example, the hardened aggregate may be washed with water and dried in air.

[0069] The hardened CO2 sequestration solids 150 can have a variety of shapes and sizes. In block 245, optionally, the hardened CO2 sequestration aggregate 150 is formed into a plurality of hardened formed aggregates having diameters ranging from 300 μm to 50,000 μm, such as 1,000 μm to 10,000 μm, and can have a variety of shapes and sizes. In some cases, the hardened CO2 sequestration aggregates 150 can have diameters ranging from 0.00001 cm 3 ~150cm 3 , e.g. 0.01 cm 3 ~10cm 3 In some cases, there are two or more pieces having such diameters or volumes, such as 5 or more, 100 or more, or 1000 or more. In some cases, the aggregate has a volume in the range of 30 lb / ft according to ASTM C330. 3 ~100lb / ft3 , e.g. 50 lb / ft 3 ~75lb / ft 3 The dry loose bulk density may range from 0.1 to 1.0.

[0070] At block 250, the hardened CO2 sequestration aggregate 150 or multiple hardened formed aggregates are ready for use as a building material, for example, as an aggregate for concrete.

[0071] FIG. 3A shows the effect of washing and curing the CaCO3 aggregate. The CaCO3 aggregate made from the CO2 absorption process (low energy process) is weak when unwashed and strengthened by washing and curing. The chart shown in FIG. 3A shows a comparison of the water washed slurry samples to those washed with 1M NaHCO3. The samples that were only cured (no bicarbonate wash) or only washed (no curing) showed lower strengths versus both the washed and cured / bagged samples. In addition to curing with bicarbonate solution, curing (spraying) the aggregate from the washed slurry with water or bagging (no solution spraying) also shows a significant effect in terms of final aggregate strength.

[0072] Figure 3B shows the effect of washing and curing of CaCO3 coated aggregates. CaCO3 coated aggregates made from CO2 absorption process (low energy process) are weak if not washed or cured with desired solutions (mainly carbonate / bicarbonate solutions). Data shows a comparison between control (not washed / cured) and control cured with Na2CO3. Results show that Na2CO3 curing also has a positive effect on the strength of the coated sand.

[0073] Figure 4 shows scanning electron spectroscopy (SEM) images of the original slurry (unwashed), the washed and aggregate, and the final aggregate after hardening (compared to the untreated control). As shown, the final hardened aggregate is much stronger than the untreated control sample.

[0074] FIG. 5A shows the effect of washing and curing on old slurry. Normally old slurry is not capable of creating strong aggregate. However, as shown, washing alone made the old slurry much stronger, but washing and curing for 2 or 3 days has the best impact on the strength of the old slurry. FIG. 5B shows the effect of sodium and pH in the wash solution. The chart in FIG. 5B shows that pH or Na does not affect the strength of the washed and cured aggregate, rather the bicarbonate wash is the main source of strength.

[0075] FIG. 6 illustrates an embodiment of a method 600 of operation of the system 100 for producing durable CaCO3 aggregate and sand by hardening the slurry from the CO2 gas absorption process. The method 600 begins at block 610 where the module 105 prepares the initial CO2 sequestration solid composition 110 as a CaCO3 slurry. At block 620, the initial CO2 sequestration CaCO3 slurry is dewatered at a rinsing station 120 and washed with a suitable liquid 115 to produce a washed solid composition 125. As an example, the precipitated CaCO3 slurry can be washed with water 1-5 times. In some samples, the slurry is mixed with a mixed solution and dewatered. The mixed solution was used as a single solution or in combination with Na2CO3, NaHCO3, SrCl2, MgCl2, Na-silicate, silica gel, NaH2PO3, Na2HPO3, Na3PO4 solutions. As a result, a dewatered wet CaCO3 cake with a solid content of about 50-80% is produced. The slurry can be used to make various products, such as pure CaCO3 coarse aggregate and pure CaCO3. As an example, at 620, the CaCO3 suspension after the gas absorption process can be dewatered by vacuum filtration and washed with water. Then, 300 mL of 1 M NaHCO3 can be decanted over the slurry in a Buchner funnel and filtered using vacuum filtration. As a result, 363 g of CaCO3 with 63% solids can be produced (165 g of total CaCO3). The dewatered slurry can be placed in a rotating drum for agglomeration. The slurry can be sprayed with water three times and agglomerated for 20 minutes with a heater that maintains a surface temperature of 22-23°C. The drum roll provided further compaction and polymorphic transition of the unstable CaCO3 phase.

[0076] In some embodiments, the method optionally further includes solidifying the washed solid composition 125 at block 630. As discussed above, the initial CO2 sequestration solid composition 110 can include compounds in a liquid state, such as liquid water, as well as compounds in a solid state. "Solidifying" is used interchangeably with "air drying" and includes placing the washed aggregate 125 in an environment such that liquid evaporates from the solid composition. Removing liquid from the solid composition can change the chemical composition and thereby the physical properties of the solid composition, e.g., the reduced volume of liquid can transition solutes dissolved in the liquid to a solid state. For example, the washed aggregate 125 can be placed on a solid surface so that it does not come into contact with another liquid, e.g., liquid from the solid composition evaporates and the solid composition does not gain liquid from another liquid. In some cases, step 220 includes a method to increase the evaporation rate, e.g., flowing a gas through the solid composition, applying a reduced gas pressure to the solid composition, increasing the temperature of the solid composition, or a combination thereof. Flowing the gas through the solid composition can be accomplished, for example, with a fan. A pump, for example, a vacuum pump, can be used to reduce the gas pressure and thereby increase the evaporation rate. The temperature of the washed aggregate 125 can be raised, for example, to a temperature in the range of 25° C. to 95° C., for example, 35° C. to 80° C., using, for example, an electric heater or a natural gas heater. In an embodiment, solidification can be accomplished by simply air drying for 1 to 30 days, or by drying at elevated temperatures (30 to 200° C. for several minutes to several hours), or by placing in a plastic bag.

