Method and system for using calcium compounds derived from calcined limestone

Abstract

Provided herein is a process comprising: a) calcining limestone at a cement plant to form carbon dioxide and a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof; b) treating the calcium compound with an N-containing salt in water to produce an aqueous solution comprising the calcium salt and the N-containing salt; and c) contacting the aqueous solution with carbon dioxide under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate, including vaterite, and an aqueous supernatant solution.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 62 / 876,711, filed Jul. 21, 2019, which is hereby incorporated by reference in its entirety into this disclosure.

Background Art

[0002] Carbon dioxide (CO2) emissions have been identified as a major contributor to the greenhouse effect. CO2 is a by - product of combustion and causes operational, economic, and environmental problems. An increase in the concentration of CO2 and other greenhouse gases in the atmosphere can be predicted to further enhance heat retention in the atmosphere, resulting in an increase in surface temperature and rapid climate change. Additionally, an increase in atmospheric CO2 levels may further acidify the world's oceans due to the dissolution of CO2 and the formation of carbonic acid. The effects of climate change and ocean acidification, if not addressed in a timely manner, may become more costly economically and harmful to the environment. To reduce the potential risks of climate change, the isolation and avoidance of CO2 from various anthropogenic processes are necessary.

Summary of the Invention

Means for Solving the Problems

[0003] In one aspect, a method is provided that includes: a) firing limestone in a cement factory to form carbon dioxide and a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof; b) treating the calcium compound with an N-containing salt in water to produce an aqueous solution containing a calcium salt and the N-containing salt; and c) contacting the aqueous solution with carbon dioxide under one or more precipitation conditions to produce a precipitate containing calcium carbonate and an upper clear aqueous solution, wherein the calcium carbonate contains baterite. In some embodiments of the foregoing aspect, the calcium oxide is unslaked lime, low-reactivity lime, high-reactivity lime, or a combination thereof. In some embodiments of the foregoing aspect and embodiments, the firing step is performed in a blast furnace or a rotary kiln. In some embodiments of the foregoing aspect and embodiments, the cement factory is a wet process factory or a dry process factory.

[0004] In some embodiments of the foregoing aspect and embodiments, the treating step further includes adding anhydrous ammonia or an aqueous ammonia solution.

[0005] In some embodiments of the foregoing aspect and embodiments, the N-containing salt is an N-containing inorganic salt, an N-containing organic salt, or a combination thereof. In some embodiments of the foregoing aspect and embodiments, the N-containing salt is an N-containing inorganic salt. In some embodiments of the foregoing aspect and embodiments, the N-containing inorganic salt is selected from the group consisting of ammonium halides, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite, and combinations thereof. In some embodiments of the foregoing aspect and embodiments, the ammonium halide is ammonium chloride. In some embodiments of the foregoing aspect and embodiments, the N-containing salt is ammonium chloride. In some embodiments of the foregoing aspect and embodiments, the N-containing salt is an N-containing organic salt having an N-containing organic compound selected from the group consisting of aliphatic amines, alicyclic amines, heterocyclic amines, and combinations thereof.

[0006] In some embodiments of the foregoing aspects and embodiments, the molar ratio of the N-containing salt to the calcium compound is between about 0.5:1 and 2:1 by weight. In some embodiments of the foregoing aspects and embodiments, the method further comprises a step of removing and optionally recovering ammonia and / or N-containing salts, the step comprising: (i) recovering a gas exhaust stream containing ammonia during a treatment step and / or a contact step; (ii) further comprising a step of recovering residual N-containing salts from the supernatant aqueous solution, wherein the supernatant aqueous solution contains residual N-containing salts; and (iii) further comprising a step of removing and optionally recovering residual N-containing salts from the precipitate, wherein the precipitate contains residual N-containing salts, and using one or more of the steps. In some embodiments of the foregoing aspects and embodiments, the residual N-containing salts are ammonium chloride, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium hydrogen sulfide, ammonium thiosulfate, ammonium nitrate, ammonium nitrite, or a combination thereof.

[0007] In some embodiments of the foregoing aspects and embodiments, the method further comprises a step of recovering residual N-containing salts from the supernatant aqueous solution using a recovery process selected from the group consisting of pyrolysis, pH adjustment, reverse osmosis, multi-stage flash, multiple effect distillation, vapor recompression, distillation, and combinations thereof.

[0008] In some embodiments of the foregoing aspects and embodiments, the method further comprises a step of recycling the recovered residual N-containing salts back to a treatment step of the process, a contact step of the process, or a combination thereof.

[0009] In some embodiments of the foregoing aspects and embodiments, the step of recovering the gas exhaust stream containing ammonia includes subjecting the gas exhaust stream containing ammonia to a scrubbing process, the scrubbing process including scrubbing the gas exhaust stream containing ammonia with carbon dioxide and water from an industrial process to produce an ammonia solution. In some embodiments of the foregoing aspects and embodiments, the step of recovering the gas exhaust stream containing ammonia includes subjecting the gas exhaust stream containing ammonia to a scrubbing process, the scrubbing process including scrubbing the gas exhaust stream containing ammonia with hydrochloric acid and water to produce an ammonium chloride solution.

[0010] In some embodiments of the foregoing aspects and embodiments, the ammonia solution optionally contains carbamate for recycling back to the contacting step.

[0011] In some embodiments of the foregoing aspects and embodiments, step (iii) of removing and optionally recovering the residual N-containing salts from the precipitate includes heating the precipitate between about 150 and 360 °C or between about 100 and 360 °C or between about 150 and 200 °C to evaporate the N-containing salts from the precipitate and optionally recovering the N-containing salts by condensation.

[0012] In some embodiments of the foregoing aspects and embodiments, the calcium carbonate contains reactive battelite. In some embodiments of the foregoing aspects and embodiments, the calcium carbonate contains reactive battelite remaining in the precipitate as reactive battelite after heating in step (iii).

[0013] In some embodiments of the foregoing aspects and embodiments, the heating of the precipitate between about 100 and 360 °C is carried out for more than about 10 minutes or between about 10 and 60 minutes. In some embodiments of the foregoing aspects and embodiments, the N-containing salts evaporate from the precipitate in a form containing ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof.

[0014] In some embodiments of the foregoing aspects and embodiments, the method further comprises adding water to a precipitate containing reactive brucite to convert the brucite to aragonite, which aggregates and hardens to form cement or a cement product.

[0015] In some embodiments of the foregoing aspects and embodiments, the cement product is a formed building material selected from stone units, building panels, conduits, basins, beams, columns, slabs, sound barriers, insulation materials, and combinations thereof.

[0016] In some embodiments of the foregoing aspects and embodiments, the aqueous solution further comprises a solid. In some embodiments of the foregoing aspects and embodiments, the method further comprises separating the solid from the aqueous solution by filtration and / or centrifugation prior to the contacting step. In some embodiments of the foregoing aspects and embodiments, the separated solid is added to the precipitate as a filler or supplementary cementitious material (SCM).

[0017] In some embodiments of the foregoing aspects and embodiments, the method further comprises recovering residual N-containing salts from the solid using a recovery process selected from the group consisting of rinsing, pyrolysis, pH adjustment, and combinations thereof.

[0018] In some embodiments of the foregoing aspects and embodiments, the solid is not separated from the aqueous solution, and the aqueous solution is contacted with carbon dioxide to produce a precipitate further comprising the solid. In some embodiments of the foregoing aspects and embodiments, the solid comprises carbon, silica, iron oxide, aluminum oxide, or combinations thereof. In some embodiments of the foregoing aspects and embodiments, the solid is present in the aqueous solution, in the precipitate, or in combinations thereof, between 1 and 40 wt%.

[0019] In some embodiments of the foregoing aspects and embodiments, one or more precipitation conditions are selected from temperature, pH, pressure, ion ratio, precipitation rate, presence of additives, presence of ionic species, concentration of additives and ionic species, stirring, residence time, mixing rate, stirring mode, seed crystal, catalyst, presence of a membrane or substrate, dehydration, drying, ball milling, and combinations thereof. In some embodiments of the foregoing aspects and embodiments, one or more precipitation conditions that are favorable for the formation of calcium carbonate or favorable for the formation of reactive brucite include a pH between 7 and 8.5 of the aqueous solution, a temperature between 20 and 80 °C of the solution, a residence time between 15 and 60 minutes, or combinations thereof.

[0020] In one aspect, products formed by the aspects and embodiments of the foregoing method are provided.

[0021] The features of the present invention are described together with the particularity of the appended claims. The features and advantages of the present invention will be better understood by referring to the following detailed description that describes exemplary embodiments in which the principles of the present invention are utilized, and the following appended drawings.

Brief Description of the Drawings

[0022]

Figure 1

[0023]

Figure 2

Modes for Carrying Out the Invention

[0024] This specification provides a method and system for producing calcium carbonate using lime and waste from a cement factory that burns limestone. The products obtained from the firing of limestone include calcium oxide (lime or quicklime), calcium hydroxide (slaked lime), and waste gases such as carbon dioxide. This specification provides a unique method and system for forming calcium carbonate using lime and CO2 from a cement factory that can be used in the various products described herein. In some embodiments of the methods provided herein, calcium oxide and / or calcium hydroxide from a cement factory are treated with an N-containing salt to solubilize the calcium compound in an aqueous solution, and then the aqueous solution is treated with carbon dioxide gas to form a precipitate or precipitated material containing calcium carbonate.

[0025] In some embodiments, calcium carbonate is formed in the vaterite polymorphic form, or in some embodiments, the calcium carbonate is precipitated calcium carbonate (PCC). The PCC may be in the form of vaterite, aragonite, calcite, or combinations thereof. In some embodiments, the calcium carbonate is in a stable vaterite form or a reactive vaterite form, both of which are described herein. In some embodiments, the precipitate containing reactive vaterite has unique properties including, but not limited to, cementation properties by converting to aragonite which coagulates with high compressive strength and cements. In some embodiments, the conversion from vaterite to aragonite results in a cement that can be used to form building materials and / or cement products, such as, but not limited to, formed building materials further described herein, such as building panels. In some embodiments, the vaterite in the product is stable (does not convert to aragonite) and can be used as a filler or supplementary cementitious material (SCM) when mixed with other cements, such as ordinary Portland cement (OPC). The precipitate containing vaterite may also be used as an aggregate where the precipitate containing reactive vaterite converts to aragonite after contact with water, the aragonite coagulates and cements, and is then ground to form the aggregate after cementation. In some embodiments where the calcium carbonate is formed as PCC, the PCC material is cementitious or can be used as a filler in products such as paper products, polymer products, lubricants, adhesives, rubber products, chalk, asphalt products, paints, abrasives for paint removal, personal care products, cosmetics, cleaning products, personal hygiene products, ingestible products, agricultural products, soil amendment products, pesticides, environmental remediation products, and combinations thereof. Such use of the precipitate as a filler in non-cement products is described in U.S. Patent No. 7,829,053, issued November 9, 2010, the entire disclosure of which is incorporated herein by reference.

[0026] The N-containing salts used to solubilize calcium ions derived from calcium compounds can leave residual N-containing salts in the supernatant solution and in the precipitate itself after the precipitate has formed. In some embodiments, by way of example only, the presence of residual N-containing salts in the precipitate, such as ammonium chloride, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium hydrogen sulfide, ammonium thiosulfate, ammonium nitrate, ammonium nitrite or any other N-containing organic salt, or combinations thereof, can be undesirable because such N-containing salts may be harmful to the cement product formed from the precipitate material. For example, chlorides in cement products can be corrosive to metal structures used with the cement products. Further, residual ammonia can add an offensive odor to the product. Additionally, wasted residual N-containing salts that are not recovered in the precipitate and supernatant solution can be economically and environmentally infeasible. Various methods are provided herein for removing and optionally recovering residual N-containing salts from the supernatant solution and precipitate.

[0027] Before the present invention is described in detail, it is to be understood that the invention is not limited to the particular embodiments described, and accordingly can, 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.

[0028] Where a range of values is provided, unless the context clearly dictates otherwise, each value between the upper and lower limits of that range, to one-tenth of the unit of the lower limit, and any other value or intervening value described within the stated range, is also encompassed by the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed by the invention, subject to any specific exclusions of the stated range. Where the stated range includes one or both of the boundaries, ranges excluding one or both of those included boundaries are also included in the invention.

[0029] A particular range is presented herein with the term "about" placed before a numerical value. As used herein, the term "about" is used to support literally both the exact number placed thereafter and a number close to or approximating the number placed thereafter. When determining whether a number is close to or approximating a specifically recited number, a number not recited as being close or approximating can be a number that provides a number substantially equivalent to the specifically recited number in the context in which it is presented.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, representative, exemplary methods and materials are described herein.

[0031] All publications, patents, and patent applications cited herein are hereby incorporated by reference as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference herein. Further, each cited publication, patent, or patent application is incorporated by reference herein to disclose and describe the subject matter with respect to which it is cited. The citation of any publication is for its disclosure prior to the filing date of the present application and should not be construed as an admission that the present invention described herein has the right to antedate such publication with respect to prior art patents. Further, the provided publication dates may be different from the actual publication dates of the publications and may need to be independently verified.

[0032] As used in this specification and the appended claims, it should be noted that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Further, it should be noted that the claims may be drafted to exclude any optional elements as desired. Accordingly, this singular form recitation is intended to serve as a precursor for the use of exclusive terms such as "solely", "only", etc., or the use of "negative" limitations, in connection with the recitation of elements of the claims.

[0033] As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has separate components and features, and they can be readily separated from or combined with any of the features of some other embodiments without departing from the scope or spirit of the present invention. Any of the methods described can be performed in the order of the events described, or in any other order that is logically possible. I. Methods and Systems

[0034] Methods and systems are provided for utilizing calcium compounds and CO2 from a cement plant that has undergone limestone calcination to form polymorphs of calcium carbonate. "Limestone", as used herein, means CaCO3 and can further include other impurities typically present in limestone. "Calcium compound", as used herein, includes any calcium compound formed from the calcination of limestone. The methods and systems provided herein utilize CO2 and a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof, from a cement plant that is calcining limestone, to form a precipitate material that includes calcium carbonate, such as, but not limited to, stable or reactive vaterite or PCC. These methods and systems are as described in more detail herein. The polymorphs of calcium carbonate, such as vaterite, formed herein can be used as cement or filler. In some embodiments, the calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof can act as both a source of divalent cations (Ca 2+ ) and a proton remover. In some embodiments, calcium hydroxide formed by solubilizing calcium oxide in water can provide calcium ions as a source of divalent cations and hydroxide as a source of proton remover, and react with carbon dioxide to form a calcium carbonate precipitate. The vaterite polymorph of the calcium carbonate precipitate may be a stable vaterite that can act as a filler in a product, or the vaterite may be a reactive vaterite that can convert to aragonite during the dissolution reprecipitation process described herein.

[0035] In some embodiments of the methods provided herein, a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof is treated with an N-containing salt to solubilize the calcium compound in an aqueous solution, and then the aqueous solution is treated with carbon dioxide gas to form a precipitate containing calcium carbonate. The above process can result in residual N-containing salts remaining in the supernatant solution and in the precipitate itself after the precipitate is formed. Various methods are provided herein for removing and optionally recovering the residual N-containing salts from the supernatant solution and the precipitate. In some embodiments, the calcium compound obtained after calcination of limestone may contain sulfur depending on the source of the limestone. Sulfur in the calcium compound can be introduced into the aqueous solution after solubilizing the calcium compound with the N-containing salt. In an alkaline solution, various sulfur compounds containing various sulfur ion species can be present in the solution, including, but not limited to, sulfite (SO3 2- ), sulfate (SO4 2- ), hydrosulfide (HS - ), thiosulfate (S2O3 2- ), polysulfide (S n 2- ), thiol (RSH), etc. As used herein, "sulfur compound" includes any sulfur ion-containing compound. Examples of sulfur compounds are provided herein. Various methods are provided herein for removing and optionally recovering the sulfur compounds from the supernatant solution and the precipitate.

[0036] In one aspect, a method is provided that includes: a) in a cement factory, firing limestone to form carbon dioxide and a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof; b) treating the calcium compound with an N-containing salt in water to produce an aqueous solution containing a calcium salt and the N-containing salt; and c) contacting the aqueous solution with carbon dioxide under one or more precipitation conditions to produce a precipitate containing calcium carbonate and containing baterlite and an upper clear aqueous solution. In some embodiments of the foregoing aspect, the method further includes dehydrating the precipitate to separate the precipitate from the upper clear aqueous solution. In some embodiments of the foregoing aspect, the calcium carbonate contains reactive baterlite. In some embodiments of the foregoing aspects and embodiments, the calcium carbonate contains more than 50 wt% reactive baterlite.

[0037] The foregoing aspects and embodiments are shown in FIG. 1. It should be understood that depending on the desired result, the steps shown in FIG. 1 can be modified, or the order of the steps can be changed, or additional steps can be added or deleted. As shown in FIG. 1, a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof, and CO2 (step A in FIG. 1) obtained from a cement factory through the firing of limestone are provided to the methods and systems provided herein to produce a precipitate containing calcium carbonate.

[0038] Firing or calcining is a heat treatment process that results in the thermal decomposition of limestone. Limestone is a naturally occurring mineral. The chemical composition of this mineral varies by region and can also vary between different deposits in the same region. Thus, the calcium oxide and / or calcium hydroxide obtained by firing limestone from each natural deposit can also vary. Typically, limestone can be composed of calcium carbonate (CaCO3), magnesium carbonate (MgCO3), silica (SiO2), alumina (Al2O3), iron (Fe), sulfur (S), or other trace elements.

