Compositions, methods, and systems for forming vaterite and magnesium oxide

Abstract

The present invention provides compositions, methods, and systems for forming vaterite and magnesium oxide. [Solution] This specification provides compositions, methods, and systems comprising vaterite and magnesium oxide. In some embodiments of the above-described aspects, the method further comprises the step of generating a solid comprising magnesium oxide in step (ii), and treating an aqueous solution comprising a calcium salt and magnesium oxide, as well as the solid comprising magnesium oxide, with a gas stream comprising carbon dioxide to form a composition comprising vaterite, magnesium oxide, and a solid comprising magnesium oxide.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the benefits of U.S. Provisional Application No. 63 / 176,709, filed on 19 April 2021, which is incorporated herein by reference in its entirety. [Background technology]

[0002] background Carbon dioxide (CO2) emissions have been identified as a major contributor to global warming. CO2 is a byproduct of combustion and causes operational, economic, and environmental problems. Increased concentrations of CO2 and other greenhouse gases in the atmosphere are predicted to further promote heat storage in the atmosphere, potentially leading to rising surface temperatures and rapid climate change. Furthermore, rising 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, are likely to become more economically costly and environmentally harmful. Reducing the potential risks of climate change requires the sequestration and avoidance of CO2 from various anthropogenic processes. [Overview of the Initiative] [Means for solving the problem]

[0003] overview This specification provides a method and system for capturing CO2 emissions and producing compositions having unique properties that can be used to manufacture cement or non-cement products.

[0004] In one embodiment, a cement or non-cemental composition comprising vaterite and magnesium oxide is provided. In some embodiments of the above-described embodiments, the vaterite is present in an amount between about 30 and 99 wt%, and the magnesium oxide is present in an amount between about 1 and 70 wt%. In some embodiments of the above-described embodiments and embodiments, the particle size of the vaterite is between about 0.1 and 100 microns. In some embodiments of the above-described embodiments and embodiments, the composition is a dry powder composition. In some embodiments of the above-described embodiments and embodiments, the composition is a wet cake composition or a slurry. In some embodiments of the above-described embodiments and embodiments, the magnesium oxide is incompletely combusted magnesium oxide, lightly calcined magnesium oxide, dead calcined magnesium oxide, or a combination thereof. In some embodiments of the above-described embodiments and embodiments, the vaterite is partially present on the surface of the magnesium oxide. In some embodiments of the above-described embodiments and embodiments, the composition further comprises admixtures, aggregates, additives, Portland cement clinker, auxiliary cement material (SCM), or a combination thereof.

[0005] In some embodiments of the aforementioned aspects and embodiments, the composition further comprises aragonite, calcite, magnesium hydroxide, or a combination thereof, and water, and the composition is a slurry composition. In one embodiment, a cement or non-cement slurry composition is provided comprising vaterite, aragonite, calcite, magnesium oxide, magnesium hydroxide, or a combination thereof, and water. In some embodiments of the aforementioned aspects, the vaterite is converted to aragonite and / or calcite upon dissolution and reprecipitation in water, and the magnesium oxide is converted to magnesium hydroxide. In some embodiments of the aforementioned aspects and embodiments, the aragonite is in the form of a needle-like network structure. In some embodiments of the aforementioned aspects and embodiments, the magnesium hydroxide binds the needle-like aragonite together. In some embodiments of the aforementioned aspects and embodiments, the magnesium hydroxide binds the calcite together. In some embodiments of the aforementioned aspects and embodiments, the magnesium hydroxide stabilizes the aragonite and prevents the conversion of aragonite to calcite. In some embodiments of the aforementioned aspects and embodiments, water is bound to the composition in the form of magnesium hydroxide. In the aforementioned embodiments and some embodiments, the composition has a pH greater than 10. In the aforementioned embodiments and some embodiments, the composition further comprises admixtures, aggregates, additives, Portland cement clinker, auxiliary cement material (SCM), or a combination thereof.

[0006] In one aspect, a cement or non-cement product containing aragonite and / or calcite, and magnesium hydroxide is provided, where the magnesium hydroxide binds aragonite and / or calcite together. In some embodiments of the foregoing aspect, the product has a porosity between 0 and 95%. In some embodiments of the foregoing aspect and embodiments, the product has a compressive strength greater than 0.05 MPa. In some embodiments of the foregoing aspect and embodiments, the product has a pH greater than 10, preventing the corrosion of steel. In some embodiments of the foregoing aspect and embodiments, the aragonite is in the shape of a needle mesh structure. In some embodiments of the foregoing aspect and embodiments, the magnesium hydroxide binds aragonite and / or calcite together. In some embodiments of the foregoing aspect and embodiments, the magnesium hydroxide fills the gaps between aragonite and / or calcite, making it denser and reducing the porosity. In some embodiments of the foregoing aspect and embodiments, the magnesium hydroxide stabilizes the aragonite and prevents the conversion of aragonite to calcite.

[0007] In one aspect, a method for forming a composition, comprising: (i) firing limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide; (ii) dissolving the mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and magnesium oxide; (iii) treating the aqueous solution containing calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide. A method is provided that includes the above steps.

[0008] In some embodiments of the foregoing aspect, the method further comprises, in step (ii), generating a solid containing magnesium oxide, and treating an aqueous solution containing a calcium salt and magnesium oxide, and the solid containing magnesium oxide, with a gas stream containing carbon dioxide to form a composition containing baterite, magnesium oxide, and the solid containing magnesium oxide.

[0009] In one aspect, a method for forming a composition, comprising: (i) firing limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide; (ii) dissolving the mixture containing lime and magnesium oxide in an N-containing salt solution to generate an aqueous solution containing a calcium salt and a solid containing magnesium oxide; (iii) separating the solid from the aqueous solution; (iv) treating the aqueous solution containing the calcium salt with a gas stream containing carbon dioxide to form a composition containing baterite; and (v) mixing the composition containing baterite and the solid containing magnesium oxide.

[0010] In one aspect, a method for forming a composition, comprising: (i) firing limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide; (ii) dissolving the mixture containing lime and magnesium oxide in an aqueous N-containing salt solution to generate a first aqueous solution containing a calcium salt and magnesium oxide, and a gas stream containing ammonia; (iii) recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, subjecting the gas streams to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonia carbamate, or a combination thereof; (iv) A first aqueous solution containing a calcium salt and magnesium oxide is treated with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and magnesium oxide. A method is provided that includes this.

[0011] In some embodiments of the aforementioned aspects, the method further includes the step of generating a solid containing magnesium oxide in step (ii), and treating a first aqueous solution containing a calcium salt and magnesium oxide, as well as the solid containing magnesium oxide, with a second aqueous solution to form a composition containing vaterite, magnesium oxide, and a solid containing magnesium oxide.

[0012] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia, (iii) A step of separating the solid from the first aqueous solution, (iv) A step of recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, subjecting the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, (v) A step of treating a first aqueous solution containing a calcium salt with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite, (vi) A step of mixing a composition containing vaterite and a solid containing magnesium oxide. A method is provided that includes this.

[0013] In some embodiments of the aforementioned aspects, the limestone contains magnesium or magnesium-supported minerals between about 1 and 70%. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of mixing the magnesium-supported minerals with the limestone before calcination. In some embodiments of the aforementioned aspects and embodiments, the magnesium-supported minerals contain magnesium between about 1 and 70%. In some embodiments of the aforementioned aspects and embodiments, during calcination, the magnesium or magnesium-supported minerals form magnesium oxide. In some embodiments of the aforementioned aspects and embodiments, the magnesium-supported minerals include magnesium carbonate, calcium magnesium carbonate, magnesium salts, potassium magnesium salts, magnesium hydroxide, magnesium silicate, magnesium iron silicate, magnesium sulfate, or a combination thereof. In some embodiments of the aforementioned aspects and embodiments, the magnesium-supported minerals include magnesium carbonate, magnesium salts, magnesium hydroxide, magnesium silicate, magnesium sulfate, or a combination thereof. In the aforementioned embodiments and some embodiments, the magnesium-supported mineral is selected from the group consisting of dolomite, magnesite, brucite, carnalite, talc, olivine, artiniite, hydromagnesite, dipingite, barringonite, neskehonite, lansfordite, kieserite, and combinations thereof.

[0014] In some embodiments of the aforementioned aspects and embodiments, the calcination step produces a mixture comprising incompletely combusted lime, lightly calcined quicklime, dead lime, incompletely combusted magnesium oxide, lightly calcined magnesium oxide, dead magnesium oxide, or a combination thereof. In some embodiments of the aforementioned aspects and embodiments, the method further includes a step of controlling the calcination process to control the components of the mixture. In some embodiments of the aforementioned aspects and embodiments, the step of controlling the calcination process includes controlling the temperature and / or duration of heating the limestone.

[0015] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of converting vaterite to aragonite and / or calcite and magnesium oxide to magnesium hydroxide upon dissolution and reprecipitation in water. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of forming needle-shaped aragonite. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of binding the aragonite and / or calcite together with magnesium hydroxide. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of stabilizing the aragonite with magnesium hydroxide to prevent conversion from aragonite to calcite. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of forming a composition having a pH greater than 10. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of binding water to the composition in the form of magnesium hydroxide so that there is no unbound water in the composition.

[0016] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of setting and hardening aragonite and / or calcite to form a cement product. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of filling the voids between aragonite and / or calcite with magnesium hydroxide to increase its density and reduce its porosity. In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of preventing the conversion of aragonite to calcite by the presence of magnesium hydroxide.

[0017] In some embodiments of the aforementioned aspects and embodiments, the N-containing salt is selected from the group consisting of N-containing inorganic salts, N-containing organic salts, and combinations thereof. In some embodiments of the aforementioned aspects and embodiments, calcination is carried out in a shaft kiln, rotary furnace, or electric furnace. In some embodiments of the aforementioned aspects 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 aforementioned aspects and embodiments, the ammonium halide is ammonium chloride.

[0018] In some embodiments of the aforementioned aspects and embodiments, the aqueous solution or the first aqueous solution further comprises ammonia and / or an N-containing inorganic salt.

[0019] In the embodiments described above and in some embodiments of the embodiments, the molar ratio of the mixture containing N-containing salt to lime and magnesium oxide is between approximately 0.5:1 and 3:1.

[0020] In the embodiments described above and in some embodiments of the embodiments, the dissolution step is one or more dissolution conditions selected from the group consisting of a temperature between about 30 and 200°C, a pressure between about 0.1 and 10 atm, a wt% of N-containing salt in water between about 0.5 and 50%, and combinations thereof.

[0021] In the aforementioned embodiments and some of the embodiments, no external sources of carbon dioxide and / or ammonia are used, and the process is a closed-loop process.

[0022] In the aforementioned embodiments and some embodiments of the model, the gas stream containing ammonia further contains water vapor.

[0023] In the aforementioned embodiments and some embodiments of the model, the gas stream further contains water vapor between approximately 20% and 90%.

[0024] In the aforementioned embodiments and some of the embodiments, no external water is added to the cooling process.

[0025] In the embodiments described above and in some embodiments of the embodiments, the cooling step is one or more cooling conditions including a temperature between about 0 and 100°C, a pressure between about 0.5 and 50 atm, a pH of the aqueous solution between about 8 and 12, a CO2 flow rate, a CO2:NH3 ratio between about 0.1:1 and 20:1, or a combination thereof.

[0026] In the aforementioned embodiments and some of the embodiments, the second aqueous solution is formed by gas condensation.

[0027] In the aforementioned embodiments and some embodiments of the model, the processing step is one or more precipitation conditions selected from the group consisting of a pH of the aqueous solution or the first aqueous solution between 7 and 9, a solution temperature between 20 and 60°C, a residence time between 5 and 60 minutes, or a combination thereof.

[0028] In the aforementioned embodiments and some embodiments in which a solid containing magnesium oxide is formed, the solid further comprises silicates, iron oxides, alumina, or a combination thereof. In the aforementioned embodiments and some embodiments in which the solid is present in an aqueous solution or the first aqueous solution, composition, or a combination thereof at a concentration of 1 to 40 wt%.

[0029] In some embodiments of the aforementioned aspects and embodiments, the method further includes a step of separating the solid from the aqueous solution or the first aqueous solution by filtration and / or centrifugation prior to the processing step. In some embodiments of the aforementioned aspects and embodiments, the separated solid is added back to the composition as a filler.

[0030] In the embodiments described above and in some embodiments of the embodiments, if the N-containing inorganic salt is ammonium halide, the separated solid further contains residual ammonium halide.

[0031] In some embodiments of the aforementioned aspects and embodiments, the method further includes a step of recovering residual ammonium halide from a solid using a recovery process selected from the group consisting of rinsing, pyrolysis, pH adjustment, and combinations thereof.

[0032] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of dehydrating the precipitate / composition to separate the composition from the supernatant solution.

[0033] In the aforementioned embodiments and some embodiments of the model, the composition and the supernatant solution contain residual nitrogen-containing salts.

[0034] In the embodiments described above and in some embodiments of the embodiments, the method further includes the steps of removing ammonia and / or N-containing inorganic salts from residual N-containing inorganic salts and recovering them if necessary, removing residual N-containing inorganic salts from a supernatant aqueous solution and recovering them if necessary, and / or removing residual N-containing inorganic salts from a precipitate / composition and recovering them if necessary.

[0035] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of recovering residual nitrogen-containing inorganic salts from the supernatant aqueous solution using a recovery process selected from the group consisting of pyrolysis, pH adjustment, reverse osmosis, multi-stage flash distillation, multiple-effect distillation, vapor recompression, distillation, and combinations thereof.

[0036] In some embodiments of the aforementioned aspects and embodiments, the step of removing and, if necessary, recovering residual nitrogen-containing inorganic salts from the precipitate / composition includes heating the composition between approximately 300 and 360°C to evaporate the nitrogen-containing inorganic salts from the composition and, if necessary, recovering the nitrogen-containing inorganic salts by condensation.

[0037] In the embodiments described above and in some embodiments of the embodiments, the N-containing inorganic salt is ammonium chloride that evaporates from the composition in a form that includes ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof.

[0038] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of recirculating the recovered residual ammonia and / or N-containing inorganic salts to the dissolution step and / or processing step of the process.

[0039] In some embodiments of the aforementioned aspects and embodiments, aragonite and / or calcite solidify and harden to form masonry units, building panels, conduits, basins, beams, columns, slides, etc. The cement products are formed from materials selected from sound barriers, thermal insulation materials, and combinations thereof.

[0040] In the aforementioned embodiments and some embodiments of the model, aragonite and / or calcite solidify and harden to form a non-cement product.

[0041] In the embodiments described above and in some embodiments of the embodiments, the method further comprises the step of adding an additive to an aqueous solution, a first aqueous solution, and / or a composition, the additive being selected from the group consisting of fatty acid esters, sodium decyl sulfate, lauric acid, sodium salt of lauric acid, urea, citric acid, sodium salt of citric acid, phthalic acid, sodium salt of phthalic acid, taurine, creatine, glucose, poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium salt of aspartic acid, magnesium chloride, acetic acid, sodium salt of acetic acid, glutamic acid, sodium salt of glutamic acid, strontium chloride, gypsum, lithium chloride, sodium chloride, glycine, anhydrous sodium citrate, sodium bicarbonate, magnesium sulfate, magnesium acetate, sodium polystyrene, sodium dodecyl sulfonate, polyvinyl alcohol, and combinations thereof.

[0042] In the embodiments described above and in some embodiments of the embodiments, the vaterite is a unimodal, bimodal, or multimodal distribution of a particulate composition having an average particle size between approximately 0.1 and 100 microns.

[0043] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of blending the composition with ordinary Portland cement (OPC), aggregate, limestone, or a combination thereof.

[0044] In some embodiments of the aforementioned aspects and embodiments, the method further includes the step of mixing the composition with an admixture selected from the group consisting of setting accelerators, setting retarders, air entrainers, foaming agents, defoaming agents, alkali reactivity reducing agents, binding admixtures, dispersants, coloring admixtures, corrosion inhibitors, moisture-proof admixtures, gas-forming agents, permeability reducing agents, pumping aids, shrinkage-correcting admixtures, fungicidal admixtures, bactericidal admixtures, insecticidal admixtures, rheological modifiers, finely ground mineral admixtures, pozzolanes, aggregates, wetting agents, strength enhancers, water repellents, reinforcing materials, and combinations thereof.

[0045] In the embodiments described above and in some embodiments of the examples, the reinforcing material is a fiber made from zirconia, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood, glass fiber, synthetic material, or a combination thereof.

[0046] In one embodiment, a product formed by the method according to the above-described embodiment is provided.

[0047] In one embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and magnesium oxide, and which is operably connected to a calcination reactor, (iii) A treatment reactor operably connected to a dissolution reactor and a calcination reactor, configured to treat an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0048] In one embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia. (iii) A cooling reactor operably connected to a dissolution reactor and a calcination reactor, configured to recover a gas stream containing carbon dioxide and a gas stream containing ammonia, and to subject the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, and (iv) A treatment reactor operably connected to a dissolution reactor and a cooling reactor, configured to treat a first aqueous solution containing a calcium salt and magnesium oxide with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0049] In some embodiments of the aforementioned features, the dissolution reactor is integrated with the cooling reactor. [Brief explanation of the drawing]

[0050] The features of the present invention are specifically described using the appended claims. The features and advantages of the present invention will be better understood by referring to the following detailed description, which describes exemplary embodiments in which the principles of the present invention are utilized, and to the following appended figures.

[0051] [Figure 1]Figure 1 shows some embodiments of the methods and systems provided herein.

[0052] [Figure 2] Figure 2 shows some embodiments of the methods and systems provided herein.

[0053] [Figure 3] Figure 3 shows some embodiments of the methods and systems provided herein.

[0054] [Figure 4] Figure 4 shows some embodiments of methods and systems including an integrated reactor provided herein.

[0055] [Figure 5] Figure 5 shows the Gibbs free energy diagram for the transition from vaterite to aragonite.

[0056] [Figure 6] Figures 6A and 6B show scanning electron microscope images of aragonite-containing calcium carbonate cement made from vaterite at 1000x magnification (Figure 6A) and 2500x magnification (Figure 6B).

[0057] [Figure 7] Figures 7A and 7B show scanning electron microscope images of calcium carbonate cement containing aragonite and magnesium hydroxide, prepared from vaterite and magnesium oxide, respectively, at 1000x magnification (Figure 7A) and 2500x magnification (Figure 7B). [Modes for carrying out the invention]

[0058] explanation In the conversion of calcium carbonate cement, water does not chemically bond with the cement, and therefore, regardless of the type of water used to prepare the calcium carbonate cement paste, mortar, or concrete, water may remain in the cement after conversion. This residual water, after evaporation, contributes to the porosity of the calcium carbonate cement paste, potentially negatively impacting the strength, hardness, and durability of the hardened cement paste. Furthermore, the conversion of vaterite to either calcite or aragonite may result in a reduction in actual volume, further increasing the porosity of the cement and potentially leading to difficulties in the durability and strength of the cemented composite.

[0059] The applicants have discovered unique compositions, methods, and systems containing vaterite and magnesium oxide (MgO) that overcome these difficulties and provide durable aragonite cement composites and / or calcite cement composites with high compressive strength. Unexpectedly, the conversion of vaterite to aragonite and / or calcite, as well as the conversion of magnesium oxide to magnesium hydroxide, were found to dissolve in water, reprecipitation, and then form magnesium hydroxide-bonded aragonite cement and / or calcite cement with high durability and strength.

[0060] Incorporating magnesium oxide (e.g., periclase) into a vaterite composition may provide one or more of the following advantages: Firstly, magnesium oxide in a vaterite-containing composition can control the conversion of vaterite to aragonite (preventing further conversion to calcite if necessary) and / or provide the magnesium ions necessary to control the conversion to calcite. Secondly, magnesium oxide can chemically react with water to form magnesium hydroxide. The bound water is then added to the volume of the hardened cement paste, thereby reducing the porosity of the cement paste. Reduced porosity can increase strength, hardness, and durability. Thirdly, the presence of magnesium hydroxide can buffer the pH of the cement pore solution to approximately above 9, which may be sufficient to prevent the reinforcing mild steel from actively corroding in the cement structure.

[0061] Accordingly, this specification provides unique compositions, methods, and systems comprising vaterite and magnesium oxide formed from limestone, which can be used to form a variety of products as described herein. Limestone is calcined to form lime, which is then treated with an aqueous solution of an N-containing salt, such as an aqueous solution of ammonium salt, e.g., an aqueous solution of ammonium chloride or ammonium acetate, to solubilize or dissolve the calcium of the lime in an aqueous solution. Magnesium oxide may be formed from minerals in the limestone during calcination, from any magnesium-supported mineral separately added to the limestone during calcination, and / or added to a composition containing vaterite after its formation. All of these methods are well within the scope of the present invention, and one or more of these methods may be combined to achieve the compositions, methods, and systems provided herein. Calcium dissolved in the form of a calcium salt is then treated with carbon dioxide gas (e.g., CO2 generated during the calcination of limestone) to form a precipitate / composition containing vaterite and magnesium oxide.

[0062] Typically, the amount of magnesium in OPC is carefully monitored. If a quarry encounters a magnesium-bearing rock seam that appears to exceed the magnesium limit, the quarry may be forced to manage that material separately. If the magnesium content is too high, the quarry may be forced to set aside the material and not use it, or to use it for low-value operations such as constructing roads within the quarry. It is undesirable for quarries to have to set aside quarried rock, as they may bear the costs of blasting and transporting the rock but do not receive compensation for the cement produced from high-magnesium-containing rock. However, the unique compositions, methods, and systems containing vaterite and magnesium oxide provided herein offer the additional advantage of utilizing these high-magnesium-bearing rocks by producing cement compositions containing vaterite and magnesium oxide. The magnesium oxide in the composition may be in a reactive form that is converted to magnesium hydroxide during hydration (the cementation process).

[0063] In some embodiments, compositions comprising vaterite and magnesium oxide have unique properties, including, but are not limited to, cementitious properties, by converting them to aragonite and / or calcite and magnesium hydroxide, respectively, which set and cement with high compressive strength, durability, and hardness. In some embodiments, the conversion of vaterite to aragonite and / or calcite yields cement that can be used to form building materials and / or cement products, such as, but are not limited to, formed building materials further described herein, such as building panels, aggregates, concrete, etc. In some embodiments, vaterite can be used as a filler or auxiliary cement material (SCM) when mixed with other cements, such as ordinary Portland cement (OPC). Compositions comprising vaterite and magnesium oxide can be used as aggregates in which vaterite and magnesium oxide are converted to aragonite and / or calcite and magnesium hydroxide, respectively, after contact with water, which then set and cementify, and are subsequently crushed to form aggregates after cementification. In some embodiments, compositions comprising vaterite and magnesium oxide can be used as fillers in non-cement 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, edible products, agricultural products, soil conditioners, biocides, environmental remediation products, and combinations thereof, after conversion to aragonite and / or calcite and magnesium hydroxide, respectively. Such non-cement products are described in U.S. Patent No. 7,829,053 issued November 9, 2010, which is incorporated herein by reference in its entirety.