[0077] At block 640, the washed solid 135 is contacted with a hardening liquid 145 in a hardening module 140. Contacting the solid 135 with the hardening liquid 145 results in the production of a hardened CO2 sequestering solid composition 150. By way of example, the washed solid 135 may be submerged in or sprayed with any of the following hardening solutions at 4° C. to 100° C. for a hardening period that may be from 30 minutes to several months in length: water, 0.1-1 M Na2CO3, 0.1-1 M NaHCO3, 10 mM-1 M Na3PO4, Na2HPO4, Na3PO4 solution. The hardening process may include hardening in an enclosed space (such as a humidity chamber or container or bag) to slow the drying rate. As an example of hardening the slurry without flocculation, a wet slurry cake having 60-80% solids can be submerged in or sprayed (hardened) with any of the following hardening solutions at 4°C to 100°C for hours to months: water, 0.1-1M Na2CO3, 0.1-1M NaHCO3, 10mM-1M SrCl2, MgCl2, Na-silicate, silica gel, NaH2PO3, Na2HPO3, Na3PO4.

[0078] The hardened CO2 sequestration solid 150 can have a variety of shapes and sizes. In block 650, the hardened CO2 sequestration solid composition 150 is formed into a plurality of hardened formed aggregates having diameters ranging from 300 μm to 50,000 μm, such as 1,000 μm to 10,000 μm, and can have a variety of shapes and sizes. In some cases, the hardened CO2 sequestration solid composition 150 can have diameters ranging from 0.00001 cm 3 ~150cm 3 , e.g. 0.01 cm 3 ~10cm 3 In some cases, there are two or more pieces having such diameters or volumes, such as 5 or more, 100 or more, or 1000 or more. In some cases, the aggregate has a volume in the range of 30 lb / ft according to ASTM C330. 3 ~100lb / ft 3 , e.g. 50 lb / ft 3 ~75lb / ft 3 The dry loose bulk density may range from 0.1 to 1.0.

[0079] As an example, in block 650, a non-scraped agglomeration (NSA) process is used to generate aggregate from the slurry. The CaCO3 slurry cake is dewatered with paper towels and compressed by a rolling pin. The compressed cake is then cut into smaller pieces and blended with dried CaCO3 powder or waste dust fines to control surface water and prevent the pieces from agglomerating. The CaCO3 pieces and powder blend are placed in a rotating drum for 3-60 minutes for further compression and drying / maturation of the unstable CaCO3 phase. The wet aggregate is removed and placed in air to further dry and solidify for several hours to 7 days. As an example, the generated aggregate can be pure CaCO3 coarse aggregate or CaCO3 coated aggregate, and can be either coarse or fine.

[0080] At block 655, in some embodiments, the method optionally further includes treating the hardened aggregate 150 to remove one or more ions / compounds associated therewith. For example, the method may include washing the hardened CO2 sequestration aggregate 150 at washing station 160 using a rinse solution 165 to remove one or more compounds, e.g., compounds or ions, associated therewith. For example, if a given production protocol results in the presence of chloride ions or compounds, the hardened solid may be washed to remove chloride ions or compounds. Similarly, if a given production protocol results in the presence of ammonia ions / compounds, the hardened aggregate 150 may be washed to remove such ions / compounds. Washing may be accomplished using any convenient protocol. For example, the hardened aggregate 150 may be contacted with a washing solution 165, e.g., tap water, under conditions sufficient to separate the desired ions / compounds from the hardened product (e.g., as described above). For example, the hardened aggregate 150 may be submerged in washing liquid 165, the washing liquid 165 may flow over the hardened solids, the washing liquid 165 may contact the hardened aggregate 150 under pressure, etc. If desired, ions / compounds removed from the hardened aggregate 150 may be recovered from the washing liquid 165, e.g., for reuse. For example, at 655, the finished aggregate is washed with a washing liquid such as water and dried, e.g., air dried.

[0081] Figure 7 shows the strength of aggregate made from slurry curing, where the slurry is cured without flocculation. As shown in Figure 7, the control aggregate (uncured) is weaker than the slurries cured for 3 and 6 days, with the slurries cured for 6 days showing a significant increase in strength.

[0082] Steam treatment of CO2 sequestration solids The inventors have recognized that green cement / concrete compositions may contain one or more impurities, for example, due to fabrication protocols that adversely affect the functionality of the composition. As described below, the inventors have identified a method to address this issue. Thus, an embodiment of the invention may include, for example, separating impurities from a CO2-sequestering solid prepared as described above. In such an embodiment, an aspect of the method includes contacting a CO2-sequestering solid, which may or may not be a solid prepared by a hardening process as described above, in a manner sufficient to remove the impurity from the CO2-sequestering solid. An aspect of the invention includes a method of separating impurities from a CO2-sequestering solid. Separating impurities means removing impurities from a CO2-sequestering solid such that the solid no longer contains or does not contain the impurity or does not otherwise have the impurity associated with it in any way. A given method may remove a single impurity or two or more different impurities, for example, three or more, four or more, five or more, ten or more, twenty or more, etc.