[0039] Limestone deposits are widely distributed. Limestones from various deposits may have different physicochemical properties and can be classified according to their chemical composition, texture, and geological formation. Limestone can be a high-calcium type where the carbonate content is mainly composed of calcium carbonate and the magnesium carbonate content is 5% or less, a magnesium type containing about 5-20% magnesium carbonate, or can contain between 20-45% MgCO3 with the balance being calcium carbonate and can be classified as a dolomite type. Limestones from different sources can vary significantly in chemical composition and physical structure. It should be understood that the methods and systems provided herein are applicable to all cement plants that calcine limestone from any of the sources listed above or commercially available sources.

[0040] The calcination of limestone is a decomposition process in which the chemical reaction of the decomposition of limestone is CaCO3 → CaO + CO2 (gas) as follows.

[0041] Calcium oxide can exist in a dry or wet form (e.g., calcium hydroxide), depending on the conditions. The production of calcium oxide (lime or quicklime) can vary depending on the type of furnace, the firing conditions, and the raw material, i.e., the properties of the limestone. At relatively low firing temperatures, the product formed in the furnace may contain both unburned carbonate and lime and may be called incompletely burned lime. As the temperature rises, soft burned lime or highly reactive lime can be produced. At even higher temperatures, dead burned lime or low reactive lime can be produced. Soft burned lime is produced when the reaction front reaches the core of the filled limestone and converts all the carbonate present to lime. High productivity products may be relatively soft, contain small lime microcrystals, and have an open porous structure with an easily assessable interior. Such lime can have optimal properties of high reactivity, high surface area, and low bulk density. Beyond this stage, increasing the degree of firing can cause the lime microcrystals to grow into larger aggregates and sintered products. This can reduce the surface area, porosity, and reactivity and increase the bulk density. This product may be known as dead burned lime or low reactive lime. Without being bound by any theory, the methods and systems provided herein utilize any one or combination of the aforementioned limes.

[0042] The production of calcium compounds by firing limestone can be carried out using various types of furnaces, such as, but not limited to, blast furnaces or rotary kilns. These devices for firing are suitable for firing limestone in the form of lumps having a diameter from a few millimeters to several tens of millimeters. The waste streams from cement factories include waste streams from both wet process factories and dry process factories, which can use blast furnaces or rotary kilns and may include pre - firing furnaces. These industrial factories can each burn a single fuel or burn two or more types of fuels, sequentially or simultaneously.

[0043] As shown in FIG. 1, the limestone obtained from the limestone quarry is fired in a cement factory, resulting in the formation of a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof, and CO2 gas. The calcium compound may be calcium oxide in solid form from a dry furnace / cementing process and / or a combination of calcium oxide and calcium hydroxide in slurry form within a wet furnace / cementing process. In the wet case, calcium oxide (also known as a basic anhydride that turns into its hydroxide form in water) may be present in its hydrated form, for example, but not limited to, calcium hydroxide. Calcium hydroxide (also called slaked lime) is the common hydrated form of calcium oxide, but other intermediate hydrated complexes and / or water complexes can also be present in the slurry, and all of them are included within the scope of the methods and systems provided herein.

[0044] In the methods and systems provided herein, the calcium compound obtained from the cement factory is treated with a solubilizing agent, such as an N-containing salt, or solvated therewith to improve its solubility (step B in FIG. 1). "Treat", "solvate", "solubilize", or their grammatical equivalents are used interchangeably herein and include the solubilization of the calcium compound in an aqueous medium. In some embodiments, the calcium compound slurry obtained from a wet process cement factory may be subjected to a dehydration step (not shown in the figure) if necessary, where residual water may be removed, and the dehydrated residue may be subjected to further treatment (e.g., solvation with a solubilizing agent, such as an N-containing salt). The calcium compound slurry can be dehydrated using any technique, such as, but not limited to, centrifugation.

[0045] Calcium oxide may be insoluble in water. In the methods and systems provided herein, the solubility of calcium oxide is increased by treating it with a solubilizing agent, such as an N-containing salt and / or a borate. In some embodiments, the calcium compound is treated with an N-containing salt.

[0046] For purposes of illustration only, in the figures, the N-containing salt solution is shown as an ammonium chloride (NH4Cl) solution, and the subsequent calcium salt is shown as calcium chloride (CaCl2). Various examples of N-containing salts are provided herein, all of which are within the scope of the present invention.

[0047] In some embodiments of the foregoing aspects and embodiments, the N-containing salt is an N-containing inorganic salt, an N-containing organic salt, or a combination thereof. "N-containing salt", as used herein, is a salt that partially or completely or substantially solubilizes or dissolves the calcium compound obtained after the calcination of limestone. The calcium compound can be calcium oxide, calcium hydroxide, any other derivative of calcium, or a combination thereof.

[0048] "N-containing inorganic salt", as used herein, includes any inorganic salt having nitrogen. Examples of N-containing inorganic salts include, but are not limited to, ammonium halides (where the halogen is any halogen), ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite, and the like. In some embodiments, the ammonium halide is ammonium chloride or ammonium bromide. In some embodiments, the ammonium halide is ammonium chloride. Such chemicals are well known in the art and are commercially available.

[0049] "N-containing organic salt", as used herein, includes any salt of an organic compound having nitrogen. Examples of N-containing organic compounds include, but are not limited to, aliphatic amines, alicyclic amines, heterocyclic amines, and combinations thereof. Such chemicals are well known in the art and are commercially available.

[0050] "Aliphatic amine", as used herein, has the formula (R) n -NH 3-nAny alkylamine containing (where n is an integer from 1 to 3 and each R is independently a linear or branched substituted or unsubstituted alkyl having from 1 to 8 carbon atoms). Formula (R) n -NH 3-n An example of the corresponding salt of the alkylamine of is (R) n -NH 4-n + Cl - or (R) n -NH 4-n + Br - In some embodiments, when R is a substituted alkyl, the substituted alkyl is independently substituted with halogen, hydroxyl, acid and / or ester.

[0051] For example, when R is alkyl in (R) n -NH 3-n the alkylamine may be, by way of example only, a primary alkylamine such as methylamine, ethylamine, butylamine, pentylamine etc., the alkylamine may be, by way of example only, a secondary amine such as dimethylamine, diethylamine, methylethylamine etc., and / or the alkylamine may be, by way of example only, a tertiary amine such as trimethylamine, triethylamine etc.

[0052] For example, when R is a substituted alkyl substituted with hydroxyl in (R) n -NH 3-n the substituted alkylamine includes, without limitation, alkanolamines such as monoalkanolamine, dialkanolamine, or trialkanolamine, for example monoethanolamine, diethanolamine, or triethanolamine etc.

[0053] For example, when R is a substituted alkyl substituted with halogen in (R) n -NH 3-n the substituted alkylamine is, for example, chloromethylamine, bromomethylamine, chloroethylamine, bromoethylamine etc.

[0054] For example, when R is a substituted alkyl substituted with an acid in (R) n -NH 3-n the substituted alkylamine is, for example, an amino acid. In some embodiments, the aforementioned amino acid has a polar uncharged alkyl chain, examples of which include, but are not limited to, serine, threonine, asparagine, glutamine, or combinations thereof. In some embodiments, the aforementioned amino acid has a charged alkyl chain, examples of which include, but are not limited to, arginine, histidine, lysine, aspartic acid, glutamic acid, or combinations thereof. In some embodiments, the aforementioned amino acid is glycine, proline, or combinations thereof.

[0055] "alicyclic amine", as used herein, refers to the formula (R) n -NH 3-n including any alicyclic amine (n is an integer from 1 to 3, and R is independently one or more rings of all carbon, and the ring may be saturated or unsaturated, but not aromatic). The alicyclic compound can have one or more attached aliphatic side chains. An example of the corresponding salt of the alicyclic amine of the formula (R) n -NH 3-n is (R) n -NH 4-n + Cl - Examples of alicyclic amines include, but are not limited to, cycloalkylamines, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, and the like.

[0056] "heterocyclic amine", as used herein, includes at least one heterocyclic aromatic ring attached to at least one amine. Examples of heterocyclic rings include, but are not limited to, pyrrole, pyrrolidine, pyridine, pyrimidine, and the like. Such chemical substances are well known in the art and are commercially available.

[0057] In some embodiments, other examples of solubilizing agents (used alone or in combination with N-containing salts) include borates. Examples of borates include, but are not limited to, borax, colemanite, ulexite, kernite, boracite, painite, or combinations thereof.

[0058] As shown in step B of FIG. 1, the N-containing salt is exemplified as ammonium chloride (NH4Cl). It should be understood that NH4Cl is shown for illustrative purposes only, and any other N-containing salt (or any borate) can be used in the methods and systems provided herein. In FIG. 1, one or more steps can be omitted or modified, or the order of the steps can be changed. Calcium oxide and calcium hydroxide are such that the reactions that can occur are CaO (solid) + 2NH4Cl (aqueous solution) → 2NH3 (aqueous solution) + CaCl2 (aqueous solution) + H2O (liquid) Ca(OH)2 + 2NH4Cl (aqueous solution) → 2NH3 + CaCl2 + 2H2O solvated or solubilized by treatment with NH4Cl (fresh and recycled as further described below).

[0059] In some embodiments, N-containing salts, such as, but not limited to, ammonium chloride solutions, can be supplemented with anhydrous ammonia or aqueous ammonia to maintain an optimal level of ammonium chloride in the solution.

[0060] In some embodiments, the amount of the N-containing salt, such as an N-containing inorganic salt, an N-containing organic salt, or a combination thereof, is 30% in excess relative to the calcium compound. In some embodiments, the N-containing salt is in a ratio of 0.5:1 to 4:1 (N-containing salt (or borate):calcium compound) or 0.5:1 to 2:1 or 0.5:1 to 1.5:1 or 1:1 to 1.5:1 or 2:1 to 4:1 or 2:1 to 3:1 or 2.5:1 to 3:1 or 3:1 to 4:1, or 1.5:1 or 2:1 or 2.5:1 or 3:1 or 3.5:1 or 4:1 with respect to the calcium compound. In some embodiments, the N-containing salt, such as the N-containing inorganic salt, is in a ratio of 0.5:1 to 4:1 (N-containing inorganic salt:calcium compound) or 0.5:1 to 2:1 or 0.5:1 to 1.5:1 or 1:1 to 1.5:1 or 2:1 to 4:1 or 2:1 to 3:1 or 2.5:1 to 3:1 or 3:1 to 4:1, or 2:1 or 3:1 or 4:1 with respect to the calcium compound. In some embodiments, the aforementioned ratio or such a ratio herein is a molar ratio or a wt% ratio.

[0061] In some embodiments of the methods described herein, no polyhydroxy compound is used to form the precipitate and / or product provided herein.

[0062] For example, stirring can be used to process the calcium compound by eliminating hot spots and cold spots. In some embodiments, the concentration of the calcium compound in water can be between 1-10 g / L, between 10-20 g / L, between 20-30 g / L, between 30-40 g / L, between 40-80 g / L, between 80-160 g / L, between 160-320 g / L, between 320-640 g / L, or between 640-1280 g / L. To optimize the purification / solvation of the calcium compound, high shear mixing, wet milling, and / or sonication can be used to break down the calcium compound. During and / or after high shear mixing and / or wet milling, the suspension of the calcium compound can be treated with an N-containing salt and then contacted with carbon dioxide from the effluent of a cement furnace (as shown in Figure 1).

[0063] In some embodiments, treatment of the calcium compound with an N-containing salt (e.g., ammonium chloride) and optionally ammonia forms a calcium salt, an aqueous solution of the N-containing salt, and optionally a solid. In some embodiments, solid insoluble impurities can be removed from the aqueous calcium chloride solution, and then the aqueous solution is treated with carbon dioxide in the above process (step C in Figure 1). The solid can be removed from the aqueous solution by filtration and / or centrifugation techniques, if necessary.

[0064] In some embodiments, the solid impurities may not be removed from the above aqueous solution (not shown in Figure 1), and the aqueous solution containing the calcium salt and the above solid are contacted with carbon dioxide to form a precipitate. In such embodiments, the precipitate further contains a solid.

[0065] In some embodiments, the solid obtained from the solvation of the calcium compound (shown as insoluble impurities in Figure 1) is a calcium-depleted solid and can be used as a cement substitute (e.g., a substitute for Portland cement).

[0066] In some embodiments, the solid is present in the aqueous solution, in the precipitate material, or a combination thereof, in an amount between 1 and 40 wt%, or between 1 and 30 wt%, or between 1 and 20 wt%, or between 1 and 10 wt%, or between 1 and 5 wt%, or between 1 and 2 wt%.

[0067] As shown in step D of FIG. 1, when an aqueous solution containing a calcium salt (and optionally a solid) is contacted with carbon dioxide from a cement factory, the following reaction occurs. CaCl2 (aqueous solution) + 2NH3 (aqueous solution) + CO2 (gas) + H2O → CaCO3 (solid) + 2NH4Cl (aqueous solution)

[0068] Absorption of CO2 into the solution produces a CO2-saturated water containing carbonic acid, which is in equilibrium with both bicarbonate and carbonate species. The precipitate material is prepared under one or more precipitation conditions (as described herein) suitable for forming a laterite-containing material or a PCC material.

[0069] An aqueous solution of a calcium salt obtained from the treatment of a calcium compound using an N-containing salt, such as an ammonium salt, can be contacted with CO2 from a cement plant at any time before, during, or after the calcium salt is subjected to one or more precipitation conditions (i.e., conditions that enable precipitation of a precipitating substance). Thus, in some embodiments, the aqueous solution of the calcium salt solution is contacted with CO2 before the aqueous solution is subjected to precipitation conditions that are favorable for the formation of a precipitating substance comprising stable or reactive vaterite or PCC. In some embodiments, the aqueous solution of the calcium salt solution is contacted with CO2 while the aqueous solution is subjected to precipitation conditions that are favorable for the formation of a precipitating substance comprising stable or reactive vaterite or PCC. In some embodiments, the aqueous solution of the calcium salt solution is contacted with CO2 before and while the aqueous solution is subjected to precipitation conditions that are favorable for the formation of a precipitating substance comprising stable or reactive vaterite or PCC. In some embodiments, the aqueous solution of the calcium salt solution is contacted with CO2 after the aqueous solution is subjected to precipitation conditions that are favorable for the formation of a precipitating substance comprising stable or reactive vaterite or PCC.

[0070] In some embodiments, the step of contacting an aqueous solution containing a calcium salt with carbon dioxide from a cement plant is achieved by contacting the aqueous solution using a convenient protocol described herein to achieve and maintain a desired pH range, a desired temperature range, and / or a desired divalent cation concentration. In some embodiments, the system includes a precipitation reactor configured to contact an aqueous solution containing a calcium salt with carbon dioxide from a cement plant.

[0071] In some embodiments, an aqueous solution containing a calcium salt can be placed in a precipitation reactor that holds water, where the amount of the aqueous solution containing the added calcium salt is sufficient to raise its pH to a desired level (e.g., a pH that induces precipitation of the precipitating substance), such as pH 7 - 14, pH 7.5 - 8.5, pH 7 - 8, pH 8 - 14, pH 9 - 14, pH 10 - 14, pH 11 - 14, pH 12 - 14, or pH 13 - 14. In some embodiments, the pH of the aqueous solution containing the calcium salt, when contacted with carbon dioxide, is maintained between 7 and 8.5 or between 7.5 and 8.5 or between 7 and 8 or between 7.6 and 8.5 or between 8 and 8.5 or between 7.5 and 9.5 to form a precipitating substance containing stable zeolite, reactive zeolite or PCC. In some embodiments, the above aqueous solution is fixed to a column or a bed. In such embodiments, water is passed through or over an amount of calcium salt solution sufficient to raise the pH of the water to a desired pH or a specific divalent cation (Ca 2+ ) concentration. In some embodiments, the above aqueous solution may be circulated two or more times, where the first precipitation cycle mainly removes calcium carbonate minerals, leaving an alkaline solution, and an additional aqueous solution containing a calcium salt can be added to the solution. When carbon dioxide is contacted with the recirculated solution of the above aqueous solution, it enables precipitation of further calcium carbonate and / or bicarbonate compounds. In these embodiments, it is recognized that the aqueous solution after the first precipitation cycle can be contacted with CO2 before, during, and / or after the addition of the aqueous solution containing the calcium salt. In these embodiments, water can be recycled or newly introduced. Thus, the order of addition of CO2 and the aqueous solution containing the calcium salt can vary. For example, carbon dioxide can be added after adding an aqueous solution containing a calcium salt to, for example, brine, seawater, or fresh water. In another example, an aqueous solution containing a calcium salt can be added after adding carbon dioxide to, for example, brine, seawater, or fresh water.

[0072] An aqueous solution containing a calcium salt can be contacted with CO2 using any convenient protocol. When CO2 is a gas, the contact protocols of interest include, but are not limited to, direct contact protocols (e.g., bubbling of CO2 gas through the aqueous solution), concurrent contact means (i.e., contact of a unidirectional flow of a gas-phase stream and a liquid-phase stream), countercurrent means (i.e., contact of a counterflowing gas-phase stream and a liquid-phase stream), and the like. Thus, contact can be achieved by using, for example, an injector, a bubbler, a fluidic venturi reactor, a sparger, a gas filter, a spray, a tray, or a packed column reactor in a precipitation reactor. In some embodiments, gas-liquid contact is achieved by forming a liquid film of the solution using a flat jet nozzle, where the CO2 gas and the liquid film move in a countercurrent, cocurrent, or counterflow direction, or in any other suitable manner. In some embodiments, gas-liquid contact is achieved by contacting droplets of the solution having an average diameter of 500 micrometers or less, such as 100 micrometers or less, with a CO2 gas source.