[0064] The compositions, methods, and systems provided herein, though not limited to them, offer several advantages, including reducing carbon dioxide emissions by reincorporating carbon dioxide into the process to form compositions containing vaterite and magnesium oxide. The production of vaterite-containing compositions in the methods and systems provided herein offers advantages including reduced operating costs due to lower fuel consumption and a reduced carbon footprint. Cement is a significant contributor to global carbon dioxide emissions, with over 1.5 billion metric tons released annually, representing approximately 5% of total emissions. Over 50% of cement emissions can originate from carbon dioxide emissions from the decomposition of limestone raw materials (CaCO3 → CaO + CO2). In the methods and systems provided herein, CO2 emissions resulting from the calcination of limestone to lime can be avoided by reincorporating it back into cement vaterite and magnesium oxide materials. By reincorporating carbon dioxide, vaterite and magnesium oxide compositions have the potential to eliminate significant carbon dioxide emissions from cement and global total emissions from any source. The vaterite and magnesium oxide compositions provided herein can be used, but are not limited to, to completely or partially replace OPC in building applications such as cement fiberboard. I. Methods and Systems

[0065] In one embodiment, a method and system for forming a composition comprising vaterite and magnesium oxide are provided.

[0066] In one embodiment, a method for forming a composition is provided, comprising the step of dissolving lime and magnesium oxide in an aqueous solution of nitrogen-containing salt under one or more precipitation conditions to produce a composition comprising vaterite and magnesium oxide.

[0067] In one embodiment, a method for forming a composition is provided, comprising the steps of: dissolving a mixture containing lime and magnesium oxide in a nitrogen-containing salt solution under one or more dissolution conditions to produce an aqueous solution containing a calcium salt and magnesium oxide; and treating the aqueous solution containing the calcium salt and magnesium oxide with a gas stream containing carbon dioxide under one or more precipitation conditions to form a composition containing vaterite and magnesium oxide.

[0068] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A step of dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and magnesium oxide, (iii) A method is provided which includes the step of treating an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide.

[0069] In the embodiments described above, in some embodiments, the aqueous solution containing the calcium salt and magnesium oxide further contains dissolved ammonia and / or a dissolved N-containing salt.

[0070] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A step of dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia, (iii) A step of treating an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide and a gas stream containing ammonia to form a composition containing vaterite and magnesium oxide. A method is provided that includes this.

[0071] In one embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and magnesium oxide, and which is operably connected to a calcination reactor, (iii) A treatment reactor operably connected to a dissolution reactor and a calcination reactor, configured to treat an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0072] In the embodiments described above, in some embodiments, the aqueous solution containing the calcium salt and magnesium oxide further contains dissolved ammonia and / or a dissolved N-containing salt.

[0073] In one embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia, and (iii) A treatment reactor operably connected to a dissolution reactor and a calcination reactor, configured to treat an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide and a gas stream containing ammonia to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0074] In some embodiments of the aforementioned models, the aqueous solution further comprises ammonia and / or an N-containing salt.

[0075] Some aspects and embodiments of the methods and systems provided herein are shown in Figures 1-4. It should be understood that the steps shown in Figures 1-4 may be modified, the order of the steps may be changed, or additional steps may be added or removed, depending on the desired results. As shown in Figures 1-4, lime is subjected to the methods and systems provided herein to produce a composition comprising vaterite and magnesium oxide.

[0076] When used herein, "lime" or "CaO" refers to calcium oxide and / or calcium hydroxide. The presence and amount of calcium oxide and / or calcium hydroxide in lime should vary depending on the conditions for lime formation.

[0077] Calcination or firing is a heat treatment process that results in the thermal decomposition of limestone. “Limestone,” as used herein, means CaCO3 and may further include other minerals typically present in limestone. Limestone is a naturally occurring substance. The chemical composition of this substance varies from region to region and can even vary between different deposits within the same region. Therefore, lime containing calcium oxide and / or calcium hydroxide obtained by calcining limestone from each natural deposit may also vary. Limestone may consist of calcium carbonate (CaCO3), magnesium carbonate (MgCO3), silica (SiO2), alumina (Al2O3), iron (Fe), sulfur (S), or other trace elements.

[0078] Limestone deposits are widely distributed. Limestone from various deposits may have different physicochemical properties and can be classified according to their chemical composition, texture, and geological formation. Limestone can be classified into high-calcium limestone, which may consist mainly of calcium carbonate with a magnesium carbonate content of 5% or less; magnesium limestone, which contains approximately 5-35% magnesium carbonate; or dolomite limestone, which may contain between 35-46% MgCO3 with the remainder being calcium carbonate. Limestone from different sources may differ significantly in chemical composition and physical structure. It should be understood that the methods and systems provided herein apply to all cement plants that calcine limestone from any of the sources listed above or commercially available sources. Quarries include, but are not limited to, quarries associated with cement furnaces, quarries for limestone for aggregates to be used in concrete, quarries for limestone for other purposes (road basements), and / or quarries associated with lime furnaces.

[0079] The calcination of limestone involves a chemical reaction that decomposes the limestone. CaCO3 → CaO + CO2 (gas) This is the decomposition process.

[0080] Limestone may contain one or more magnesium-supported minerals. In some embodiments of the aforementioned aspects, the limestone contains magnesium or magnesium-supported minerals between approximately 1 and 70%, or between approximately 1 and 60%, 1 and 50%, 1 and 40%, 1 and 30%, 1 and 20%, or 1 and 10%.

[0081] In some embodiments, the limestone may be pure calcium carbonate. In some embodiments, the limestone may contain magnesium or a magnesium-supported mineral, and / or a separate magnesium-supported mineral may be mixed with the limestone before and / or during calcination. As used herein, “magnesium-supported mineral” includes any mineral containing magnesium.

[0082] In some embodiments of the aforementioned aspects and embodiments, magnesium in limestone and / or magnesium-supported minerals partially or completely forms magnesium oxide during calcination. The chemical formula for forming magnesium oxide from a magnesium-supported mineral, such as magnesium carbonate, is as follows: MgCO3 → MgO + CO2 (gas)

[0083] In some embodiments of the aforementioned aspects and embodiments, the magnesium-supporting mineral includes magnesium carbonate, e.g., calcium magnesium carbonate, magnesium salts, e.g., potassium magnesium salts, magnesium hydroxide, magnesium silicate, e.g., magnesium iron silicate, magnesium sulfate, or combinations thereof. In some embodiments of the aforementioned aspects and embodiments, the magnesium-supporting mineral includes dolomite (CaMg(CO3)2), magnesite, bruxite (Mg(OH)2), carnalite (KMgCl3·6(H2O)), talc (Mg3Si4O 10 (OH)2), olivine ((Mg 2+ Fe 2+The group consists of (2SiO4) and combinations thereof. Other examples, but not limited to, include artiniite (MgCO3·Mg(OH)2·3H2O), hydromagnesite (Mg5(CO3)4(OH)2·4H2O), dippingite (4MgCO3·Mg(OH)2·5H2O), burlingonite (MgCO3·2H2O), neskehonite (MgCO3·3H2O), lancefoldite (MgCO3·5H2O), kieserite (MgSO4·H2O), or any other hydrated state of magnesium carbonate or magnesium sulfate. Sometimes, magnesium-supported minerals occur with limestone.

[0084] This step is shown in Figures 1-3 as the first step in calcining limestone containing a magnesium-supported mineral and / or limestone combined with a magnesium-supported mineral to form a mixture containing lime and magnesium oxide. Depending on the conditions, the lime may exist in a dry form, i.e., calcium oxide, and / or a wet form, such as calcium hydroxide. The production of lime may vary depending on the type of furnace, calcination conditions, and the properties of the raw materials, i.e., limestone. At relatively low calcination temperatures, the product formed in the furnace may contain both unburned carbonate and lime, and is sometimes called incompletely burned lime. As the temperature rises, lightly calcined quicklime or highly reactive lime may be produced. At even higher temperatures, dead calcined lime or low reactive lime may be produced. Lightly calcined quicklime is produced when the reaction front reaches the core of the packed limestone and converts all present carbonate into lime. Highly productive products may be relatively soft, contain small lime microcrystals, and / or have an open porous structure with an easily quantifiable interior. Such lime can possess optimal properties of high reactivity, high surface area, and low bulk density. Beyond this stage, increasing the degree of calcination can cause the lime microcrystals to grow into larger aggregates and sintered materials. This can lead to decreased surface area, porosity, and reactivity, and increased bulk density. This product may be known as decomposed lime or low-reactivity lime. Without adhering to any particular theory, the methods and systems provided herein utilize one or a combination of the aforementioned limes. Therefore, in some embodiments, the lime is incompletely combusted lime, lightly calcined quicklime, decomposed lime, or a combination thereof. Similarly, at relatively low calcination temperatures, the product formed in the furnace may contain both uncombusted magnesium-supported minerals and magnesium oxide, and may be called incompletely combusted magnesium oxide. As the temperature increases, lightly calcined magnesium oxide or high-reactivity magnesium oxide may be produced. At even higher temperatures, decomposed magnesium oxide or low-reactivity magnesium oxide may be produced.Lightly calcined magnesium oxide is produced when the reaction front reaches the core of a packed magnesium-supported mineral, converting the existing magnesium-supported mineral into magnesium oxide. Highly productive products may be relatively soft and contain magnesium oxide microcrystals. Such magnesium oxide can have optimal properties of high reactivity, high surface area, and low bulk density. If the degree of calcination is increased beyond this stage, the magnesium oxide microcrystals may grow into larger aggregates and sintered materials. This can lead to decreased surface area, porosity, and reactivity, and increased bulk density. This product may be known as dead-calcined magnesium oxide or low-reactivity magnesium oxide. In some embodiments, the aforementioned reactivity of magnesium oxide relates to its ability to combine with water to form magnesium hydroxide (Mg(OH)2).

[0085] In some embodiments, the firing temperature for firing limestone and / or magnesium-supported minerals is between approximately 300°C and 1200°C, or between approximately 400°C and 1200°C, or between approximately 500°C and 1200°C, or between approximately 600°C and 1200°C, or between approximately 700°C and 1200°C, or between approximately 800°C and 1200°C, or between approximately 900°C and 1200°C, or between approximately 1000°C and 1200°C, or between approximately 300°C and 1000°C, or between approximately 300°C and 800°C, or between approximately 300°C and 500°C.

[0086] In some embodiments, the methods and systems provided herein further include the step of controlling the calcination process to control the components of a mixture containing lime and magnesium oxide. In some embodiments, the calcination process may be controlled to obtain lightly calcined or reactive lime and lightly calcined magnesium oxide. In some embodiments, the calcination process may be controlled by controlling the temperature and / or duration of heating the limestone. In some embodiments, the methods and systems provided herein further include the step of controlling the calcination temperature between about 300°C and 1200°C, or between about 300°C and 800°C, in order to burn or combust the lime and magnesium-supported minerals.

[0087] The production of lime by calcining limestone can be carried out using various types of furnaces, such as, but not limited to, shaft kilns, rotary furnaces, or electric furnaces. The use of electric furnaces for calcination and the associated advantages are described in U.S. Provisional Application No. 63 / 046,239, filed June 30, 2020, which is incorporated herein by reference in its entirety.

[0088] These calcination apparatuses or calcination reactors are suitable for calcining limestone in the form of lumps having a diameter of several millimeters to tens of millimeters. The waste streams of cement plants include waste streams from both wet process plants and dry process plants, which may use shaft kilns, rotary furnaces, electric furnaces, or a combination thereof, and may include pre-calcination furnaces. Each of these industrial plants may burn a single fuel, or two or more fuels, sequentially or simultaneously.

[0089] As shown in Figures 1-3, limestone containing magnesium-supported minerals and / or limestone combined with magnesium-supported minerals are calcined in a cement plant, resulting in the formation of a mixture containing lime and magnesium oxide, as well as CO2 gas. The lime may be calcium oxide in solid form derived from a dry furnace / cementation process, or / or a combination of calcium oxide and calcium hydroxide in slurry form within a wet furnace / cementation process. In the wet process, calcium oxide (also known as a basic anhydride that converts to its hydroxide form in water) may exist in its hydrated form, for example, calcium hydroxide, but is not limited to these. Calcium hydroxide (also called slaked lime) is the common hydrated form of calcium oxide, but other intermediate hydrated complexes and / or water complexes may also be present in the slurry, and all of these are within the scope of the methods and systems provided herein. It should be understood that while lime is shown as CaO in some of the figures herein, it may exist as Ca(OH)2 or a combination of CaO and Ca(OH)2.

[0090] Lime can be poorly soluble in water. In the methods and systems provided herein, the solubility of lime is increased by treating it with a solubilizing agent.

[0091] In the methods and systems provided herein, a mixture comprising lime and magnesium oxide is solvated, dissolved, or solubilized in a dissolution reactor under one or more dissolution conditions with a solubilizing agent, such as a weakly acidic aqueous solution of a nitrogen-containing salt (step A in Figures 1-3), to produce an aqueous solution comprising a calcium salt and magnesium oxide. For illustrative purposes only, in the figures, the nitrogen-containing salt, such as a nitrogen-containing inorganic salt solution, is shown as an ammonium chloride (NH4Cl) solution, and the subsequent calcium salt is shown as calcium chloride (CaCl2). Various examples of nitrogen-containing salts are provided herein and are all within the scope of the present invention.

[0092] The N-containing salts include, but are not limited to, N-containing inorganic salts, N-containing organic salts, or combinations thereof.

[0093] As used herein, "N-containing inorganic salts" include any inorganic salts having nitrogen. Examples of N-containing inorganic salts include, but are not limited to, ammonium halides (where the halide is any halogen), ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite, etc. In some embodiments, the ammonium halide is ammonium chloride or ammonium bromide. In some embodiments, the ammonium halide is ammonium chloride.

[0094] As used herein, "N-containing organic salts" include any salts of organic compounds having nitrogen. Examples of N-containing organic compounds include, but are not limited to, aliphatic amines, cycloaliphatic amines, heterocyclic amines, and combinations thereof.

[0095] As used herein, "aliphatic amines" refers to any alkylamine of the formula (R) n -NH 3-n where n is an integer from 1 to 3 and each R is independently a straight-chain or branched substituted or unsubstituted alkyl having from 1 to 8 carbon atoms. A corresponding halide salt (chloride salt, bromide salt, fluoride salt, or iodide salt) of the alkylamine of the formula (R) n -NH 3-n is, for example, (R) n -NH 4-n + Cl - In some embodiments, when R is a substituted alkyl, the substituted alkyl is independently substituted with halogen, hydroxyl, acid, and / or ester.

[0096] For example, when R is (R) n -NH 3-nIf the alkylamine is alkyl, this alkylamine may be, as merely an example, a primary alkylamine such as methylamine, ethylamine, butylamine, or pentylamine; this alkylamine may be, as merely an example, a secondary amine such as dimethylamine, diethylamine, or methylethylamine; and / or this alkylamine may be, as merely an example, a tertiary amine such as trimethylamine or triethylamine.

[0097] For example, R is (R) n -NH 3-n In the case of a substituted alkyl group that is substituted with a hydroxyl group, this substituted alkylamine is an alkanolamine, but is not limited to monoalkanolamines, dialkanolamines, or trialkanolamines, such as monoethanolamine, diethanolamine, or triethanolamine.

[0098] For example, R is (R) n -NH 3-n In the case of a substituted alkyl group that is substituted with a halogen, examples of substituted alkylamines include chloromethylamine, bromomethylamine, chloroethylamine, and bromoethylamine.

[0099] For example, R is (R) n -NH 3-n In the case where the substituted alkyl is an acid-substituted alkyl, the substituted alkylamine is, for example, an amino acid. In some embodiments, the aforementioned amino acid has a polar uncharged alkyl chain, and examples 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, and examples 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.

[0100] When used herein, "alicyclic amine" refers to formula (R) n -NH 3-n The formula (R) contains any alicyclic amine (where n is an integer from 1 to 3, and R is independently one or more all-carbon rings, which may be saturated or unsaturated but not aromatic). The alicyclic compound may have one or more aliphatic side chains attached. n -NH 3-n An example of the corresponding salt of the alicyclic amine is (R) n -NH 4-n + Cl - Examples of alicyclic amines, though not limited to them, include cycloalkylamines, namely cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, cycloheptylamine, and cyclooctylamine.

[0101] When used herein, a "heterocyclic amine" comprises at least one heterocyclic aromatic ring bonded to at least one amine. Examples of heterocyclic rings, but not limited to, include pyrroles, pyrrolidines, pyridines, and pyrimidines. Such chemicals are well known in the art and are commercially available.

[0102] In the methods and systems provided herein, a mixture comprising lime and magnesium oxide is dissolved or solubilized with a solubilizer, such as a nitrogen-containing salt solution, under one or more dissolution conditions (step A in Figures 1-3) to produce an aqueous solution comprising a calcium salt and magnesium oxide. During and / or thereafter, ammonia and / or nitrogen-containing salts may remain dissolved in the aqueous solution and / or a gas stream containing ammonia may be formed.

[0103] As shown in step A of Figures 1-3, the N-containing salt is shown as ammonium chloride (NH4Cl). The possible reactions of lime are as follows: CaO+2NH4Cl(aqueous solution) → CaCl2(aqueous solution)+2NH3+H2O Ca(OH)2+2NH4Cl(aqueous solution) → 2NH3+CaCl2+2H2O If so, it can be solubilized by treatment with NH4Cl (fresh and recycled as described below).

[0104] Similarly, if the base is an N-containing organic salt, the reaction can be shown as follows: CaO+2NH3RCl → CaCl2(aqueous solution)+2NH2R+H2O

[0105] In some embodiments, nitrogen-containing salts, such as nitrogen-containing inorganic salts, including but not limited to ammonium salts, such as ammonium chloride solution or ammonium acetate solution, may be supplemented with anhydrous ammonia or aqueous ammonia solution to maintain an optimal level of nitrogen-containing salt in the solution, such as ammonium chloride or ammonium acetate.

[0106] In some embodiments, the aqueous solution containing calcium salts and magnesium oxide obtained after dissolving a mixture containing lime and magnesium oxide may contain sulfur, depending on the source of lime. Sulfur can be introduced into the aqueous solution after solubilizing lime with one of the N-containing salts described herein. In alkaline solutions, but not limited to sulfite ions (SO3), sulfite ions may be present. 2- ), sulfate ions (SO4 2- ), water sulfide ions (HS - ), thiosulfate ion (S2O3 2- ), polysulfide (S n 2- Various sulfur compounds containing various sulfur ion species, including thiols (RSH), may be present in the solution. "Sulfur compounds" include any sulfur ion-containing compound as used herein.

[0107] In some embodiments, the aqueous solution further comprises an N-containing salt, such as ammonia, and / or an N-containing inorganic salt or an N-containing organic salt.

[0108] In some embodiments, the amount of N-containing salt, such as an N-containing inorganic salt, an N-containing organic salt, or a combination thereof, is in excess of more than 20% or more than 30% relative to the mixture containing lime and magnesium oxide. In some embodiments, the molar ratio of N-containing salt to the mixture containing lime and magnesium oxide (or an N-containing inorganic salt to a mixture containing lime and magnesium oxide, or an N-containing organic salt to a mixture containing lime and magnesium oxide, or an ammonium chloride to a mixture containing lime and magnesium oxide, or an ammonium acetate to a mixture containing lime and magnesium oxide) is between 0.5:1 and 3:1, or between 0.5:1 and 2:1, or between 0.5:1 and 1.5:1, or between 1:1 and 1.5:1, or between 1.5:1, or 2:1, or 2.5:1, or 1:1, or 3:1.

[0109] In some embodiments of the methods described herein, polyhydroxy compounds are not used to form the precipitate and / or product provided herein.

[0110] In some embodiments of the methods and systems described herein, one or more dissolution conditions are between approximately 30 and 200°C, or between approximately 30 and 150°C, or between approximately 30 and 100°C, or between approximately 30 and 75°C, or between approximately 30 and 50°C, or between approximately 40 and 200°C, or between approximately 40 and 150°C, or between approximately 40 and 100°C, or between approximately 40 and 75°C, or between approximately 40 and 50°C, or between approximately 50 and 200°C, or between approximately 50 and 150°C, or approximately The following are selected from the group consisting of a temperature between 50 and 100°C, a pressure between approximately 0.1 and 50 atm, or between approximately 0.1 and 40 atm, or between approximately 0.1 and 30 atm, or between approximately 0.1 and 20 atm, or between approximately 0.1 and 10 atm, or between approximately 0.5 and 20 atm, and a wt% of N-containing inorganic or organic salt in water between approximately 0.5 and 50%, or between approximately 0.5 and 25%, or between approximately 0.5 and 10%, or between approximately 3 and 30%, or between approximately 5 and 20%, or combinations thereof.

[0111] For example, stirring can be used to dissolve a mixture containing lime and magnesium oxide using an aqueous N-containing salt solution in a dissolution reactor, by eliminating hot and cold spots. In some embodiments, the aqueous concentrations of lime and magnesium oxide may be between 1 and 10 g / L, between 10 and 20 g / L, between 20 and 30 g / L, between 30 and 40 g / L, between 40 and 80 g / L, between 80 and 160 g / L, between 160 and 320 g / L, between 320 and 640 g / L, or between 640 and 1280 g / L. To optimize the dissolution / solvation of lime, high-shear mixing, wet mill grinding, and / or sonication can be used to break up the lime. During or after high-shear mixing and / or wet mill grinding, the lime suspension may be treated with an N-containing salt solution.

[0112] In some embodiments, an aqueous solution containing a calcium salt and a solid is formed by dissolving a mixture containing lime and magnesium oxide using a nitrogen-containing salt solution (e.g., shown as ammonium chloride). In some embodiments, the magnesium oxide formed after calcination may remain as a solid, may not dissolve, or may partially dissolve in the nitrogen-containing salt solution. This solid may and may not be separated from the aqueous solution containing the calcium salt.

[0113] Therefore, in one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A step of dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and a solid containing magnesium oxide, (iii) A step of separating the solid from the aqueous solution, (iv) A step of treating an aqueous solution containing a calcium salt with a gas stream containing carbon dioxide to form a composition containing vaterite, (v) A method is provided which includes the step of mixing a composition containing vaterite with a solid containing magnesium oxide.

[0114] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia, (iii) A step of separating the solid from the aqueous solution, (iv) A step of treating an aqueous solution containing a calcium salt with a gas stream containing carbon dioxide and a gas stream containing ammonia to form a composition containing vaterite, (v) A method is provided which includes the step of mixing a composition containing vaterite with a solid containing magnesium oxide.

[0115] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A step of dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and a solid containing magnesium oxide, (iii) The step of treating an aqueous solution containing a calcium salt and a solid containing magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and a solid containing magnesium oxide. Methods including the following are also provided.

[0116] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia, (iii) The step of treating an aqueous solution containing a calcium salt and a solid containing magnesium oxide with a gas stream containing carbon dioxide and a gas stream containing ammonia to form a composition containing vaterite and a solid containing magnesium oxide. Methods including the following are also provided.