[0083] The impurities that may be removed from a given solid by the method of the invention may vary. Impurities that may be removed include, but are not limited to, compounds, elements, ions, and the like. Examples of impurities that may be removed include ammonia, ammonium, chlorine, chloride anions, sodium, magnesium, calcium, bicarbonate ions, and the like. In some cases, the impurities are mediators of the CO2 sequestration solid production method, for example, as described in more detail below, and examples of these types of impurities include, but are not limited to, ammonia, ammonium, or combinations thereof. In some cases, the impurities are by-products of the CO2 sequestration solid production method, for example, as described in more detail below, and examples of these types of impurities include, but are not limited to, salts or ions thereof, for example, chloride ions. Because the method of the invention separates one or more impurities from the CO2 sequestration solid, the CO2 sequestration solid processed according to the method has a reduced mass after processing compared to before processing. The magnitude of the mass reduction may vary, but in some cases, the magnitude of the mass reduction is in the range of 0.1% to 10%, for example, 0.5% to 5%.

[0084] In certain embodiments of the invention, the CO2-sequestering solid is contacted with steam in a manner sufficient to remove one or more impurities from the CO2-sequestering solid. The term "steam" is used in its conventional sense to refer to water in the gas phase. The steam contacting the solid can be wet steam or saturated / superheated steam. In some cases, the steam has a heat of vaporization of 970 Btu / lb or less, e.g., 910 Btu / lb or less, including 880 Btu / lb or less. The solid may be contacted with the steam using any convenient protocol. In some cases, the steam flows across one or more surfaces of the solid. The flow rate of the steam across the solid surface may vary, and in some cases ranges from 1 lb / hr to 100 lb / hr, e.g., 5 lb / hr to 75 lb / hr.

[0085] The steam may be contacted with the solids in any convenient type of system. In some cases, the system used to contact the steam with the solids is a closed system, e.g., a system in which the steam and solids are not accessible by the outside environment (a system in which mass or energy can be lost to or gained from the environment). In such examples, the pressure in the closed system may vary and may be greater than atmospheric pressure, in some cases ranging from 1 to 100 psig, e.g., 3 to 15 psig. The temperature of the steam in such a system may also vary, in some cases, ranging from 100 to 170°C, e.g., 105 to 120°C. FIG. 8A provides a diagram of a closed system. As shown in FIG. 8A, aggregates are held on a mesh screen against boiling water in a sealed vessel where the pressure is greater than atmospheric pressure. Steam rising from the water flows upward through the aggregate, circulating around the aggregate on its surface and entering the pores of the aggregate, thereby treating the aggregate to remove impurities, e.g., ammonium, ammonium salts, and combinations thereof.

[0086] In some cases, the system is an open system, e.g., where the steam and solids are accessible by the outside environment (e.g., a system in which mass or energy can be lost to or gained from the environment). In an open system, the steam in contact with the solids at atmospheric pressure, e.g., 0 psig, can have a temperature of 100° C. FIG. 8B provides a diagram of an open system. As shown in FIG. 8B, the CO2 sequestering aggregate is suspended in a sieve screen (although other types of suspensions, e.g., mesh bags, may be used) above water maintained at 100° C., such that the steam generated flows upward through the aggregate and into the surface pores of the aggregate, thereby treating the aggregate to remove impurities, e.g., ammonium, ammonium salts, and combinations thereof.

[0087] In one embodiment, the CO2-sequestering solid aggregate is contacted with steam in a closed system, i.e., a closed steaming system as shown in FIG. 8A, at a contact pressure greater than atmospheric pressure in the range of about 4.3 psig to 12 psig, and at a temperature in the range of about 107° C. to 118° C., for a period of 10 minutes to 60 minutes. The impurities in the CO2-sequestering solid aggregate include a combination of ammonium, calcium, and chloride, which are by-products of the process used to prepare the CO2-sequestering solid aggregate. To verify the separation of impurities from the CO2-sequestering solid aggregate, the steamed aggregate is subjected to an ammonia test, whereby the steamed aggregate is submerged in 1 M NaOH for 5 minutes to convert any residual ammonium to ammonia, which is then quantified using an ammonia sensor. For the steamed aggregate to pass the ammonia test, in some cases it reaches an ammonia value of less than 25 ppm. Table 1 summarizes the data collected from this embodiment.

[0088] [Table 1]

[0089] With respect to the steaming embodiment described above, the present invention is not limited to the use of steaming only with hardened CO2 sequestration solids prepared as described above. Instead, steaming can be used with any CO2 sequestration solid. Examples of CO2-arranged solids that can be steamed according to embodiments of the present invention include, but are not limited to, those described in U.S. Patent Nos. 9,707,513, 9,714,406, 9,993,799, 10,197,747, 10,203,434, 10,287,439, 10,322,371, 10,711,236, 10,766,015, 10,898,854, 10,960,350, and 11,154,813, the disclosures of which are incorporated herein by reference. CO2 sequestration solids that may be treated with steam according to embodiments of the invention also include those prepared by an alkaline aggregation protocol in which a CO2-containing gas is contacted with an aqueous medium at a pH of about 10 or greater. Examples of such protocols include, but are not limited to, those described in U.S. Patents 8,333,944, 8,177,909, 8,137,455, 8,114,214, 8,062,418, 8,006,446, 7,939,336, 7,931,809, 7,922,809, and 7,914,685. Nos. 7,906,028, 7,887,694, 7,829,053, 7,815,880, 7,771,684, 7,753,618, 7,749,476, 7,744,761, and 7,735,274, the disclosures of which are incorporated herein by reference. Further details regarding steam treatment are provided in U.S. Provisional Application No. 63 / 128,483, the disclosure of which is incorporated herein by reference.