[0073] The gaseous stream of CO2 from a cement plant may be substantially pure CO2 or may contain CO2 and one or more additional gases and / or other substances, such as ash and other particulates, in a plurality of components. A portion of the gaseous CO2 waste stream from a cement plant (i.e., not the entire gaseous waste stream) can be used to produce a precipitate. In some embodiments, the portion of the gaseous CO2 waste stream used for precipitation of the precipitate can be 75% or less of the gaseous waste stream, such as 60% or less, including 50% and less. In still other embodiments, substantially all (e.g., 80% or more) of the gaseous CO2 waste stream produced by the cement plant is used for precipitation of the precipitate.

[0074] The gas-liquid contact protocol described herein can be utilized any number of times. The gas-liquid contact is continued until the pH of the precipitation reaction mixture is optimized (e.g., various pH values optimal for forming a precipitate containing reactive barium titanate are described herein), after which the precipitation reaction mixture can be stirred. The rate of pH decrease can be controlled by further adding an aqueous solution containing a calcium salt during the gas-liquid contact. Further, the additional aqueous solution can be added after sparging to raise the pH to a basic level to redissolve some or all of the precipitate. In any case, the precipitate can be formed when removing protons from certain species (e.g., carbonic acid, bicarbonate, hydronium) in the precipitation reaction mixture. Next, the precipitate containing carbonate is separated and can be further processed as needed.

[0075] The rate of pH decrease can be controlled by adding an additional supernatant or the above aqueous solution containing a calcium salt during the gas-liquid contact. Further, the additional supernatant or the above aqueous solution containing a calcium salt can be added after contacting the gas and liquid to raise the pH to a basic level (e.g., between 7 and 9 or between 7 and 8.5 or between 7 and 8) to redissolve some or all of the precipitate.

[0076] In some embodiments, the gas exiting the absorber or precipitation reactor (shown as "scrubbed gas" in FIG. 1) goes to a gas treatment unit for the scrubbing process. The mass balance and equipment design for the gas treatment unit can vary depending on the properties of the gas. In some embodiments, the gas treatment unit can incorporate an HCl scrubber to recover a small amount of NH3 in the gas exhaust stream that can be carried from the precipitation step for CO2 absorption by the gas. The NH3 can be captured via NH3 (gas) + HCl (aqueous solution) → NH4Cl (aqueous solution) as described.

[0077] The NH4Cl (aqueous solution) derived from the HCl scrubber can be recycled to the solvation step B.

[0078] In some embodiments, a gas exhaust stream containing ammonia (shown as "scrubbed gas" in FIG. 1) can be subjected to a scrubbing process, where the gas exhaust stream containing ammonia is scrubbed with carbon dioxide and water from an industrial process to produce an ammonia solution. The inlet to the scrubber can be carbon dioxide (CO2 (gas)), reactor gas exhaust containing ammonia (NH3 (gas)), and fresh makeup water (or some other dilution water stream). The effluent can be a slip stream of the scrubber's recirculating fluid (e.g., H3N-CO2 (aqueous solution) or carbamate), which can be returned to the main reactor for contact with carbon dioxide and precipitates as needed. The pH of the system can be controlled by adjusting the flow rate of CO2 (gas) to the scrubber. The conductivity of the system can be controlled by adding dilution makeup water to the scrubber. The volume can be kept constant by using a level detector in the scrubber or its reservoir. Ammonia is a basic gas, while carbon dioxide gas is an acidic gas. In some embodiments, the acidic gas and the basic gas can ionize with each other to increase their solubility.

[0079] Without being bound by any theory, the following reaction NH3 (aqueous solution) + CO2 (aqueous solution) + H2O → HCO3 - + NH4 + is intended to occur.

[0080] An aqueous solution containing a calcium salt forms a precipitate of calcium carbonate when contacted with CO2 gas. One or more precipitation conditions for forming stable or reactive vaterite or PCC in this process are described herein below. In some embodiments, the precipitated material comprises stable vaterite and / or reactive vaterite or PCC. "Stable vaterite" or its grammatical equivalents, as used herein, includes vaterite that does not convert to aragonite or calcite during and / or after the dissolution reprecipitation process in water. "Reactive vaterite" or "activated vaterite" or its grammatical equivalents, as used herein, includes vaterite that forms aragonite during and / or after the dissolution reprecipitation process in water. "Precipitated calcium carbonate" or "PCC", as used herein, includes conventional PCC having high purity and particles sized micron or less. PCC may be any polymorphic form of calcium carbonate including, but not limited to, vaterite, aragonite, calcite, or combinations thereof. In some embodiments, the PCC has a particle size between nanometers or 0.001 micron to 5 microns.

[0081] A precipitated material containing reactive vaterite (optionally containing solids) converts to aragonite, coagulates, and cures into a cement product (shown as product (A) in Figure 1), and the solids can be incorporated into the cement product. This provides the additional advantage of reducing the number of steps to remove solids, minimizing NH4Cl loss, eliminating potential waste streams, thereby increasing efficiency and improving the economic aspect of the above process. In some embodiments, the solid impurities do not have an adverse effect on the conversion of vaterite to aragonite and / or the reactivity of vaterite to aragonite. In some embodiments, the solid impurities do not have an adverse effect on the strength (e.g., compressive strength or flexural strength) of the cement product.

[0082] In some embodiments, the method described above further includes separating (e.g., dewatering) the precipitate from the aqueous solution by dewatering, optionally rinsing, and optionally drying the precipitate (referred to as calcium carbonate cake in FIG. 1). Next, the precipitate can be used to make cement products or non-cement products (shown as product (B) in FIG. 1).

[0083] In some embodiments, the wollastonite in the precipitate can be formed under suitable conditions such that the wollastonite is reactive with respect to aragonite and converts to aragonite during the dissolution-precipitation process in water (during cementation). Aragonite can impart one or more unique characteristics to the product, including but not limited to high compressive strength, a complex fine network structure, a neutral pH, etc. In some embodiments, the wollastonite in the precipitate can be formed under suitable conditions such that the wollastonite is stable and is used as a filler in various applications. In some embodiments, the PCC in the precipitate can be formed under suitable conditions such that the PCC is highly pure and is PCC with very small sized particles.

[0084] In some embodiments, the calcium carbonate cake, as described above, may contain impurities of ammonium (NH4 + ) ions, sulfur ions, and / or chloride (Cl - ) ions (e.g., 1-2 wt% or more). Rinsing of the filtered cake of precipitated CaCO3 can remove some or all of the N-containing salts and / or sulfur compounds as described above, while at the same time a dilute concentration of N-containing salts (in the supernatant) can be brought about, and the salts may need to be concentrated before being recycled back to the process.

[0085] The calcium carbonate slurry is dehydrated, rinsed if necessary, and forms calcium carbonate slurry (using reduced water) or calcium carbonate cake (as shown in Figure 1), and water containing a residual N-containing salt solution, such as an ammonium salt solution. The residual N-containing salt solution and rinse stream obtained from dehydration can be recycled back for solvation treatment with a calcium compound after being concentrated if necessary. Further N-containing salts and / or ammonia (anhydrous or aqueous solution) can be added to the recycled solution during the process to compensate for the loss of N-containing salts and bring the concentration of the N-containing salts to the optimal level.

[0086] In some embodiments, residual N-containing salts, such as the ammonium chloride solution shown in Figure 1, are recovered from the supernatant aqueous solution and can be concentrated using a recovery process, such as but not limited to, pyrolysis, pH adjustment, reverse osmosis, multi-stage flash, multiple effect distillation, vapor recompression, distillation, or combinations thereof. Systems configured to perform these processes are commercially available. For example, the pH of the solution can be increased (using a strong base such as NaOH). This can shift the equilibrium towards volatile ammonia (NH3(aqueous) / NH3(gas)). Both the removal rate and the total removal rate can potentially be improved by heating the solution.

[0087] In some embodiments, the residual N-containing salts can be separated from the calcium carbonate precipitate by a pyrolysis process and recovered. This process can be incorporated into the process shown in Figure 1 after the separation of the CaCO3 precipitate (step E) and / or after the step of the dried CaCO3 precipitate or powder (step F).

[0088] Typically, solid NH4Cl can decompose into ammonia (NH3) gas and hydrogen chloride (HCl) gas at 338°C. On the other hand, solid CaCO3 decomposes into calcium oxide (CaO) solid and carbon dioxide (CO2) gas at 840°C. NH4Cl (solid) ←→ NH3 (gas) + HCl (gas) CaCO3(solid) ⇌ CaO(solid) + CO2(gas)

[0089] In some embodiments, residual N-containing salts in CaCO3 precipitate and / or dried CaCO3 precipitate, such as, but not limited to, ammonium chloride, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium hydrogen sulfide, ammonium thiosulfate, ammonium nitrate, ammonium nitrite, or combinations thereof, can be removed by thermal decomposition at a temperature between 150 °C and 360 °C or between 150 °C and 200 °C or between 150 °C and 300 °C or between 300 °C and 850 °C or between 338 °C and 840 °C. This can be done during the normal drying process of the filter cake and / or as a second post-drying heat treatment. While decomposing the residual N-containing salts in the precipitate, it is desirable to preserve the cementitious properties of the reactive belite in the precipitate material, so that the reactive belite remains as reactive belite after heating and successfully converts to aragonite after combination with water to form a cement product. In some embodiments of the foregoing aspects and embodiments, step (iii) of removing and optionally recovering residual N-containing salts from the precipitate material comprises heating the precipitate material between about 150 °C and 375 °C or between about 150 °C and 300 °C or between about 290 °C and 375 °C or between about 300 °C and 360 °C or between about 300 °C and 350 °C or between about 310 °C and 345 °C or between about 320 °C and 345 °C or between about 330 °C and 345 °C or between about 300 °C and 345 °C to evaporate the N-containing salts from the precipitate material and optionally condensing the N-containing salts for recovery. In some embodiments of the foregoing aspects and embodiments, step (iii) of removing and optionally recovering residual N-containing salts from the precipitate material comprises heating the precipitate material for a period exceeding about 10 minutes or exceeding about 15 minutes or exceeding about 5 minutes, or between about 10 minutes and about 1 hour or between about 10 minutes and about 1.5 hours or between about 10 minutes and about 2 hours or between about 10 minutes and about 5 hours or between about 10 minutes and about 10 hours.

[0090] In some embodiments, after dehydrating the precipitate (to remove the supernatant aqueous solution) and drying it to remove water (e.g., by heating at or above about 100 °C), the precipitate is subjected to heating step (iii) to remove the N-containing salts and, if necessary, recover them. In some embodiments, after partially dehydrating the precipitate (to remove the bulk of the supernatant aqueous solution) and partially drying it to remove water (or avoiding the drying step), the precipitate is subjected to heating step (iii) to remove the N-containing salts and, if necessary, recover them. In some embodiments, the reactive tobermorite in the precipitate remains as reactive tobermorite after heating. In some embodiments of the foregoing embodiments, it is desirable that the reactive tobermorite in the precipitate remains as reactive tobermorite, thus preserving the cementitious properties of the material. In some embodiments, the N-containing salts evaporate from the precipitate in a form that includes ammonia gas, hydrogen chloride gas, chlorine gas, or combinations thereof. The applicants have found that, in some embodiments, maintaining a combination of heating temperature and amount of heating period can be very important for removing N-containing salts from the precipitate while preserving the cementitious properties of the reactive tobermorite material. Conventionally, reactive tobermorite is very unstable and readily converts to aragonite / calcite. However, the applicants have found that, if necessary, by combining the temperature range with a heating period that minimizes the conversion of reactive tobermorite, residual N-containing salts can also be removed from the material. In some embodiments of the foregoing embodiments, after removal of the N-containing salts, the tobermorite in the precipitate remains as reactive tobermorite, which converts to aragonite (dissolution reprecipitation process) when combined with water, coagulates, and cements to form a cement product. The cement product thus formed has a minimal or no chloride content and no foul odor of ammonia or sulfur. In some embodiments, the chloride content is approximately at or below the ASTM standard value allowed for cement products.

[0091] In some embodiments, the temperature conditions described above, optionally combined with a heating period, can be combined with pressure conditions that provide a driving force to improve the thermodynamics of the decomposition of the residual N-containing salts. For example, heating of the precipitate can be carried out in a system where the headspace is at a pressure lower than atmospheric pressure. A pressure lower than atmospheric pressure can create a driving force for a heating reaction with gas-phase products (e.g., but not limited to, ammonia gas, hydrogen chloride gas, chlorine gas, or combinations thereof) by reducing the partial pressure of the reactants in the gas phase. Another advantage of operating under reduced pressure or in a vacuum is that at lower pressures, some sublimation reactions occur at lower temperatures, thereby improving the energy requirement of the heating reaction.

[0092] In some embodiments of the thermal decomposition process described above, the separated ammonium chloride in the form of ammonia gas and HCl gas can be recovered for reuse either by recrystallization of the combined thermally generated gases or by absorbing the gases into an aqueous medium. Both of those mechanisms can result in an NH4Cl product that can be concentrated sufficiently for reuse in the process shown in FIG. 1.

[0093] In some embodiments, the N-containing salts can be separated and recovered in the process described above (or as shown in FIG. 1) by generating pH-adjusted NH3 gas from ammonium salts. This process can be incorporated into the process shown in FIG. 1 during the separation of the CaCO3 cake. The final pH of the water in the filter cake can typically be about 7.5. At this pH, NH4 + (pKa = 9.25) can be the major species. Increasing the pH of this water can drive the acid-base equilibrium with NH3 gas as described by the following equation. NH4 + ←→ H + + NH3 (gas)

[0094] Any alkaline source can be used to raise the pH of the filtered cake water. In some embodiments, an aqueous solution of calcium oxide and / or calcium hydroxide or a limestone slurry can provide a highly alkaline source. In some embodiments, the aqueous fraction of the calcium compound is combined at the rinse stage of the dehydration process (e.g., the step of filtering the cake) to raise the pH of the system and drive the generation of NH3 gas. Since ammonia dissolves substantially in water, heat and / or vacuum pressure can be applied to further drive the equilibrium towards the gas phase. Ammonia can be recovered for reuse by recrystallization with ammonium chloride of ammonia or by absorbing ammonia into an aqueous medium. Both of those mechanisms can result in an ammonia solution or an NH4Cl product that can be sufficiently concentrated for reuse in the process shown in FIG. 1.

[0095] The calcium carbonate cake (e.g., battery grade or PCC) can be sent to a dryer to form a calcium carbonate powder containing stable or reactive battery grade or PCC (step F in FIG. 1). The powder form of the precipitate containing stable or reactive battery grade or PCC can be further used in applications for forming products as described herein. The cake can be dried using any drying technique known in the art, such as, but not limited to, a fluid bed dryer or a swirl fluidizer. The resulting solid powder can then be mixed with additives to make various products described herein. In some embodiments, the slurry form containing reduced water or the cake form of the precipitate can be used directly to form products such as building panels as described herein.

[0096] Optionally, the separated solid can be dried and used as a pozzolan. In some embodiments, the separated solid can be added as a filler or an auxiliary cementitious material to the powder form of the precipitate containing battery grade.

[0097] In the method provided herein, an aqueous solution containing a calcium salt is contacted with CO2 (both obtained from a cement factory), and the resulting aqueous solution containing CO2-charged water is subjected to one or more precipitation conditions sufficient to produce a precipitate material comprising stable or reactive vaterite or PCC, and a supernatant (i.e., a portion of the precipitation reaction mixture remaining after precipitation of the precipitate material) (step D). The one or more precipitation conditions are favorable for the production of a precipitate material comprising stable or reactive vaterite or PCC.

[0098] Precipitation conditions include conditions that modulate the environment of the CO2-charged precipitation reaction mixture to produce a desired precipitate material comprising stable or reactive vaterite or PCC. Such one or more precipitation conditions suitable for forming a carbonate precipitate material containing stable or reactive vaterite or PCC that can be used in embodiments of the methods described herein include, but are not limited to, temperature, pH, pressure, ion ratio, precipitation rate, presence of additives, presence of ionic species, concentrations of additives and ionic species, agitation, residence time, mixing rate, agitation modalities such as ultrasound, seed crystals, catalysts, presence of membranes or substrates, dehydration, drying, ball milling, etc. In some embodiments, the average particle size of the stable or reactive vaterite or PCC can also vary depending on one or more precipitation conditions used in the precipitation of the precipitate material. In some embodiments, the percentage of stable or reactive vaterite in the precipitate material can also vary depending on one or more precipitation conditions used in the precipitation process.

[0099] For example, the temperature of the precipitation reaction mixture filled with CO2 can be raised to a temperature at which an amount suitable for the precipitation of the desired precipitate is obtained. In such an embodiment, the temperature of the precipitation reaction mixture filled with CO2 can be raised to a value such as 20°C to 80°C, including 25°C to 45°C or 20°C to 70°C or 20°C to 60°C or 20°C to 50°C or 20°C to 40°C or 20°C to 30°C. A given set of precipitation conditions can have a temperature in the range of 0°C to 100°C, but in certain embodiments, the temperature can be raised to produce the desired precipitate. In certain embodiments, the temperature of the precipitation reaction mixture is raised using energy from a low-carbon dioxide or zero-carbon dioxide emission source (e.g., a solar energy source, a wind energy source, a hydroelectric energy source, waste heat obtained from the flue gas of carbon emissions, etc.).