[0117] In another embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and a solid containing magnesium oxide, and (iii) A processing reactor operably connected to a dissolution reactor and a calcination reactor, configured to process an aqueous solution containing a calcium salt and a solid containing magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0118] In another embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia; (iii) A processing reactor operably connected to the dissolution reactor and calcination reactor, configured to treat the aqueous solution containing calcium salt and the solid containing magnesium oxide with a gas stream containing carbon dioxide and a gas stream containing ammonia to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0119] In another embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and a solid containing magnesium oxide, (iii) A separation device configured to separate a solid from an aqueous solution, which is operablely connected to a dissolution reactor. (iv) A processing reactor operably connected to a separation device, a dissolution reactor, and a calcination reactor, configured to treat an aqueous solution containing a calcium salt with a gas stream containing carbon dioxide to form a composition containing vaterite, and (v) A mixer configured to mix a composition containing vaterite and a solid containing magnesium oxide, operably connected to the processing reactor and separation apparatus. A system including this is provided.

[0120] As described in the preceding embodiments, the solid containing magnesium oxide may and / or may not be separated from the aqueous solution containing the calcium salt in the methods and systems provided herein. This step is shown as step B (including the dashed arrow) in Figures 1-3.

[0121] In some embodiments, the solid containing magnesium oxide can be removed from the aqueous solution of the calcium salt before the aqueous solution is treated with carbon dioxide in the process (shown as a dashed line from step B in Figures 1-3). The solid containing magnesium oxide may be removed or separated from the aqueous solution by separation devices, such as filtration and / or centrifugation, if necessary.

[0122] The separation in step B of Figures 1-3 is optional, and in some embodiments, the solid containing magnesium oxide does not need to be removed from the aqueous solution and the aqueous solution containing the calcium salt. The solid containing magnesium oxide is brought into contact with carbon dioxide (step C of Figures 1-3) to form a precipitate. In such embodiments, the composition containing vaterite further contains the solid containing magnesium oxide.

[0123] In some embodiments, the solid containing magnesium oxide obtained after the dissolution of lime further includes a calcium-depleted solid and can be used as a cement substitute (e.g., a substitute for Portland cement) as needed. In some embodiments, the solid containing magnesium oxide may further include silicates, iron oxides, aluminates, or combinations thereof. Silicates include, but are not limited to, clay (phyllosilicates) and aluminosilicates.

[0124] In some embodiments, the magnesium oxide-containing solid is present in aqueous solutions, vaterite cakes, vaterite-containing compositions, or combinations thereof, in amounts between 1 and 75 wt%, or between 1 and 70 wt%, or between 1 and 60 wt%, or between 1 and 50 wt%, or 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%, of the mass of the dissolved cement. In some embodiments, the solid containing magnesium oxide is present in amounts between 1 and 75 wt%, or between 1 and 70 wt%, or between 1 and 60 wt%, or between 1 and 50 wt%, or 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%, of the total solid produced (vaterite and solid).

[0125] As shown in step C of Figure 1, aqueous solutions containing calcium salts and magnesium oxide, and optionally solids containing magnesium oxide, and dissolved ammonia and / or ammonium salts are brought into contact with a gas stream containing carbon dioxide recycled from the calcination step of each process under one or more precipitation conditions to form compositions / precipitates containing vaterite, magnesium oxide, and supernatant solutions as shown in the following reactions. CaCl2 (aqueous solution) + 2NH3 (aqueous solution) + MgO + CO2 (gas) + H2O → CaCO3 (solid) + MgO + 2NH4Cl (aqueous solution)

[0126] The absorption of CO2 into the aqueous solution produces CO2-filled water containing carbonic acid, which is in equilibrium with both bicarbonates and carbonates. The precipitate / composition is prepared under one or more precipitation conditions (as described herein) suitable for forming vaterites.

[0127] In some embodiments, as shown in Figure 2, the gas stream containing CO2 from the calcination step and the gas stream containing NH3 from step A of the process are recycled to a precipitation reactor for the formation of the composition / precipitate (step C). The remaining steps in Figure 2 are identical to those in Figure 1. It should be understood that both processes in Figure 1 and Figure 2 can also be carried out simultaneously so that the nitrogen-containing salt, e.g., nitrogen-containing inorganic or nitrogen-containing organic salt, and the by-product ammonia may be partially present in the aqueous solution and partially in the gas stream.

[0128] The reaction carried out in the aforementioned embodiment may be shown as follows. CaCl2 (aqueous solution) + 2NH3 (gas) + CO2 (gas) + MgO + H2O → CaCO3 (solid) + MgO + 2NH4Cl (aqueous solution)

[0129] In some embodiments of the aspects and embodiments provided herein, the gas stream containing ammonia may have ammonia from an external source and / or be recovered from step A of the process and recycled.

[0130] In some embodiments and examples of the representations provided herein, where the gas stream contains ammonia and / or carbon dioxide, no external source of carbon dioxide and / or ammonia is used, and the process is a closed-loop process. Such a closed-loop process is illustrated in the figures provided herein.

[0131] In some embodiments, the dissolution of a mixture containing lime and magnesium oxide using an N-containing organic salt may not result in the formation of ammonia gas, or the amount of ammonia gas formed may be substantial. In embodiments where ammonia gas is not formed or is formed in substantial amounts, the method and system shown in Figure 1, in which an aqueous solution containing the calcium salt is treated with carbon dioxide gas, is applicable. In such embodiments, the organic amine salt may remain completely or partially dissolved in the aqueous solution, or it may separate as an organic amine layer, as shown in the reactions below. CaO + MgO + 2NH3R + Cl - → CaCl2(aqueous solution)+MgO+2NH2R+H2O

[0132] The nitrogen-containing organic salt or nitrogen-containing organic compound remaining in the supernatant after precipitation may be called a residual nitrogen-containing organic salt or residual nitrogen-containing organic compound. This method and system are described herein for the recovery of residual compounds from the precipitate and supernatant.

[0133] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia, (iii) A step of recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, subjecting the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, (iv) A first aqueous solution containing a calcium salt and magnesium oxide is treated with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and magnesium oxide. A method is provided that includes this.

[0134] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia, (iii) A step of separating the solid from the first aqueous solution, (iv) A step of recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, subjecting the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, (v) A step of treating a first aqueous solution containing a calcium salt with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite, (vi) A step of mixing a composition containing vaterite and a solid containing magnesium oxide. A method is provided that includes this.

[0135] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia, (iii) A step of recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, subjecting the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, (iv) The first aqueous solution containing a calcium salt and a solid containing magnesium oxide are treated with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and a solid containing magnesium oxide. A method is provided that includes this.

[0136] In one embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia. (iii) A cooling reactor operably connected to a dissolution reactor and a calcination reactor, configured to recover a gas stream containing carbon dioxide and a gas stream containing ammonia, and to subject the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, and (iv) A treatment reactor operably connected to a dissolution reactor and a cooling reactor, configured to treat a first aqueous solution containing a calcium salt and magnesium oxide with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and magnesium oxide. A system including this is provided.

[0137] In another embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia. (iii) A separation device configured to separate a solid from a first aqueous solution, which is operably connected to a dissolution reactor. (iv) A cooling reactor operably connected to a dissolution reactor and a calcination reactor, configured to recover a gas stream containing carbon dioxide and a gas stream containing ammonia, and to subject the gas streams to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof. (v) A processing reactor operably connected to a separation device and a cooling reactor, configured to treat a first aqueous solution with a second aqueous solution to form a composition containing vaterite, and (vi) A mixer configured to mix a composition containing vaterite and a solid containing magnesium oxide, operably connected to the processing reactor and separation apparatus. A system including this is provided.

[0138] In another embodiment, a system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to a calcination reactor, configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt, a solid containing magnesium oxide, and a gas stream containing ammonia. (iii) A cooling reactor operably connected to a dissolution reactor and a calcination reactor, configured to recover a gas stream containing carbon dioxide and a gas stream containing ammonia, and to subject the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, and (iv) A processing reactor operably connected to a dissolution reactor and a cooling reactor, configured to treat a solid containing a first aqueous solution and magnesium oxide with a second aqueous solution to form a composition containing vaterite and a solid containing magnesium oxide. A system including this is provided.

[0139] The above embodiment is shown in Figure 3, where the gas stream containing CO2 from the calcination step / reactor and the gas stream containing NH3 from step A of the process are recycled to the cooling reactor / reaction for the formation of carbonate and bicarbonate solutions, as further shown in the following reactions herein (step F). The remaining steps in Figure 3 are identical to the steps in Figures 1 and 2. It should be understood that the first aqueous solution containing calcium salt provided herein is the same as the aqueous solution containing calcium salt described herein. When it is necessary to distinguish the aqueous solution containing calcium salt from the second aqueous solution, it is simply referred to as the first aqueous solution for clarity.

[0140] The embodiments shown in Figure 3 can be combined with the embodiments shown in Figures 1 and / or 2. Therefore, it should be understood that precipitation step C includes treating a first aqueous solution containing a calcium salt and magnesium oxide, or a solid containing magnesium oxide, with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, or a combination thereof (as shown in Figure 3), and treating the aqueous solution containing a calcium salt and magnesium oxide, or a solid containing magnesium oxide, with a gas stream containing carbon dioxide (as shown in Figure 1), and / or treating the aqueous solution containing a calcium salt and magnesium oxide, or a solid containing magnesium oxide, with a gas stream containing carbon dioxide and a gas stream containing ammonia (as shown in Figure 2). In such embodiments, the gas stream containing carbon dioxide is divided into a stream toward the cooling process and a stream toward the precipitation process. Similarly, in such embodiments, the gas stream containing ammonia is divided into a stream toward the cooling process and a stream toward the precipitation process. Any combination of processes illustrated in Figures 1-3 is possible and all are within the scope of this disclosure.

[0141] In some embodiments of the aforementioned features, the second aqueous solution contains ammonium carbamate. Ammonium carbamate is composed of ammonium ions NH4 +, and carbamate ion H2NCO2 - It has the formula NH4[H2NCO2] consisting of the above. In the aforementioned embodiments and some embodiments of the embodiments, the second aqueous solution includes ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof.

[0142] The combination of these condensation products in the second aqueous solution may depend on one or more of the cooling conditions. Table 1, presented below, shows various combinations of condensation products in the second aqueous solution. [Table 1-1] [Table 1-2]

[0143] In some embodiments of the aforementioned aspects and embodiments, the gas stream (e.g., the gas stream toward the cooling reaction / reactor (step F in Figure 3)) further includes steam. In some embodiments of the aforementioned aspects and embodiments, the gas stream is between approximately 20 and 90%, or between approximately 20 and 80%, or between approximately 20 and 70%, or between approximately 20 and 60%, or between approximately 20 and 55%, or between approximately 20 and 50%, or between approximately 20 and 40%, or between approximately 20 and 30%, or between approximately 20 and 25%, or between approximately 30 and 90%, or between approximately 30 and 80%, or between approximately 30 and 70%, or between approximately 30 and 60%, or between approximately 30 and 50%, or Further containing water vapor between approximately 30-40%, or between approximately 40-90%, or between approximately 40-80%, or between approximately 40-70%, or between approximately 40-60%, or between approximately 40-50%, or between approximately 50-90%, or between approximately 50-80%, or between approximately 50-70%, or between approximately 50-60%, or between approximately 60-90%, or between approximately 60-80%, or between approximately 60-70%, or between approximately 70-90%, or between approximately 70-80%, or between approximately 80-90%.

[0144] In the aforementioned embodiments and some of the embodiments, no external water is added to the cooling process. The cooling process is similar to the condensation of gas in existing water vapor (but not to gas absorption), and therefore, it should be understood that the gas is not absorbed by the water but is cooled itself along with the water vapor. Condensing the gas into a liquid stream can offer advantages in process control compared to vapor absorption. As just one example, condensing the gas into a liquid stream may allow the liquid stream to be pumped into the sedimentation step. Pumping a liquid stream can be less costly than compressing a vapor stream into the absorption process.

[0145] The cooling reaction / reactor intermediate step may include the formation of ammonium carbonate and / or ammonium bicarbonate and / or ammonium carbamate by the following reactions: 2NH3 + CO2 + H2O → (NH4)2CO3 NH3 + CO2 + H2O → (NH4)HCO3 2NH3 + CO2 → (NH4)NH2CO2

[0146] Similar reactions may also be observed with N-containing organic salts. 2NH2R + CO2 + H2O → (NH3R)2CO3 NH2R + CO2 + H2O → (NH3R)HCO3

[0147] The advantage of cooling ammonia in a cooling reaction / reactor is that ammonia can have a limited vapor pressure in the gas phase of the dissolution reaction. By reacting ammonia with CO2, as shown in the reaction above, some of the ammonia can be removed from the vapor space, leaving more ammonia in the dissolution solution.

[0148] Next, a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof (exiting the cooling reaction / reactor in Figure 3) is treated in the precipitation reaction / reactor with the first aqueous solution containing calcium salts and magnesium oxide or a solid containing magnesium oxide, originating from the dissolution reaction / reactor (step C), to form a precipitate containing vaterite. (NH4)2CO3 + CaCl2 + MgO → CaCO3 (vaterite) + MgO + 2NH4Cl (NH4)HCO3 + NH3 + CaCl2 + MgO → CaCO3 (vaterite) + MgO + 2NH4Cl + H2O 2(NH4)HCO3 + CaCl2 + MgO → CaCO3 (vaterite) + MgO + 2NH4Cl + H2O + CO2 (NH4)NH2CO2 + H2O + CaCl2 + MgO → CaCO3 (vaterite) + MgO + 2NH4Cl

[0149] Independent of any intermediate steps, the combination of reactions leads to the following overall process chemistry. CaO (lime) + MgO → CaCO3 (vaterite) + MgO

[0150] In some embodiments of the aspects and embodiments provided herein, one or more cooling conditions are between approximately 0 and 200°C, or between approximately 0 and 150°C, or between approximately 0 and 75°C, or between approximately 0 and 100°C, or between approximately 0 and 80°C, or between approximately 0 and 60°C, or between approximately 0 and 50°C, or between approximately 0 and 40°C, or between approximately 0 and 30°C, or between approximately 0 and 20°C, or between approximately 0 and 10°C, or between approximately 10 and 100°C, or between approximately 10 and 80°C, or between approximately 10 and 60°C, or between approximately 10 and 50°C, or between approximately 10 and 40°C, or between approximately 10 and 30°C, or between approximately 20 and 1 This includes temperatures between 0°C, or between approximately 20 and 80°C, or between approximately 20 and 60°C, or between approximately 20 and 50°C, or between approximately 20 and 40°C, or between approximately 20 and 30°C, or between approximately 30 and 100°C, or between approximately 30 and 80°C, or between approximately 30 and 60°C, or between approximately 30 and 50°C, or between approximately 30 and 40°C, or between approximately 40 and 100°C, or between approximately 40 and 80°C, or between approximately 40 and 60°C, or between approximately 50 and 100°C, or between approximately 50 and 80°C, or between approximately 60 and 100°C, or between approximately 60 and 80°C, or between approximately 70 and 100°C, or between approximately 70 and 80°C.

[0151] In some embodiments of the aspects and embodiments provided herein, one or more cooling conditions include pressures between about 0.5 and 50 atm, or between about 0.5 and 25 atm, or between about 0.5 and 10 atm, or between about 0.1 and 10 atm, or between about 0.5 and 1.5 atm, or between about 0.3 and 3 atm.

[0152] In some embodiments, the formation and quality of compositions comprising vaterite and magnesium oxide formed in the methods and systems provided herein depend on the amount and / or ratio of condensation products in a second aqueous solution comprising ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof.

[0153] In some embodiments, the presence or absence or distribution of condensation products in a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof can be controlled to maximize the formation of a composition containing vaterite and magnesium oxide and / or to obtain a desired particle size distribution. This control can be based on one or more cooling conditions, such as the pH of the aqueous solution in the cooling reactor, the flow rates of CO2 and NH3 gases, and / or the CO2:NH3 gas ratio. The inflow into the cooling reactor (F in Figure 3) may be exhaust gas from the dissolution reactor containing carbon dioxide (CO2(gas)), ammonia (NH3(gas)), steam, and, if necessary, new makeup water (or some other dilution water stream). The outflow may be a slipstream of the reactor's recirculating fluid (second aqueous solution), which is directed towards a precipitation reactor to contact the first aqueous solution and, if necessary, additional carbon dioxide and / or ammonia. The pH of the system can be controlled by adjusting the flow rates of CO2 and NH3 into the cooling reactor. The conductivity of the system can be controlled by adding makeup water for dilution to the cooling reactor. The volume can be kept constant by using a level detector in the cooling reactor or its reservoir.

[0154] In some embodiments, a higher pH of the aqueous solution in the cooling reactor (which can be achieved by a higher flow rate of ammonia) may be favorable for the formation of carbamates, while a lower pH of the aqueous solution in the cooling reactor (which can be achieved by a lower flow rate of ammonia) may be favorable for the formation of carbonates and / or bicarbonates. In some embodiments, one or more cooling conditions include the pH of the aqueous solution formed in the cooling reactor being between about 8 and 12, or between about 8 and 11, or between about 8 and 10, or between about 8 and 9.

[0155] In some embodiments, the carbon dioxide flow rate can be modified to achieve a desired pH of the second aqueous solution exiting the cooling reactor. For example, if the pH of the second aqueous solution is high, the carbon dioxide flow rate can be increased to lower the pH, or if the pH of the second aqueous solution is low, the carbon dioxide flow rate can be decreased to raise the pH.

[0156] In some embodiments, one or more cooling conditions include a CO2:NH3 ratio in the cooling reactor between approximately 0.1:1 and 20:1, or between approximately 0.1:1 and 1:1, or between approximately 0.1:1 and 2:1, or between approximately 5:1 and 10:1, or between approximately 1:1 and 5:1, or between approximately 2:1 and 5:1.

[0157] Although Figure 3 shows a separate cooling reaction / reactor, it should be understood that in some embodiments, the dissolution reaction / reactor can be integrated with the cooling reaction / reactor, as shown in Figure 4. For example, the dissolution reactor can be integrated with a condenser that acts as a cooling reactor. A mixture containing lime and magnesium oxide, along with a nitrogen-containing salt solution (shown as NH4Cl in Figure 4), are supplied together to the dissolution reaction / reactor, so that a first aqueous solution containing calcium salt (shown as CaCl2) and magnesium oxide is formed. This solution may optionally contain a solid containing magnesium oxide, which may remain at the bottom of the dissolution reactor. The first aqueous solution containing calcium salt (shown as CaCl2) and magnesium oxide is withdrawn from the dissolution reaction / reactor for further processing for precipitation. A gas stream containing ammonia and water vapor passes through the upper section of the dissolution reactor (i.e., the cooling reactor shown in Figure 4), where it is cooled with carbon dioxide and condensed into a second aqueous solution. Carbon dioxide can be obtained from a plant where limestone is calcined into lime and carbon dioxide. Next, carbon dioxide is supplied to the gas phase of the cooling reactor. A second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof is collected from the cooling reactor using various means, such as one or more trays (as shown, for example, in Figure 4).

[0158] In one embodiment, an integrated reactor is provided, and the reactor is, It includes a dissolution reactor integrated into the cooling reactor, and this dissolution reactor is located below the cooling reactor. This dissolution reactor is configured to dissolve a mixture containing lime and magnesium oxide in an aqueous solution of an inorganic salt containing nitrogen or an organic salt containing nitrogen to produce a first aqueous solution containing calcium salt and MgO, as well as a gas stream containing ammonia and water vapor, and This cooling reactor is operably connected to the dissolution reactor and is configured to receive and condense gas streams containing ammonia and water vapor from the dissolution reactor, as well as gas streams containing carbon dioxide from the calcination of limestone to lime, to form a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof.

[0159] In some embodiments, the cooling reactor is filled with a packing material. The packing material may be any inert material used to facilitate the mass transfer of NH3 and CO2 from the vapor to the liquid phase. The packing may be random or ordered. Random packing material may be any material having individual parts that are packed into the container or reactor. Ordered packing material may be any material having individual monoliths that are shaped to provide surface area and enhance mass transfer. Examples of loose, irregular, or random packing materials, but not limited to, include Raschig rings (e.g., of ceramic material), Paul rings (e.g., of metal and plastic), Lessing rings, Michael Bialecki rings (e.g., of metal), Berl saddles, Interox saddles (e.g., of ceramic), Super Interox saddles, Tellerette® rings (e.g., helical shapes of polymer material), and the like.

[0160] Examples of ordered packing materials include, but are not limited to, thin corrugated metal plates or gauze (honeycomb structure) of various shapes with specific surface area. The ordered packing material may be used as rings or layers, or stacks of rings or layers, having a diameter that can fit the diameter of the reactor. The rings may be individual rings or stacks of rings that completely fill the reactor. In some embodiments, any voids left in the reactor by ordered packing are filled with irregular or random packing material.

[0161] Examples of ordered packing materials include, but are not limited to, Flexipac®, Intalox®, and Flexipac® ​​HC®. In ordered packing materials, corrugated sheets can be arranged in a cross pattern to create channels for the gas phase. Intersections of the corrugated sheets can create mixing points for the liquid and gas phases. Ordered packing materials can be rotated around the column (reactor) axis to cross-mix the vapor and liquid streams and allow them to diverge in all directions. Ordered packing materials can be used with various corrugation sizes, and the packing arrangement can be optimized to obtain the highest efficiency, capacity, and pressure drop requirements of the reactor. Ordered packing materials can be made from building materials, but are not limited to, titanium, stainless steel alloys, carbon steel, aluminum, nickel alloys, copper alloys, zirconium, thermoplastics, etc. The corrugated wrinkles in ordered packing materials may be of any size, but are not limited to, including packing designated Y with a 45° inclination angle from the horizontal or packing designated X with a 60° inclination angle from the horizontal. X-filling can theoretically provide a lower pressure drop for each stage over the same surface area. The specific surface area of ​​ruled filling is 50-800 m². 2 / m 3 Between 75 and 350 meters 2 / m 3 Between, or 200-800m 2 / m 3 Between, or 150-800m 2 / m 3 Between, or 500-800m2 / m 3 It could be between these two points.

[0162] In some embodiments, the cooling reactor further includes an inlet for introducing a scrubbing fluid, such as ammonium chloride solution, ammonium acetate, or water, to the top of the packing material in the cooling reactor. The scrubbing fluid, such as ammonium chloride solution, ammonium acetate solution, ammonia solution, or water, promotes the formation of condensation products, such as ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or combinations thereof. The scrubbing fluid can provide more liquid volume for gas condensation. In some embodiments, the scrubbing fluid can further assist the condensation process if pre-cooled. If the scrubbing fluid is ammonium chloride solution, the ammonium chloride solution may be part of the ammonium chloride solution supplied to the dissolution reactor. In some embodiments, a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, ammonium chloride, or combinations thereof, collected from the condensate originating from the cooling reactor, can be recycled to the cooling reactor as a scrubbing fluid to further promote the condensation process. In some embodiments, the second aqueous solution can be cooled in a heat exchanger before being recycled to the cooling reactor.

[0163] Other gases, such as flue gas in the carbon dioxide-containing gas stream (obtained from the calcination process), can be released from the cooling reactor (shown in Figure 4).