[0090] solidifiable composition In some cases, the hardened CO2 sequestration solid 150 is used in a settable composition. Settable compositions of the invention, such as concrete and mortar, are produced by combining hydraulic cement with an amount of hardened CO2 sequestration solid, such as aggregate (fine for mortar, e.g., sand, coarse with or without fines for concrete), and an aqueous liquid, such as water, either simultaneously or by precombining the cement with the aggregate and then combining the resulting dry components with water. Selection of coarse aggregate material for concrete mixes using the cement compositions of the invention may have a minimum size of about 0.05 inches (16 sieve size) and may vary in size from that minimum to 1 inch or more, including gradients between these limits, and in some cases the size of the coarse aggregate ranges from 0.0117 inches (300 microns, No. 50 sieve size) to 4 inches (100 mm). Finely divided aggregate is less than 3 / 8 inch in size and can again be graduated in much finer sizes up to about 200 sieve size, in some cases fine aggregates range in size from 0.0029 inch (75 microns, No. 200 sieve) to 0.375 inch (9.5 mm). Fine aggregates can be present in both mortars and concretes of the invention. The weight ratio of cement to aggregate in the dry component of the cement can vary and in certain embodiments ranges from 1:10 to 4:10, such as 2:10 to 5:10, including 55:100 to 70:100.

[0091] The liquid phase, e.g., an aqueous fluid, into which the dry components are combined to produce a settable composition, e.g., concrete, can vary, as desired, from pure water to water containing one or more solutes, additives, co-solvents, etc. The ratio of dry components to liquid phase combined in preparing the settable composition can vary and in certain embodiments ranges from 2:10 to 7:10, such as 3:10 to 6:10, including 4:10 to 6:10.

[0092] In certain embodiments, cement may be used with one or more admixtures. Admixtures are compositions added to concrete to provide desirable properties not available in the basic concrete mix, or to modify the properties of concrete to make it easier to use or more suitable for a particular purpose or to reduce costs. As known in the art, an admixture is any material or composition, other than hydraulic cement, aggregate, and water, used as an ingredient in concrete or mortar to improve some characteristic or reduce its cost. The amount of admixture used may vary depending on the nature of the admixture. In certain embodiments, the amount of these ingredients ranges from 1 to 50% w / w, for example, 2 to 10% w / w.

[0093] Admixtures of interest include finely divided mineral admixtures such as cementitious materials, pozzolans, pozzolans and cementitious materials, and nominally inert materials. Pozzolans include diatomaceous earth, opalescent chert, clay, shale, fly ash, silica fume, volcanic ash, and floatstone, which are some of the known pozzolans. Certain ground granular blast furnace slags and high calcium fly ash have both pozzolanic and cementitious properties. Nominally inert materials can also include finely divided ore, dolomite, limestone, marble, granite, and others. Fly ash is defined in ASTM C618.

[0094] Other types of admixtures of interest include plasticizers, accelerators, retarders, aerators, foaming agents, reduced water, corrosion inhibitors, and pigments.

[0095] Thus, admixtures of interest include, but are not limited to, set promoters, set retarders, aerators, defoamers, alkali reactivity reducers, bonding admixtures, dispersants, coloring admixtures, corrosion inhibitors, moisture-proofing admixtures, gas formers, permeability reducers, pump aids, shrinkage compensating admixtures, bactericidal admixtures, bactericidal admixtures, bactericidal admixtures, insecticidal admixtures, rheology modifiers, finely divided mineral admixtures, pozzolans, aggregates, wetting agents, strength enhancers, water repellents, as well as any other concrete or mortar admixtures or additives. Admixtures are well known in the art and any suitable admixture of the above types or any other desired type may be used, see, for example, U.S. Patent No. 7,735,274, which is incorporated herein by reference in its entirety.

[0096] In some cases, the settable composition is produced using an amount of a bicarbonate rich product (BRP) admixture, which may be in liquid or solid form, for example, as described in U.S. Pat. No. 9,714,406, the disclosure of which is incorporated herein by reference.

[0097] In certain embodiments, the settable compositions of the present invention include cement used in conjunction with fibers, for example, to form fiber-reinforced concrete. The fibers can be made from zirconia-containing materials, steel, carbon, fiberglass, or synthetic materials such as polypropylene, nylon, polyethylene, polyester, rayon, high-strength aramid (i.e., Kevlar®), or mixtures thereof.

[0098] The components of the solidifiable composition can be combined using any convenient protocol. The materials can be mixed at the time of operation, or some or all of the materials can be premixed. Alternatively, some of the materials can be mixed with water, with or without admixtures such as high-range reducing water admixtures, and then the remaining materials can be mixed with them. As a mixing device, any conventional device can be used. For example, Hobart mixers, tilted cylinder mixers, Omni mixers, Henschel mixers, V-type mixers, and Nauta mixers can be used.

[0099] Following combination of the ingredients to produce a settable composition (e.g., concrete), the settable composition, in some cases, is initially a flowable composition and then set after a given period of time. Set times may vary and in certain embodiments range from 30 minutes to 48 hours, such as 30 minutes to 24 hours, including 1 hour to 4 hours.