[0100] The pH of the precipitation reaction mixture filled with CO2 can also be raised to an amount suitable for the precipitation of the desired precipitate. In such an embodiment, the pH of the precipitation reaction mixture filled with CO2 is raised to an alkaline level suitable for precipitation where carbonate is preferred over bicarbonate. In some embodiments, the pH of an aqueous solution containing a calcium salt contacted with carbon dioxide gas has an effect on the formation of reactive vaterite or PCC. In some embodiments, the precipitation conditions required to form a precipitate containing reactive vaterite or PCC include contacting carbon dioxide with an aqueous solution containing a calcium salt at a pH higher than 7 or pH 8 or between pH 7.1 and 8.5 or between pH 7.5 and 8 or between 7.5 and 8.5 or between 8 and 8.5 or between 7.6 and 8.4 to form reactive vaterite or PCC. The pH can be raised to a pH of 9 or higher, for example pH 10 or higher, including a pH of 11 or higher or a pH of 12.5 or higher.

[0101] Adjustment of the main ion ratios in the precipitation can affect the properties of the precipitate. The main ion ratios can have a significant impact on polymorph formation. For example, as the magnesium:calcium ratio in water increases, aragonite can become the main polymorph of calcium carbonate in the precipitate, superseding low-magnesium vaterite. At low magnesium:calcium ratios, low-magnesium calcite can become the main polymorph. In some embodiments, Ca 2+ and Mg 2+ are both present, the ratio of Ca 2+ to Mg 2+ in the precipitate (i.e., Ca 2+ :Mg 2+ ) is 1:1 to 1:2.5, 1:2.5 to 1:5, 1:5 to 1:10, 1:10 to 1:25, 1:25 to 1:50, 1:50 to 1:100, 1:100 to 1:150, 1:150 to 1:200, 1:200 to 1:250, 1:250 to 1:500, or 1:500 to 1:1000. In some embodiments, the ratio of Mg 2+ to Ca 2+ in the precipitate (i.e., Mg 2+ :Ca 2+ ) is 1:1 to 1:2.5, 1:2.5 to 1:5, 1:5 to 1:10, 1:10 to 1:25, 1:25 to 1:50, 1:50 to 1:100, 1:100 to 1:150, 1:150 to 1:200, 1:200 to 1:250, 1:250 to 1:500, or 1:500 to 1:1000.

[0102] The precipitation rate can also affect the formation of the compound phase, and the fastest precipitation rate is achieved by seeding the solution with the desired phase. Without seeding, rapid precipitation can be achieved by rapidly increasing the pH of the precipitation reaction mixture, which can result in a more amorphous composition. The higher the pH, the more rapidly precipitation occurs, which can result in a more amorphous precipitate.

[0103] The residence time of the reaction mixture after contacting the aqueous solution with CO2 can also have an effect on the formation of the compound phase. For example, in some embodiments, a longer residence time can cause a conversion from reactive vaterite to aragonite / calcite in the reaction mixture. In some embodiments, if the residence time is too short, the formation of reactive vaterite in the reaction mixture can be incomplete. Thus, the residence time can be very important for the precipitation of reactive vaterite. Further, the residence time can also affect the particle size of the precipitate. For example, if the residence time is too long, particles forming larger-sized particles may aggregate, which is not desirable for PCC formation. Thus, in some embodiments, the reaction residence time is between about 10 minutes and 1 hour, or between about 15 minutes and 60 minutes, or between about 15 minutes and 45 minutes, or between about 15 minutes and 30 minutes, or between about 30 minutes and 60 minutes.

[0104] In some embodiments, a set of precipitation conditions for generating the desired precipitate material from the precipitation reaction mixture can include, as described above, temperature and pH, and in some cases, the concentration of additives and ionic species in the water. Additives are described herein below. The presence and concentration of the additives can also be favorable for the formation of stable or reactive vaterite or PCC. In some embodiments, medium-chain or long-chain fatty acid esters can be added to the aqueous solution during precipitation to form PCC. Examples of fatty acid esters include, but are not limited to, cellulose, such as carboxymethyl cellulose, sorbitol, citrate, such as sodium citrate or potassium citrate, stearate, such as sodium stearate or potassium stearate, phosphate, such as sodium phosphate or potassium phosphate, sodium tripolyphosphate, hexametaphosphate, EDTA, or combinations thereof. In some embodiments, a combination of stearate and citrate can be added during the contacting step of the process to form PCC.

[0105] Precipitation conditions can also include factors such as mixing speed, agitation form such as ultrasonic waves, and the presence of seed crystals, catalysts, films or substrates. In some embodiments, precipitation conditions include supersaturation conditions, temperature, pH and / or concentration gradients, or circulation or variation of any of these parameters. The protocol used to prepare the precipitate according to the present invention can be a batch, semi-batch, or continuous protocol. The precipitation conditions for generating a given precipitate may be different in a continuous flow system compared to a semi-batch or batch system.

[0106] After the precipitate is generated from the precipitation reaction mixture, as shown in step E of FIG. 1, it is separated from the reaction mixture to produce a separated precipitate (e.g., wet cake) and supernatant. In the systems provided herein, the separation step can be performed on a separation station. The precipitate can be stored in the supernatant for a period of time after precipitation and before separation (e.g., by drying). For example, the precipitate can be stored in the supernatant at a temperature in the range of 1°C to 40°C, such as 20°C to 25°C, for a period ranging from several minutes to several hours to 1 to 1000 days or more, such as a period in the range of 1 to 10 days or longer. The separation of the precipitate from the precipitation reaction mixture is achieved using any of several convenient techniques, including draining (e.g., draining after gravitational sedimentation of the precipitate), decantation, filtration (e.g., gravity filtration, vacuum filtration, filtration using forced air), centrifugation, pressurization, or any combination thereof. Separation of bulk water from the precipitate produces a wet cake of the precipitate or a dehydrated precipitate. Liquid-solid separation devices, such as the Extrem-Separator ("ExSep") liquid-solid separation device manufactured by Epuramat, the spiral concentrator manufactured by Xerox PARC, or a modified device of either the ExSep manufactured by Epuramat or the spiral concentrator manufactured by Xerox PARC, may be useful for separating the precipitate from the precipitation reaction mixture.

[0107] In some embodiments, the resulting dehydrated precipitate material, e.g., the wet cake material (after thermally removing the N-containing salts), is used directly to produce the products described herein. For example, the wet cake of the dehydrated precipitate material is mixed with one or more additives described herein, spread on a conveyor belt, where the reactive vaterite or PCC in the precipitate material converts to aragonite, coagulates, and hardens (the N-containing salts are thermally removed). Next, the hardened material is cut into a desired shape, e.g., a board or panel described herein. In some embodiments, the wet cake is poured onto the top paper sheet of the conveyor belt. Another paper sheet can be placed on the wet cake and then compressed, removing excess water. After the precipitate material has coagulated and hardened (conversion of vaterite to aragonite), the material is cut into desired shapes, e.g., cement shingles and drywall. In some embodiments, the amount of one or more additives can be optimized according to the desired time (described below) required for the conversion of vaterite to aragonite. For example, in some applications, it may be desirable for the material to convert rapidly, while in certain other cases, a slow conversion may be desirable. In some embodiments, the wet cake can be heated on the conveyor belt to speed up the conversion of vaterite to aragonite. In some embodiments, the wet cake can be poured into a mold of the desired shape, and then the mold is heated in an autoclave to speed up the conversion of vaterite to aragonite (and to remove residual N-containing salts). Thus, all continuous flow processes, batch processes, or semi-batch processes are fully within the scope of the present invention.

[0108] In some embodiments, once the precipitated material is separated from the precipitation reaction mixture, it is washed with deionized water and then fed into a filter press to produce a filter cake containing 30 - 60% solids. Next, this filter cake is mechanically compressed in a mold using any convenient means, such as a hydraulic press, at an appropriate pressure in the range of, for example, 5 - 5000 psi, for example, 1000 - 5000 psi, to produce formed solids, such as rectangular bricks. Next, these resulting solids are cured, for example, by placing them outdoors and storing them, or by placing them in a chamber subjected to high levels of humidity and heat. Next, these resulting cured solids are used as the building material itself or crushed to produce aggregates.

[0109] In a process involving the use of temperature and pressure, the dehydrated precipitate cake can be dried. Next, the cake is exposed to a combination of re - introduced water and high temperature and / or high pressure for a period of time. The amount of water added back, the combination of temperature, pressure and exposure time, as well as the thickness of the cake, can vary according to the composition of the starting material and the desired result.

[0110] Several different ways of exposing the material to temperature and pressure are described herein, but it should be recognized that any convenient method may be used. The thickness and size of the cake can be adjusted as desired, but the thickness can vary, in some embodiments, from 0.05 inches to 5 inches, such as from 0.1 to 2 inches, or from 0.3 to 1 inch. In some embodiments, the cake may be 0.5 inches to 6 feet or thicker. Next, the cake is exposed to high temperature and / or high pressure for a given period of time by any convenient method, such as using heated platens in a platen press. For example, the heat for raising the temperature for the platens can be provided, for example, by heat from an industrial waste gas stream, such as a flue gas stream. The temperature can be any suitable temperature, but generally, the thicker the cake, the higher the temperature is desirable, and examples of temperature ranges are 40 - 150 °C, such as 60 - 120 °C, such as 70 - 110 °C, or 80 - 100 °C. Similarly, the pressure can be any pressure suitable for achieving the desired result, and exemplary pressures include 1000 - 100,000 pounds per square inch (psi), including 2000 - 50,000 psi, or 2000 - 25,000 psi, or 2000 - 20,000 psi, or 3000 - 5000 psi. Finally, the time for which the cake is compressed can be any suitable time, such as 1 - 100 seconds, or 1 - 100 minutes, or 1 - 50 minutes, or 2 - 25 minutes, or 1 - 10,000 days. Next, the resulting tablets can be cured, if necessary, for example, by placing them outdoors, storing them, or placing them in a chamber exposed to high levels of humidity and heat. Next, these cured tablets can be used as the building material itself or crushed to produce aggregates if necessary.

[0111] Another way to provide temperature and pressure is by using a compressor. An appropriate compressor, such as a platen compressor, can be used to provide pressure at a desired temperature over a desired time (e.g., using heat supplied by flue gas or by other steps of a process that generates a precipitate, such as from an electrochemical method). A set of rollers can also be used similarly.

[0112] Another way to expose the cake to high temperature and pressure is by using an extruder, such as a screw-type extruder. The barrel of the extruder can be equipped, for example, with a jacket to achieve a high temperature, which can be supplied, for example, by flue gas. Extrusion can be used as a means to preheat and dry the raw material before the compression operation. Such compression can be carried out by using a compression type, via rollers, through rollers having a formed push-in type (which can provide in fact aggregates of any desired shape) between belts that provide compression when moving, or by any other convenient method. Alternatively, an extruder can be used to extrude the material through a die, exposing the material to pressure when extruded through the die and giving it any desired shape. In some embodiments, the carbonate precipitate is mixed with fresh water and then placed within the feed section of a rotary screw extruder. The extruder and / or the die at the outlet can be heated to further assist the process. The rotation of the screw conveys the material along its length and compresses the material as the height of the flight decreases. The screw and barrel of the extruder can further include vents in the barrel, and the decompression zone of the screw aligns with the vent openings of the barrel. In particular, in the case of a heated extruder, these vented areas can release steam from the conveyed mass and remove water from the material.

[0113] Next, the material conveyed by the screw is extruded through a die section that further compresses and shapes the material. Typical openings of the die can be circular, elliptical, square, rectangular, trapezoidal, etc., but any shape desired for the final aggregate can potentially be created by adjusting the shape of the opening. The material exiting the die can be cut to any convenient length by any convenient method, such as by a fly knife. The use of a heated die section can further assist in the formation of the product by accelerating the transition of the carbonate mineral to a hard and stable form. In the case of a binder, a heated die can also be used to cure or coagulate the binder. In a heated die section, a temperature generally in the range of 100°C to 600°C is used.

[0114] In still other embodiments, the precipitate can be used for the fabrication of in-situ or form-in-place structures. For example, a road, a paved area, or other structures can be made from the precipitate by applying, for example, a layer of the aforementioned precipitate to a substrate such as the ground, a roadbed, etc., and then hydrating the precipitate by exposing it to water applied naturally, such as in the form of rain, or by irrigation. By hydration, the precipitate solidifies into the desired in-situ or form-in-place structure, such as a road, a paved area, etc. The process may be repeated, for example, if a thicker layer of the structure formed in-situ is desired.

[0115] In some embodiments, the generation of the precipitate material and the product occurs within the same facility. In some embodiments, the precipitate material is generated in one facility and transported to another facility to produce the final product. The precipitate material can be transported in slurry form, wet cake form, or dry powder form.

[0116] In some embodiments, the resulting dehydrated precipitate material obtained from the separation station is dried in a drying station to produce a powder form of a carbonate precipitate material containing stable or reactive zeolites or PCC. Drying can be achieved by air-drying the precipitate material. In certain embodiments, drying is achieved by freeze-drying (i.e., lyophilization), where the precipitate material is frozen, the ambient pressure is reduced, and heat sufficient to directly sublimate the frozen water in the precipitate material into gas is applied. In yet another embodiment, the precipitate material is spray-dried to dry the precipitate material, where the liquid containing the precipitate material is dried by being supplied through a hot gas (e.g., a gaseous waste stream from a power plant), the supply liquid is pumped through an atomizer into the main drying chamber, and the hot gas passes through in parallel flow or countercurrent flow with respect to the atomizer direction. Depending on the specific drying protocol of the system, the drying station may include a filtration element, a freeze-drying structure, a spray-drying structure, and the like. In some embodiments, the precipitate can be dried by a fluidized bed dryer. In certain embodiments, when appropriate, waste heat from a power plant or similar operation can be used to perform the drying step. For example, in some embodiments, the dried product is produced by using high temperature (e.g., from waste heat of a power plant), pressure, or a combination thereof. Next, after drying the precipitate material, the material can be heated at a high temperature to remove the N-containing salts as described herein.

[0117] The supernatant and slurry of the precipitate formed from the precipitation process can also be processed as desired. For example, the supernatant or slurry can be returned to an aqueous calcium compound solution or to another location. In some embodiments, the supernatant can be contacted with a CO2 source as described above to capture additional CO2. For example, in embodiments where the supernatant is to be returned to the precipitation reactor, the supernatant can be contacted with a waste gas source of CO2 in a manner sufficient to increase the concentration of carbonate ions present in the supernatant. As described above, the contact can be carried out using any convenient protocol. In some embodiments, the supernatant has an alkaline pH and the contact with the CO2 source is carried out in a manner sufficient to reduce the pH to a range between pH 5-9, between pH 6-8.5, or between pH 7.5-8.2.

[0118] In some embodiments, the precipitate formed by the method is used as a building material (e.g., building materials for some types of man-made structures such as buildings, roads, bridges, dams, etc.) so that CO2 is effectively captured in the built environment. Any man-made structure such as a foundation, parking structure, house, office building, commercial office, government building, infrastructure (e.g., sidewalks, roads, bridges, overpasses, walls, scaffolding for gates, fences and poles, etc.) is considered part of the built environment. Mortar is used to bind building blocks (e.g., bricks) together and fill the gaps between the building blocks. Mortar can also be used, among other uses, to repair existing structures (e.g., to replace portions where the original mortar is damaged or eroded).

[0119] In certain embodiments, a powder form of the precipitate containing reactive brucite is used as cement, which converts to aragonite (dissolution reprecipitation process), coagulates and hardens after being combined with water.

[0120] In some embodiments, the aggregate is formed from the resulting precipitate material. In such embodiments where the drying process produces particles of the desired size, little additional processing is required to form the aggregate. In still other embodiments, further processing of the precipitate material is performed to produce the desired aggregate. For example, the precipitate material can be combined with fresh water in a manner sufficient for the precipitate to form a solid product, where reactive brucite converts to aragonite. By controlling the water content of the wet material, the porosity of the final aggregate, as well as the final strength and density, can be controlled. Typically, the wet cake can be 40 - 60% by volume water. For more dense aggregates, the wet cake can be <50% water, and for less dense cakes, the wet cake can be >50% water. Next, the solid product resulting after curing is mechanically processed, for example crushed or otherwise broken, and can be sorted to produce an aggregate with desired characteristics such as size, specific shape, etc. In these processes, the coagulation and mechanical processing steps can be performed substantially continuously or at intervals. In certain embodiments, large volumes of precipitate can be stored in an open environment where the precipitate is exposed to the atmosphere. In the coagulation step, the precipitate can be conveniently irrigated with fresh water or exposed to natural rainwater to produce a coagulation product. The coagulation product can then be mechanically processed as described above. After the precipitate is formed, the precipitate is processed to produce the desired aggregate. In some embodiments, the precipitate can be placed outdoors and rainwater can be used as a source of fresh water to cause a stabilization reaction of the meteoric water to cure the precipitate and form the aggregate.