[0164] In the embodiments described above, both the dissolution reactor and the cooling reactor are equipped with inlets and outlets to receive the required gas and collect the aqueous stream. In some embodiments of the embodiments described above, the dissolution reactor includes a stirrer for mixing a mixture containing lime and magnesium oxide with an aqueous solution of nitrogen-containing salt. The stirrer can also facilitate the upward movement of the gas. In some embodiments of the embodiments described above, the dissolution reactor is configured to collect a solid containing magnesium oxide that has settled at the bottom of the reactor after removing the first aqueous solution containing calcium salt and optionally magnesium oxide. In some embodiments of the embodiments described above, the cooling tower includes one or more trays configured to capture and collect the condensed second aqueous solution and prevent the second aqueous solution from falling back into the dissolution reactor. Thus, cooling / condensation can be achieved by using injectors, bubblers, fluid venturi reactors, spaggers, gas filters, sprays, trays, or packed column reactors, etc.

[0165] In some embodiments, the cooling reactor includes a heat exchanger or heat exchange surface within the reactor. The heat exchanger may include one or more tubes through which a cold fluid circulates, and thus the cold fluid is isolated from the gas phase in the cooling reactor but promotes a temperature drop in the cooling reactor for gas condensation. The cold fluid may be cooling water, the aforementioned scrubbing solution, and the like. In some embodiments, a second aqueous solution exiting the cooling reactor is cooled by the heat exchanger before being used as a scrubbing solution.

[0166] As shown in step C of Figures 1-2, a first aqueous solution containing calcium salt and magnesium oxide, obtained from the treatment of a mixture containing lime and magnesium oxide using an N-containing salt solution as described herein, e.g., an ammonium salt, e.g., ammonium halide or ammonium acetate, is contacted at any time before, during, or after the aqueous solution containing calcium salt and magnesium oxide is subjected to one or more precipitation conditions (i.e., conditions that allow the precipitation of the composition / precipitate) with CO2 and optionally NH3 from step A. Similarly, as shown in step C of Figure 3, a first aqueous solution containing calcium salt and magnesium oxide, obtained from the treatment of a mixture containing lime and magnesium oxide using an N-containing salt solution as described herein for step A, e.g., an ammonium salt, e.g., ammonium halide or ammonium acetate, is contacted at any time before, during, or after the first aqueous solution containing calcium salt and magnesium oxide is subjected to one or more precipitation conditions (i.e., conditions that allow the precipitation of the composition / precipitate) with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, from the cooling reaction / reactor.

[0167] Therefore, in some embodiments, an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, is brought into contact with CO2 (and, for example, NH3 in the case of Figure 2 or a second aqueous solution in the case of Figure 3) before the aqueous solution or the first aqueous solution is subjected to one or more precipitation conditions favorable for the formation of a composition containing vaterite and magnesium oxide. In some embodiments, an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, is brought into contact with CO2 (and, for example, NH3 in the case of Figure 2 or a second aqueous solution in the case of Figure 3) while the aqueous solution or the first aqueous solution is subjected to one or more precipitation conditions favorable for the formation of a composition containing vaterite and magnesium oxide. In some embodiments, an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, is brought into contact with CO2 (and, for example, NH3 in the case of Figure 2 or a second aqueous solution in the case of Figure 3) before and while the aqueous solution or the first aqueous solution is subjected to one or more precipitation conditions favorable for the formation of a composition containing vaterite and magnesium oxide. In some embodiments, an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, is subjected to one or more precipitation conditions favorable for the formation of a composition containing vaterite and magnesium oxide, and then brought into contact with CO2 (and, for example, NH3 in the case of Figure 2 or a second aqueous solution in the case of Figure 3).

[0168] In some embodiments, the step of contacting an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, with carbon dioxide and optionally ammonia or a second aqueous solution is achieved by contacting the aqueous solution or the first aqueous solution to achieve and maintain a desired pH range, a desired temperature range, and / or a desired divalent cation concentration using a convenient protocol (one or more precipitation conditions) described herein. In some embodiments, the system includes a precipitation reactor configured to contact an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, with carbon dioxide and optionally ammonia derived from step A of the process, or the system includes a precipitation reactor configured to contact an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, (optionally ammonium carbamate), or a combination thereof.

[0169] In some embodiments, an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, can be placed in a precipitation reactor, where the amount of the aqueous solution containing the calcium salt and magnesium oxide, or the first aqueous solution, added is sufficient to raise its pH to a desired level (e.g., a pH that induces precipitation of the precipitate), such as pH 7-9, pH 7-8.7, pH 7-8.5, pH 7-8, pH 7.5-8, pH 8-8.5, pH 8.5-9, pH 9-14, pH 10-14, pH 11-14, pH 12-14, or pH 13-14. In some embodiments, the pH of an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, is maintained between 7 and 9, or between 7 and 8.7, or 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, in order to form a composition containing vaterite and magnesium oxide when brought into contact with carbon dioxide and optionally NH3 or a second aqueous solution.

[0170] In some embodiments, the aqueous solution or the first aqueous solution is fixed to a column or bed (example of precipitation reactor configuration). In such embodiments, the water is adjusted to a desired pH or to a specific divalent cation (Ca 2+ A sufficient amount of calcium salt solution is passed through or over it to raise the concentration to a certain level. In some embodiments, the aqueous solution or the first aqueous solution may be circulated more than once, where the first precipitation cycle mainly removes calcium carbonate minerals, leaving an alkaline solution to which an additional aqueous solution or the first aqueous solution containing calcium salts and magnesium oxide may be added. A gas stream containing carbon dioxide and optionally NH3, or the second aqueous solution, is brought into contact with the recirculated aqueous solution to allow for further precipitation of calcium carbonate and / or bicarbonate compounds. In these embodiments, it will be recognized that the aqueous solution after the first precipitation cycle may be brought into contact with a gas stream containing CO2 and optionally NH3 (or the second aqueous solution) before, during, and / or after the addition of the aqueous solution containing calcium salts and magnesium oxide or the first aqueous solution. In these embodiments, water can be recirculated or newly introduced. Therefore, the order of addition of the gas stream containing CO2 and optionally NH3, as well as the aqueous solution or the first aqueous solution containing calcium salts and magnesium oxide, may vary. For example, an aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution, can be added to, for example, brine, seawater, or freshwater, and then a gas stream containing CO2 and optionally NH3, or a second aqueous solution, can be added. In another example, a gas stream containing CO2 and optionally NH3, or a second aqueous solution, can be added to, for example, brine, seawater, or freshwater, and then an aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution, can be added. In yet another example, a gas stream containing CO2 and optionally NH3, or a second aqueous solution, can be added directly to the aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution.

[0171] An aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution, can be brought into contact with a gas stream containing CO2 and optionally NH3 using any convenient protocol. The desired contact protocols include, but are not limited to, direct contact protocols (e.g., gas foaming through the aqueous solution or the first aqueous solution), simultaneous contact means (i.e., contact between a unidirectional gas-phase stream and a liquid-phase stream), counter-flow means (i.e., contact between a reverse-flow gas-phase stream and a liquid-phase stream), and so on. Thus, contact can be achieved by using injectors, bubblers, fluid venturi reactors, spurgers, gas filters, sprays, trays, or packed column reactors within 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 gas and liquid film move in counter-flow, parallel-flow, or reverse-flow directions, or in any other suitable manner. In some embodiments, gas-liquid contact is achieved by bringing droplets of a solution having an average diameter of 500 micrometers or less, for example, 100 micrometers or less, into contact with a gas source.

[0172] In some embodiments, substantially all (e.g., 80% or more, or 90%, 99.9%, or 100%) of the CO2 gas (of calcination origin) and optionally the NH3 waste stream generated by step A of the process illustrated in the figures herein are used for the precipitation of the precipitate material. In some embodiments, a portion of the CO2 gas and optionally the NH3 waste stream is used for the precipitation of the precipitate material, which may be 75% or less of the waste gas stream, or 60% or less, including 50% and less.

[0173] The gas-liquid contact protocols described herein may be used any number of times. The gas-liquid contact or liquid-liquid contact is continued until the pH of the precipitation reaction mixture is optimal (for example, various pH values ​​optimal for forming compositions / precipitates containing vaterite and magnesium oxide are described herein), after which the precipitation reaction mixture may be stirred. The rate at which the pH decreases can be controlled by further adding an aqueous solution or a first aqueous solution containing the calcium salt and magnesium oxide during the gas-liquid contact or liquid-liquid contact. Furthermore, additional aqueous solutions or the first aqueous solution may be added after sparging to raise the pH back to a basic level for precipitating some or all of the precipitate. In any case, the precipitate may be formed when protons are removed from certain species in the precipitation reaction mixture. The precipitate containing the carbonate may then be separated and further processed as needed.

[0174] The rate at which the pH decreases can be controlled by adding an additional supernatant, or an aqueous solution containing calcium salt and magnesium oxide, or the first aqueous solution, during gas-liquid contact or liquid-liquid contact. Furthermore, an additional supernatant, or an aqueous solution containing calcium salt and magnesium oxide, or the first aqueous solution, may be added after gas-liquid or liquid-liquid contact to raise the pH back to a basic level (e.g., between 7 and 9, or between 7 and 8.5, or between 7 and 8, or between 8 and 9) to precipitate some or all of the composition / precipitate.

[0175] In the methods and systems provided herein, an aqueous solution produced by contacting an aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, with a gas stream containing CO2 and optionally NH3, or an aqueous solution produced by contacting a first aqueous solution containing a calcium salt and magnesium oxide with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, (optionally ammonium carbamate), or a combination thereof, is subjected to one or more precipitation conditions sufficient to produce a composition containing vaterite and magnesium oxide, as well as a supernatant (i.e., the portion of the solution remaining after the precipitation of the composition / precipitate) (step C in Figures 1-3). One or more precipitation conditions are convenient for producing a composition containing vaterite and magnesium oxide.

[0176] One or more precipitation conditions include those that modulate the environment of the precipitation reaction mixture to produce a desired composition containing vaterite and magnesium oxide. Such one or more precipitation conditions suitable for forming a composition containing vaterite and magnesium oxide, which can be used in the embodiments and methods of the systems described herein, include, but are not limited to, 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 method such as ultrasonic waves, presence of seed crystals, catalysts, membranes or substrates, dehydration, drying, ball milling, etc. In some embodiments, the average particle size of the vaterite may also vary depending on one or more precipitation conditions used in the precipitation of the composition.

[0177] For example, the temperature of the precipitation reaction can be raised to a temperature at which a suitable amount of the desired composition can be precipitated. In such embodiments, the temperature of the precipitation reaction can be raised to values ​​including 25°C to 60°C, or 30°C to 60°C, or 35°C to 60°C, or 40°C to 60°C, or 50°C to 60°C, or 25°C to 50°C, or 30°C to 50°C, or 35°C to 50°C, or 40°C to 50°C, or 25°C to 40°C, or 30°C to 40°C, or 25°C to 30°C. In some embodiments, the temperature of the precipitation reaction can be raised using energy from low- or zero-carbon emission sources (e.g., solar energy sources, wind energy sources, hydroelectric energy sources, waste heat obtained from carbon emission flue gases, etc.).

[0178] The pH of the precipitation reaction can also be raised to a level suitable for precipitation of the desired composition containing vaterite and magnesium oxide. In such embodiments, the pH of the precipitation reaction can be raised to an alkaline level suitable for precipitation. In some embodiments, the pH of an aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution, which is brought into contact with a gas stream containing carbon dioxide gas and optionally NH3 gas (or a second aqueous solution), is effective for the formation of the composition containing vaterite and magnesium oxide. In some embodiments, the precipitation conditions involve carrying out a step of precipitating a gas stream (or a second aqueous solution) containing carbon dioxide gas and optionally NH3 gas with an aqueous solution containing calcium salt and magnesium oxide, or a first aqueous solution, with a pH higher than 7, i.e., pH 8, or between pH 7.1–8.5, or between pH 7.5–8, or between 7.5–8.5, or between 8–8.5, or between 8–9, or between 7.6–8.4, in order to form the composition / precipitate. The pH can be increased to a pH of 9 or higher, for example, a pH of 10 or higher, including pH 11 or higher, or pH 12.5 or higher.

[0179] Adjusting the main ion ratio in a precipitate can affect the properties of the precipitate. The main ion ratio can have a significant influence on polymorph formation. For example, an increase in the magnesium:calcium ratio in water causes aragonite to become the main polymorph of calcium carbonate in the precipitate, surpassing low-magnesium vaterite.

[0180] The precipitation rate can also have an effect on the formation of the composition, and the fastest precipitation rate is achieved by seeding the desired phase into the solution. Without seeding, rapid precipitation can be achieved by rapidly increasing the pH of the precipitation reaction mixture, which may result in more amorphous components. Higher pH leads to more rapid precipitation, which may result in more amorphous precipitated material.

[0181] The residence time of the precipitation reaction after contacting the aqueous solution or the first aqueous solution with a gas stream containing carbon dioxide gas and optionally NH3 gas (or the second aqueous solution) can also have an effect on the formation of the precipitate. For example, in some embodiments, a longer residence time may result in the conversion of vaterite to aragonite / calcite in the reaction mixture. In some embodiments, if the residence time is too short, the formation of vaterite in the reaction mixture may be incomplete. Therefore, the residence time can be very important for vaterite precipitation. Furthermore, the residence time may also affect the particle size of the precipitate. For example, if the residence time is too long, the particles may aggregate to form larger particles. Therefore, in some embodiments, the reaction residence time is between about 5 and 60 minutes, or between about 5 and 15 minutes, or between about 10 and 60 minutes, or between about 15 and 60 minutes, or between about 15 and 45 minutes, or between about 15 and 30 minutes, or between about 30 and 60 minutes.

[0182] In some embodiments, one or more precipitation conditions for generating a composition from the precipitation reaction may include, as described above, temperature and pH, and, if any, the concentrations of additives and ionic species in the water. Additives are described below herein. The presence and concentration of additives may also be favorable for the formation of a composition containing vaterite and magnesium oxide. In some embodiments, medium-chain or long-chain fatty acid esters may be added to the aqueous solution or the first aqueous solution during precipitation. Examples of fatty acid esters, but not limited to, include cellulose, e.g., carboxymethylcellulose; sorbitol; citrates, e.g., sodium citrate or potassium citrate; stearates, e.g., sodium stearate or potassium stearate; phosphates, e.g., sodium phosphate or potassium phosphate; sodium tripolyphosphate; hexametaphosphate; EDTA; or combinations thereof. In some embodiments, a combination of stearate and citrate may be added during the precipitation step of the process to form a composition containing vaterite and MgO.

[0183] One or more precipitation conditions may also include factors such as mixing rate, stirring method (e.g., ultrasonic), and the presence of seed crystals, catalysts, membranes, or substrates. In some embodiments, one or more precipitation conditions may include supersaturation conditions, temperature, pH, and / or concentration gradients, or the circulation or variation of any of these parameters. The protocol used to prepare the precipitate may be a batch, semi-batch, or continuous protocol. One or more precipitation conditions for generating precipitate material in a continuous flow system may differ from those in a semi-batch or batch system.

[0184] In some embodiments, the gas exiting the precipitation reactor (shown as "scrubbed gas" in step C of Figures 1-3) is directed to a gas treatment unit for a scrubbing process. The mass equilibrium and apparatus design for the gas treatment unit may vary depending on the gas characteristics. In some embodiments, the gas treatment unit may incorporate an acid scrubber, such as a hydrochloric acid (HCl) scrubber or a sulfuric acid (H2SO4) scrubber, to absorb CO2 and recover small amounts of NH3 in the exhaust gas stream that may be carried by the gas from the precipitation step. The NH3 is then removed by the HCl solution. NH3 (gas) + HCl (aqueous solution) → NH4Cl (aqueous solution) It can be captured via.

[0185] The NH4Cl (aqueous solution) derived from the HCl scrubber or the NH4SO4 (aqueous solution) derived from the H2SO4 scrubber can be recycled back to dissolution step A.

[0186] In some embodiments, an ammonia-containing exhaust gas stream (indicated as “scrubbed gas” in Figures 1-3) can be subjected to a scrubbing process, where the ammonia-containing exhaust gas stream is scrubbed with carbon dioxide and water from an industrial process to produce an ammonia solution. The inflow into the scrubber may be reactor waste gas containing carbon dioxide (CO2(gas)), ammonia (NH3(gas)), and fresh makeup water (or some other dilution water stream). The outflow may be a slipstream of the scrubber's recirculated fluid (e.g., H3N-CO2(aqueous solution) or carbamate), which may be returned to the main reactor for contact with carbon dioxide and precipitate as needed. The pH of the system can be controlled by adjusting the flow rate of CO2(gas) into 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 on the scrubber or its reservoir. Ammonia is a basic gas, while carbon dioxide gas is an acidic gas. In some embodiments, acidic and basic gases can be ionized to increase their solubility.

[0187] I don't want to be bound by any particular theory, but here's the response: NH3 (aqueous solution) + CO2 (aqueous solution) + H2O → HCO3 - +NH4 + However, this is intended to occur within the scrubber.

[0188] An aqueous solution containing a calcium salt and magnesium oxide, or a first aqueous solution, when contacted with a gas stream containing CO2 gas and optionally NH3 gas, or a second aqueous solution, under one or more precipitation conditions, yields a precipitate of a composition containing vaterite and magnesium oxide. One or more precipitation conditions for forming the composition containing vaterite and magnesium oxide in this process are described herein.

[0189] In some embodiments, vaterite in the composition may be formed under suitable conditions such that the vaterite is reactive during the dissolution and precipitation process in water (during cementation) and is converted to aragonite and / or calcite. Magnesium oxide is converted to magnesium hydroxide during the cementation process. Aragonite and / or calcite, together with magnesium hydroxide, may impart one or more distinctive features to the cemented product, including, but not limited to, high compressive strength, a complex micro-network structure, neutral pH, and filling of voids in the aragonite and / or calcite network structure with magnesium hydroxide. Compositions containing vaterite and magnesium oxide (as part of the composition throughout the process as described herein, or as added solids containing magnesium oxide) are converted to aragonite and / or calcite, set, and harden into cemented products (shown as product (A) in Figures 1-3). By not removing the solid magnesium oxide in the process of forming a composition containing vaterite and magnesium oxide, one step of solid removal is eliminated, a potential waste stream is eliminated, and this provides the additional benefit of increased efficiency and improved economic aspects of the process.

[0190] In some embodiments, the methods and systems provided herein further include the step of separating the composition / precipitate from an aqueous solution by dehydration (step D in Figures 1-3) to form a calcium carbonate and magnesium oxide cake (as shown in Figures 1-3). The calcium carbonate and magnesium oxide cake may be rinsed and dried as needed (step E in Figures 1-3). Drying the cake form of the composition containing calcium carbonate and magnesium oxide forms a powder form of the composition containing calcium carbonate and magnesium oxide, which can then be used to produce cement products or non-cement products (indicated as product (B) in Figures 1-3). In some embodiments, the calcium carbonate and magnesium oxide cake is ammonium (NH4) + ) ions, sulfur ions, and / or chloride (Cl -) May contain ionic impurities (e.g., 1-2% by weight or more). Rinsing the calcium carbonate and magnesium oxide cake may remove some or all of the ammonium salts and / or sulfur compounds, which may result in a diluted concentration of ammonium salts (in the supernatant), which may need to be concentrated before being recycled back into the process.

[0191] The methods and systems provided herein allow residual nitrogen-containing inorganic or nitrogen-containing organic salts, such as residual ammonium salts, to remain in the supernatant and the precipitate itself after the precipitate has formed. Residual nitrogen-containing inorganic or nitrogen-containing organic salts, such as residual ammonium salts (e.g., residual NH4Cl or residual NH4CH3CO2 (ammonium acetate)), as used herein, include any salts that can be formed by ammonium ions present in the solution, and, but not limited to, halogen ions, such as chloride ions, acetate ions, nitrate ions or nitrite ions, and sulfur ions, such as sulfate ions, sulfite ions, thiosulfate ions, hydrogen sulfide ions, etc. In some embodiments, the residual nitrogen-containing inorganic salts include ammonium halides, ammonium acetate, ammonium sulfate, ammonium sulfite, ammonium hydrogen sulfide, ammonium thiosulfate, ammonium nitrate, ammonium nitrite, or combinations thereof. Various methods for removing residual salts from the supernatant and precipitate and recovering them as needed are provided herein. In some embodiments, the supernatant solution further containing an N-containing inorganic or N-containing organic salt, such as a residual ammonium salt (e.g., residual NH4Cl or residual NH4CH3CO2), is recycled to a dissolution reactor for dissolving the mixture (step A in Figures 1-3).

[0192] The residual nitrogen-containing inorganic salt solution or nitrogen-containing organic salt solution obtained from the dewatering and rinsing stream, such as a residual ammonium salt solution (e.g., residual NH4Cl or residual NH4CH3CO2), can be concentrated as needed and then recycled back for dissolution of the mixture. Further bases, such as ammonium chloride and / or ammonia (anhydrous or aqueous solution), can be added to the recycled solution during the process to compensate for the loss of ammonium chloride and to bring the concentration of ammonium chloride to an optimal level.

[0193] In some embodiments, residual nitrogen-containing inorganic or nitrogen-containing organic salt solutions, such as residual ammonium salt solutions (e.g., residual NH4Cl or residual NH4CH3CO2), can be recovered from the supernatant aqueous solution as shown in Figures 1-3 and concentrated using recovery processes, including, but not limited to, pyrolysis, pH adjustment, reverse osmosis, multi-stage flash distillation, multiple-effect distillation, vapor recompression, distillation, or a combination thereof. Systems configured to perform these processes are commercially available. For example, the pH of the solution can be increased (e.g., by using a strong base such as NaOH). This can shift the equilibrium towards volatile ammonia (NH3 (aqueous solution) / NH3 (gas)). Both the removal rate and the total removal rate could be improved by heating the solution.

[0194] In some embodiments, residual nitrogen-containing inorganic or nitrogen-containing organic salt solutions, such as residual ammonium salt solutions (e.g., residual NH4Cl or residual NH4CH3CO2), can be separated from the precipitate and recovered by a thermal decomposition process. This process can be incorporated into the process shown in Figures 1-3 during the separation of the composition containing vaterite and magnesium oxide (step D), and / or after the step of drying the powder (step E).

[0195] 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 solid calcium oxide (CaO) and carbon dioxide (CO2) gas at 840°C. NH4Cl (solid) ←→ NH3 (gas) + HCl (gas) CaCO3 (solid) ←→ CaO (solid) + CO2 (gas)

[0196] In some embodiments, residual ammonium salts in the precipitate and / or dried powder, 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 temperatures between 80 and 840°C. This can be done during the normal drying process of the filtered cake and / or as a second post-drying heat treatment. A temperature range is desirable that decomposes the residual ammonium salts in the precipitate while preserving the cementitious properties of the vaterite in the composition, so that the vaterite remains as vaterite after heating and is successfully converted to aragonite and / or calcite after being combined with water to form a cement product.

[0197] In some embodiments of the aforementioned aspects and embodiments, the step of removing residual N-containing inorganic or N-containing organic salts, such as ammonium salts, from the precipitate and recovering them as necessary includes heating the precipitate between approximately 80 and 380°C, or between approximately 100 and 360°C, or between approximately 150 and 360°C, or between approximately 200 and 360°C, or between approximately 250 and 360°C, or between approximately 300 and 360°C, or between approximately 150 and 200°C, or between approximately 100 and 200°C, or between approximately 200 and 300°C, or between approximately 300 and 350°C, or between approximately 310 and 345°C, or between approximately 320 and 345°C, or between approximately 330 and 345°C, to evaporate the residual N-containing inorganic or N-containing organic salts from the precipitate and recovering them by condensing them as necessary.