[0100] The strength of the set product may also vary. In certain embodiments, the strength of the set cement may range from 5 MPa to 70 MPa, such as 10 MPa to 50 MPa, including 20 MPa to 40 MPa. In certain embodiments, the set product produced from the cement of the present invention is highly durable, for example, as determined using the test method set forth in ASTM C1157.

[0101] structure Aspects of the invention further include structures produced from the hardened CO2 sequestration solids 150 and solidifiable compositions of the invention. Accordingly, further embodiments include man-made structures containing the hardened CO2 sequestration solids of the invention and methods for their manufacture. Thus, in some embodiments, the invention provides man-made structures comprising one or more hardened CO2 sequestration solids 150 as described herein. The man-made structures may be any structures in which hardened CO2 sequestration solids may be used, such as buildings, dams, dikes, roads, or any other man-made structures incorporating aggregates or rocks. In some embodiments, the invention provides man-made structures, e.g., buildings, dams, or roads, comprising the hardened CO2 sequestration solids 150 of the invention, and in some cases, the hardened CO2 sequestration solids 150 may contain CO2 from a fossil fuel source, e.g., as described above. In some embodiments, the invention provides methods for making structures, including providing aggregates of the invention.

[0102] Regardless of the scope of the appended claims, the present disclosure is also defined by the following caveats.

[0103] 1. A method for producing a hardened CO2 sequestration solid, comprising: a) preparing an initial CO2 sequestration solid composition; b) contacting the initial CO2 sequestering solid composition with sufficient hardening liquid to produce a hardened CO2 sequestering solid; A method comprising: 2. The method of claim 1, wherein the setting liquid comprises a carbonate setting liquid, a bicarbonate setting liquid, a phosphate setting liquid, a divalent alkaline earth metal setting liquid, or tap water. 3. The method of claim 2, wherein the setting liquid comprises a carbonate setting liquid. 4. The method of claim 3, wherein the carbonate hardening liquid comprises sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3), or potassium carbonate (K2CO3). 5. The method of claim 2, wherein the hardening liquid comprises a bicarbonate hardening liquid.

[0104] 6. The method of claim 5, wherein the bicarbonate setting liquid comprises sodium bicarbonate (NaHCO3), ammonium bicarbonate (NH4HCO3), or potassium bicarbonate (KHCO3). 7. The method according to any one of claims 1 to 6, wherein the hardening liquid has a dissolved inorganic carbon concentration in the range of 0.05M to 5M. 8. The method of claim 2, wherein the hardening liquid comprises a phosphate hardening liquid. 9. Phosphate hardener is H2PO4 - , HPO4 2- , and PO4 3- The method of claim 8, comprising a phosphate anion selected from the group consisting of: 10. The method of claim 2, wherein the hardening liquid comprises a divalent alkaline earth metal hardening liquid.

[0105] 11. The method of claim 10, wherein the divalent alkaline earth metal hardening liquid comprises a calcium hardening liquid. 12. The method of claim 11, wherein the calcium hardening solution comprises CaCl2. 13. The method of claim 2, wherein the hardening liquid comprises tap water. 14. The method of claim 2, wherein the setting liquid comprises a complex of two or more setting liquids selected from the group consisting of carbonate setting liquids, bicarbonate setting liquids, phosphate setting liquids, divalent alkaline earth metal setting liquids, and tap water. 15. The method of any one of claims 1 to 14, wherein the hardening liquid has a pH in the range of 5 to 14.

[0106] 16. The method of any one of claims 1 to 15, wherein the curing liquid is at a temperature in the range of 20°C to 50°C during at least a portion of the contacting. 17. The method of any one of claims 1 to 16, wherein the contacting is carried out for 1 minute to 30 days. 18. The method of any one of claims 1-17, wherein hardening results in the carbonate compound changing from a first crystal structure in the initial CO2 sequestering solid to a second crystal structure in the hardened CO2 sequestering solid. 19. The method of claim 18, wherein the carbonate compound is calcium carbonate, the first crystal structure is vaterite or amorphous calcium carbonate, and the second crystal structure is aragonite or calcite. 20. Preparing an initial CO2 sequestration solid (i) contacting the aqueous capture solution with a gaseous CO source under conditions sufficient to produce a carbonate capture solution; (ii) combining a cation source with a carbonate capture liquid under conditions sufficient to produce an initial CO2 sequestration solid; 20. The method according to any one of claims 1 to 19, comprising:

[0107] 21. The method of any one of claims 1-19, wherein preparing the initial CO2 sequestering solid composition comprises contacting an aqueous capture liquid containing a cation source with a gaseous CO2 source under conditions sufficient to produce an initial CO2 sequestering solid. 22. The method of claim 20 or 21, wherein the aqueous capture liquid comprises aqueous captured ammonia, and preparing the initial CO2 sequestering solid composition also results in the production of an aqueous ammonium salt. 23. The method of claim 22, further comprising regenerating the aqueous captured ammonia from the aqueous ammonium salt. 24. The method of any one of claims 20 to 23, wherein the cation source comprises a divalent alkaline earth metal cation. 25. The divalent alkaline earth metal cation is Ca 2+ or Mg 2+ 25. The method according to claim 24,

[0108] 26. The method of any one of claims 20 to 23, wherein the cation source comprises a transition metal cation. 27. The method according to claim 26, wherein the transition metal cation is a Mn, Fe, Ni, Cu, Co, or Zn cation. 28. The method of any one of claims 20 to 27, further comprising preparing the aqueous capture liquid by at least partially dissolving in the initial aqueous liquid a material selected from the group consisting of cement, concrete, fly ash, rock, and steel slag. 29. The method of claim 28, wherein the initial aqueous liquid comprises aqueous ammonia. 30. The method of any one of claims 1 to 29, wherein the initial CO2 sequestration solid composition comprises a precipitate and the method produces a hardened precipitate composition.