[0121] As shown in FIG. 1, the method produces a precipitate material (in wet, slurry or dry form) comprising stable or reactive vaterite or PCC. "Composition", "precipitate" and "precipitate material" are used interchangeably herein. As described herein, after removing residual N-containing salts, the precipitate material formed in the methods and systems provided herein comprises vaterite or PCC. Stable vaterite includes vaterite that does not convert to aragonite or calcite during and / or after the dissolution reprecipitation process. Reactive vaterite or activated vaterite includes vaterite that forms aragonite during and / or after the dissolution reprecipitation process. In some embodiments, the PCC formed is in vaterite form. In some embodiments, the methods described herein further comprise contacting the precipitate material (in dry or wet form) with water to convert reactive vaterite to aragonite. In some embodiments, stable vaterite does not convert to aragonite when contacted with water and remains in vaterite form or converts to calcite over a long period of time.

[0122] Typically, when calcium carbonate precipitates, first amorphous calcium carbonate (ACC) precipitates and can convert to one or more of its three more stable phases (vaterite, aragonite, or calcite). As described by Ostwald's Step Rule (Ostwald, W. Zeitschrift fur Physikalische Chemie 289 (1897)), there may be a thermodynamic driving force for the conversion from an unstable phase to a more stable phase. For this reason, the calcium carbonate phases convert in the order of ACC to vaterite, aragonite, and calcite, where intermediate phases may or may not be present. During this conversion, as shown by FIG. 2, excess energy is released. This intrinsic energy can be utilized to produce strong aggregation tendencies and surface interactions that can lead to aggregation and coagulation or cementation. The values reported in FIG. 2 are well known in the art and it should be understood that they can vary.

[0123] The methods provided herein produce or isolate a precipitated material in the vaterite form or in the form of PCC which may be present in the vaterite, aragonite or calcite form. The precipitated material may be in a wet form, a slurry form, or a dry powder form. This precipitated material can have a stable vaterite form that does not readily convert to any other polymorph, or can have a reactive vaterite form that converts to the aragonite form. The aragonite form does not further convert to the more stable calcite form. Products containing a precipitate in the aragonite form exhibit one or more unexpected properties including, but not limited to, high compressive strength, high porosity (low density or lightweight), neutral pH (useful as an artificial reef as described below), and a fine network structure.

[0124] Minor amounts of other polymorphic forms of calcium carbonate that may be present in the precipitated material containing carbonate in addition to vaterite include, but are not limited to, amorphous calcium carbonate, aragonite, calcite, a vaterite precursor phase, an aragonite precursor phase, an intermediate phase less stable than calcite, a polymorph between these polymorphs, or a combination thereof.

[0125] Vaterite can be present in a monodisperse form or an aggregated form and can be spherical, ellipsoidal, plate-like in shape, or hexagonal. Vaterite typically has a hexagonal crystal structure and forms polycrystalline spherical particles upon growth. The precursor form of vaterite includes vaterite nanoclusters, and the precursor form of aragonite includes submicron to nanocluster acicular aragonite. Aragonite, when present in a composition with vaterite, can be needle-shaped, columnar, or orthorhombic crystals. Calcite, when present in a composition with vaterite, can be cubic, spindle-shaped, or hexagonal crystals. The intermediate phase less stable than calcite can be a phase between vaterite and calcite, a phase between a vaterite precursor and calcite, a phase between aragonite and calcite, and / or a phase between an aragonite precursor and calcite.

[0126] The conversion between calcium carbonate polymorphs can occur via a solid-state transition, may be mediated by a solution, or both. In some embodiments, the conversion is solution-mediated because solution-mediated requires less energy than a thermally activated solid-state transition. Vaterite is metastable, and the differences in the thermodynamic stability of calcium carbonate polymorphs may manifest as differences in solubility, where the least stable phase is the most soluble (Ostwald as described above). Thus, vaterite can readily dissolve in solution and conveniently convert to a more stable polymorph, such as aragonite. In a polymorphic system such as calcium carbonate, two dynamic processes, dissolution of the metastable phase and growth of the stable phase, can coexist in solution. In some embodiments, aragonite crystals can grow while vaterite is dissolved in an aqueous medium.

[0127] In one aspect, reactive vaterite can be activated such that during a dissolution reprecipitation process, it follows a path to aragonite and not to calcite. In some embodiments, a composition containing reactive vaterite is activated in such a way that after a dissolution reprecipitation process, the formation of aragonite is enhanced and the formation of calcite is inhibited. By activating a composition containing reactive vaterite, the formation and crystal growth of aragonite can be controlled. The activation of a composition containing vaterite can be achieved by various processes. Various examples of vaterite activation, such as, but not limited to, nucleation activation, thermal activation, mechanical activation, chemical activation, or combinations thereof, are described herein. In some embodiments, vaterite is activated via various processes such that the formation and morphology of aragonite and / or crystal growth can be controlled when the composition containing vaterite reacts with water. The aragonite formed provides higher tensile strength and fracture resistance to the product formed from the reactive vaterite.

[0128] In some embodiments, the reactive tobermorite can be activated by mechanical means as described herein. For example, a composition containing reactive tobermorite can be activated by creating surface defects on the tobermorite composition such that the formation of aragonite is accelerated. In some embodiments, the activated tobermorite is ball-milled reactive tobermorite or reactive tobermorite having surface defects such that the formation pathway of aragonite is promoted.

[0129] A composition containing reactive tobermorite can also be activated by chemically activating or nucleating the tobermorite composition. Such chemical activation or nucleation can be provided by one or more of aragonite seed crystals, inorganic additives, or organic additives. The aragonite seed crystals present in the compositions provided herein can be obtained from natural or synthetic sources. Natural sources include, but are not limited to, hard skeletal materials of certain freshwater and marine invertebrates, including reef sand, limestone, brachiopods, gastropods, mollusk shells, and calcareous endoskeletons of warm and cold water corals, pearls, rocks, sediments, ore minerals (e.g., serpentine), etc. Synthetic sources include, but are not limited to, precipitated aragonite formed from, for example, sodium carbonate and calcium chloride, or aragonite formed by the conversion of tobermorite to aragonite, such as the converted tobermorite described herein.

[0130] In some embodiments, the inorganic or organic additives in the compositions provided herein can be any additives that activate reactive faujasite. Some examples of inorganic or organic additives in the compositions provided herein include, but are not limited to, sodium decyl sulfate, lauric acid, sodium laurate, urea, citric acid, sodium citrate, phthalic acid, sodium phthalate, taurine, creatine, glucose, poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium aspartate, magnesium chloride, acetic acid, sodium acetate, glutamic acid, sodium glutamate, strontium chloride, calcium carbonate, lithium chloride, sodium chloride, glycine, sodium citrate anhydrous, sodium bicarbonate, magnesium sulfate, magnesium acetate, sodium polystyrene, sodium dodecyl sulfonate, polyvinyl alcohol, or combinations thereof. In some embodiments, the inorganic or organic additives in the compositions provided herein include, but are not limited to, taurine, creatine, poly(n-vinyl-1-pyrrolidone), lauric acid, sodium laurate, urea, magnesium chloride, acetic acid, sodium acetate, strontium chloride, magnesium sulfate, magnesium acetate, or combinations thereof. In some embodiments, the inorganic or organic additives in the compositions provided herein include, but are not limited to, magnesium chloride, magnesium sulfate, magnesium acetate, or combinations thereof.

[0131] Without being bound by any theory, it is contemplated that the formation of aragonite can be controlled, including, but not limited to, controlling properties such as polymorph, morphology, particle size, cross-linking, aggregation, coagulation, agglomeration, sedimentation, crystal structure analysis, inhibiting growth along certain faces of the crystal, enabling growth along certain faces of the crystal, or combinations thereof, during the dissolution and reprecipitation process of activated reactive wollastonite by ball milling or by activation of wollastonite by addition of aragonite seeds, inorganic additives, organic additives, or combinations thereof. For example, aragonite seeds, inorganic additives, or organic additives can selectively target the morphology of aragonite, inhibit the growth of calcite, and promote the formation of aragonite, which is generally kinetically unfavorable.

[0132] In some embodiments, one or more inorganic additives can be added to facilitate the conversion of wollastonite to aragonite. One or more additives can be added during any step of the process. For example, one or more additives can be added during the contact of the calcium compound solution with carbon dioxide, after the contact of the calcium compound solution with carbon dioxide, during the precipitation of the precipitating substance, after the precipitation of the precipitating substance in the slurry, to the slurry after dehydration of the precipitating substance, to the powder after drying of the slurry, to the aqueous solution to be mixed with the powdered precipitating substance, or to the slurry made from the powdered precipitating substance using water, or any combination thereof. In some embodiments, the water used in the process for making the precipitating substance may pre-contain one or more additives or one or more additive ions. For example, if seawater is used in the process, the additive ions may pre-exist in the seawater.

[0133] In some embodiments of the foregoing method, the amount of one or more additives added during the process is more than 0.1 wt%, or more than 0.5 wt%, or more than 1 wt%, or more than 1.5 wt%, or more than 1.6 wt%, or more than 1.7 wt%, or more than 1.8 wt%, or more than 1.9 wt%, or more than 2 wt%, or more than 2.1 wt%, or more than 2.2 wt%, or more than 2.3 wt%, or more than 2.4 wt%, or more than 2.5 wt%, or more than 2.6 wt%, or more than 2.7 wt%, or more than 2.8 wt%, or more than 2.9 wt%, or more than 3 wt%, or more than 3.5 wt%, or more than 4 wt%, or more than 4.5 wt%, or more than 5 wt%, or between 0.5 and 5 wt%, or between 0.5 and 4 wt%, or between 0.5 and 3 wt%, or between 0.5 and 2 wt%, or between 0.5 and 1 wt%, or between 1 and 3 wt%, or between 1 and 2.5 wt%, or between 1 and 2 wt%, or between 1.5 and 2.5 wt%, or between 2 and 3 wt%, or between 2.5 and 3 wt%, or 0.5 wt%, or 1 wt%, or 1.5 wt%, or 2 wt%, or 2.5 wt%, or 3 wt%, or 3.5 wt%, or 4 wt%, or 4.5 wt%, or 5 wt%. In some embodiments of the foregoing method, the amount of one or more additives added during the process is between 0.5 and 3 wt% or between 1.5 and 2.5 wt%.

[0134] In some embodiments, the precipitate is in powder form. In some embodiments, the precipitate is in dry powder form. In some embodiments, the precipitate is disordered or not in an ordered array or in a powdered form. In still further embodiments, the precipitate is in a partially or fully hydrated form. In still further embodiments, the precipitate is present in salt water or fresh water. In still further embodiments, the precipitate is present in water containing sodium chloride. In still further embodiments, the precipitate is present in water containing alkaline earth metal ions such as, but not limited to, calcium, magnesium, etc. In some embodiments, the precipitate is not for medical use or for medical procedures.

[0135] The products produced from the compositions or precipitate materials provided herein exhibit one or more properties such as high compressive strength, high durability, high porosity (light weight), high flexural strength, and lower maintenance costs. In some embodiments, the compositions or precipitate materials that coagulate and harden when combined with water have a compressive strength of at least 3 MPa (megapascals), or at least 7 MPa, or at least 10 MPa, or in some embodiments, between 3 and 30 MPa, or between 14 and 80 MPa, or between 14 and 35 MPa.

[0136] In some embodiments of the foregoing aspects and embodiments, the composition or the precipitated substance is at least 10 w / w% of faujasite, or at least 20 w / w% of faujasite, or at least 30 w / w% of faujasite, or at least 40 w / w% of faujasite, or at least 50 w / w% of faujasite, or at least 60 w / w% of faujasite, or at least 70 w / w% of faujasite, or at least 80 w / w% of faujasite, or at least 90 w / w% of faujasite, or at least 95 w / w% of faujasite, or at least 99 w / w% of faujasite, or from 10 w / w% to 99 w / w% of faujasite, or from 10 w / w% to 90 w / w% of faujasite, or from 10 w / w% to 80 w / w% of faujasite, or from 10 w / w% to 70 w / w% of faujasite, or from 10 w / w% to 60 w / w% of faujasite, or from 10 w / w% to 50 w / w% of faujasite, or from 10 w / w% to 40 w / w% of faujasite, or from 10 w / w% to 30 w / w% of faujasite, or from 10 w / w% to 20 w / w% of faujasite, or from 20 w / w% to 99 w / w% of faujasite, or from 20 w / w% to 95 w / w% of faujasite, or from 20 w / w% to 90 w / w% of faujasite, or from 20 w / w% to 75 w / w% of faujasite, or from 20 w / w% to 50 w / w% of faujasite, or from 30 w / w% to 99 w / w% of faujasite, or from 30 w / w% to 95 w / w% of faujasite, or from 30 w / w% to 90 w / w% of faujasite, or from 30 w / w% to 75 w / w% of faujasite, or from 30 w / w% to 50 w / w% of faujasite, or from 40 w / w% to 99 w / w% of faujasite, or from 40 w / w% to 95 w / w% of faujasite, or from 40 w / w% to 90 w / w% of faujasite, or from 40 w / w% to 75 w / w% of faujasite, or from 50 w / w% to 99 w / w% of faujasite, or from 50 w / w% to 95 w / w% of faujasite, or from 50 w / w% to 90 w / w% of faujasite, or from 50 w / w% to 75 w / w% of faujasite, or from 60 w / w% to 99 w / w% of faujasite, or from 60 w / w% to 95 w / w% of faujasite, or from 60 w / w% to 90 w / w% of faujasite, or from 70 w / w% to 99 w / w% of faujasite, or from 70 w / w% to 95 w / w% of faujasite,Or 70 w / w% to 90 w / w% of bauxite, or 80 w / w% to 99 w / w% of bauxite, or 80 w / w% to 95 w / w% of bauxite, or 80 w / w% to 90 w / w% of bauxite, or 90 w / w% to 99 w / w% of bauxite, or 10 w / w% of bauxite, or 20 w / w% of bauxite, or 30 w / w% of bauxite, or 40 w / w% of bauxite, or 50 w / w% of bauxite, or 60 w / w% of bauxite, or 70 w / w% of bauxite, or 75 w / w% of bauxite, or 80 w / w% of bauxite, or 85 w / w% of bauxite, or 90 w / w% of bauxite, or 95 w / w% of bauxite, or 99 w / w% of bauxite. The bauxite can be stable bauxite or reactive bauxite or PCC.,

[0137] In some embodiments of the foregoing aspects and foregoing embodiments, the precipitate material comprising wadelite that condenses and hardens (i.e., converts to aragonite) after being combined with water, or stable wadelite after being mixed with cement and water and then condensed and hardened, has a compressive strength of at least 3 MPa, at least 7 MPa, at least 14 MPa, or at least 16 MPa, or at least 18 MPa, or at least 20 MPa, or at least 25 MPa, or at least 30 MPa, or at least 35 MPa, or at least 40 MPa, or at least 45 MPa, or at least 50 MPa, or at least 55 MPa, or at least 60 MPa, or at least 65 MPa, or at least 70 MPa, or at least 75 MPa, or at least 80 MPa, or at least 85 MPa, or at least 90 MPa, or at least 95 MPa, or at least 100 MPa, or 3 to 50 MPa, or 3 to 25 MPa, or 3 to 15 MPa, or 3 to 10 MPa, or 14 to 25 MPa, or 14 to 100 MPa, or 14 to 80 MPa, or 14 to 75 MPa, or 14 to 50 MPa, or 14 to 25 MPa, or 17 to 35 MPa, or 17 to 25 MPa, or 20 to 100 MPa, or 20 to 75 MPa, or 20 to 50 MPa, or 20 to 40 MPa, or 30 to 90 MPa, or 30 to 75 MPa, or 30 to 60 MPa, or 40 to 90 MPa, or 40 to 75 MPa, or 50 to 90 MPa, or 50 to 75 MPa, or 60 to 90 MPa, or 60 to 75 MPa, or 70 to 90 MPa, or 70 to 80 MPa, or 70 to 75 MPa, or 80 to 100 MPa, or 90 to 100 MPa, or 90 to 95 MPa, or 14 MPa, or 3 MPa, or 7 MPa, or 16 MPa, or 18 MPa, or 20 MPa, or 25 MPa, or 30 MPa, or 35 MPa, or 40 MPa, or 45 MPa.For example, in some embodiments of the foregoing aspects and the foregoing embodiments, the composition after condensation and curing has a compressive strength of 3 MPa to 25 MPa, or 14 MPa to 40 MPa, or 17 MPa to 40 MPa, or 20 MPa to 40 MPa, or 30 MPa to 40 MPa, or 35 MPa to 40 MPa. In some embodiments, the compressive strength described herein is the compressive strength after a period of 1 day, or 3 days, or 7 days, or 28 days, or 56 days, or a longer period has elapsed.