[0198] In some embodiments of the aforementioned aspects and embodiments, the step of removing residual N-containing inorganic or N-containing organic salts, such as residual ammonium salts, from the precipitate and recovering them as necessary includes heating the precipitate for a period of time exceeding about 10 minutes, or exceeding about 15 minutes, or exceeding about 5 minutes, or for a period of time 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.

[0199] In some embodiments, the composition / precipitate is dehydrated (to remove the supernatant aqueous solution), dried to remove water (for example, by heating to about 100°C or above), and then subjected to the aforementioned heating step to remove residual nitrogen-containing inorganic or nitrogen-containing organic salts, such as residual ammonium salts, and recovered as necessary. In some embodiments, the composition is partially dehydrated (to remove the bulk of the supernatant aqueous solution), partially dried to remove water (or the drying step is avoided), and then subjected to the heating step to remove residual nitrogen-containing inorganic or nitrogen-containing organic salts, such as residual ammonium salts, and recovered as necessary. In some embodiments, the ammonium salts evaporate from the precipitate in forms including ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof. The applicants have found that in some embodiments, maintaining a combination of heating temperature and heating duration can be crucial for removing ammonium salts from the precipitate while simultaneously preserving the cement properties of the vaterite. The cement products thus formed have minimal or no chloride content and are completely free of ammonia or sulfurous odors. In some embodiments, the chloride content is approximately at or below the ASTM acceptable limit for cement products.

[0200] In some embodiments, the heating period and, as needed, the temperature conditions described above can be combined with pressure conditions that provide a driving force to improve the thermodynamics of the decomposition of residual nitrogen-containing inorganic or nitrogen-containing organic salts, such as residual ammonium salts. For example, heating of a precipitate can be carried out in a system where the headspace pressure is lower than atmospheric pressure. A pressure lower than atmospheric pressure can provide a driving force for heating reactions involving gas-phase products (e.g., but not limited to ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof) by reducing the partial pressure of reactants in the gas phase. Another advantage of operating under reduced pressure or vacuum is that at lower pressures, some sublimation reactions can occur at lower temperatures, thereby improving the energy requirements of the heating reaction.

[0201] In some embodiments of the pyrolysis process described above, the separated ammonium chloride in the form of ammonia gas and HCl gas can be recovered for reuse by recrystallizing the combination of gases generated thermally or by absorbing the gases into an aqueous medium. Together, these mechanisms can yield an NH4Cl product that can be sufficiently concentrated for reuse in the processes shown in Figures 1-3.

[0202] In some embodiments, the ammonium salt can be separated and recovered in the aforementioned process by adjusting the pH from the ammonium salt to generate NH3 gas. This process can be incorporated into the process shown in Figures 1-3 when separating the vaterite and magnesium oxide cakes. The final pH of the water in the filtered cake can typically be about 7.5. At this pH, NH4 + (pKa=9.25) can be the main species. Increasing the pH of this water can shift the acid-base equilibrium, as described in the following equation, toward NH3 gas. NH4 + ←→ H + +NH3 (gas)

[0203] Any alkaline source can be used to increase the pH of the filtered cake water. In some embodiments, an aqueous solution of calcium oxide and / or calcium hydroxide or lime slurry can provide a highly alkaline source. In some embodiments, an aqueous fraction of lime can be integrated into the rinsing step of the dewatering process (e.g., the filtered cake step) to increase the system's pH and drive the generation of NH3 gas. Since ammonia is quite soluble in water, heat and / or vacuum pressure can be applied to further drive equilibrium toward the gas phase. Ammonia can be recovered for reuse by recrystallizing ammonia with chloride or by absorbing ammonia into an aqueous medium. Together, these mechanisms can result in an ammonia solution or NH4Cl product that can be sufficiently concentrated for reuse in the processes shown in Figures 1-3.

[0204] A cake composition containing vaterite and magnesium oxide can be sent to a dryer to form a powder composition containing vaterite and magnesium oxide (step E in Figures 1-3). The powder form of the composition 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, for example, a fluidized bed dryer or a swirl fluidizer, but not limited to these. The resulting solid powder can then be mixed with additives to produce a variety of products as described herein. In some embodiments, a slurry form containing reduced water or a cake form of the composition can be used directly to form products such as building panels, concrete, or aggregates, as described herein.

[0205] In the systems provided herein, separation or dehydration step D may be performed at a separation station. The composition containing vaterite and magnesium oxide may be stored in the supernatant for a certain period of time after precipitation and before separation. For example, the composition may be stored in the supernatant at a temperature in the range of 1°C to 40°C, for example, 20°C to 25°C, for a period ranging from a few minutes to several hours, 1 to 1000 days or longer, for example, 1 to 10 days or longer. Separation or dehydration may be achieved using any of several convenient methods, including drainage (e.g., drainage after gravity settling of the precipitated material), decantation, filtration (e.g., gravity filtration, vacuum filtration, filtration using forced air), centrifugation, pressurization, or any combination thereof. Separation of bulk water from the composition produces a wet cake of the composition, i.e., the dehydrated composition. Liquid-solid separators, e.g., Epuramat's Extreme-Separator ("ExSep") liquid-solid separator, Xerox PARC's spiral separator, or Epuramat's ExSep or Xerox Any modification of a spiral ore separator manufactured by PARC may be useful for separating compositions from precipitation reactions.

[0206] In some embodiments, the resulting dehydrated composition, for example, a wet cake material (after removing N-containing salts, for example, thermally), can be used directly to produce product (A) as described herein. For example, a wet cake of a composition containing vaterite and magnesium oxide is mixed with one or more additives as described herein and spread on a conveyor belt, where the vaterite is converted to aragonite and / or calcite, the magnesium oxide to magnesium hydroxide, and the mixture sets and hardens. The hardened material is then cut into desired shapes, for example, boards or panels as described herein. In some embodiments, the wet cake is poured onto paper at the top of a conveyor belt. Another sheet of paper can be placed on top of the wet cake and then compressed to remove excess water. After the composition sets and hardens (vaterite is converted to aragonite and / or calcite, and magnesium oxide to magnesium hydroxide), the material is cut into desired shapes, for example, cement paneling and drywall. In some embodiments, the amounts of one or more additives may be optimized according to the desired time required for the conversion from vaterite to aragonite and / or calcite (as described below). For example, in some applications, a rapid conversion of the material may be desirable, while in certain other cases, a slow conversion may be desirable. In some embodiments, the wet cake may be heated on a conveyor belt to accelerate the conversion from vaterite to aragonite and / or calcite, as well as the conversion from magnesium oxide to magnesium hydroxide. In some embodiments, the wet cake may be poured into a mold of a desired shape, and the mold may then be heated in an autoclave to accelerate the conversion from vaterite to aragonite and / or calcite, as well as the conversion from magnesium oxide to magnesium hydroxide (and, if necessary, to remove residual salts). Thus, continuous flow processes, batch processes, or semi-batch processes are all well within the scope of the present invention.

[0207] In some embodiments, after separating a composition containing vaterite and magnesium oxide from a precipitation reaction, it is washed with fresh water and then placed in a filtration compressor to produce a filtration cake containing 30-60% solid. This filtration cake is then mechanically compressed in a mold using any convenient means, such as a hydraulic compressor, at a sufficient pressure in the range of 5-5000 psi, for example, 1000-5000 psi, to produce a formed solid (where vaterite is converted to aragonite and / or calcite, and magnesium oxide is converted to magnesium hydroxide), such as rectangular bricks. These resulting solids are then cured, for example, by being stored outdoors or placed in a chamber exposed to high levels of humidity and heat. These cured solids are then used as building material itself or crushed to produce aggregate.

[0208] In a process involving the use of temperature and pressure, the dehydrated cake can be dried. The cake is then exposed to a combination of re-watering and high temperature and / or high pressure for a certain period of time. The combination of the amount of water added and returned, temperature, pressure, and exposure time, as well as the thickness of the cake, can vary depending on the composition of the starting material and the desired result.

[0209] Several different ways of exposing the material to temperature and pressure are described herein, but it will be recognized that any convenient method may be used. The thickness and size of the cake may be adjusted as desired, but the thickness may vary in some embodiments from 0.05 inches to 5 inches, e.g., 0.1 to 2 inches, or 0.3 to 1 inch. In some embodiments, the cake may be 0.5 inches to 6 feet or thicker. The cake is then exposed to high temperature and / or high pressure for a given time by any convenient method, e.g., using a heated platen in a platen compressor. For example, the heat to raise the temperature for the platen can be provided by heat derived from an industrial waste gas stream, e.g., a flue gas stream. The temperature may be any suitable temperature, but generally, higher temperatures are desirable for thicker cakes, and examples of temperature ranges are 40 to 150°C, e.g., 60 to 120°C, e.g., 70 to 110°C, or 80 to 100°C. Similarly, the pressure may be any pressure suitable for producing the desired result, and exemplary pressures include 1,000 to 100,000 pounds per square inch (psi), including 2,000 to 50,000 psi, 2,000 to 25,000 psi, 2,000 to 20,000 psi, or 3,000 to 5,000 psi. Finally, the time for the cake to be compressed may be any appropriate time, e.g., 1 to 100 seconds, or 1 to 100 minutes, or 1 to 50 minutes, or 2 to 25 minutes, or 1 to 10,000 days. The resulting hard tablets can then be cured as needed, for example, by storing them outdoors or by placing them in a chamber exposed to high levels of humidity and heat. These cured hard tablets can then be used as building materials themselves or crushed to produce aggregates.

[0210] Another method for providing temperature and pressure is the use of a compressor. Using a suitable compressor, such as a platen compressor, it is possible to provide a desired temperature (for example, by using heat supplied by flue gas or by other steps in the process for producing the precipitate, such as by electrochemical methods) and pressure for a desired time. A set of rollers can be used in a similar manner.

[0211] Another way to expose the cake to high temperature and pressure is by using an extruder, such as a screw extruder. The barrel of the extruder can be equipped, for example, by having a jacket to achieve high temperature, and this high temperature can be supplied, for example, by exhaust gas. Extrusion can be used as a means of preheating and drying the raw material before the compression operation. Such compression can be carried out by using a compression die, through rollers, through rollers having a molded press die (which can provide aggregate of virtually any desired shape), between belts that provide compression as they move, or by any other convenient method. Alternatively, an extruder can be used to extrude the material through a die, exposing the material to pressure as it is extruded through the die to give it any desired shape. In some embodiments, a composition containing vaterite and magnesium oxide is mixed with fresh water and then placed in the feed section of a rotary screw extruder. The extruder and / or outlet die can be heated to further assist the process. The rotation of the screw transports the material along its length and compresses the material as the height of the screw threads (flite) decreases. The barrel may further include vents, and the reduced pressure zone of the screw may coincide with the vent openings of the barrel. In particular, in the case of a heated extruder, these vented areas can release steam from the material being conveyed, thereby removing water from the material.

[0212] Next, the material transported by the screw is extruded through a die section that further compresses and shapes the material. Typical die openings can be circular, elliptical, square, rectangular, trapezoidal, etc., but any shape desired for the final aggregate can be produced by adjusting the shape of the opening. The material exiting the die can be cut to any convenient length by any convenient method, for example, by a fly knife. The use of a heated die section can further aid in product formation by accelerating the transition from carbonate minerals to a hard, stable form. In the case of binders, a heated die can also be used to harden or solidify the binder. In heated die sections, temperatures generally range from 100°C to 600°C.

[0213] In further embodiments, compositions comprising vaterite and magnesium oxide can be used for the fabrication of form-in-place structures. For example, roads, pavement areas, or other structures can be fabricated from the composition by, for example, applying a layer of the composition to a substrate, such as the ground or subgrade, and then hydrating the composition by exposure to water that is naturally applied, such as in the form of rain, or by irrigation. Through hydration, the composition solidifies into the desired form-in-place structure, such as a road or pavement area (vaterite is converted to aragonite and / or calcite, and magnesium oxide is converted to magnesium hydroxide). The process may be repeated, for example, if a thicker layer of the form-in-place structure is desired.

[0214] In some embodiments, the production of the composition and the product takes place within the same facility. In some embodiments, the composition is produced in one facility and transported to another facility to produce the final product. The composition may be transported in slurry form, wet cake form, or dry powder form.

[0215] In some embodiments, the resulting dehydrated composition obtained from the separation station is dried in a drying station to produce a powder form of the composition containing vaterite and magnesium oxide. Drying can be achieved by air-drying the composition. In certain embodiments, drying is achieved by freeze-drying (i.e., lyophilization), where the composition is frozen, the ambient pressure is reduced, and enough heat is applied to directly sublimate the frozen water in the composition into gas. In yet another embodiment, the composition is spray-dried to dry it, where the liquid containing the composition is dried by being supplied via a hot gas (e.g., a waste gas stream from a power plant), the supply liquid is pumped through an atomizer into a main drying chamber, and the hot gas passes in parallel or countercurrent relative to the atomizer. 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, etc. In some embodiments, the precipitate can be dried by a fluidized bed dryer. In certain embodiments, where appropriate, waste heat from a power plant or similar operation can be used to carry out the drying step. For example, in some embodiments, the drying product is produced by using high temperature (e.g., derived from waste heat of a power plant), pressure, or a combination thereof. After drying the composition, the substance can then be heated at a high temperature to remove residual nitrogen-containing salts, such as residual ammonium salts, as described herein.

[0216] The supernatant or slurry of the composition resulting from the precipitation process can also be treated as desired. For example, the supernatant or slurry can be returned to an aqueous solution or a first aqueous solution, or to another location. In some embodiments, the supernatant can be contacted with a gas stream containing CO2 and optionally ammonia gas as described herein to capture further CO2. For example, in embodiments where the supernatant is to be returned to the precipitation reactor, the supernatant can be contacted with a gas stream of CO2 and optionally ammonia gas in a manner sufficient to increase the concentration of carbonate ions present in the supernatant. As stated above, the contact can be carried out using any convenient protocol. In some embodiments, the supernatant has an alkaline pH, and the contact with CO2 gas is carried out in a manner sufficient to reduce the pH to a range of pH 5 to 9, pH 6 to 8.5, or pH 7.5 to 8.7.

[0217] In some embodiments, compositions produced by the methods provided herein are used as building materials (e.g., building materials for certain types of man-made structures such as buildings, roads, bridges, and dams) so that CO2 is effectively captured in the built environment. Any man-made structure such as foundations, parking structures, houses, office buildings, commercial offices, government buildings, and infrastructure (e.g., scaffolding for sidewalks, roads, bridges, overpasses, walls, gates, fences, and poles) is considered part of the built environment. Mortar is used to bind building blocks (e.g., bricks) together and to fill gaps between building blocks. Among other uses, mortar can also be used to repair existing structures (e.g., to replace parts where the original mortar is damaged or eroded).

[0218] In some embodiments, a powdered composition containing vaterite and magnesium oxide is used as cement, and after being mixed with water, the vaterite is converted to aragonite and / or calcite (dissolution-reprecipitation process), and the magnesium oxide is converted to magnesium hydroxide, which then sets and hardens.

[0219] In some embodiments, the aggregate is produced from the composition. In such embodiments, where a drying process produces particles of the desired size, there is little or no additional processing required to produce the aggregate. In yet another embodiment, further processing of the composition is carried out to produce the desired aggregate. For example, the composition can be combined with fresh water in a manner sufficient to form a solid product, where vaterite is converted to aragonite and / or calcite (dissolution-reprecipitation process) and magnesium oxide is converted to magnesium hydroxide. By controlling the water content of the wet material, the porosity of the final aggregate, as well as its final strength and density, can be controlled. Typically, the wet cake may be 40-60% by volume of water. For denser aggregates, the wet cake may be <50% water, and for less dense cakes, the wet cake may be >50% water. The solid product then produced after hardening can be mechanically processed, e.g., crushed or otherwise broken down, and sorted to produce aggregate with desired characteristics, e.g., size, specific shape. In these processes, the setting and mechanical processing steps may be carried out substantially continuously or at intervals of time. In certain embodiments, large volumes of composition may be stored in an open environment where the composition is exposed to the atmosphere. In the setting step, the composition may be conveniently irrigated with fresh water or exposed to rainwater naturally to produce a setting product. The setting product may then be mechanically processed as described above. After the formation of the composition, the composition is processed to produce the desired aggregate. In some embodiments, the composition may be placed outdoors, where rainwater can be used as a fresh water source to induce a stabilization reaction in the rainwater to harden the composition and form aggregate.

[0220] Typically, when calcium carbonate precipitates, initially, amorphous calcium carbonate (ACC) can precipitate and can convert to one or more of its three more stable phases (vaterite, aragonite, or calcite). There may be a thermodynamic driving force to convert the less stable phases to the more stable phases. 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. 5, excess energy is released. This intrinsic energy can be utilized to create strong aggregation tendencies and surface interactions that can lead to aggregation and coagulation or cementation. It should be understood that the values reported in FIG. 5 are well known in the art and can vary.

[0221] The methods and systems provided herein produce or isolate a composition comprising vaterite and magnesium oxide that converts to an aragonite form and / or a calcite form containing magnesium hydroxide upon dissolution and reprecipitation. The aragonite form may or may not convert further to the more stable calcite form. Products containing an aragonite and / or calcite form containing magnesium hydroxide 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), a fine network structure, and the like.

[0222] Minor amounts of other polymorphic forms of calcium carbonate that may be present in the precipitate material containing carbonate in addition to vaterite include, but are not limited to, amorphous calcium carbonate, aragonite, calcite, a precursor phase of vaterite, a precursor phase of aragonite, an intermediate phase less stable than calcite, polymorphs between these polymorphs, or combinations thereof.

[0223] Vaterite can exist in monodisperse or aggregated forms and may be spherical, elliptic, plate-like, or hexagonal. Vaterite typically has a hexagonal crystalline structure and forms polycrystalline spherical particles during growth. Precursors of vaterite include vaterite nanoclusters, and precursors of aragonite include submicron to nanoclusters of acicular aragonite. When present in a composition with vaterite, aragonite may be acicular, cylindrical, or orthorhombic crystals. When present in a composition with vaterite, calcite may be cubic, fusiform, or hexagonal crystals. Intermediate phases less stable than calcite may be phases between vaterite and calcite, between vaterite precursors and calcite, between aragonite and calcite, and / or between aragonite precursors and calcite.

[0224] Conversion between calcium carbonate polymorphs can occur via solid-state transitions, which may be mediated by solution, or both. In some embodiments, solution-mediated conversion requires less energy than thermally activated solid-state transitions, and therefore the conversion is solution-mediated. Vaterite is metastable, and differences in the thermodynamic stability of calcium carbonate polymorphs may manifest as differences in solubility, where the least stable phase is the most soluble. Therefore, vaterite readily dissolves in solution and can be conveniently converted to more stable polymorphs, such as aragonite and / or calcite. In polymorphic systems like calcium carbonate, two dynamic processes—dissolution of the metastable phase and growth of the stable phase—can coexist in solution simultaneously. In some embodiments, aragonite and / or calcite crystals may grow while vaterite is undergoing dissolution in an aqueous medium.

[0225] In some embodiments of the compositions, methods, and systems provided herein, a combination of vaterite and magnesium oxide activates the vaterite so that it follows a pathway to aragonite and not to calcite during the dissolution-reprecipitation process. In some embodiments, a composition containing vaterite is activated after the dissolution-reprecipitation process in such a way that aragonite formation is enhanced and calcite formation is inhibited. Activation of a composition containing vaterite can also control aragonite formation and crystal growth. This selection and activation of vaterite in a composition, directed only towards aragonite and not towards calcite, can be facilitated by the presence of magnesium oxide. As previously described herein, magnesium oxide can not only control the conversion of vaterite to aragonite during condensation and hardening, but it also converts itself to magnesium hydroxide, filling and bonding with acicular aragonite, thereby providing a stable, durable hard material.

[0226] It should be understood that magnesium hydroxide can bond completely or partially to acicular aragonite or calcite, and not all magnesium hydroxide necessarily needs to bond to that acicular aragonite or calcite.

[0227] In some embodiments of the compositions, methods, and systems provided herein, a combination of vaterite and magnesium oxide activates a vaterite-to-calcite pathway during a dissolution-reprecipitation process. This process can be driven in such a way that vaterite is converted to calcite, along with a conversion of magnesium oxide to magnesium hydroxide. The magnesium hydroxide fills and binds with the calcite, thereby providing a stable, durable, and rigid material.

[0228] In some embodiments of the compositions, methods, and systems provided herein, a combination of vaterite and magnesium oxide activates pathways from vaterite to both aragonite and calcite during the dissolution-reprecipitation process. This process may be driven in such a way that vaterite is converted to aragonite, and aragonite is partially or completely converted to calcite, along with the conversion of magnesium oxide to magnesium hydroxide. Magnesium hydroxide fills and binds with aragonite and calcite, thereby providing a stable, durable, hard material.

[0229] During the dissolution-reprecipitation process, magnesium ions are released into the solution to form magnesium hydroxide. Similarly, vaterite is converted to aragonite and / or calcite by the dissolution-precipitation reaction. Surprisingly, the applicants found that, in parallel with the dissolution of vaterite, magnesium oxide for the magnesium ions may need to be dissolved in the solution in an amount sufficient to promote aragonite formation. The timing of dissolution can be controlled simultaneously by controlling the solubility and dissolution rate of vaterite and magnesium oxide (see Example 3). In some embodiments, the dissolution rate of vaterite can be modified by changing the grain size and crystal lattice. For example, reducing the grain size of vaterite can increase the rate of dissolution and conversion. In some embodiments, the solubility of vaterite can be increased by inducing defects in the crystal lattice, and certain ions, such as ammonium ions and sulfate ions, can be further utilized to stabilize vaterite and reduce its dissolution rate. In some embodiments, the dissolution rate of magnesium oxide may be influenced by its size and crystallinity. In some embodiments, the size and properties of magnesium oxide (incomplete combustion, light burning, or dead burning) can be controlled by grinding and calcination (combustion) conditions. In some embodiments, the dissolution rate of magnesium oxide can be increased by reducing the particle size of magnesium oxide, shortening the burning time, and lowering the burning temperature.

[0230] In one embodiment, a method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A step of dissolving a mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and magnesium oxide, (iii) A step of treating an aqueous solution containing a calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide, (iv) The steps of controlling the average grain size of the vaterite and / or the calcination / burning temperature of the limestone and / or magnesium-supported mineral to form magnesium oxide, convert the vaterite to aragonite and / or calcite, and convert the magnesium oxide to magnesium hydroxide, A method is provided that includes this.

[0231] The embodiments described above further include the step of controlling the average grain size of the vaterite between approximately 1 and 50 microns or between 1 and 20 microns. The embodiments described above further include the step of controlling the calcination / combustion temperature of the limestone and / or magnesium-supported mineral for forming lime and magnesium oxide between approximately 300°C and 1200°C, or between approximately 300°C and 1000°C, or between approximately 300°C and 800°C, or between approximately 500°C and 1000°C.