[0109] 31. The method of claim 30, further comprising producing aggregate from the hardened precipitate composition. 32. The method of any one of claims 1 to 31, wherein the initial CO2 sequestration solid composition comprises an initial aggregate. 33. The method of any one of claims 1 to 32, further comprising forming the hardened CO2 sequestration solid into a plurality of hardened formed aggregates, each having a diameter in the range of 75 μm to 100,000 μm.

[0110] 34. A hardened CO2 sequestration solid comprising: a) preparing an initial CO2 sequestration solid composition; b) contacting the initial CO2 sequestering solid composition with a carbonate hardening liquid to produce a hardened CO2 sequestering solid; 20. A hardened CO2 sequestering solid prepared by a process comprising: 35. The hardened CO2 sequestration solid of claim 34, wherein the hardened CO2 sequestration solid has a hardness of 2 or greater according to the Mohs hardness scale. 36. Concrete specimens containing hardened CO2 sequestration solids were subjected to 2,500 psi to 4,000 psi and 100 lb / ft3 compression tests, respectively, in accordance with ASTM C330. 3 ~115lb / ft 3 36. The hardened CO2 sequestration solid of claim 34 or 35, having an average 28-day compressive strength and calculated equilibrium density in the range of: 37. The hardened CO2 sequestration solid of any one of claims 34 to 36, wherein the hardened CO2 sequestration solid has a crystalline structure. 38. The hardened CO2 sequestration solid of claim 37, wherein the hardened CO2 sequestration solid comprises aragonite, calcite, or a combination thereof. 39. The hardened CO2 sequestration solid of any one of claims 34 to 38, wherein the hardened CO2 sequestration solid has a diameter in the range of 75 μm to 100,000 μm.

[0111] 40. A system for producing hardened CO2 sequestration solids, comprising: an initial CO2 sequestration solid composition preparation module; Curing module and A system comprising: 41. The system of claim 40, wherein the hardening module includes a hardening liquid comprising a carbonate hardening liquid, a bicarbonate hardening liquid, a phosphate hardening liquid, a divalent alkaline earth metal hardening liquid, or tap water. 42. The system of claim 41, wherein the hardening liquid comprises sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3), potassium carbonate (K2CO3), sodium bicarbonate (NaHCO3), ammonium bicarbonate (NH4HCO3), potassium bicarbonate (KHCO3), or combinations thereof. 43. The system of any one of claims 39 to 42, further comprising an aqueous captured ammonia regeneration module configured to supply aqueous captured ammonia to the aggregate composition preparation module. 44. The system of claim 43, wherein the aqueous captured ammonia regeneration module is configured to produce aqueous captured ammonia by distillation.

[0112] 45. The system of any one of claims 43 to 44, wherein the aqueous captured ammonia regeneration module is configured to generate aqueous captured ammonia by contacting an ammonium salt with an alkaline source. 46. ​​The initial CO2 sequestration solid composition preparation module comprises: a CO2 gas / aqueous liquid contactor module; Solid carbonate generation module and The system according to any one of appendices 40 to 45, comprising: 47. The system of any one of claims 40 to 46, wherein the initial CO2 sequestration solid composition preparation module is configured to contact CO2 gas with an aqueous liquid containing a cation source to produce a solid carbonate salt. 48. The system of any one of claims 40 to 46, wherein the initial CO2 sequestration solid composition preparation module is operably coupled to a source of flue gas.

[0113] Regardless of the scope of the appended claims, the present disclosure is also defined by the following caveats.

[0114] 1. A method for separating impurities from a CO2 sequestration solid, comprising: 16. A method comprising contacting a CO2 sequestering solid with steam in a manner sufficient to remove impurities from the CO2 sequestering solid. 2. The method of claim 1, wherein the CO2 sequestering solid is contacted with steam for a period ranging from 1 to 60 minutes. 3. The method of claim 1 or 2, wherein the CO2 sequestering solid is contacted with steam at 0 psig and 100° C. 4. The method of claim 3, wherein the CO2 sequestration solid is contacted with steam in an open system. 5. The method of any one of claims 1 to 3, wherein the CO2 sequestration solid is contacted with steam in a closed system.

[0115] 6. The method of claim 5, wherein the CO2 sequestration solid is contacted with steam at a contact pressure greater than atmospheric pressure. 7. The method of claim 6, wherein the contact pressure is in the range of 1 to 100 psig. 8. The method according to any one of claims 5 to 7, wherein the temperature is in the range of 101 to 170°C. 9. The method of any one of claims 1 to 8, wherein the impurities include a mediator of a CO2 sequestration solid production method. 10. The method of claim 9, wherein the mediator comprises ammonia, ammonium, or a combination thereof.

[0116] 11. The method of any one of claims 1 to 10, wherein the impurities include by-products of a CO2 sequestration solids production process. 12. The method of claim 11, wherein the by-product comprises a salt or ion thereof. 13. The method of claim 12, wherein the by-products include chloride ions. 14. The method of any one of claims 1 to 13, wherein the CO2 sequestration solid comprises an aggregate. 15. The method of any one of claims 1 to 14, further comprising preparing a CO2 sequestering solid.