[0138] In some embodiments, the precipitate material containing the batteryite is a particulate composition having an average particle size of 0.1 to 100 microns. The average particle size (or average particle diameter) can be determined using any conventional particle size determination method, for example, but not limited to, multi-detector laser scattering or laser diffraction or sieving. In certain embodiments, a unimodal or multimodal, for example, bimodal or other distribution exists. A bimodal distribution can provide smaller reactive particles for the initial reaction while minimizing the surface area and thus allowing for a lower liquid / solid mass ratio when the composition is mixed with water. In some embodiments, the compositions or precipitate materials provided herein are 0.1 to 1000 microns, or 0.1 to 500 microns, or 0.1 to 100 microns, or 0.1 to 50 microns, or 0.1 to 20 microns, or 0.1 to 10 microns, or 0.1 to 5 microns, or 1 to 50 microns, or 1 to 25 microns, or 1 to 20 microns, or 1 to 10 microns, or 1 to 5 microns, or 5 to 70 microns, or 5 to 50 microns, or 5 to 20 microns, or 5 to 10 microns, or 10 to 100 microns, or 10 to 50 microns, or 10 to 20 microns, or 10 to 15 microns, or 15 to 50 microns, or 15 to 30 microns, or 15 to 20 microns, or 20 to 50 microns, or 20 to 30 microns, or 30 to 50 microns, or 40 to 50 microns, or 50 to 100 microns, or 50 to 60 microns, or 60 to 100 microns, or 60 to 70 microns, or 70 to 100 microns, or 70 to 80 microns, or 80 to 100 microns, or 80 to 90 microns, or 0.1 micron, or 0.5 micron, or 1 micron, or 2 microns, or 3 microns, or 4 microns, or 5 microns, or 8 microns, or 10 microns, or 15 microns, or 20 microns, or 30 microns, or 40 microns, or 50 microns, or 60 microns, or 70 microns, or 80 microns, or 100 microns particulate composition having an average particle size of.For example, in some embodiments, the compositions or precipitated substances provided herein are particulate compositions having an average particle size of from 0.1 to 20 microns, or from 0.1 to 15 microns, or from 0.1 to 10 microns, or from 0.1 to 8 microns, or from 0.1 to 5 microns, or from 1 to 25 microns, or from 1 to 20 microns, or from 1 to 15 microns, or from 1 to 10 microns, or from 1 to 5 microns, or from 5 to 20 microns, or from 5 to 10 microns. In some embodiments, the composition or precipitated substance comprises two or more, or three or more, or four or more, or five or more, or ten or more, or twenty or more, or from 3 to 20, or from 4 to 10 different sized particles. For example, the composition or precipitated substance can comprise two or more, or three or more, or from 3 to 20 particles in the range of 0.1 to 10 microns, 10 to 50 microns, 50 to 100 microns, 100 to 200 microns, 200 to 500 microns, 500 to 1000 microns and / or submicron particle sizes. In some embodiments, the PCC in the precipitated substance can have an average particle size of less than 0.1 microns, for example between 0.001 microns and 1 micron or greater. In some embodiments, the PCC can be of nanometer particle size.

[0139] In some embodiments, the composition or precipitate material can further include ordinary Portland cement (OPC) or Portland cement clinker. The amount of the Portland cement component may vary and can be in the range of 10 - 95 w / w%, or 10 - 90 w / w%, or 10 - 80 w / w%, or 10 - 70 w / w%, or 10 - 60 w / w%, or 10 - 50 w / w%, or 10 - 40 w / w%, or 10 - 30 w / w%, or 10 - 20 w / w%, or 20 - 90 w / w%, or 20 - 80 w / w%, or 20 - 70 w / w%, or 20 - 60 w / w%, or 20 - 50 w / w%, or 20 - 40 w / w%, or 20 - 30 w / w%, or 30 - 90 w / w%, or 30 - 80 w / w%, or 30 - 70 w / w%, or 30 - 60 w / w%, or 30 - 50 w / w%, or 30 - 40 w / w%, or 40 - 90 w / w%, or 40 - 80 w / w%, or 40 - 70 w / w%, or 40 - 60 w / w%, or 40 - 50 w / w%, or 50 - 90 w / w%, or 50 - 80 w / w%, or 50 - 70 w / w%, or 50 - 60 w / w%, or 60 - 90 w / w%, or 60 - 80 w / w%, or 60 - 70 w / w%, or 70 - 90 w / w%, or 70 - 80 w / w%. For example, the composition or precipitate material can include a blend of 75% OPC and 25% composition, or 80% OPC and 20% composition, or 85% OPC and 15% composition, or 90% OPC and 10% composition, or 95% OPC and 5% composition.

[0140] In certain embodiments, the composition or precipitate material can further include an aggregate. The aggregate can be included in the composition or precipitate material to provide mortar including fine aggregate and concrete including coarse aggregate. The fine aggregate is a material that generally entirely passes through a No. 4 sieve (ASTM C125 and ASTM C33), such as silica sand. The coarse aggregate is a material that is mainly retained by a No. 4 sieve (ASTM C125 and ASTM C33), such as silica, quartz, crushed round marble, glass spheres, granite, limestone, calcite, feldspar, alluvial sand, sand or any other durable aggregate, and mixtures thereof. Thus, the term "aggregate" is used broadly to refer to some different types of particulate materials, both coarse and fine, including, but not limited to, sand, gravel, crushed stone, slag, and recycled concrete. The amount and nature of the aggregate can vary widely. In some embodiments, the amount of the aggregate can be in the range including 25 to 80 w / w%, such as 40 to 70 w / w%, and 50 to 70 w / w% of the total composition produced from both the composition and the aggregate.

[0141] In some embodiments, the composition or precipitate prepared by the aforementioned method coagulates and hardens after being treated with an aqueous medium under one or more suitable conditions. The aqueous medium includes, but is not limited to, fresh water or brine containing additives as required. In some embodiments, one or more suitable conditions include, but are not limited to, temperature, pressure, period for coagulation, ratio of the aqueous medium to the composition, and combinations thereof. The temperature may be the temperature with respect to the temperature of the aqueous medium. In some embodiments, the temperature ranges from 0 to 110 °C, or 0 to 80 °C, or 0 to 60 °C, or 0 to 40 °C, or 25 to 100 °C, or 25 to 75 °C, or 25 to 50 °C, or 37 to 100 °C, or 37 to 60 °C, or 40 to 100 °C, or 40 to 60 °C, or 50 to 100 °C, or 50 to 80 °C, or 60 to 100 °C, or 60 to 80 °C, or 80 to 100 °C. In some embodiments, the pressure is atmospheric pressure or above. In some embodiments, the period for coagulating the cement product is 30 minutes to 48 hours, or 30 minutes to 24 hours, or 30 minutes to 12 hours, or 30 minutes to 8 hours, or 30 minutes to 4 hours, or 30 minutes to 2 hours, 2 to 48 hours, or 2 to 24 hours, or 2 to 12 hours, or 2 to 8 hours, or 2 to 4 hours, 5 to 48 hours, or 5 to 24 hours, or 5 to 12 hours, or 5 to 8 hours, or 5 to 4 hours, or 5 to 2 hours, 10 to 48 hours, or 10 to 24 hours, or 24 to 48 hours.

[0142] While mixing the composition or the precipitate with an aqueous medium, the precipitate can be subjected to a high-shear mixer. After mixing, the precipitate can be dehydrated again and placed into a pre-formed mold to produce a formed building material, or it can be used to produce a formed building material using a process well-known in the art or as described herein. Alternatively, the precipitate can be mixed with water and coagulated. The precipitate can coagulate over several days and can then be placed in an oven for drying at, for example, 40°C, or 40°C - 60°C, or 40°C - 50°C, or 40°C - 100°C, or 50°C - 60°C, or 50°C - 80°C, or 50°C - 100°C, or 60°C - 80°C, or 60°C - 100°C. The precipitate can be cured at a high temperature, such as 50°C - 60°C, or 50°C - 80°C, or 50°C - 100°C, or 60°C - 80°C, or 60°C - 100°C, or 60°C, or 80°C - 100°C, at a high humidity, such as 30%, or 40%, or 50%, or 60% humidity.

[0143] The products produced by the methods described herein can be aggregates or building materials or pre-cast materials or formed building materials. In some embodiments, the products produced by the methods described herein include non-cement materials such as paper, paint, PVC, etc. In some embodiments, the products produced by the methods described herein include artificial reefs. These products are described herein.

[0144] In some embodiments, the precipitated material in wet or dry form can be mixed with one or more admixtures to impart one or more properties, including but not limited to strength, flexural strength, compressive strength, porosity, thermal conductivity, etc., to the product. The amount of admixture used can vary depending on the nature of the admixture. In some embodiments, the amount of one or more admixtures ranges from 1 to 50 w / w%, such as 1 to 30 w / w%, or 1 to 25 w / w%, or 1 to 20 w / w%, or 2 to 10 w / w%. Examples of admixtures include, but are not limited to, setting accelerators, setting retarders, air-entraining agents, foaming agents, defoaming agents, alkali reactivity reducers, binding admixtures, dispersants, coloring admixtures, corrosion inhibitors, moisture-proof admixtures, gas-forming agents, permeability reducers, pumping aids, shrinkage compensating admixtures, fungicidal admixtures, bactericidal admixtures, insecticidal admixtures, rheology modifiers, finely ground mineral admixtures, pozzolans, aggregates, wetting agents, strength enhancers, water repellents, reinforcing materials, such as fibers, and any other admixtures. When an admixture is used, the composition or precipitated material into which the admixture raw material is introduced is mixed for a time sufficient to disperse the admixture raw material relatively uniformly in the composition.

[0145] Setting accelerators can be used to accelerate the setting and initial strength development of cement. Examples of setting accelerators that can be used include, but are not limited to, POZZOLITH® NC534, a non-chloride type setting accelerator, and / or RHEOCRETE® CNI, a corrosion inhibitor based on calcium nitrite, both of which are sold under the foregoing trademarks by BASF Admixtures Inc. of Cleveland, Ohio. Retarding admixtures, also known as retarders or water hydration controllers, are used to slow, delay, or retard the setting rate of cement. Most set retarders can act as low-level water reducers and can also be used to entrain some air into the product. An example of a retarder is DELVO® by BASF Admixtures Inc. of Cleveland, Ohio. Air-entraining agents include any substance that entrains air into the composition. Some air-entraining agents can also reduce the surface tension of the composition at low concentrations. Air-entraining admixtures are used to intentionally entrain microscopic air bubbles into the cement. Entraining air can increase the workability of the mix while eliminating or reducing segregation and bleeding. Materials used to achieve these desired effects can be selected from wood resins, natural resins, synthetic resins, sulfonated lignin, petroleum acids, proteinaceous materials, fatty acids, resin acids, alkylbenzene sulfonates, sulfonated hydrocarbons, vinsol resins, anionic surfactants, cationic surfactants, non-ionic surfactants, natural rosins, synthetic rosins, inorganic air-entraining agents, synthetic detergents, and their corresponding salts, as well as mixtures thereof. Air-entraining agents are added in an amount that provides the desired level of air in the cement composition. Examples of air-entraining agents that can be utilized in an admixture system include, but are not limited to, MB AE90, MB VR, and MICRO AIR®, all of which are available from BASF Admixtures Inc. of Cleveland, Ohio.

[0146] In some embodiments, the precipitated material is mixed with a foaming agent. The foaming agent incorporates a large amount of air pores / porosity and promotes reduction of the material density. Examples of foaming agents include, but are not limited to, soap, detergent (alkyl ether sulfate), millifoam TM (alkyl ether sulfate), cedepal TM (ammonium alkyl ethoxysulfate), witcolate TM 12760 and the like.

[0147] Defoaming agents are also targeted as admixtures. Defoaming agents are used to reduce the air content in the cement composition. Dispersants are also targeted as admixtures. Dispersants include, but are not limited to, polycarboxylate dispersants with or without polyether units. The term dispersant also means a chemical that functions as a plasticizer, water reducer, such as a high-range water reducer, fluidizing agent, anti-agglomerant, or superplasticizer for the composition, such as lignin sulfonate, salts of sulfonated naphthalene sulfonate condensates, salts of sulfonated melamine sulfonate condensates, beta-naphthalene sulfonate, sulfonated melamine formaldehyde condensates, naphthalene sulfonate formaldehyde condensate resins, such as LOMAR D® dispersant (Cognis Inc., Cincinnati, Ohio), polyaspartic acid, or oligomeric dispersants. Polycarboxylate dispersants can be used, which means a dispersant having a carbon skeleton with pendant side chains, where at least a portion of the side chains are attached to the skeleton via carboxyl groups or ether groups.

[0148] Natural and synthetic admixtures can be used to color products for aesthetic and safety reasons. These coloring admixtures may be composed of pigments, which include carbon black, iron oxide, phthalocyanine, amber, chromium oxide, titanium oxide, cobalt blue, and organic colorants. Corrosion inhibitors are also targeted as admixtures. Corrosion inhibitors can serve to protect embedded reinforcing bars from corrosion. Materials commonly used to inhibit corrosion are calcium nitrite, sodium nitrite, sodium benzoate, certain phosphates or fluorosilicates, fluoroaluminite, amines, and related chemicals. Moisture-proof admixtures are also targeted. Moisture-proof admixtures reduce the permeability of products with low cement content, high water-cement ratio, or fine-grained deficiencies in the aggregates. These mixtures retard the penetration of moisture into the dry product and include certain soaps, stearates, and petroleum products. Gas-forming admixtures are also targeted. Gas-forming agents or chemicals that form gas are sometimes added to the mix to cause a slight expansion before hardening. The amount of expansion is determined by the amount of gas-forming material used and the temperature of the new admixture. Aluminum powder, resin soap, and vegetable or animal glue, saponin or hydrolyzed protein can be used as gas-forming agents. Permeability reducers are also targeted. Permeability reducers can reduce the rate at which water travels through the mix under pressure. Silica fume, fly ash, ground slag, natural pozzolan, water reducers, and latex can be used to reduce the permeability of the mix.

[0149] Blending agents for rheology modifiers are also targeted. Rheology modifiers can be used to increase the viscosity of the composition. Suitable examples of rheology modifiers include fumed silica, colloidal silica, hydroxyethyl cellulose, starch, hydroxypropyl cellulose, fly ash (as defined in ASTM C618), mineral oil (e.g., light naphthene), clay, such as hectorite clay, polyoxyalkylene, polysaccharides, natural gums, or mixtures thereof. Some of the mineral extenders, such as, but not limited to, sepiolite clay, are rheology modifiers.

[0150] Shrinkage correction blending agents are also targeted. TETRAGUARD® is an example of a shrinkage reducing agent and is available from BASF Admixtures Inc. in Cleveland, Ohio. The growth of bacteria and fungi on or in the cured product can be partially controlled by the use of fungicidal and bactericidal blending agents. Materials for this purpose include, but are not limited to, polyhalogenated phenols, dialdrin emulsions, and copper compounds. In some embodiments, processing aid blending agents are also targeted. Entrained air can act as a lubricant and can be used as an agent to improve processability. Other processing agents are water reducers and certain pulverizing blending agents.

[0151] In some embodiments, the composition or precipitate material is used with a reinforcing material, such as fibers, for example when a fiber-reinforced product is desired. The fibers can be made from zirconia-containing materials, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood, fiberglass, or synthetic materials such as polypropylene, polycarbonate, polyvinyl chloride, polyvinyl alcohol, nylon, polyethylene, polyester, rayon, high-strength aramid (i.e., Kevlar®), or mixtures thereof. The reinforcing material is described in U.S. Patent Application No. 13 / 560,246, filed July 27, 2012, which is hereby incorporated by reference in its entirety into this disclosure.

[0152] The components of the precipitate material can be combined using any suitable protocol. Each material can be mixed during operation, or some or all of the materials can be pre-mixed. Alternatively, some of the materials can be mixed with water, with or without a mixing agent, such as a high-range water-reducing admixture, and then mixed with the remaining materials. Any conventional device can be used as the mixing device. For example, a Hobart mixer, a slant cylinder mixer, an Omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer can be used.

[0153] In one aspect, a treatment device configured to treat or solvate a calcium compound using an N-containing salt and, optionally, ammonia to produce an aqueous solution containing a calcium salt and an N-containing salt; a reactor configured to treat the aqueous solution containing the calcium salt and, optionally, a solid with carbon dioxide from a cement plant to produce a precipitate material containing baterite or PCC and a supernatant containing an aqueous solution of residual N-containing salt; and a recovery system for recovering the residual N-containing salt from the aqueous solution and returning it to the treatment device for recycling are provided. The recovery system is a system configured to perform pyrolysis, reverse osmosis, multi-stage flash, multiple effect distillation, vapor recompression, distillation, and combinations thereof.

[0154] The methods and systems provided herein can be practiced on land (e.g., where there is a cement plant that calcines limestone, or where it can be easily and economically transported), at sea, or in the ocean. In some embodiments, a cement plant that calcines limestone can additionally introduce the systems described herein to form a precipitate material and further to form a product from the precipitate material.

[0155] Some aspects include a system, including a treatment plant or manufacturing facility, for practicing the methods described herein. The system can have any configuration that enables the implementation of a particular production method of interest.

[0156] In certain embodiments, the system includes a source of a calcium compound or an aqueous solution containing a calcium compound from a cement factory, and a structure having an inlet for the aqueous solution. For example, the system can include a pipeline or similar supply for the aqueous calcium compound solution, where the aqueous solution is brine, seawater, or fresh water. The system further includes an inlet for CO2 from a cement factory and components for combining these sources with water (optionally an aqueous solution such as water, brine, or seawater) before or in the precipitation reactor. In some embodiments, the gas-liquid contact device is configured to contact sufficient CO2 to produce 1 ton, 10 tons, 100 tons, 1,000 tons, or more than 10,000 tons of precipitate per day.

[0157] The system further includes a precipitation reactor that subjects the water introduced into the precipitation reactor to one or more of the precipitation conditions (described herein) to produce a precipitate and a supernatant. In some embodiments, the precipitation reactor is configured to hold sufficient water to produce 1 ton, 10 tons, 100 tons, 1,000 tons, or more than 10,000 tons of precipitate per day. The precipitation reactor can also be configured to include any of several different elements, such as a temperature modulation element (e.g., configured to heat the water to a desired temperature), a chemical addition element (e.g., configured to introduce additives, etc. into the precipitation reaction mixture), computer automation, and the like.