[0232] The activation of compositions containing vaterite and magnesium oxide may be further achieved by various other processes as needed. Various examples of vaterite activation, including but not limited to nucleation activation, thermal activation, mechanical activation, chemical activation, or combinations thereof, are described herein. In some embodiments, vaterite is activated through various processes so that the formation of aragonite and / or calcite, as well as its morphology and / or crystal growth, can be controlled during the reaction of the vaterite-containing composition with water. The formed aragonite and / or calcite contribute to higher tensile strength and fracture resistance in products formed from vaterite.

[0233] In some embodiments, vaterite may be activated by mechanical means as described herein. For example, a composition comprising vaterite and magnesium oxide may be activated by creating surface defects on the composition so as to accelerate the formation of aragonite and / or calcite. In some embodiments, the composition comprising vaterite and magnesium oxide is a ball-milled composition.

[0234] Compositions containing vaterite and magnesium oxide may also be activated by providing chemical or nucleation activation to the vaterite composition. Such chemical or nucleation activation may be provided by one or more aragonite seed crystals, calcite seed crystals, inorganic additives, or organic additives. The aragonite and / or calcite seed crystals present in the compositions provided herein may be obtained from natural or synthetic sources. Natural sources include, but are not limited to, reef sands, limestone, the shells of bluntopods, gastropods, mollusks, and hard skeletal materials of certain freshwater and marine invertebrates, including the calcareous endoskeletons of warm-water and cold-water corals, as well as pearls, rocks, sediments, and ore minerals (e.g., serpentine). Synthetic sources include, but are not limited to, precipitated aragonite and / or calcite formed from, for example, sodium carbonate and calcium chloride, or aragonite and / or calcite formed by conversion from vaterite, such as the converted vaterite described herein.

[0235] In some embodiments, the inorganic or organic additives in the compositions provided herein may be any additives that activate vaterite. Some examples of inorganic or organic additives in the compositions provided herein, but not limited to, include sodium decyl sulfate, lauric acid, sodium salt of lauric acid, urea, citric acid, sodium salt of citric acid, phthalic acid, sodium salt of phthalic acid, taurine, creatine, glucose, poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium salt of aspartic acid, magnesium chloride, acetic acid, sodium salt of acetic acid, glutamic acid, sodium salt of glutamic acid, strontium chloride, gypsum, lithium chloride, sodium chloride, glycine, anhydrous sodium citrate, 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 lauric acid, urea, magnesium chloride, acetic acid, sodium acetic acid, 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.

[0236] In some embodiments, the inorganic additive in the compositions provided herein may be additional magnesium oxide added externally to a composition containing vaterite and magnesium oxide.

[0237] While not adhering to any particular theory, it is intended that the formation of aragonite and / or calcite can be controlled during the dissolution-reprecipitation process of vaterite by activation of vaterite with magnesium oxide, and / or further activation of vaterite by ball milling, or by adding aragonite seed crystals and / or calcite seed crystals, inorganic or organic additives, or a combination thereof, including, but not limited to, control of properties such as polymorphism, morphology, particle size, bridging, aggregation, solidification, aggregation, sedimentation, crystal structure analysis, inhibition of growth along certain faces of the crystal, enabling growth along certain faces of the crystal, or a combination thereof. For example, the presence of magnesium oxide and, optionally, other additives such as aragonite seed crystals, inorganic or organic additives may selectively target the morphology of aragonite, inhibit calcite growth, and promote the formation of aragonite, which may generally be kinetically undesirable.

[0238] In some embodiments, one or more inorganic additives may be added to facilitate the conversion of vaterite to aragonite and / or calcite, and the conversion of magnesium oxide to magnesium hydroxide. One or more additives may be added at any step of the process. For example, one or more additives may be added during contact between an aqueous solution or a first aqueous solution and carbon dioxide gas and optionally ammonia gas or a second aqueous solution, after contact between an aqueous solution or a first aqueous solution and carbon dioxide gas and optionally ammonia gas or a second aqueous solution, during precipitation of the composition, after precipitation of the composition in a slurry, to the slurry after dehydration of the composition, to the powder after drying the slurry, to the aqueous solution to be mixed with the powdered composition, or to a slurry prepared from the powdered composition using water, or to any combination thereof. In some embodiments, the water used in the process of preparing the composition may already contain one or more additives or one or more additive ions. For example, if seawater is used in the process, the additive ions may already be present in the seawater.

[0239] In some embodiments of the method described above, the amount of one or more additives added during the process is greater than 0.1% by weight, or greater than 0.5% by weight, or greater than 1% by weight, or greater than 1.5% by weight, or greater than 1.6% by weight, or greater than 1.7% by weight, or greater than 1.8% by weight, or greater than 1.9% by weight, or greater than 2% by weight, or greater than 2.1% by weight, or greater than 2.2% by weight, or greater than 2.3% by weight, or greater than 2.4% by weight, or greater than 2.5% by weight, or greater than 2.6% by weight, or greater than 2.7% by weight, or greater than 2.8% by weight, or greater than 2.9% by weight, or greater than 3% by weight, or greater than 3.5% by weight, or greater than 4% by weight. , or more than 4.5% by weight, or more than 5% by weight, or between 0.5 and 5% by weight, or between 0.5 and 4% by weight, or between 0.5 and 3% by weight, or between 0.5 and 2% by weight, or between 0.5 and 1% by weight, or between 1 and 3% by weight, or between 1 and 2.5% by weight, or between 1 and 2% by weight, or between 1.5 and 2.5% by weight, or between 2 and 3% by weight, or between 2.5 and 3% by weight, or between 0.5% by weight, or 1% by weight, or 1.5% by weight, or 2% by weight, or 2.5% by weight, or 3% by weight, or 3.5% by weight, or 4% by weight, or 4.5% by weight, or 5% by weight. In some embodiments of the method described above, the amount of one or more additives added during the process is between 0.5 and 3% by weight or between 1.5 and 2.5% by weight.

[0240] In some embodiments, compositions comprising vaterite and magnesium oxide, prepared by the methods and systems described herein, are treated with an aqueous medium under one or more suitable conditions, after which they coagulate and harden (vaterite is converted to aragonite and / or calcite, and magnesium oxide is converted to magnesium hydroxide). The aqueous medium includes, but is not limited to, freshwater or brine containing additives as needed. In some embodiments, one or more suitable conditions include, but is not limited to, temperature, pressure, duration for coagulation, ratio of the aqueous medium to the composition, and combinations thereof. The temperature may be the temperature of the aqueous medium. In some embodiments, the temperature is in the range of 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, or 100 to 200°C. In some embodiments, the pressure is atmospheric pressure or above atmospheric pressure. In some embodiments, the time required to set 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, or 2 to 48 hours, or 2 to 24 hours, or 2 to 12 hours, or 2 to 8 hours, or 2 to 4 hours, or 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, or 10 to 48 hours, or 10 to 24 hours, or 24 to 48 hours.

[0241] While mixing the composition or 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 in a pre-formed mold to produce a formed building material, or 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 then be placed in an oven for drying at, for example, 40°C, or 40°C to 60°C, or 40°C to 50°C, or 40°C to 100°C, or 50°C to 60°C, or 50°C to 80°C, or 50°C to 100°C, or 60°C to 80°C, or 60°C to 100°C. The precipitate can be cured at high temperatures, such as 50°C to 60°C, or 50°C to 80°C, or 50°C to 100°C, or 60°C to 80°C, or 60°C to 100°C, or 60°C, or 80°C to 100°C, or 100°C to 200°C, at a high humidity, for example, at a relative humidity of 30%, or 40%, or 50%, or 60%, or 100%.

[0242] In some embodiments of the foregoing aspects and embodiments, the system further includes a recovery system for recovering residual N-containing salts from an aqueous solution and recycling them back to the dissolution reactor. The recovery system is a system configured to perform pyrolysis, reverse osmosis, multi-stage flash distillation, multiple-effect distillation, vapor recompression, distillation, and combinations thereof, as described hereinabove. <0>

[0243] The methods and systems provided herein can be performed on land (e.g., near a limestone quarry or a location that can be easily and economically transported), at sea, or in the ocean. In some embodiments, a cement factory that calcines lime can additionally introduce the system described herein to form a composition and further to form a product from the composition.

[0244] Some embodiments include a system, including a processing plant or manufacturing facility, for carrying out the methods described herein. The system may have any stereochemical configuration that enables the specific production method of the object of interest to be carried out.

[0245] In certain embodiments, the system includes a structure having a lime source and an inlet for an aqueous N-containing salt solution. For example, the system may include a pipeline or similar supply for an aqueous N-containing salt solution as described herein. The system further includes an inlet for CO2 and components for combining these sources with water (an aqueous solution as needed, e.g., water, brine, or seawater) before or in the precipitation or treatment reactor. In some embodiments, the treatment reactor is a gas-liquid contactor configured to contact enough CO2 to produce more than 1 ton, 10 tons, 100 tons, 1,000 tons, or 10,000 tons of composition per day.

[0246] The system further includes a processing reactor that subjects the aqueous solution introduced into the processing reactor or a first aqueous solution to one or more precipitation conditions (as described herein) to produce a composition and a supernatant. In some embodiments, the processing reactor is configured to hold enough water to produce more than 1 ton, 10 tons, 100 tons, 1,000 tons, or 10,000 tons of the composition per day. The processing reactor may 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), or computer automation.

[0247] The waste gas stream, containing CO2 and optionally NH3, can be supplied to the processing reactor and / or cooling reactor by any convenient method. In some embodiments, the waste gas stream is supplied using a gas conveyor (e.g., a duct) traveling from the dissolution reactor to the processing reactor and / or cooling reactor.

[0248] If the water source that the system processes to generate precipitate is seawater, for example, if the inlet is a pipeline or supply pipe from seawater to a land-based system or a ship's inlet port, for example, if the system is part of a ship in a marine system, then the inlet is fluidly connected to the seawater source.

[0249] The method and system may also include one or more detectors (not shown) configured to monitor a nitrogen-containing salt solution, lime, and / or carbon dioxide. Monitoring may include, but is not limited to, the collection of data regarding the pressure, temperature, and composition of water or carbon dioxide gas. The detectors may be any convenient device configured to monitor, e.g., pressure sensors (e.g., electromagnetic pressure sensors, potentiometric pressure sensors, etc.), temperature sensors (e.g., resistance temperature detectors, thermocouples, gas thermometers, thermistors, pyrometers, infrared radiation sensors, etc.), volume sensors (e.g., geophysical diffraction tomography, X-ray tomography, underwater acoustic probes, etc.), and devices for determining the chemical composition of water or carbon dioxide gas (e.g., IR spectrometers, NMR spectrometers, UV-vis spectrophotometers, high-performance liquid chromatographs, inductively coupled plasma emission spectrometers, inductively coupled plasma mass spectrometers, ion chromatographs, X-ray diffractometers, gas chromatographs, gas chromatography-mass spectrometers, flow injection analysis, scintillation counters, acid titrations, and flame emission spectrometers, etc.).

[0250] In some embodiments, the detector may also include a computer interface configured to provide the user with collected data regarding N-containing salt solutions, lime and magnesium oxide, and / or carbon dioxide / ammonia gas. In some embodiments, the summary may be stored as a computer-readable data file or printed as a user-readable document.

[0251] In some embodiments, the detector may be a monitoring device capable of collecting real-time data (e.g., internal pressure, temperature, etc.). In other embodiments, the detector may be one or more detectors configured to periodically determine the parameters of a nitrogen-containing salt solution, lime, and / or carbon dioxide and / or NH3 gas, for example, by determining its composition every minute, every 5 minutes, every 10 minutes, every 30 minutes, every 60 minutes, every 100 minutes, every 200 minutes, every 500 minutes, or any other interval.

[0252] In certain embodiments, the system may further include a station for preparing building materials such as cement or aggregate from the composition. Other materials, such as the formed building materials and / or non-cementary materials, can also be formed from the composition and a station suitable for their preparation can be used.

[0253] As previously shown, this system can exist on land or at sea. For example, the system could be a land-based system located in a coastal area near a seawater source, or even in an inland location where water is piped to the system from a water source, such as the ocean. Alternatively, the system could be a water-based system, i.e., a system existing on or underwater. Such a system could exist on a boat, a marine platform, or the like, as desired.

[0254] The calcium carbonate slurry is pumped to a drying system, which in some embodiments includes a filtration step followed by spray drying. The water separated from the drying system is either discharged or recycled back into the reactor. The solid or powder produced from the drying system is used as cement or aggregate to produce building materials. The solid or powder can also be used as a filler in non-cement products, such as paper, plastics, and paints. The solid or powder can also be used in the formation of formed building materials, such as drywalls and cement boards.

[0255] In some embodiments, the system may include a control station configured to control the amount of N-containing aqueous salt solution and / or lime transported to a processing reactor or dissolution reactor; the amount of precipitate transported to a separation unit; the amount of precipitate transported to a drying station; and / or the amount of precipitate transported to a purification station. The control station may include a set or multiple valve system controlled manually, mechanically, or digitally, or may use any other convenient flow control protocol. In some cases, the control station may include a computer interface configured to provide the user with input and output parameters for controlling the amounts (the control may be computer-assisted or fully computer-controlled). II. Composition

[0256] In one embodiment, a cement or non-cement composition comprising vaterite and magnesium oxide is provided.

[0257] As described herein, magnesium oxide is incompletely combusted magnesium oxide, lightly calcined magnesium oxide, dead-calcined magnesium oxide, or a combination thereof.

[0258] In some embodiments of the compositions, methods, and systems provided herein, vaterite is partially formed on the surface of magnesium oxide. The aforementioned embodiments may occur when lime and magnesium oxide undergo the processes outlined in Figures 1-4 to form a composition comprising vaterite and magnesium oxide.

[0259] In some embodiments, the compositions provided herein are in powder form. In some embodiments, the compositions provided herein are in dry powder form. In some embodiments, the compositions provided herein are in wet cake composition or slurry form. In some embodiments, the compositions provided herein are disordered, i.e., not in an ordered arrangement. In some further embodiments, the compositions provided herein are in a partially or fully hydrated form. In some further embodiments, the compositions provided herein exist in saline or freshwater. In some further embodiments, the compositions provided herein exist in water containing sodium chloride. In some further embodiments, the compositions provided herein exist in water containing alkaline earth metal ions, e.g., calcium, magnesium, etc., for example, but not limited to these. In some embodiments, the compositions provided herein are not for medical use or for medical procedures.

[0260] In one embodiment, a cement or non-cement slurry composition is provided comprising vaterite, aragonite, calcite, magnesium oxide, magnesium hydroxide, or a combination thereof, and water. In the aforementioned embodiment, when the composition comprising vaterite and magnesium oxide comes into contact with water to form a slurry, it undergoes conversion from vaterite to aragonite and / or calcite (dissolution in water and reprecipitation), as well as conversion from magnesium oxide to magnesium hydroxide.

[0261] In some embodiments, the aragonite in the compositions, methods, and systems provided herein has a needle-like network structure. In some embodiments, magnesium hydroxide binds the needle-like aragonite together. In some embodiments, magnesium hydroxide stabilizes the aragonite and prevents its conversion to calcite. In some embodiments, magnesium hydroxide binds the calcite crystals together. In some embodiments, magnesium hydroxide stabilizes the calcite.

[0262] In some embodiments, water is bonded to the composition in the form of magnesium hydroxide.

[0263] In some embodiments, the compositions provided herein have a pH greater than 10.

[0264] In the aforementioned embodiments and some embodiments of the model, the composition contains at least 10 wt% vaterite, or at least 20 wt% vaterite, or at least 30 wt% vaterite, or at least 40 wt% vaterite, or at least 50 wt% vaterite, or at least 60 wt% vaterite, or at least 70 wt% vaterite, or at least 80 wt% vaterite, or at least 90 wt% vaterite, or at least 95 wt% vaterite, or at least 99 wt% vaterite, or 10 Vaterite of wt% to 99 wt%, or vaterite of 10 wt% to 90 wt%, or vaterite of 10 wt% to 80 wt%, or vaterite of 10 wt% to 70 wt%, or vaterite of 10 wt% to 60 wt%, or vaterite of 10 wt% to 50 wt%, or vaterite of 10 wt% to 40 wt%, or vaterite of 10 wt% to 30 wt%, or vaterite of 10 wt% to 20 wt%, or vaterite of 20 wt% to 99 wt%, or vaterite of 20 wt% to 95 wt%, or vaterite of 20 wt% to 90 wt%, or 20wt%~75wt% vaterite, or 20wt%~50wt% vaterite, or 30wt%~99wt% vaterite, or 30wt%~95wt% vaterite, or 30wt%~90wt% vaterite, or 30wt%~75wt% vaterite, or 30wt%~50wt% vaterite, or 40wt%~99wt% vaterite, or 40wt%~95wt% vaterite, or 40wt%~90wt% vaterite, or 40wt%~75wt% vaterite, or 50wt%~99wt% vaterite, or 50wt%~95wt% vaterite, or 50wt%~90wt% vaterite, or 50wt%~75wt% vaterite, or 60wt%~99wt% vaterite, or 60wt%~95wt% vaterite, or 60wt%~90wt% vaterite, or 70wt%~99wt% vaterite, or 70wt%~95wt% vaterite, or 70wt%~90wt% vaterite, or 80wt%~99wt% vaterite, or 80wt%~95wt% vaterite,Or it includes 90 wt% to 99 wt% vaterite, or 10 wt% vaterite, or 20 wt% vaterite, or 30 wt% vaterite, or 40 wt% vaterite, or 50 wt% vaterite, or 60 wt% vaterite, or 70 wt% vaterite, or 75 wt% vaterite, or 80 wt% vaterite, or 85 wt% vaterite, or 90 wt% vaterite, or 95 wt% vaterite, or 99 wt% vaterite.

[0265] In the aforementioned aspects and some embodiments, the composition contains, in some embodiments, magnesium oxide between approximately 10 and 70 wt%, or between approximately 10 and 60 wt%, or between approximately 10 and 50 wt%, or between approximately 10 and 45 wt%, or between approximately 10 and 40 wt%, or between approximately 10 and 35 wt%, or between approximately 10 and 30 wt%, or between approximately 10 and 25 wt%, or between approximately 10 and 20 wt%, or between approximately 10 and 15 wt%. , or containing magnesium oxide in amounts between approximately 20-70 wt%, or between approximately 20-60 wt%, or between approximately 20-50 wt%, or between approximately 20-40 wt%, or between approximately 20-30 wt%, or between approximately 20-25 wt%, or between approximately 30-70 wt%, or between approximately 30-60 wt%, or between approximately 30-50 wt%, or between approximately 30-40 wt%, or between approximately 40-70 wt%, or between approximately 40-60 wt%, or between approximately 40-50 wt%.

[0266] In the aforementioned aspects and some embodiments of the embodiments, the composition comprises vaterite in an amount of about 30 to 99 wt% and magnesium oxide in an amount of about 1 to 70 wt%, or vaterite in an amount of about 50 to 90 wt% and magnesium oxide in an amount of about 10 to 50 wt%, or vaterite in an amount of about 60 to 90 wt% and magnesium oxide in an amount of about 10 to 40 wt%, or vaterite in an amount of about 70 to 90 wt% and magnesium oxide in an amount of about 10 to 30 wt%, or vaterite in an amount of about 80 to 99 wt% and magnesium oxide in an amount of about 1 to 20 wt%.

[0267] In some embodiments, the composition comprising vaterite and magnesium oxide is a particulate composition having an average particle size between approximately 0.1 and 100 microns. The average particle size (or average particle diameter) can be determined using any conventional particle size determination method, for example, multi-detector laser scattering or laser diffraction or sieving, but not limited to these. In certain embodiments, unimodel or multimodal distributions exist, such as bimodal or other distributions. A bimodal distribution can provide smaller reactive particles for the initial reaction while minimizing surface area and thus allowing for a lower liquid / solid mass ratio when the composition is mixed with water. In some embodiments, the composition or precipitate provided herein, comprising vaterite and magnesium oxide, is 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 This is a particulate composition having an average particle size of 20-50 microns, or 20-30 microns, or 30-50 microns, or 40-50 microns, or 50-100 microns, or 50-60 microns, or 60-100 microns, or 60-70 microns, or 70-100 microns, or 70-80 microns, or 80-100 microns, or 80-90 microns, or 0.1 microns, or 0.5 microns, 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.For example, in some embodiments, the composition comprising vaterite and magnesium oxide provided herein is a particulate composition having an average particle size of 0.1 to 20 microns, or 0.1 to 15 microns, or 0.1 to 10 microns, or 0.1 to 8 microns, or 0.1 to 5 microns, or 1 to 25 microns, or 1 to 20 microns, or 1 to 15 microns, or 1 to 10 microns, or 1 to 5 microns, or 5 to 20 microns, or 5 to 10 microns. In some embodiments, the composition comprising vaterite and magnesium oxide contains two or more, or three or more, or four or more, or five or more, or ten or more, or twenty or more, or three to twenty, or four to ten particles of different sizes in the composition or precipitate. For example, a composition may contain two or more, three or more, or between three and twenty particles with particle sizes 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 sizes. In some embodiments, a composition may have an average particle size of less than 0.1 microns, or submicron, or between 0.001 microns and 1 micron or greater.

[0268] In some embodiments, the composition comprising vaterite and magnesium oxide may further comprise OPC or Portland cement clinker. The amount of Portland cement components may vary, such as 10-95 wt%, or 10-90 wt%, or 10-80 wt%, or 10-70 wt%, or 10-60 wt%, or 10-50 wt%, or 10-40 wt%, or 10-30 wt%, or 10-20 wt%, or 20-90 wt%, or 20-80 wt%, or 20-70 wt%, or 20-60 wt%, or 20-50 wt%, or 20-40 wt%, or 20-30 wt%, or 30-90 wt%, or 30- It may also be in the range of 80 wt%, or 30-70 wt%, or 30-60 wt%, or 30-50 wt%, or 30-40 wt%, or 40-90 wt%, or 40-80 wt%, or 40-70 wt%, or 40-60 wt%, or 40-50 wt%, or 50-90 wt%, or 50-80 wt%, or 50-70 wt%, or 50-60 wt%, or 60-90 wt%, or 60-80 wt%, or 60-70 wt%, or 70-90 wt%, or 70-80 wt%. For example, a composition containing vaterite and magnesium oxide may include blends of a 75% OPC and 25% composition, or an 80% OPC and 20% composition, or an 85% OPC and 15% composition, or a 90% OPC and 10% composition, or a 95% OPC and 5% composition.

[0269] In certain embodiments, a composition containing vaterite and magnesium oxide may further contain aggregate. Aggregate may be included in the composition or precipitate to provide mortar containing fine aggregate and concrete also containing coarse aggregate. Fine aggregate is material that passes almost entirely through a No. 4 sieve (ASTM C125 and ASTM C33), such as silica sand. Coarse aggregate is material that is mainly held in place by a No. 4 sieve (ASTM C125 and ASTM C33), such as silica, quartz, crushed round marble, glass spheres, granite, lime, calcite, feldspar, alluvial sand, sand or any other durable aggregate, and mixtures thereof. Therefore, aggregate is used broadly to refer to several different kinds of fine and coarse particulate materials, including, but not limited to, sand, gravel, crushed stone, slag, and recycled concrete. The quantity and properties of aggregate can vary widely. In some embodiments, the amount of aggregate may range from 25 to 80 wt%, for example, 40 to 70 wt%, and 50 to 70 wt%, of the total composition produced from both the composition and the aggregate.