[0117] 16. The method of claim 15, wherein preparing comprises combining a gaseous CO2 source with a capture liquid and a cation source in a manner sufficient to produce a CO2 sequestering solid. 17. The method of claim 15, wherein a gaseous CO2 source is combined with a capture liquid under conditions sufficient to produce an aqueous solution containing carbonate, bicarbonate, dissolved CO2, or a mixture thereof, and subsequently a cation source and an aqueous solution under conditions sufficient to produce a CO2 sequestering solid. 18. The method of claim 15, wherein preparing the CO2 sequestering solid composition comprises contacting an aqueous capture liquid containing a cation source with a gaseous CO2 source under conditions sufficient to produce a CO2 sequestering solid. 19. The method of any one of claims 16 to 18, wherein the aqueous capture liquid comprises aqueous captured ammonia, and preparing the CO2 sequestering solid composition also results in the production of an aqueous ammonium salt. 20. The method of claim 19, further comprising regenerating the aqueous captured ammonia from the aqueous ammonium salt.

[0118] 21. The method of any one of claims 16 to 20, wherein the cation source comprises a divalent alkaline earth metal cation. 22. The divalent alkaline earth metal cation is Ca 2+ or Mg 2+ 22. The method according to claim 21, 23. The method of any one of claims 16 to 20, wherein the cation source comprises a transition metal cation. 24. The method according to claim 23, wherein the transition metal cation is a Mn, Fe, Ni, Cu, Co, or Zn cation. 25. The method of any one of claims 16 to 24, further comprising preparing the aqueous capture liquid by at least partially dissolving in the initial aqueous liquid a material selected from the group consisting of cement, concrete, fly ash, rock, and steel slag.

[0119] 26. The method of claim 25, wherein the initial aqueous liquid comprises aqueous ammonia. 27. The method of any one of claims 1 to 26, further comprising hardening the CO2 sequestering solid. 28. The method of claim 27, wherein the CO2 sequestering solid is cured prior to contacting the CO2 sequestering solid with steam. 29. The method of claim 28, wherein the CO2 sequestering solid is cured after contacting the CO2 sequestering solid with steam.

[0120] 30. Processed CO2 sequestration solids produced in accordance with any one of appendices 1 to 29. 31. A composition comprising a treated CO2-sequestering solid according to claim 30. 32. The composition of claim 31, wherein the composition comprises concrete. 33. The composition of claim 32, wherein the composition comprises a formed object.

[0121] 34. A system for producing treated CO2 sequestration solids, comprising: A CO2 sequestering solid composition preparation module; Steam Processing Module and A system comprising: 35. The system of claim 34, wherein the steam treatment module is an open module. 36. The system of claim 34, wherein the steam treatment module is a closed module. 37. The system of claim 36, wherein the steam treatment module is a pressurized module.

[0122] In at least some of the foregoing embodiments, one or more elements used in one embodiment may be used interchangeably in another embodiment unless such substitution is technically feasible. It will be understood by those skilled in the art that various other omissions, additions and modifications may be made to the methods and structures described above without departing from the scope of the claimed subject matter. All such modifications and variations are intended to be within the scope of the subject matter defined by the appended claims.

[0123] It will be understood by those of skill in the art that, in general, the terms used herein, and in particular, in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including, but not limited to," etc.). It will be further understood by those of skill in the art that where a particular number of introduced claim recitations are intended, such intent will be expressly recited in the claim, and in the absence of such recitation, no such intent exists. For example, as an aid to understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, even if the same claim includes the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an," the use of such phrases should not be interpreted as meaning that the introduction of a claim recitation with the indefinite article "a" or "an" limits any particular claim that includes such an introduced claim recitation to an embodiment that includes only one such recitation (e.g., "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"), and the same is true for the use of definite articles used to introduce claim recitations. Also, even if a particular number of introduced claim recitations are explicitly recited, one of ordinary skill in the art will recognize that such recitation should be interpreted as meaning at least the number recited (e.g., a bare recitation of "two recitations" without other modifiers means at least two recitations, or more than two recitations).Furthermore, where a convention similar to "at least one of A, B, and C, etc." is used, such syntax is generally intended in the sense that one of ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having A alone, B alone, C alone, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). Where a convention similar to "at least one of A, B, or C, etc." is used, such syntax is generally intended in the sense that one of ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having A alone, B alone, C alone, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). Those skilled in the art will further appreciate that virtually any disjunctive word and / or disjunctive phrase presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" is understood to include the possibilities of "A" or "B" or "A and B."

[0124] Furthermore, where features or aspects of the disclosure are described in terms of a Markush group, those skilled in the art will recognize that the disclosure is also thereby described in terms of the individual members of the Markush group, or any subgroup of members of the Markush group.

[0125] As will be understood by those skilled in the art, for any and all purposes, such as providing a written description, all ranges disclosed herein also encompass any and all possible subranges, as well as combinations of subranges. Any listed range can be readily recognized as fully indicating and allowing the same range to be broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, a middle third, an upper third, etc. As will also be understood by those skilled in the art, all terms such as "up to," "at least," "greater than," "less than," etc. refer to ranges that are inclusive of the numbers recited and that can subsequently be broken down into subranges as discussed above. Finally, as will be understood by those skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 items refers to a group having 1, 2, or 3 items. Similarly, a group having 1-5 items refers to a group having 1, 2, 3, 4, or 5 items, etc.