[0158] The gaseous waste stream of CO2 can be provided from the cement factory to the precipitation site in any convenient manner. In some embodiments, the gaseous waste stream is provided using a gas conveyor (e.g., a duct) that travels from the site of the cement factory to one or more locations at the precipitation site. The source of the gaseous waste stream may be located at a location far from the precipitation site such that the source of the gaseous waste stream is at a distance of one mile or more, including distances of 100 miles or more from the precipitation site, e.g., 10 miles or more. For example, the gaseous waste stream may have been transported from a remote cement factory to the precipitation site via a CO2 gas transport system (e.g., a pipeline). The CO2-containing gas generated by the cement factory may or may not be treated (e.g., to remove other components) before reaching the precipitation site (i.e., the site where the precipitation and / or generation of the product takes place). In still other cases, the source of the gaseous waste stream is in proximity to the precipitation site. For example, the precipitation site is integrated with a source of the gaseous waste stream, such as a cement factory, that incorporates a precipitation reactor for precipitating a precipitation substance that can be used to produce a product.

[0159] When the brine source processed by the system to produce the composition of carbonate compounds is seawater, for example, when the inlet is a pipeline or supply pipe from seawater to an inlet port of a ground system or a hull, for example, when the system is part of a ship in a marine system, the inlet is in fluid connection with the seawater source.

[0160] The method and system can also include one or more detectors (not shown) configured to monitor a source of an aqueous medium or a source of carbon dioxide. Monitoring can include, but is not limited to, collecting data regarding the pressure, temperature, and composition of water or carbon dioxide gas. The detector can be any convenient device configured to monitor, such as a pressure sensor (e.g., an electromagnetic pressure sensor, a differential pressure sensor, etc.), a temperature sensor (a resistance temperature detector, a thermocouple, a gas thermometer, a thermistor, a pyrometer, an infrared radiation sensor, etc.), a volume sensor (e.g., a geophysical reflection tomography, an X-ray tomography, an underwater sonar, etc.), and a device for determining the chemical constitution of water or carbon dioxide gas (e.g., an IR spectrometer, an NMR spectrometer, a UV-vis spectrophotometer, a high-performance liquid chromatograph, an inductively coupled plasma optical emission spectrometer, an inductively coupled plasma mass spectrometer, an ion chromatograph, an X-ray diffractometer, a gas chromatograph, a gas chromatography-mass spectrometer, a flow injection analysis, a scintillation counter, an acid titration, and a flame emission spectrometer, etc.).

[0161] In some embodiments, the detector can also include a computer interface configured to provide the user with data collected regarding the aqueous medium, the calcium compound, and / or the carbon dioxide gas. In some embodiments, the summary can be saved as a computer-readable data file or printed as a user-readable document.

[0162] In some embodiments, the detector can be a monitoring device so that it can collect real-time data (e.g., internal pressure, temperature, etc.). In other embodiments, the detector can be one or more detectors configured to periodically determine parameters of the aqueous medium and / or the carbon dioxide gas, for example, to determine its composition every 1 minute, 5 minutes, 10 minutes, 30 minutes, 60 minutes, 100 minutes, 200 minutes, 500 minutes, or some other interval.

[0163] In certain embodiments, the system can further include a station for preparing building materials such as cement or aggregates from the precipitate. Other materials such as the formed building materials and / or non-cement materials can also be formed from the precipitate and a station suitable for their preparation can be used.

[0164] As shown above, the system can be present on land or at sea. For example, the system can be a land-based system, e.g., on the coast near a seawater source or at an inland location where water is piped to the system from a seawater source, e.g., the ocean. Alternatively, the system is an aquatic system, i.e., a system present on or in water. Such a system can be present as desired, e.g., on a boat, an ocean-based platform, etc.

[0165] In some embodiments, the calcium carbonate slurry is pumped through a drying system that includes spray drying after the filtration step. The water separated from the drying system is either released or recycled to the reactor. The solid or powder resulting from the drying system is utilized as cement or aggregate for producing building materials that effectively capture CO2. The solid or powder can also be used as a PCC filler in non-cement products such as paper, plastics, paints, etc. The solid or powder can also be used in the formation of formed building materials such as drywall, cement board, etc.

[0166] In some embodiments, the system can include a control station configured to control the amount of carbon dioxide, the amount of N-containing salts, and / or the amount of calcium compounds transported to a precipitation or filling device; the amount of precipitate transported to a separation device; the amount of precipitate transported to a drying station; and / or the amount of precipitate transported to a purification station. The control station can include a set of valves or a multi-valve system that is controlled manually, mechanically, or digitally, or any other convenient flow control protocol can be used. In some cases, the control station can include a computer interface configured to provide the user with input and output parameters for controlling the amounts (the adjustment can be computer-assisted or fully controlled by a computer). II. Product

[0167] Disclosed herein are methods and systems for producing a precipitate material containing calcite and / or aragonite polymorphic forms of calcium carbonate using a gaseous waste stream of CO2 and a calcium compound from a cement factory, wherein the vaterite is converted to aragonite to form cement. Also disclosed herein is an environmentally friendly method of removing or separating CO2 from a gaseous waste stream from a cement factory and fixing the CO2 in a storage-stable non-gaseous form (e.g., materials for constructing structures such as buildings and infrastructure, as well as the structures themselves or formed building materials such as drywall, or non-cement materials such as paper, paint, plastic, etc., or artificial reefs), thus preventing the CO2 from escaping into the atmosphere. Building materials

[0168] As used herein, "building materials" include materials used in construction. In one aspect, there is provided a structure or building material that includes, for example, a precipitate in which reactive vaterite has turned into aragonite, or a coagulated and hardened form of PCC that has coagulated and hardened. Products containing aragonite-form precipitates exhibit one or more unexpected properties, including, but not limited to, high compressive strength, high porosity (low density or lightweight), neutral pH (useful, for example, as an artificial reef), and a fine network structure.

[0169] Examples of such structures or building materials include, but are not limited to, buildings, driveways, foundations, kitchen slabs, furniture, sidewalks, roads, bridges, highways, overpasses, parking structures, bricks, blocks, walls, scaffolding for gates, fences, or poles, and combinations thereof. The formed building material

[0170] As used herein, "formed building materials" include materials formed into structures having defined physical shapes (e.g., molded, cast, cut, or otherwise produced). Formed building materials can be precast building materials, such as precast cement or concrete products. The formed building materials and the methods of making and using the formed building materials are described in U.S. Patent Application No. 12 / 571,398, filed September 30, 2009, which is hereby incorporated by reference in its entirety. Formed building materials can vary significantly and include materials formed into structures having defined physical shapes, i.e., three-dimensional configurations (e.g., molded, cast, cut, or otherwise produced). Formed building materials do not have defined stable shapes and are different from amorphous building materials (e.g., powders, pastes, slurries, etc.) that conform to the containers in which they are held, such as bags or other containers. Formed building materials are also different from irregularly or inaccurately formed materials (e.g., discarded aggregates, bulk forms, etc.) in that the formed building materials are produced according to specifications that enable, for example, the use of the formed building materials in a building. Formed building materials can be prepared according to conventional manufacturing protocols for such structures, except that the compositions of the present invention are used in the production of such materials.

[0171] In some embodiments, the methods provided herein further include the step of coagulating, hardening, and forming formed building materials from a precipitate material that includes reactive wattleite (reactive wattleite has changed to aragonite) or coagulated and hardened PPC.

[0172] In some embodiments, formed building materials made from precipitate materials have a compressive strength or flexural strength of at least 3 MPa, at least 10 MPa, or at least 14 MPa, or between 3 and 30 MPa, or between about 14 and 100 MPa, or between about 14 and 45 MPa, or have the compressive strength of the precipitate material after coagulation and hardening as described herein.

[0173] Examples of formed building materials that can be produced by the aforementioned method include, but are not limited to, stone units, such as, by way of example only, bricks, blocks, and tiles, including, but not limited to, ceiling tiles; building panels, such as, by way of example only, cement boards (boards conventionally made from cement, such as fiber cement boards) and / or drywall (boards conventionally made from plaster); conduits; sinks; beams; columns, slabs; sound barriers; insulation materials; or combinations thereof. Building panels are formed building materials used in a broad sense to refer to any non-load-bearing structural element characterized in that its length and width are substantially greater than its thickness. Thus, the panel may be a thick plate, board, roof panel, and / or tile. Exemplary building panels formed from sedimentary materials include cement boards and / or drywall. Building panels are polygonal structures having dimensions that vary significantly depending on their intended use. The dimensions of the building panel can range from a length of 100 to 300 cm, such as 50 to 500 cm including 250 cm; a width of 75 to 150 cm, such as 25 to 200 cm including 100 cm; and a thickness of 7 to 20 mm, such as 5 to 25 mm including 10 to 15 mm.

[0174] In some embodiments, the cement board and / or drywall can be used in the production of different types of boards, such as, but not limited to, paper-faced boards (e.g., surface reinforcement using cellulose fibers), fiber glass-faced or glass mat-faced boards (e.g., surface reinforcement using a glass fiber mat), fiber glass mesh-reinforced boards (e.g., surface reinforcement using a glass mesh), and / or fiber-reinforced boards (e.g., cement reinforcement using cellulose, glass, fibers, etc.). These boards can be used in a variety of applications, such as, but not limited to, shiplap, such as fiber-cement shiplap, roofing, soffits, sills, cladding, decking, ceilings, shaft liners, wall boards, backing, trim, friezes, roof panels, and fascia, and / or underlayment.

[0175] Cement boards have conventionally been made from cement, such as ordinary Portland cement (OPC), magnesium oxide cement and / or calcium silicate cement. The cement boards produced by the methods provided herein are made from a precipitate material that partially or completely replaces the conventional cement in the board. In some embodiments, the cement board can include a building panel prepared as a combination of aragonite cement (which coagulates and hardens when vaterite converts to aragonite) and fibers and / or fiberglass, and both sides of the board may be reinforced with additional fibers and / or fiberglass.

[0176] In some embodiments, the cement board is a formed building material that can be used as a backing board for ceramics, such as for use on the back side of bathroom tiles, kitchen countertops, backsplashes, etc., and can have a length in the range of 100 - 200 cm. The physical and mechanical properties of the cement board can vary. In some embodiments, the flexural strength can vary in the range of 2 - 6 MPa, for example between 1 - 7.5 MPa including 5 MPa. Also, the compressive strength can vary in the range of 5 - 50 MPa, for example between 10 - 30 MPa including 15 - 20 MPa. In some embodiments, the cement board can be used in environments that are extensively exposed to moisture, such as commercial saunas. The compositions or precipitate materials described herein can be used to produce the desired shape and size for forming the cement board. Further, various additional constituents can be added to the cement board, including but not limited to plasticizers, clays, foaming agents, accelerators, retarders and air entraining additives. Next, the composition can be poured into a sheet form or a sheet of the desired thickness can be formed using rollers. The formed composition can be further compressed by roller compression, hydraulic pressure, vibratory compression, or resonant shock compression. Next, the sheet is cut into cement boards of the desired dimensions.

[0177] Another type of building panel formed from the compositions or precipitated materials described herein is a backer board. The backer board can be used for the construction of interior and / or exterior floors, walls, and ceilings. In some embodiments, the backer board is made partially or completely from the precipitated material.

[0178] Another type of building panel formed from the composition or precipitated material is drywall. As used herein, "drywall" includes boards used for the construction of interior and / or exterior floors, walls, and ceilings. Conventionally, drywall has been formed from gypsum (referred to as plasterboard). In some embodiments, the drywall is made partially or completely from a carbonate precipitated material, thereby replacing the gypsum in the drywall product. In some embodiments, the drywall can include building panels prepared as a combination of aragonite cement (which sets and hardens when the batelite converts to aragonite) and cellulose, fibers, and / or fiberglass, and both sides of the board may be reinforced with additional paper, fibers, fiberglass mesh, and / or fiberglass mat. Various processes for making drywall products are well known in the art and are fully within the scope of the present invention. Some examples, but not limited to, include wet processes, semi-dry processes, extrusion processes, wonderborad® processes, etc., which are described herein.

[0179] In some embodiments, the drywall is a panel made from a paper liner that wraps around an inner core. For example, in some embodiments, during the process of making a drywall product from a precipitate material, a slurry of the precipitate material containing batelite is poured onto a paper sheet. Next, another paper sheet is placed on top of the precipitate material, and thus the precipitate material has paper disposed on both sides (the resulting composition is sandwiched between two sheets of an outer material, such as cardboard or a fiberglass mat). Next, the batelite in the precipitate material is converted to aragonite (using additives and / or heat), and then the aragonite coagulates and hardens. When the core coagulates and is dried in a large drying chamber, the sandwich panel becomes rigid and strong enough to be used as a building material. Next, the drywall sheets are cut and separated.

[0180] The bending and compressive strength of the drywall formed from the precipitate is the same as or higher than that of conventional drywalls prepared using gypsum plaster, which is known to be a soft building material. In some embodiments, the bending strength can range between 0.5 - 2 MPa, for example between 0.1 - 3 MPa including 1.5 MPa. The compressive strength also varies and can be in the range of 5 - 15 MPa in some cases, for example between 1 - 20 MPa including 8 - 10 MPa. In some embodiments, the formed building materials, such as building panels, for example but not limited to, cement boards and drywalls, produced by the methods described herein are of low density and high porosity, thereby making them suitable for lightweight insulation applications. The highly porous and lightweight formed building materials, such as building panels, can be obtained by the formation of an aragonite microstructure when the wattleite converts to aragonite. The conversion of wattleite during the dissolution / precipitation process can result in microporosity, while the voids formed between the formed aragonite crystals provide nanoporosity, thereby resulting in a highly porous lightweight structure. During the conversion process, certain admixtures such as, but not limited to, foaming agents, rheology modifiers, and mineral extenders such as, but not limited to, clay, starch, etc. can be added, whereby the foaming agent can entrain air in the mixture, thus adding porosity to the product and reducing the overall density. Also, mineral extenders such as sepiolite clay increase the viscosity of the mixture, thereby preventing the separation of the precipitate from the water.

[0181] One application of the cement board or drywall is fiber cement sheathing. The fiber-cement sheathing formed by the methods provided herein includes building panels prepared as a combination of aragonite cement, aggregate, woven cellulose, and / or polymer fibers and can have a texture and flexibility similar to wood.

[0182] In some embodiments, the formed building material is a stone unit. A stone unit is a formed building material that is generally used in the construction of load-bearing and non-load-bearing structures assembled using mortar, grout, etc. Exemplary stone units formed from the present composition include bricks, blocks, and tiles.

[0183] Another formed building material formed from the precipitate materials described herein is a conduit. A conduit is a pipe or similar structure configured to transport gas or liquid from one location to another. The conduit can include any of a number of different structures used for transporting liquids or gases, including, but not limited to, pipes, culverts, box culverts, drains and portals, inlet structures, intake towers, gate wells, outlet structures, etc.

[0184] Another formed building material formed from the precipitate materials described herein is a water basin. The term water basin can include any configuration of container used to hold a liquid, such as water. Thus, water basins can include structures such as, but not limited to, wells, collection boxes, sanitary manholes, septic tanks, catch basins, grease traps / separators, rainwater collection storage tanks, etc.

[0185] Another formed building material formed from the precipitate materials described herein is a beam, which in a broad sense refers to a horizontal load-bearing structure having high flexural strength and compressive strength. The beam can be a square cross-type, C-channel type, L-shaped cross-section edge beam, I-beam, spandrel beam, H-beam, and can have an inverted T design, etc. Also, the beam of the present invention can be a horizontal load-bearing unit, including, but not limited to, joists, sill stones, archways, and cantilever beams.

[0186] Another formed building material formed from the precipitate described in this specification is a column, which, in a broad sense, mainly refers to a vertical load-bearing structure that withstands loads mainly by axial compression and includes structural elements such as compression members. Other vertical compression members of the present invention may include, but are not limited to, columns, piers, pedestals, or postal posts.

[0187] Another formed building material formed from the precipitate described in this specification is a concrete slab. A concrete slab is a building material used in the construction of prefabricated foundations, floors, and wall panels. In some cases, the concrete slab can be used as a floor unit (e.g., a hollow-core slab unit or a double-tee design).

[0188] Another formed building material formed from the precipitate described in this specification is a sound barrier, which refers to a structure used as a barrier for sound attenuation or absorption. Thus, sound barriers may include, but are not limited to, structures such as soundproof panels, reflective barriers, absorption barriers, reactive barriers, etc.

[0189] Another formed building material formed from the precipitate described in this specification is a heat-insulating material, which refers to a material used to attenuate or suppress heat conduction. Heat-insulating materials may also include materials that reduce or suppress radiative heat transfer.