[0270] In some embodiments, a composition comprising vaterite and magnesium oxide in wet or dry form further includes, but is not limited to, one or more admixtures to impart one or more properties to the product, including strength, flexural strength, compressive strength, porosity, and thermal conductivity. The amount of admixture used may vary depending on the properties of the admixture. In some embodiments, the amount of one or more admixtures is in the range of 0.01 to 50 wt%, for example, 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, or 2 to 10 wt%. Examples of admixtures include, but are not limited to, setting accelerators, setting retarders, air entrainers, 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-correcting admixtures, fungicidal admixtures, bactericidal admixtures, insecticidal admixtures, rheological modifiers, finely ground mineral admixtures, pozzolanes, aggregates, wetting agents, strength enhancers, water repellents, reinforcing materials such as fibers, and any other admixtures. When admixtures are used, the composition or precipitate into which the admixture material is introduced is mixed for a sufficient amount of time to relatively uniformly disperse the admixture material in the composition.

[0271] Setting accelerators can be used to accelerate the setting and initial strength growth of cement. Examples of setting accelerators that can be used include, but are not limited to, the non-chloride type setting accelerator POZZOLITH® NC534 and / or the calcium nitrite-based corrosion inhibitor RHEOCRETE® CNI. Setting retarding admixtures, also known as delayed setting or hydration control admixtures, are used to slow, delay, or slow the setting rate of cement. Most setting retarders can act as low-level water-reducing agents and can also be used to entrain some air into the product. An example of a retarder is DELVO®. Air entrainers include any substance that entrains air into a composition. Some air entrainers can also reduce the surface tension of a composition at low concentrations. Air entraining admixtures are used to intentionally entrain microscopic air bubbles into cement. Air entrainment can increase the workability of the mix while simultaneously eliminating or reducing separation and bleeding. The 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, nonionic surfactants, natural rosin, synthetic rosin, inorganic air entrainers, synthetic detergents, and their corresponding salts, as well as mixtures thereof. Air entrainers are added in amounts that bring the desired level of air into the cement composition. Examples of air entrainers that can be used in admixture systems, but are not limited to, MB AE90, MB VR, and MICRO AIR®, all of which are available from BASF Admixtures Inc. in Cleveland, Ohio.

[0272] In some embodiments, the composition containing vaterite and magnesium oxide further includes a foaming agent. The foaming agent incorporates a large amount of bubbles / porosity, promoting a reduction in material density. Examples of foaming agents, but not limited to, include soap, detergents (alkyl ether sulfates), millifoam® (alkyl ether sulfate), cedepal® (ammonium alkyl ethoxy sulfate), and witcolate® 12760.

[0273] In some embodiments, compositions containing vaterite and magnesium oxide further include an antifoaming agent. The antifoaming agent is used to reduce the air content in the cement composition. Dispersants are also covered as admixtures. Dispersants include, but are not limited to, polycarboxylate dispersants containing or not containing polyether units. The term dispersant also means chemicals that also function as plasticizers, water-reducing agents, e.g., high-range water-reducing agents, fluidizers, anti-coagulants, or superplasticizers for the composition, e.g., lignin sulfonates, salts of sulfonated naphthalene sulfonate condensates, salts of sulfonated melamine sulfonate condensates, beta-naphthalene sulfonates, sulfonated melamine formaldehyde condensates, naphthalene sulfonate formaldehyde condensate resins, e.g., LOMAR D® dispersant (Cognis Inc., Cincinnati, Ohio), polyaspartic acid, or oligomeric dispersants. Polycarboxylate dispersants can be used, which means dispersants having a carbon skeleton including pendant side chains, where at least a portion of the side chains is bonded to the skeleton via carboxyl or ether groups.

[0274] Natural and synthetic admixtures can be used to color products for aesthetic and safety reasons. These coloring admixtures may consist of pigments, including carbon black, iron oxide, phthalocyanine, amber, chromium oxide, titanium dioxide, cobalt blue, and organic colorants. Corrosion inhibitors are also considered admixtures. Corrosion inhibitors can work to protect embedded rebar from corrosion. Materials commonly used to inhibit corrosion include calcium nitrite, sodium nitrite, sodium benzoate, certain phosphates or fluorosilicates, aluminite, amines, and related chemicals. Moisture-proof admixtures are also considered. Moisture-proof admixtures are, These admixtures reduce the permeability of products with low cement content, high water-cement ratio, or fine aggregate deficiencies. These admixtures slow down the penetration of moisture into the dry product and include certain soaps, stearates, and petroleum products. Gas-forming admixtures are also included. Gas-forming agents, i.e., gas-forming agents, are sometimes added to the mix to cause slight expansion before hardening. The amount of expansion depends on the amount of gas-forming material used and the temperature of the new admixture. Aluminum powder, resin soaps, and vegetable or animal glues, saponins, or hydrolyzed proteins can be used as gas-forming agents. Permeability-reducing agents are also included. Permeability-reducing agents can reduce the rate at which water travels through the mix under pressure. Silica fume, fly ash, ground slag, natural pozzolanes, water-reducing agents, and latex can be used to reduce the permeability of the mix.

[0275] In some embodiments, a composition containing vaterite and magnesium oxide further includes a rheological modifier admixture. The rheological modifier can be used to increase the viscosity of the composition. Suitable examples of rheological modifiers include hardened silica, colloidal silica, hydroxyethylcellulose, starch, hydroxypropylcellulose, fly ash (as defined in ASTM C618), mineral oils (e.g., light naphthenes), clays, such as hectorite clay, polyoxyalkylenes, polysaccharides, natural gums, or mixtures thereof. Some mineral extenders, for example, but not limited to meersal clay, are rheological modifiers.

[0276] In some embodiments, compositions containing vaterite and magnesium oxide further include shrinkage-correcting admixtures. TETRAGUARD® is an example of a shrinkage-reducing admixture. Bacterial and fungal growth on or within the surface of cured products can be partially controlled by the use of antifungal and antibacterial admixtures. Materials intended for these purposes include, but are not limited to, polyhalogenated phenols, dieldrin emulsions, and copper compounds. In some embodiments, processability-improving admixtures are also included. Entrained air can be used as a lubricant and processability-improving agent. Other processants include water-reducing agents and certain fine-grit admixtures.

[0277] In some embodiments, the composition comprising vaterite and magnesium oxide further comprises, for example, fibers, if a reinforcing material, such as a fiber-reinforced product, is desired. The fibers can be made from zirconia-containing materials, aluminum, glass, steel, carbon, ceramics, grass, bamboo, wood, glass fibers, or synthetic materials, such as polypropylene, polycarbonate, polyvinyl chloride, polyvinyl alcohol, nylon, polyethylene, polyester, rayon, high-strength aramid (e.g., Kevlar®), or mixtures thereof. The reinforcing material is described in U.S. Patent Application No. 13 / 560,246, filed July 27, 2012, which is incorporated herein by reference in its entirety.

[0278] In some embodiments, the compositions provided herein, though not limited to, further include one or more additional components, including blast furnace slag, fly ash, diatomaceous earth, and other natural or artificial pozzolanes, silica fume, limestone, gypsum, slaked lime, air-entraining agents, retarders, waterproofing agents, and colorants. These components may be added to modify cement properties, for example, to achieve a desired strength or to provide a desired setting time. The amounts of such components present in the composition may vary, and in certain embodiments, the amounts of these components range from 0.01 to 50 wt%, or 10 to 50 wt%, for example, 2 to 10 wt%.

[0279] In some embodiments, the compositions provided herein further comprise an auxiliary cement material (SCM). In some embodiments, the SCM is slag, fly ash, silica fume, or calcined clay.

[0280] The components of the composition can be combined using any suitable protocol. Each material can be mixed during the process, or some or all of the materials can be mixed in advance. Alternatively, some of the materials can be mixed with water, with or without an admixture, such as a high-range water-reducing admixture, and then mixed with the remaining materials. Any conventional mixing apparatus can be used. For example, Hobart mixers, slant cylinder mixers, Omni mixers, Henschel mixers, V-type mixers, and Nauta mixers can be used. III.Product

[0281] This specification provides methods and systems for forming cement and / or non-cementary products using compositions comprising vaterite and magnesium oxide formed from the calcination of limestone containing magnesium-supported minerals and / or limestone mixed with magnesium-supported minerals. This specification also provides environmentally friendly methods and systems for removing or separating CO2 from waste gas streams derived from limestone calcination and fixing the CO2 in a storage-stable non-gasic form (e.g., building materials for structures such as buildings and infrastructure, as well as the structures themselves or formed building materials, e.g., drywall, or non-cementary materials, e.g., paper, paint, plastic, or artificial reefs), thus preventing the CO2 from escaping into the atmosphere.

[0282] Products produced by the methods described herein may be aggregates or building materials or precast or formed building materials. In some embodiments, products produced by the methods described herein include non-cement materials, such as paper, paint, and PVC. In some embodiments, products produced by the methods described herein include artificial reefs. These products are described herein.

[0283] In one embodiment, a cement or non-cementary product comprising aragonite and / or calcite and magnesium hydroxide is provided. In some embodiments, the aragonite is in the form of a needle-like network structure. In some embodiments, magnesium hydroxide binds the aragonite and / or calcite together. In some embodiments, but not limited to, magnesium hydroxide imparts unique characteristics to aragonite cement and / or calcite cement, including filling the voids between the aragonite and / or calcite to increase density and reduce porosity, stabilizing the aragonite and preventing conversion from aragonite to calcite, binding the needle-like aragonite together to enhance its strength and durability, binding the calcite together to enhance its strength and durability, and imparting a pH greater than 10 to the product, thereby preventing any steel corrosion of reinforcing steel in cement structures.

[0284] In some embodiments, the porosity of the product is between approximately 0 and 95%, or between approximately 0 and 90%, or between approximately 0 and 80%, or between approximately 0 and 70%, or between approximately 0 and 60%, or between approximately 0 and 50%, or between approximately 0 and 40%, or between approximately 0 and 30%, or between approximately 0 and 20%, or between approximately 0 and 10%, or between approximately 10 and 95%, or between approximately 10 and 80%, or between approximately 10 and 70%, or between approximately 10 and 60%, or between approximately 10 and 50%, or between approximately 10 and 40%, or between approximately 10 and 30%. , or between approximately 10-20%, or between approximately 20-95%, or between approximately 20-80%, or between approximately 20-70%, or between approximately 20-60%, or between approximately 20-50%, or between approximately 20-40%, or between approximately 20-30%, or between approximately 30-95%, or between approximately 30-80%, or between approximately 30-70%, or between approximately 30-60%, or between approximately 30-50%, or between approximately 30-40%, or between approximately 50-95%, or between approximately 70-80%, or between approximately 40-70%. In some embodiments, the amount of magnesium oxide can be optimized in a composition containing vaterite, and thus the porosity of the product formed from the composition can be optimized (after the vaterite is converted to aragonite and / or calcite, and the magnesium oxide is converted to magnesium hydroxide).

[0285] Compositions comprising vaterite and magnesium oxide can be formed by mixing a vaterite-containing composition with magnesium oxide, without being limited by the methods and systems provided herein, where magnesium oxide is added to the composition as an additive. In some embodiments, magnesium oxide can be added to replenish magnesium oxide already present in the composition.

[0286] Products derived from the compositions or precipitates provided herein exhibit one or more properties such as high compressive strength, high durability, high porosity (lightweight), high flexural strength, and lower maintenance costs. In some embodiments, compositions comprising vaterite and magnesium oxide, which condense and harden when combined with water, have a compressive strength of at least 0.05 MPa (megapascals), at least 3 MPa, or at least 7 MPa, or at least 10 MPa, or in some embodiments, between 0.05 and 30 MPa, or between 3 and 30 MPa, or between 14 and 80 MPa, or between 14 and 35 MPa.

[0287] In the embodiments described above and in some embodiments of the embodiments described above, a composition comprising vaterite and magnesium oxide that condenses and hardens after being combined with water (i.e., vaterite is converted to aragonite and / or calcite, and magnesium oxide is converted to magnesium hydroxide) is available at a pressure of at least 0.05 MPa, 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 0.05 to 50 MPa, or 3 to 50 MPa, or 3-25 MPa, or 3-15 MPa, or 3-10 MPa, or 14-25 MPa, or 14-100 MPa, or 14-80 MPa, or 14-75 MPa, or 14-50 MPa, or 14-25 MPa, or 17-35 MPa, or 17-25 MPa, or 20-100 MPa, or 20-75 MPa, or 20-50 MPa, or 20-40 MPa, or 30-90 MPa, or 30-75 MPa, or 30-60 MPa, or 40-90 MPa, or 40-75 It has a compressive strength of MPa, or 50-90 MPa, or 50-75 MPa, or 60-90 MPa, or 60-75 MPa, or 70-90 MPa, or 70-80 MPa, or 70-75 MPa, or 80-100 MPa, or 90-100 MPa, or 90-95 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 the embodiments described above and in some embodiments of the embodiments described above, the composition after setting 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 1 day, or 3 days, or 7 days, or 28 days, or 56 days, or longer. building materials

[0288] As used herein, “building materials” includes materials used in construction. In one embodiment, a structure or building material is provided, comprising a solidified and hardened form of a composition containing vaterite and magnesium oxide, where vaterite is converted to aragonite and / or calcite and magnesium oxide is converted to magnesium hydroxide, which then solidifies and hardens. In one embodiment, a structure or building material is provided comprising aragonite and / or calcite and magnesium hydroxide. Products containing the aragonite and / or calcite and magnesium hydroxide forms (products (A) or (B) in Figures 1-3) exhibit one or more unexpected properties, including, but not limited to, high compressive strength, high porosity (low density or light weight), neutral pH (useful as, for example, artificial reefs), and a fine network structure.

[0289] Examples of such structures or building materials include, but are not limited to, concrete, aggregates, buildings, driveways, foundations, kitchen slabs, furniture, sidewalks, roads, bridges, highways, overpasses, parking structures, bricks, blocks, scaffolding for walls and gates, fences or poles, and combinations thereof. Formed building materials

[0290] As used herein, “formed building materials” include materials that have been formed into structures having a defined physical shape (e.g., molded, cast, cut, or otherwise produced). Formed building materials may also be pre-cast building materials, such as pre-cast cement or concrete products. Formed building materials and methods for producing and using formed building materials are described in U.S. Patent Application No. 12 / 571,398, filed September 30, 2009, which is incorporated herein by reference in its entirety. Formed building materials can vary considerably and include materials that have been formed into structures having a defined physical shape, i.e., a three-dimensional arrangement (e.g., molded, cast, cut, or otherwise produced). Formed building materials do not have a defined stable shape and are rather different from amorphous building materials (e.g., powders, pastes, slurries, etc.) that fit into a container, such as a bag or other container, in which they are held. Formed building materials differ from irregularly or imprecisely formed materials (e.g., discarded aggregates, bulk forms, etc.) in that the formed building materials are produced according to specifications that enable the use of the formed building materials in, for example, buildings. Formed building materials can be prepared according to conventional manufacturing protocols for such structures, except that the compositions provided herein are used in the production of such materials.

[0291] In some embodiments, the methods and systems provided herein further include the step of setting and curing a composition comprising vaterite and magnesium oxide, where the vaterite is converted to aragonite and / or calcite and the magnesium oxide is converted to magnesium hydroxide, which then sets and cures to form a constructed building material. In one embodiment, a constructed building material comprising aragonite and / or calcite and magnesium hydroxide is provided.

[0292] In some embodiments, a formed building material made from a composition comprising vaterite and magnesium oxide has a compressive or flexural strength of at least 0.05 MPa, 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 the compressive strength of the composition after setting and curing as described herein.

[0293] Examples of formed building materials that can be produced by the methods and systems described herein include, but are not limited to, masonry units, bricks, blocks, and tiles, including ceiling tiles, as merely examples; building panels, as merely examples, cement boards (boards conventionally made from cement, e.g., fiber cement boards) and / or drywalls (boards conventionally made from gypsum); conduits; basins; beams; columns, slabs; sound barriers; thermal 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 by having length and width substantially greater than thickness. Thus, panels may be plates, boards, roofing boards, and / or tiles. Exemplary building panels formed from precipitated materials provided herein include cement boards and / or drywalls. Building panels are polygonal structures having dimensions that vary considerably depending on their intended use. The dimensions of the building panels can range from 100 to 300 cm in length, for example, 50 to 500 cm including 250 cm; from 75 to 150 cm in width, for example, 25 to 200 cm including 100 cm; and from 7 to 20 mm in thickness, for example, 5 to 25 mm including 10 to 15 mm.

[0294] In some embodiments, cement boards and / or drywalls can be used in the manufacture of different types of boards, for example, but not limited to, paper-clad boards (e.g., surface-reinforced with cellulose fibers), fiberglass-clad or fiberglass mat-clad boards (e.g., surface-reinforced with fiberglass mats), fiberglass mesh-reinforced boards (e.g., surface-reinforced with fiberglass mesh), and / or fiber-reinforced boards (e.g., cement-reinforced with cellulose, glass, fibers, etc.). These boards can be used in a variety of applications, but not limited to, paneling, e.g., fiber-cement paneling, roofing, underlayment, sheathing, cladding, decking, ceilings, shaft liners, wall boards, backers, trim, frieze, roofing panels, and fascia, as well as / or underlayment.

[0295] The cement boards produced by the methods and systems provided herein are made from compositions comprising vaterite and magnesium oxide that partially or completely replace conventional cement in the board. In some embodiments, the cement boards may include building panels prepared as a combination of aragonite cement and magnesium hydroxide cement, or a combination of calcite cement and magnesium hydroxide cement with fibers and / or glass fibers, and both sides of the board may be reinforced with additional fibers and / or glass fibers.

[0296] Cement board is a formed building material used as a backerboard for ceramics, which can be used in some embodiments as a backing board for bathroom tiles, kitchen counters, backsplashes, etc., and can have lengths ranging from 100 to 200 cm. The physical and mechanical properties of cement board can vary. In some embodiments, the flexural strength can vary in the range between 1 and 7.5 MPa, including 2 to 6 MPa, e.g., 5 MPa. The compressive strength can also vary in the range between 5 and 50 MPa, including 10 to 30 MPa, e.g., 15 to 20 MPa. In some embodiments, cement board can be used in environments that are extensively exposed to moisture (e.g., commercial saunas). The compositions or precipitates described herein can be used to produce the desired shapes and sizes for forming cement board. Furthermore, various additional components, including, but not limited to, plasticizers, clays, foaming agents, accelerators, retarders, and air-entraining additives, can be added to the cement board. The composition can then be poured into a sheet mold or used with a roller to form sheets of the desired thickness. The molded composition can be further compressed by roller compression, hydraulic pressure, vibration compression, or resonant shock compression. The sheet is then cut into cement boards of the desired dimensions.

[0297] Another type of building panel formed from the compositions described herein is backerboard. Backerboard can be used for the construction of interior and / or exterior floors, walls, and ceilings. In some embodiments, backerboard is made partially or completely from a composition comprising vaterite and magnesium oxide.

[0298] Another type of building panel formed from this composition is drywall. Drywall includes boards used for the construction of interior and / or exterior floors, walls, and ceilings. Traditionally, drywall is formed from gypsum (called paper-backed board). In some embodiments, drywall is partially or completely made from a composition containing vaterite and magnesium oxide, thereby replacing gypsum in drywall products. In some embodiments, drywall may include building panels prepared as a combination of aragonite cement and / or calcite cement and magnesium hydroxide cement with cellulose, fibers, and / or glass fibers, and both sides of the board may be reinforced with additional paper, fibers, glass fiber mesh, and / or glass fiber mats. Various processes for producing drywall products are well known in the art and are well within the scope of the present invention. Some examples, but not limited to, include wet processes, semi-dry processes, extrusion processes, and wonderboard® processes, which are described herein.

[0299] 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 composition containing vaterite and magnesium oxide, a slurry of the composition containing vaterite and magnesium oxide is poured onto paper. Another sheet of paper is then placed on top of the composition, so that the composition has paper on both sides (the resulting composition is sandwiched between two outer materials, e.g., cardboard or fiberglass mat). The vaterite in the composition is then converted to aragonite and / or calcite, and the magnesium oxide is converted to magnesium hydroxide (using heat if necessary), and then it sets and hardens. Once the core has set and is dried in a large drying chamber, the sandwich panel becomes rigid and strong enough to be used as a building material. The drywall sheets are then cut and separated.

[0300] The flexural and compressive strengths of drywalls formed from compositions containing vaterite and magnesium oxide are the same as, or higher than, those of conventional drywalls prepared using gypsum plaster, which is known to be a flexible building material. In some embodiments, the flexural strength may be in the range of 0.1 to 3 MPa, including 0.5 to 2 MPa, e.g., 1.5 MPa. The compressive strength may also vary, in some cases being in the range of 1 to 20 MPa, including 5 to 15 MPa, e.g., 8 to 10 MPa. In some embodiments, formed building materials, e.g., building panels, e.g., cement boards and drywalls, produced by the methods and systems described herein, are low-density and highly porous, thereby making them suitable for lightweight insulation applications. The highly porous and lightweight formed building materials, e.g., building panels, may be due to the creation of a microstructure of aragonite and / or calcite when vaterite is converted to aragonite and / or calcite, and the filling of the voids between the aragonite and / or calcite with magnesium hydroxide. The transformation of vaterite during the dissolution / reprecipitation process can result in microporosity, and the voids created between the formed aragonite crystals and / or calcite can be filled with magnesium hydroxide to provide strength and a lightweight structure. During the transformation process, but not limited to, foaming agents, rheological modifiers, and mineral extenders, such as certain admixtures including, but not limited to, clay and starch, can be added, thereby adding porosity to the product and reducing the overall density, as foaming agents can entrain air into the mixture, and mineral extenders such as sepiolite clay can increase the viscosity of the mixture, thereby preventing the separation of the composition from water.

[0301] One application of cement board or drywall is fiber cement paneling. Fiber cement paneling formed by the methods and systems provided herein includes building panels prepared as a combination of aragonite cement and / or calcite cement, aggregate, woven cellulose, and / or polymer fibers, which can have a wood-like texture and flexibility.

[0302] In some embodiments, the formed building material is a masonry unit. A masonry unit is a formed building material used in the construction of load-bearing and non-load-bearing structures, generally assembled using mortar, grout, etc. Exemplary masonry units formed from this composition include bricks, blocks, and tiles.

[0303] Another formed building material formed from the compositions described herein is a conduit. A conduit is a pipe or similar structure configured to transport a gas or liquid from one place to another. A conduit may include, but is not limited to, any of many different structures used for transporting liquids or gases, including pipes, culverts, box culverts, drainage channels and portals, inlet structures, intake towers, gate wells, outlet structures, and the like.

[0304] Another formed building material formed from the compositions described herein is a water basin. The term water basin may include any container of any configuration used to hold a liquid, such as water. Thus, water basins may include, but are not limited to, structures such as wells, collection boxes, public health manholes, septic tanks, catch basins, grease traps / separators, and rainwater collection and storage tanks.