[0126] Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be readily apparent to those skilled in the art in light of the teachings of this invention that certain changes and modifications can be made thereto without departing from the spirit or scope of the appended claims.

[0127] The examples are presented by way of illustration and not by way of limitation. The examples are presented to provide those of skill in the art with a complete disclosure and description of how to make and use the invention, and are not intended to limit the scope of what the inventors regard as their invention, nor are they intended to represent that the following experiments are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperatures, etc.), but some experimental error and deviation should be accounted for. Unless otherwise indicated, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Celsius, and pressure is at or near atmospheric pressure. Standard abbreviations may be used, such as bp (base pairs), kb (kilobases), pl (picoliters), s or sec (seconds), min (minutes), h or hr (hours), aa (amino acid), nt (nucleotide), etc.

[0128] Thus, the foregoing merely illustrates the principles of the present invention. It will be appreciated that those skilled in the art can devise various configurations that embody the principles of the present invention and are within the spirit and scope thereof, although not expressly described or shown herein. Furthermore, all examples and conditional language recited herein are intended primarily to aid the reader in understanding the principles of the present invention and the concepts contributed by the inventors to further the art, and should not be construed as limitations to such specifically recited examples and conditions. Furthermore, all descriptions herein reciting the principles, aspects, and embodiments of the present invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, such equivalents are intended to include both currently known equivalents and equivalents developed in the future, i.e., any developed elements that perform the same function, regardless of structure. Furthermore, nothing disclosed herein is intended to be made available to the public, regardless of whether such disclosure is expressly recited in the claims.

[0129] Therefore, the scope of the present invention is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of the present invention is embodied by the appended claims. In the claims, 35 U.S.C. 112(f) or 35 U.S.C. 112(6) is expressly defined to be invoked to limit a claim only if the precise phrase "means for" or the precise phrase "step for" is recited at the beginning of the limitation to such claim, and if such precise phrase is not used in the limitation to the claim, 35 U.S.C. 112(f) or 35 U.S.C. 112(6) is not invoked.

[0130] CROSS-REFERENCE TO RELATED APPLICATIONS Pursuant to 35 U.S.C. §119(e), this application claims priority to the filing dates of U.S. Provisional Application No. 63 / 128,487, filed December 21, 2020, and U.S. Provisional Application No. 63 / 128,483, filed December 21, 2020, the disclosures of which are incorporated herein by reference.

Claims

1. hardening CO ２ 1. A method for producing a sequestration solid, comprising: a) Initial CO ２ Preparing a sequestration solid composition; b) the initial CO ２ The sequestering solid composition is subjected to hardening CO ２ with sufficient hardening liquid to produce a segregation solid; A method comprising:

2. 10. The method of claim 1, wherein the setting liquid comprises a carbonate setting liquid, a bicarbonate setting liquid, a phosphate setting liquid, a divalent alkaline earth metal setting liquid, or tap water.

3. 3. The method of claim 2, wherein the setting liquid comprises a carbonate setting liquid consisting of sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3), or potassium carbonate (K2CO3).

4. The method of claim 2 , wherein the setting liquid comprises a bicarbonate setting liquid consisting of sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), or potassium bicarbonate (KHCO 3 ).

5. 3. The method of claim 2, wherein the setting liquid comprises a phosphate setting liquid comprising phosphate anions selected from the group consisting of H 2 PO 4 − , HPO 4 2− , and PO 4 3− .

6. 3. The method of claim 2, wherein the setting liquid comprises a divalent alkaline earth metal setting liquid consisting of a calcium setting liquid.

7. The method of claim 2 , wherein the setting liquid comprises tap water.

8. 3. The method of claim 2, wherein the setting liquid comprises a composite of two or more setting liquids selected from the group consisting of carbonate setting liquids, bicarbonate setting liquids, phosphate setting liquids, divalent alkaline earth metal setting liquids, and tap water.

9. The initial CO ２ Preparing the segregated solid comprises: (i) reacting the aqueous capture solution with gaseous CO under conditions sufficient to produce a carbonate capture solution; ２ contacting the source with the (ii) the initial CO ２ combining a cation source with said carbonate capture liquid under conditions sufficient to produce a sequestered solid; The method according to any one of claims 1 to 8, comprising:

10. The initial CO ２ Preparing a sequestering solid composition comprises: ２ cation source to the aqueous capture solution containing the cation source under conditions sufficient to produce a sequestered solid. ２ The method of any one of claims 1 to 8, comprising contacting with a source.

11. The aqueous capture liquid comprises aqueous capture ammonia, and the initial CO ２ 10. The method of claim 9, wherein preparing the sequestering solid composition also results in the production of an aqueous ammonium salt.

12. The curing CO ２ The sequestered solid is ２ 9. The method of any one of claims 1 to 8, further comprising contacting with steam in a manner sufficient to remove impurities from the isolated solid.

13. The initial CO ２ the sequestering solid composition comprises a precipitate, and the method produces a hardened precipitate composition; The method further comprises producing an aggregate from the hardened precipitate composition. The method according to any one of claims 1 to 8.

14. hardening CO ２ A separator solid, comprising: a) Initial CO ２ Preparing a sequestration solid composition; b) the initial CO ２ The sequestering solid composition is contacted with a carbonate hardening liquid to form a hardened CO ２ generating a segregation solid; The cured CO2 is prepared by a process comprising: ２ isolated solid.

15. hardening CO ２ 1. A system for producing sequestration solids, comprising: Initial CO ２ a sequestered solid composition preparation module; Curing module and A system comprising:

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