[0190] In some embodiments, other formed building materials include, but are not limited to, precast concrete products such as bunker silos, livestock feed bins, cattle grids, agricultural fences, H - type bins, J - type bins, livestock slats, livestock water troughs, building panel walls, cladding (brick), building trims, foundations, floors including dirt slabs, walls, precast sandwich panels with double walls, waterways, mechanically stabilized earth panels, box culverts, three - sided culverts, bridge systems, railroad crossings (RR crossing), railroad ties (RR tie), sound barriers / barriers, jersey barriers, tunnel segments, reinforced concrete boxes, utility protection structures, handholes, hollow core products, lighting pole bases, meter boxes, panel vaults, pull boxes, telecommunication structures, transformer pads, transformer rooms, trenches, utility vaults, utility poles, controlled environment rooms, underground bunkers, mausoleums, tombstones, coffins, hazardous material storage containers, detention vaults, drainage manholes, manholes, ventilation systems, distribution boxes, dosing tanks, dry wells, grease interceptors, leach pits, sand - oil / oil - water separators, septic tanks, water / sewer storage tanks, wet wells, fire water tanks, floating bridges, underwater infrastructure, decks, railings, breakwaters, roof tiles, paving stones, regional retaining walls, residential retaining walls, modular block systems, and segmental retaining walls. Non - cement composition

[0191] In some embodiments, the methods described herein include, but are not limited to, making other products, including non-cement compositions including paper, polymer products, lubricants, adhesives, rubber products, chalk, asphalt products, paints, abrasives for paint removal, personal care products, cosmetics, cleaning products, personal hygiene products, ingestible products, agricultural products, soil amendment products, pesticides, environmental remediation products, and combinations thereof, from the precipitate materials described herein. Such compositions are described in U.S. Patent No. 7,829,053, issued November 9, 2010, which is hereby incorporated by reference in its entirety. Artificial marine structures

[0192] In some embodiments, the methods described herein include, but are not limited to, making artificial marine structures, including artificial corals and reefs, from the precipitate materials described herein. In some embodiments, the artificial structures can be used in aquariums or in the sea. In some embodiments, these products are made from precipitate materials that include reactive vaterite that converts to aragonite after coagulating and hardening. Aragonite cement provides a neutral pH or near-neutral pH that can promote the maintenance and growth of marine organisms. Aragonite reefs can provide a suitable habitat for marine species.

[0193] The following examples are set forth to provide those of ordinary 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 the following experiments intended to represent all or the only experiments that have been performed. Efforts have been made to ensure accuracy with respect to the numerical values (e.g., amounts, temperatures, etc.) used, 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.

Examples

[0194] Example 1 Formation and conversion of precipitate substances from the calcination of limestone NH4Cl was dissolved in water. Limestone was calcined at 950 °C for 4 hours, cooled to room temperature, added to the NH4Cl aqueous solution, and mixed for several hours. The resulting mixture was decanted to remove heavy impurities. The unfiltered solution was transferred to an airtight container. The solution was supplied through a heat exchanger, thereby preheating the solution to 40 °C. The carbonation reactor was an acrylic cylinder equipped with baffles, a gas diffuser, a pH electrode, a thermocouple, a turbine impeller, and inlet and outlet ports for liquids, gases, and slurries. The CO2 inflow gas was allocated by a mass flow controller. During startup, the solution in the container was pumped into the reactor through a heat exchanger. While stirring the mixer, CO2 gas was introduced through the gas diffuser. The continuous inflow of the new reactant solution was controlled by maintaining the reactor at pH 8. The resulting reactive zeolite slurry was continuously collected in a holding container. The slurry was vacuum filtered. The reactive zeolite filter cake was oven dried at 100 °C. The cake showed 100% zeolite with an average particle size of 9 μm. The clear filtrate containing the regenerated NH4Cl was recycled for subsequent experiments. Example 2 Formation and conversion of precipitate substances from lime and CO2

[0195] Dissolve NH4Cl in water. Add calcium oxide to the aqueous solution and mix for several hours. Filter the resulting mixture under vacuum to remove insoluble impurities. Transfer the clear filtrate to a foldable airtight bag. Immerse the bag in a water bath to preheat the solution to 35 °C. The carbonation reactor is an acrylic cylinder equipped with baffles, a gas diffuser, a pH electrode, a thermocouple, a turbine impeller, and inlet and outlet ports for liquid, gas, and slurry. Assign the CO2 inlet gas by a mass flow controller. During startup, pump the solution in the bag into the reactor. While stirring the mixer, introduce CO2 gas through the gas diffuser. Control the continuous inflow of the new reactant solution by a computer automated control loop to maintain the pH at 7.5. Continuously collect the resulting reactive zeolite slurry in a holding container. Filter the slurry under vacuum. Dry the reactive zeolite filter cake in an oven at 100 °C. The cake shows 100% zeolite with an average PSA. Recycle the clear filtrate containing the regenerated NH4Cl for subsequent experiments.

[0196] Mix the dried reactive zeolite solid into a paste. The XRD of the paste after 1 day shows 99.9% aragonite (the zeolite has completely changed to aragonite). Cast the paste into 2’’×2’’×2’’ cubes and condense and cure them in a humidity chamber set at 60 °C and 80% relative humidity for 7 days. Dry the cemented cubes in an oven at 100 °C. By a destructive test, it is determined that the compressive strength of the cubes is 4600 psi (about 31 MPa).

[0197] The foregoing invention has been described in some detail by way of illustration and example for the purpose of a clear understanding. However, in light of the teachings of the present invention, it should be readily apparent to those skilled in the art that certain changes and modifications can be made thereto without departing from the spirit or scope of the appended claims. Accordingly, the foregoing is merely illustrative of the principles of the present invention. It will be appreciated by those skilled in the art that, although not explicitly described or shown herein, they can embody the principles of the present invention and devise various combinations that are within its spirit and scope. Further, all examples and conditional language set forth herein are principally intended to aid the reader in understanding the principles of the present invention and the concepts contributed by the inventors to advance the art, and are to be construed without limitation to such specifically recited examples and conditions. Moreover, all descriptions in this specification that set forth 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. Further, such equivalents are intended to include both currently known equivalents and equivalents developed in the future, i.e., any element developed that performs the same function regardless of structure. Accordingly, it is not intended that the scope of the present invention be limited to the exemplary embodiments shown and described herein. The following claims are intended to define the scope of the present invention, and methods and structures within the scope of these claims, as well as their equivalents, are intended to be protected thereby. The present invention provides, for example, the following items. (Item 1) a) A step of calcining limestone in a cement factory to form carbon dioxide and a calcium compound selected from calcium oxide, calcium hydroxide, or a combination thereof; b) A step of treating the calcium compound with an N-containing salt in water to produce an aqueous solution containing a calcium salt and an N-containing salt; c) A step of contacting the aqueous solution with the carbon dioxide under one or more precipitation conditions to produce a precipitate containing calcium carbonate and a supernatant aqueous solution, wherein the calcium carbonate contains baterite. A method comprising the above steps. (Item 2) The method according to Item 1, wherein the calcium oxide is underburned lime, low-reactivity lime, high-reactivity lime, or a combination thereof. (Item 3) The method according to Item 1 or 2, wherein the calcination step is performed in a blast furnace or a rotary kiln. (Item 4) The method according to any one of the above items, wherein the cement factory is a wet process factory or a dry process factory. (Item 5) The method according to any one of the above items, wherein the treatment step further comprises adding anhydrous ammonia or an aqueous ammonia solution. (Item 6) The method according to any one of the above items, wherein the N-containing salt is an N-containing inorganic salt, an N-containing organic salt, or a combination thereof. (Item 7) The method according to Item 6, wherein the N-containing salt is an N-containing inorganic salt. (Item 8) The method according to Item 7, wherein the N-containing inorganic salt is selected from the group consisting of ammonium halide, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite, and combinations thereof. (Item 9) The method according to Item 8, wherein the ammonium halide is ammonium chloride. (Item 10) The method according to any one of the above items, wherein the N-containing salt is ammonium chloride. (Item 11) The method according to Item 6, wherein the N-containing salt is an N-containing organic salt having an N-containing organic compound selected from the group consisting of aliphatic amines, alicyclic amines, heterocyclic amines, and combinations thereof. (Item 12) The method according to any one of the above items, wherein the molar ratio of the N-containing salt to the calcium compound is between about 0.5:1 and 2:1 by weight. (Item 13) A step of removing and optionally recovering ammonia and / or N-containing salts, comprising: (i) recovering a gas exhaust stream containing ammonia during the treatment step and / or the contacting step; (ii) further comprising a step of recovering the residual N-containing salts from the clarified aqueous solution, wherein the clarified aqueous solution contains the residual N-containing salts; and (iii) further comprising a step of removing and optionally recovering the residual N-containing salts from the precipitate, wherein the precipitate contains the residual N-containing salts. The method according to any one of the preceding items further comprises using one or more of the steps. (Item 14) The method according to item 13, further comprising a step of recovering the residual N-containing salts from the clarified aqueous solution using a recovery process selected from the group consisting of pyrolysis, pH adjustment, reverse osmosis, multi-stage flash, multiple effect distillation, vapor recompression, distillation, and combinations thereof. (Item 15) The method according to item 14, further comprising a step of recycling the recovered residual N-containing salts back to the treatment step, the contacting step of the process, or a combination thereof. (Item 16) The method according to item 13, wherein the step of recovering the gas exhaust stream containing ammonia comprises subjecting the gas exhaust stream containing ammonia to a scrubbing process, and the scrubbing process comprises scrubbing the gas exhaust stream containing ammonia with the carbon dioxide and water from the industrial process to produce an ammonia solution. (Item 17) The method according to item 13, wherein the step of recovering the gas exhaust stream containing ammonia comprises subjecting the gas exhaust stream containing ammonia to a scrubbing process, and the scrubbing process comprises scrubbing the gas exhaust stream containing ammonia with hydrochloric acid and water to produce an ammonium chloride solution. (Item 18) The method according to item 16, wherein the ammonia solution optionally contains carbamate that is recycled back to the contacting step. (Item 19) The step (iii) of removing the residual N-containing salt from the precipitate and recovering it if necessary, includes heating the precipitate between about 150 and 360 °C to evaporate the N-containing salt from the precipitate and recovering the N-containing salt by condensation if necessary, according to the method of item 13. (Item 20) The method according to any one of the above items, wherein the calcium carbonate contains reactive battelite. (Item 21) The method according to item 19, wherein the calcium carbonate contains reactive battelite remaining in the precipitate as reactive battelite after heating in step (iii). (Item 22) The method according to item 21, wherein the heating of the precipitate between about 150 and 360 °C is carried out for more than about 10 minutes or between about 10 and 60 minutes. (Item 23) The method according to item 19, wherein the N-containing salt evaporates from the precipitate in a form containing ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof. (Item 24) The method according to item 20 or 21, further including a step of adding water to the precipitate containing reactive battelite to convert the battelite to aragonite, and the aragonite condenses and hardens to form cement or a cement product. (Item 25) The method according to item 24, wherein the formed building material of the cement product is selected from stone units, building panels, conduits, washbasins, beams, columns, slabs, sound barriers, heat insulating materials, and combinations thereof. (Item 26) The method according to any one of the above items, wherein the aqueous solution further contains a solid. (Item 27) The method according to item 26, further including a step of separating the solid from the aqueous solution by filtration and / or centrifugation before the contacting step. (Item 28) The method according to item 27, wherein the separated solid is added to the precipitate as a filler. (Item 29) The method according to item 27, further including a step of recovering the residual N-containing salt from the solid using a recovery process selected from the group consisting of rinsing, pyrolysis, pH adjustment, and combinations thereof. (Item 30) The method according to item 26, wherein the solid is not separated from the aqueous solution, and the aqueous solution is contacted with the carbon dioxide to produce the precipitate further containing the solid. (Item 31) The method according to any one of items 26 to 30, wherein the solid contains carbon, silica, iron oxide, aluminum oxide, or a combination thereof. (Item 32) The method according to any one of Items 26 to 31, wherein the solid is present in the aqueous solution, in the precipitate, or in a combination thereof, in an amount between 1 and 40 wt%. (Item 33) The method according to any one of the preceding items, wherein the one or more precipitation conditions are selected from temperature, pH, pressure, ion ratio, precipitation rate, presence of additives, presence of ionic species, concentration of additives and ionic species, stirring, residence time, mixing rate, agitation mode, seed crystal, catalyst, presence of a membrane or substrate, dehydration, drying, ball milling, and combinations thereof. (Item 34) The method according to any one of the preceding items, wherein the one or more precipitation conditions favorable for the formation of calcium carbonate or favorable for the formation of reactive zeolite include a pH between 7 and 8.5 of the aqueous solution, a temperature between 20 and 80 °C of the solution, a residence time between 15 and 60 minutes, or a combination thereof. (Item 35) A product formed by the method according to Item 1.

Claims

1. a) A step of firing limestone to form a calcium compound containing carbon dioxide and calcium oxide, wherein the limestone contains at least one magnesium carbonate and magnesium oxide, and the calcium oxide contains soft burnt lime; b) A step of treating the calcium compound with an N-containing salt in water to produce an aqueous solution containing a calcium salt and a solid; c) A step of contacting the aqueous solution containing the calcium salt and the solid with the carbon dioxide to produce a precipitate containing calcium carbonate and the solid, wherein the calcium carbonate contains wadelite; A method comprising the above steps.

2. The method according to claim 1, wherein the limestone has a magnesium carbonate content of 5% or less, 5-20% or 20-45%, and the calcium oxide further contains unburnt lime, low-reactivity lime, or a combination thereof.

3. The method according to claim 1 or 2, wherein step b) further comprises adding anhydrous ammonia or an aqueous ammonia solution.

4. The N-containing salt is an N-containing inorganic salt, an N-containing organic salt, or a combination thereof, wherein the N-containing salt is an N-containing inorganic salt, the N-containing inorganic salt is selected from the group consisting of ammonium halides, ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite, and combinations thereof, the N-containing salt is an N-containing organic salt having an N-containing organic compound selected from the group consisting of aliphatic amines, alicyclic amines, heterocyclic amines, and combinations thereof, the ratio of the N-containing salt to the calcium compound is between 0.5:1 and 4:1, and the ratio is a molar ratio or a wt% ratio. The method according to any one of claims 1 to 3.

5. A step of removing and recovering ammonia and / or N-containing salts, comprising: (i) a step of recovering a gas exhaust stream containing ammonia during step b) and / or step c); (ii) step c) generates an upper clear aqueous solution, the upper clear aqueous solution contains residual N-containing salts, and further includes a step of recovering the residual N-containing salts from the upper clear aqueous solution; and (iii) the precipitate contains residual N-containing salts, and further includes a step of removing and recovering the residual N-containing salts from the precipitate. The method according to any one of claims 1 to 4 further includes using one or more of the steps.

6. Further comprising a step of recovering the residual N-containing salts from the upper clear aqueous solution using a recovery process selected from the group consisting of pyrolysis, pH adjustment, reverse osmosis, multi-stage flash, multiple effect distillation, vapor recompression, distillation, and combinations thereof, and / or The step of removing and recovering the residual N-containing salts from the precipitate further includes heating the precipitate between 150 and 360 °C to evaporate the N-containing salts from the precipitate and recovering the N-containing salts by condensation. The method according to claim 5.

7. The step of recovering the gas exhaust stream containing ammonia includes subjecting the gas exhaust stream containing ammonia to a scrubbing process, the scrubbing process includes scrubbing the gas exhaust stream containing ammonia with carbon dioxide and water to generate an ammonia solution, and the ammonia solution contains carbamate that is returned to step c) for recycling, and / or The scrubbing process includes scrubbing the gas exhaust stream containing ammonia with hydrochloric acid and water to generate an ammonium chloride solution. The method according to claim 5.

8. The method according to any one of claims 1 to 7, wherein the bauxite is reactive bauxite or stable bauxite.

9. The method according to claim 8, further comprising a step of adding water to the precipitate containing the reactive zeolite and converting the zeolite to aragonite, wherein the aragonite aggregates and hardens to form cement or a cement product, and wherein the cement product is a formed building material selected from stone units, building panels, conduits, washbasins, beams, columns, slabs, sound barriers, heat insulating materials, and combinations thereof.

10. The method according to any one of claims 1 to 9, wherein the solid contains carbon, silica, iron oxide, aluminum oxide, or a combination thereof, and the solid is present in the aqueous solution in step b), in the precipitate, or a combination thereof, in an amount between 1 and 40 wt%.

11. The method according to any one of claims 1 to 10, further comprising a step of adding an additive to the aqueous solution or the precipitate in step b), wherein the additive is selected from the group consisting of fatty acid esters, sodium dodecyl sulfate, lauric acid, sodium laurate, urea, citric acid, sodium citrate, phthalic acid, sodium phthalate, taurine, creatine, glucose, poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium aspartate, magnesium chloride, acetic acid, sodium acetate, glutamic acid, sodium glutamate, strontium chloride, gypsum, lithium chloride, sodium chloride, glycine, sodium anhydrous citrate, sodium bicarbonate, magnesium sulfate, magnesium acetate, sodium polystyrene, sodium dodecyl sulfonate, polyvinyl alcohol, and combinations thereof.

12. The method according to any one of claims 1 to 11, wherein the zeolite is a particulate composition having an average particle size of 0.1 to 100 microns, and the zeolite has a unimodal or multimodal (such as bimodal) distribution.

13. The method further comprises a step of blending the precipitate with ordinary Portland cement (OPC) or an aggregate, or further comprising the step of mixing the precipitate with one or more admixtures selected from the group consisting of a coagulation accelerator, a coagulation retarder, an air entrainer, a foaming agent, an antifoaming agent, an alkali reactivity reducer, a binder admixture, a dispersant, a coloring admixture, a corrosion inhibitor, a moisture-proof admixture, a gas former, a permeability reducer, a pumping aid, a shrinkage compensating admixture, a fungicidal admixture, a bactericidal admixture, an insecticidal admixture, a rheology modifier, a finely divided mineral admixture, a pozzolan, an aggregate, a wetting agent, a strength enhancer, a water repellent, a reinforcing material, and combinations thereof, The method according to any one of claims 1 to 12, wherein the reinforcing material is a fiber made of zirconia, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood, fiberglass, a synthetic material, or a combination thereof.

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