[0305] Another formed building material formed from the compositions described herein is a beam, which in a broad sense refers to a horizontal load-bearing structure having high bending and compressive strength. The beam may be a square cross type, C channel type, L-shaped cross section edge beam, I-beam, spandrel beam, H-beam, and may have an inverted T design. The beam may also be a horizontal load-bearing unit including, but is not limited to, joists, lintels, arch channels and cantilever beams.

[0306] Another formed building material formed from the compositions described herein is a column, which in a broad sense refers to a vertical load-bearing structure that primarily withstands loads due to 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, supports, piers, pedestals, or piles.

[0307] Another formed building material formed from the compositions described herein is a concrete slab. Concrete slabs are building materials used in the construction of prefabricated foundations, floors, and wall panels. In some cases, concrete slabs can be used as floor units (e.g., hollow slab units or double-T designs).

[0308] Another formed building material formed from the compositions described herein 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, absorbing barriers, and reactive barriers.

[0309] Another formed building material formed from the compositions described herein is an insulating material, which refers to a material used to reduce or suppress heat conduction. Insulating materials may also include materials that reduce or suppress radiative heat transfer.

[0310] In some embodiments, other formed building materials, such as precast concrete products, are not limited to bunker silos, livestock feed troughs, cattle grids, agricultural fences, H-shaped latticework, J-shaped latticework, livestock slats, livestock water tanks, building panel walls, cladding (bricks), building trim, foundations, floors including slabs, walls, precast sandwich panels for double walls, waterways, mechanically stabilized earth panels, box culverts, three-sided culverts, bridge systems, railroad crossings (RR crossings), railroad ties (RR ties), sound barriers / walls, and Jersey bars. Rear, tunnel segments, reinforced concrete boxes, utility protection structures, handholes, hollow core products, lighting pole bases, meter boxes, panel vaults, pull boxes, telecommunications structures, transformer pads, transformer rooms, trenches, utility vaults, utility poles, control environment rooms, bunkers, mausoleums, tombstones, coffins, hazardous materials storage containers, detention vaults, drainage pits, manholes, ventilation systems, distribution boxes, dozing tanks, drywells, grease traps, leachate pits, sand-oil / oil-water separators, septic tanks, water / sewage storage tanks, wetwells, fire cisterns, floating docks, underwater infrastructure, decks, railings, breakwaters, roof tiles, paving stones, and local use. Retaining walls, residential retaining walls, modular block systems, and reinforced (segmental) retaining walls It is included. Non-cement composition

[0311] In some embodiments, the methods and systems described herein include, but are not limited to, the steps of preparing other products from the compositions described herein, including non-cement compositions, such as paper, polymer products, lubricants, adhesives, rubber products, chalk, asphalt products, paints, abrasives for paint removal, personal care products, cosmetics, cleaning products, personal hygiene products, edible products, agricultural products, soil conditioners, biocides, environmental remediation products, and combinations thereof. Such compositions are described in U.S. Patent No. 7,829,053 issued November 9, 2010, which is incorporated herein by reference in its entirety. artificial marine structures

[0312] In some embodiments, the methods described herein, though not limited to them, include the step of preparing artificial marine structures, including artificial corals and reefs, from the compositions described herein. In some embodiments, the artificial structures can be used in aquariums or in the ocean. In some embodiments, these products are prepared from compositions comprising vaterite and magnesium oxide, which convert to aragonite and / or calcite and magnesium hydroxide after setting and hardening. Aragonite cement and / or calcite cement can provide a neutral or near-neutral pH that can lead to the maintenance and growth of marine organisms. Aragonite reefs can provide a suitable habitat for marine species.

[0313] Throughout this description, when a composition is described as having, including, or comprising, certain components, or when a process and method is described as having, including, or comprising, certain steps, it is intended that there exist compositions of the present invention that are essentially composed of or consist of the described components, and that there exist processes and methods of the present invention that are essentially composed of or consist of the described processing steps.

[0314] In this application, when an element or component is said to be included in and / or selected from the list of elements or components described, it should be understood that the element or component may be any one of the elements or components described, or it may be selected from a group consisting of two or more of the elements or components described.

[0315] Furthermore, it should be understood that the elements and / or features of the compositions or methods described herein, whether express or implied herein, can be combined in various ways without departing from the spirit and scope of the invention. For example, where a particular composition is referred to, that composition can be used in various embodiments of the compositions of the invention and / or in the methods of the invention unless otherwise understood from the context. In other words, while embodiments in this application are described and shown in a manner that allows for clear and concise application to be written and depicted, it is intended and intended that embodiments may be combined or separated in various ways without being destined from the teachings and the invention. For example, it should be recognized that all features described and shown herein may be applicable to all aspects of the invention described and shown herein.

[0316] Where a range of values ​​is provided, unless otherwise explicitly stated by the circumstances, each value up to one-tenth of the lower limit that lies between the upper and lower limits of that range, and any other described or intervening values ​​within that described range, are understood to be included in the present invention. The upper and lower limits of these smaller ranges may independently be included within those smaller ranges, and these are also included in the present invention, provided that any boundaries in the described range are specifically excluded. Where the described range includes one or both of the boundaries, the range excluding one or both of those included boundaries is also included in the present invention.

[0317] The use of the terms “include,” “includes,” “including,” “have,” “has,” “having,” “contain,” “contains,” or “containing,” including their grammatical equivalents, should be understood to be generally unrestricted and non-restrictive, and not to exclude any further elements or steps not mentioned, for example, unless otherwise specifically stated or understood from the context.

[0318] In this specification, certain ranges are presented with the term “approximately” preceding the numerical value. The term “approximately” is used in this specification to provide lettering to the exact number that follows, and to numbers that are close to or approximate the number that follows. Where used herein, the term “approximately” refers to a variation of ±10% from the nominal value, unless otherwise specified or inferred.

[0319] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention pertains. Any methods and materials similar to or equivalent to those described herein may be used in the practice or testing of the present invention, but representative exemplary methods and materials are described herein.

[0320] All publications, patents, and patent applications referenced herein are incorporated by reference as if each individual publication, patent, or patent application were specifically indicated to be incorporated by reference. Furthermore, each cited publication, patent, or patent application is incorporated by reference to disclose and describe the subject matter of which the publication is cited. Any citation of a publication is intended to disclose them prior to the filing date and should not be construed as an acknowledgment that the invention described herein does not have prior rights to such publication with respect to prior patents. Furthermore, the publication dates provided may differ from the actual publication dates and may need to be independently verified.

[0321] The phrase "at least one of" should be understood, unless otherwise understood from context and usage, to include each of the objects listed after it, and various combinations of two or more of the listed objects.

[0322] Where used herein and in the appended claims, the singular forms "a," "an," and "the" should be noted to include multiple references unless otherwise indicated by the context. Furthermore, it should be noted that claims may be written to exclude any element as necessary. Thus, this singular form is intended to function as an antecedent for the use of exclusive terms such as "solely" and "only," or for the use of "negative" limitation, relating to the enumeration of elements of the claims.

[0323] As will become apparent to those skilled in the art as they read this disclosure, each of the individual embodiments described and shown herein has distinct components and features that can be readily separated or combined with features of any of several other embodiments without departing from the scope or spirit of this disclosure. Any method described may be carried out in the order of events described, or in any other order that is theoretically possible. It should be understood that the order of steps or the order in which certain operations are performed is not important as long as the invention remains operable. Furthermore, two or more steps or operations may be carried out simultaneously.

[0324] The following examples are provided to give a complete disclosure and explanation of how the present invention is made and used, and are not intended to limit the scope of what the inventors consider to be the present invention, nor to indicate that the following experiments are all or only experiments performed. While efforts have been made to ensure accuracy with respect to the numerical values ​​used (e.g., quantities, temperatures, etc.), some experimental error and deviation should be taken into consideration. [Examples]

[0325] (Example 1) Formation and conversion of vaterite and magnesium oxide NH4Cl was dissolved in water. Lime containing magnesium oxide was added to the aqueous solution and mixed in a container at 30°C. The precipitation reactor was an acrylic cylinder equipped with baffles, a pH electrode, a thermocouple, a turbine impeller, and inlet and outlet ports for the liquid feed and product slurry. During startup, a solution containing CaCl2 was pumped into the reactor, and a 4:1 N2:CO2 gas mixture was sparged into the reactor until the desired pH was reached. After the desired pH was reached, a solution containing CaCl2 was pumped into the reactor at a fixed flow rate. The mixture was continuously stirred. A slurry of vaterite and magnesium oxide was formed and removed from the top of the reactor. The obtained vaterite and magnesium oxide slurry was continuously collected in a holding container. The collected slurry was periodically vacuum filtered. The filtered vaterite and magnesium oxide cake was oven-dried at 100°C. X-ray diffraction revealed the cake to be 74% vaterite, 1% calcite, and 25% periclase, with a median particle size of 13.1 microns. The clear filtrate containing the regenerated NH4Cl was reused in subsequent experiments.

[0326] Dried vaterite and magnesium oxide powder were mixed with water to form a paste. The paste was cured at 80°C and 98% relative humidity. After 1 day, the hardened paste was removed from the curing environment and dried at 100°C. XRD analysis of the hardened paste showed 1% vaterite, 65% aragonite, 1% calcite, 1% periclase, and 32% bruxite. (Example 2) Formation and conversion of vaterite and magnesium oxide

[0327] This experiment demonstrated that when magnesium oxide is hydrated to form magnesium hydroxide, the volume of the solid fraction of the cement paste (vaterite converted to aragonite) increases due to the chemically bonded water. Conversely, the conversion of vaterite to aragonite (in the absence of magnesium oxide) reduces the volume of the cement paste because aragonite is denser than vaterite. Table 2 compares the actual volume of (a) pure calcium carbonate cement paste with (b) the actual volume of calcium carbonate cement paste containing 25% magnesium oxide. Table 2 below shows that vaterite, periclase (MgO), and water formed the cement paste, and after it set and hardened, it formed aragonite and brucite (Mg(OH)2). The water in paste (b) bonded to Mg(OH)2 after the cement set and hardened. Replacing 25% vaterite with magnesium oxide increased the actual volume of the hardened cement by 20%. This means that the cement had lower porosity, as well as higher strength, hardness, and durability compared to 100% calcium carbonate cement paste. [Table 2]

[0328] Figures 6-7 show the difference in microstructure between calcium carbonate cement made from vaterite (Figures 6A-6B) and calcium carbonate cement made from vaterite and magnesium oxide (Figures 7A-7B). Figures 6A-B show the interconnected aragonite network structure of the calcium carbonate cement. Figures 7A-7B show that magnesium hydroxide surrounds the aragonite network structure, thereby filling the gaps in the network and helping to bind the needle-like aragonites together, resulting in lower porosity as well as higher strength, hardness, and durability. (Example 3) Controlling the conversion from vaterite to aragonite by controlling the MgO combustion temperature.

[0329] Vaterite with a median diameter of 4 μm was combined with separately burned magnesium oxide in a 4:1 ratio. Magnesium oxide was produced by burning magnesium hydroxide at either 750°C or 950°C for 4 hours. A cement paste was formed by mixing the vaterite / magnesium oxide mixture with water at a solid-to-water ratio of 0.6. The paste was then cured in a sealed container at 80°C for 24 hours. After curing, the paste was dried at 110°C and then analyzed by X-ray diffraction. Table 3 shows the X-ray diffraction results of the paste conversion study. As shown in Table 3, combining 4 μm vaterite with lightly burned magnesium oxide (at 750°C) yielded a magnesium ion dissolution rate sufficient to control the conversion from vaterite to aragonite. In contrast, magnesium oxide burned at 950°C did not dissolve sufficiently, and the vaterite was converted to calcite. [Table 3]

[0330] While the aforementioned invention has been described in some detail by examples and embodiments for the purpose of clear understanding, it will be readily apparent to those skilled in the art that certain changes and modifications can be made therein without departing from the spirit or scope of the appended claims, in light of the teachings of the invention. Therefore, the foregoing is merely illustrative of the principles of the invention. Those skilled in the art will recognize that various combinations can be devised that embody the principles of the invention and fall within its spirit and scope, even if they are not explicitly stated or shown herein. Furthermore, the wording of all embodiments and conditions described herein is intended primarily to assist the reader in understanding the principles of the invention and the concepts given by the inventors to advance the art, and should be interpreted without limiting oneself to such specifically described embodiments and conditions. Moreover, all descriptions herein describing the principles, aspects and embodiments of the invention, and specific examples thereof, are intended to encompass both structural and functional equivalents. Furthermore, such equivalents are intended to include both currently known equivalents and future equivalents, i.e., any developed elements that perform the same function regardless of structure. Accordingly, the scope of the present invention is not intended to be limited to the exemplary embodiments shown and described herein. The following claims are intended to define the scope of the present invention, and the methods and structures within 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 cement or non-cement composition containing vaterite and magnesium oxide. (Item 2) The composition according to item 1, wherein the vaterite is present in an amount between approximately 30 and 99 wt%, and the magnesium oxide is present in an amount between approximately 1 and 70 wt%. (Item 3) The composition according to item 1 or 2, wherein the particle size of the vaterite is between approximately 0.1 and 100 microns. (Item 4) The composition according to any one of the above items, wherein the composition is a dry powder composition, a wet cake composition, or a slurry. (Item 5) The composition according to any one of the above items, wherein the magnesium oxide is incompletely combusted magnesium oxide, lightly calcined magnesium oxide, dead-calcined magnesium oxide, or a combination thereof. (Item 6) The composition according to any one of the above items, further comprising an admixture, aggregate, additive, Portland cement clinker, auxiliary cement material (SCM), or a combination thereof. (Item 7) A cement or non-cement slurry composition comprising vaterite, aragonite, calcite, magnesium oxide, magnesium hydroxide, or a combination thereof, and water. (Item 8) The composition according to item 7, wherein the aragonite has a needle-like network structure. (Item 9) The composition according to item 8, wherein the magnesium hydroxide binds together with the needle-shaped aragonite. (Item 10) The composition according to any one of the above items, further comprising an admixture, aggregate, additive, Portland cement clinker, auxiliary cement material (SCM), or a combination thereof. (Item 11) A method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) The step of dissolving the mixture containing lime and magnesium oxide in an N-containing salt solution to produce an aqueous solution containing calcium salt and magnesium oxide, (iii) an aqueous solution containing the calcium salt and magnesium oxide, and the carbon dioxide The steps include processing with a gas stream to form a composition containing vaterite and magnesium oxide, and Methods that include... (Item 12) The method according to item 11, further comprising the steps of generating a solid containing magnesium oxide in step (ii), and treating an aqueous solution containing the calcium salt and magnesium oxide, as well as the solid containing magnesium oxide, with a gas stream containing carbon dioxide to form a composition comprising vaterite, magnesium oxide, and a solid containing magnesium oxide. (Item 13) A method for forming a composition, (i) A step of calcining limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) Dissolving the mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia, (iii) recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, and subjecting the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, (iv) The first aqueous solution containing the calcium salt and magnesium oxide is treated with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof to form a composition containing vaterite and magnesium oxide. Methods that include... (Item 14) The method according to item 13, further comprising the steps of generating a solid containing magnesium oxide in step (ii), and treating a first aqueous solution containing the calcium salt and magnesium oxide, and the solid containing magnesium oxide, with a second aqueous solution to form a composition containing vaterite, magnesium oxide, and a solid containing magnesium oxide. (Item 15) The method according to any one of items 11 to 14, wherein the limestone contains between approximately 1 and 70% magnesium or magnesium-supported minerals. (Item 16) The method according to any one of items 11 to 15, further comprising the step of mixing a magnesium-supported mineral with the limestone before the calcination, wherein the magnesium-supported mineral contains magnesium between about 1 and 70%. (Item 17) The method according to item 15 or 16, wherein during the firing process, the magnesium or the magnesium-supported mineral forms the magnesium oxide. (Item 18) The method according to any one of items 15 to 17, wherein the magnesium-supported mineral includes magnesium carbonate, magnesium salts, magnesium hydroxide, magnesium silicate, magnesium sulfate, or a combination thereof. (Item 19) The method according to any one of items 15 to 18, wherein the magnesium-supported mineral is selected from the group consisting of dolomite, magnesite, brucite, carnalite, talc, olivine, artiniite, hydromagnesite, dipingite, barringonite, neskehonite, lancefoldite, kieserite, and combinations thereof. (Item 20) The method according to any one of items 11 to 19, wherein the calcination step produces a mixture comprising incompletely combusted lime, lightly calcined quicklime, dead lime, incompletely combusted magnesium oxide, lightly calcined magnesium oxide, dead magnesium oxide, or a combination thereof. (Item 21) The method according to item 20, further comprising the step of controlling the calcination process to control the components of the mixture, wherein the step of controlling the calcination process includes controlling the temperature and / or duration of heating the limestone. (Item 22) The method according to any one of items 11 to 21, further comprising the steps of converting the vaterite to aragonite and / or calcite upon dissolution and reprecipitation in water, and converting the magnesium oxide to magnesium hydroxide. (Item 23) The method according to item 22, further comprising the step of forming the needle-shaped aragonite. (Item 24) The method according to item 22 or 23, further comprising the step of bonding the aragonite and / or the calcite together with the magnesium hydroxide. (Item 25) The method according to any one of items 22 to 24, further comprising the step of stabilizing the aragonite with magnesium hydroxide to prevent the conversion of the aragonite to calcite. (Item 26) The method according to any one of items 22 to 25, further comprising the step of setting and hardening the aragonite and / or calcite to form a cement product. (Item 27) The method according to any one of items 22 to 26, further comprising the step of filling the voids between the aragonite and / or the calcite with magnesium hydroxide to increase its density and reduce its porosity. (Item 28) The method according to any one of items 11 to 27, wherein the N-containing salt is selected from the group consisting of N-containing inorganic salts, N-containing organic salts, and combinations thereof. (Item 29) The method according to item 28, wherein 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. (Item 30) The method according to item 29, wherein the ammonium halide is ammonium chloride. (Item 31) The method according to any one of items 11 to 30, wherein the aqueous solution or the first aqueous solution further comprises ammonia and / or an N-containing salt. (Item 32) The method according to any one of items 11 to 31, wherein the molar ratio of the N-containing salt to the mixture containing lime and magnesium oxide is between approximately 0.5:1 and 3:1. (Item 33) The method according to any one of items 11 to 32, wherein the dissolving step is carried out under one or more dissolving conditions selected from the group consisting of a temperature between about 30 and 200°C, a pressure between about 0.1 and 10 atm, the N-containing salt in wt% water between about 0.5 and 50%, and combinations thereof. (Item 34) The method according to any one of items 13 to 33, wherein the cooling step is carried out under one or more cooling conditions including a temperature between about 0 and 100°C, a pressure between about 0.5 and 50 atm, a pH of the aqueous solution between about 8 and 12, a flow rate of CO2, a CO2:NH3 ratio between about 0.1:1 and 20:1, or a combination thereof. (Item 35) The method according to any one of items 11 to 34, wherein the processing step is carried out under one or more precipitation conditions selected from the group consisting of a pH of the aqueous solution or the first aqueous solution between 7 and 9, a temperature of the solution between 20 and 60°C, a residence time between 5 and 60 minutes, or a combination thereof. (Item 36) The method according to any one of items 12 to 35, wherein the solid further comprises silicates, iron oxides, alumina, or combinations thereof. (Item 37) The method according to any one of items 22 to 36, wherein the aragonite and / or calcite set and harden to form cement products selected from masonry units, building panels, conduits, basins, beams, columns, slabs, sound barriers, thermal insulation materials, and combinations thereof. (Item 38) The method according to any one of items 11 to 37, further comprising the step of adding an additive to the aqueous solution, the first aqueous solution, and / or the composition, wherein the additive is selected from the group consisting of fatty acid esters, sodium decyl sulfate, lauric acid, sodium salt of lauric acid, urea, citric acid, sodium salt of citric acid, phthalic acid, sodium salt of phthalic acid, taurine, creatine, glucose, poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium salt of aspartic acid, magnesium chloride, acetic acid, sodium salt of acetic acid, glutamic acid, sodium salt of glutamic acid, strontium chloride, gypsum, lithium chloride, sodium chloride, glycine, anhydrous sodium citrate, sodium bicarbonate, magnesium sulfate, magnesium acetate, sodium polystyrene, sodium dodecyl sulfonate, polyvinyl alcohol, and combinations thereof. (Item 39) The method according to any one of items 11 to 38, wherein the vaterite has a unimodal, bimodal, or multimodal distribution of a particulate composition having an average particle size between approximately 0.1 and 100 microns. (Item 40) The method according to any one of items 11 to 39, further comprising the step of blending the composition with ordinary Portland cement (OPC), aggregate, limestone, or a combination thereof. (Item 41) The method according to any one of items 11 to 40, further comprising the step of mixing the composition with an admixture selected from the group consisting of setting accelerators, setting retarders, air entrainers, foaming agents, defoaming agents, alkali reactivity reducing agents, binding admixtures, dispersants, coloring admixtures, corrosion inhibitors, moisture-proof admixtures, gas-forming agents, permeability reducing agents, pumping aids, shrinkage-correcting admixtures, fungicidal admixtures, bactericidal admixtures, insecticidal admixtures, rheological modifiers, finely ground mineral admixtures, pozzolanes, aggregates, wetting agents, strength enhancers, water repellents, reinforcing materials, and combinations thereof. (Item 42) The method according to item 41, wherein the reinforcing material is a fiber made from zirconia, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood, glass fiber, synthetic material, or a combination thereof. (Item 43) A product formed by the method described in any one of the above items 11 to 42. (Item 44) A system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor configured to dissolve the mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce an aqueous solution containing calcium salt and magnesium oxide, and which is operably connected to the calcination reactor, (iii) A processing reactor operably connected to the dissolution reactor and the calcination reactor, configured to process an aqueous solution containing the calcium salt and magnesium oxide with a gas stream containing carbon dioxide to form a composition containing vaterite and magnesium oxide. A system that includes this. (Item 45) The system according to item 44, wherein the aqueous solution further comprises ammonia and / or the N-containing salt. (Item 46) A system for forming a composition, (i) A calcination reactor configured to calcine limestone to form a mixture containing lime and magnesium oxide, and a gas stream containing carbon dioxide, (ii) A dissolution reactor operably connected to the calcination reactor, configured to dissolve the mixture containing lime and magnesium oxide in an aqueous solution of N-containing salt to produce a first aqueous solution containing calcium salt and magnesium oxide, and a gas stream containing ammonia. (iii) A cooling reactor operably connected to the dissolution reactor and the calcination reactor, configured to recover the gas stream containing carbon dioxide and the gas stream containing ammonia, and to subject the gas stream to a cooling process to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, and (iv) A processing reactor operably connected to the dissolution reactor and the cooling reactor, configured to treat a first aqueous solution containing the calcium salt and magnesium oxide with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate, or a combination thereof, to form a composition containing vaterite and magnesium oxide. A system that includes this. (Item 47) The system according to item 46, wherein the dissolution reactor is integrated with the cooling reactor.

Claims

[Claim 1] The invention described in the specification.

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