Process and system for capturing carbon dioxide

Abstract

Provided herein are processes and systems related to a carbon dioxide sequestration process comprising a) calcining limestone using fossil fuel instead of an input to form a mixture comprising lime and a gas stream comprising greater than about 30 vol% carbon dioxide; and b) treating the mixture comprising lime with the atmosphere and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof. Also provided herein are processes and systems related to a carbon dioxide sequestration process comprising a) calcining limestone using fossil fuel instead of an input to form a mixture comprising lime and a gas stream comprising greater than about 30 vol% carbon dioxide; and b) treating the mixture comprising lime with natural water and allowing carbon dioxide dissolved in the natural water to react with the mixture to form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 424,251, filed on November 10, 2022, entitled "PROCESSES AND SYSTEMS TO CAPTURE CARBON DIOXIDE", the disclosure of which is incorporated herein by reference in its entirety.

[0003] Background

[0004] Carbon dioxide (CO₂) emissions have been recognized as a major cause of the global warming phenomenon. CO₂ is a by - product of combustion, and it creates operational, economic, and environmental problems. The elevated atmospheric concentrations of CO₂ and other greenhouse gases are known to promote more heat storage in the atmosphere, leading to increased surface temperatures and rapid climate change. Additionally, the elevated levels of CO₂ in the atmosphere may further acidify the world's oceans due to the dissolution of CO₂ and the formation of carbonic acid. If left unaddressed, the effects of climate change and ocean acidification can be economically costly and environmentally harmful. Mitigating the potential risks of climate change requires sequestering and avoiding CO₂ from multiple anthropogenic processes.

[0005] Overview

[0006] Various embodiments relate to the development of robust, energy - efficient, and low - cost strategies for removing carbon dioxide from air and water (such as, for example, seawater and other natural waters).

[0007] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0008] a) calcining limestone using a fossil fuel alternative input to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide; and

[0009] b) treating the mixture containing lime with the atmosphere and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0010] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0011] a) calcining limestone using a fossil fuel alternative input to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide; and

[0012] b) Treating a lime-containing mixture with natural water and allowing the carbon dioxide dissolved in the natural water to react with the mixture to form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

[0013] In some embodiments of the foregoing aspects, the process further comprises disposing of a gas stream comprising greater than about 30 volume % carbon dioxide, wherein the disposing comprises cooling, compressing, and / or storing. In some embodiments of the foregoing aspects and embodiments, the storing comprises geologically sequestering a gas stream comprising greater than about 30 volume % carbon dioxide.

[0014] In some embodiments of the foregoing aspects and embodiments, a gas stream comprising greater than about 30 volume % carbon dioxide does not contain gaseous or non-gaseous components from the combustion of fossil fuels.

[0015] In some embodiments of the foregoing aspects and embodiments, the gas stream comprises greater than about 90 volume % carbon dioxide. In some embodiments of the foregoing aspects and embodiments, the gas stream comprises between about 90 volume % and 100 volume % carbon dioxide. In some embodiments of the foregoing aspects and embodiments, the gas stream comprises about 99 volume % carbon dioxide.

[0016] In some embodiments of the foregoing aspects and embodiments, the fossil fuel replacement inputs include electric kilns, renewable electricity, hydrogen, biofuels, indirect heating, or a combination thereof. In some embodiments of the foregoing aspects and embodiments, the renewable electricity includes solar, wind, geothermal, and / or hydroelectric energy. In some embodiments of the foregoing aspects and embodiments, the biofuels include biomass. In some embodiments of the foregoing aspects and embodiments, the biomass includes torrefied biomass, lignin, and / or shredded biomass. In some embodiments of the foregoing aspects and embodiments, the indirect heating includes using a heat input to calcine limestone, wherein the gas stream from the heat input is separated from the gas stream comprising greater than about 30 volume % carbon dioxide.

[0017] In some embodiments of the foregoing aspects and embodiments, the lime-containing mixture comprises underburned lime. In some embodiments of the foregoing aspects and embodiments, the lime-containing mixture comprises lightly burned lime. In some embodiments of the foregoing aspects and embodiments, the lime-containing mixture comprises dead burned lime.

[0018] In some embodiments of the foregoing aspects, the process further comprises c) treating a slip stream of the lime-containing mixture with an N-containing salt solution to produce an aqueous solution comprising a calcium salt; and contacting the aqueous solution comprising the calcium salt with a gas stream comprising greater than about 30 volume % carbon dioxide to produce a precipitate comprising calcium carbonate.

[0019] In some embodiments of the foregoing aspects and embodiments, the process further comprises c) treating a slipstream of the mixture comprising lime with a salt solution containing N to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with a gas stream containing less than about 25% by volume of carbon dioxide to produce a precipitate containing calcium carbonate. In some embodiments of the foregoing aspects and embodiments, the gas stream containing less than about 25% by volume of carbon dioxide is obtained from limestone calcination using fossil fuels.

[0020] In some embodiments of the foregoing aspects and embodiments, treating the mixture comprising lime with the atmosphere includes spreading the mixture on land and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0021] In some embodiments of the foregoing aspects and embodiments, treating the mixture comprising lime in natural water includes directly sealing the mixture in natural water. In some embodiments of the foregoing aspects and embodiments, treating the mixture comprising lime in natural water includes mixing the mixture comprising lime with cooling natural water at a power generation facility and sealing the mixture back into natural water. In some embodiments of the foregoing aspects and embodiments, the natural water is seawater, and treating the mixture comprising lime in seawater includes mixing the mixture comprising lime with concentrated salt seawater at a desalination facility and sealing the mixture back into seawater.

[0022] In some embodiments of the foregoing aspects and embodiments, the gas stream containing greater than about 30% by volume of carbon dioxide contains less than about 20% of at least one component selected from the group consisting of: SOx; thermal NOx; carbon monoxide; metals; volatile organic compounds; particulate matter; and combinations thereof. In some embodiments of the foregoing aspects and embodiments, the gas stream containing greater than about 90% by volume of carbon dioxide contains less than about 1% of at least one component selected from the group consisting of: SOx; thermal NOx; carbon monoxide; metals; volatile organic compounds; particulate matter; and combinations thereof. In some embodiments of the foregoing aspects and embodiments, the gas stream containing greater than about 99% by volume of carbon dioxide contains less than about 1% of at least one component selected from the group consisting of: SOx; thermal NOx; carbon monoxide; metals; volatile organic compounds; particulate matter; and combinations thereof.

[0023] In some embodiments of the foregoing aspects and embodiments, the composition containing calcium carbonate, calcium bicarbonate, or a combination thereof formed in seawater is pH-neutral. In some embodiments of the foregoing aspects and embodiments, the process further comprises settling the composition containing calcium carbonate, calcium bicarbonate, or a combination thereof on the sea floor. In some embodiments of the foregoing aspects and embodiments, the process further comprises forming a coral reef on the composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0024] In one aspect, a carbon dioxide sequestration process is provided, the process comprising:

[0025] a) combusting a heat input to generate heat and a first gas stream; and

[0026] b) indirectly heating and calcining limestone using heat from the heat input to form a mixture containing lime and a second gas stream containing greater than about 90 volume % carbon dioxide,

[0027] wherein the first gas stream from the heat input is separated from the second gas stream containing greater than about 90 volume % carbon dioxide.

[0028] In some embodiments of the foregoing aspect, the heat input is a fossil fuel input or a fossil fuel substitute input. In some embodiments of the foregoing aspect and embodiments, the fossil fuel input or fossil fuel substitute input can be switched for grid load balancing and / or economy. In some embodiments of the foregoing aspect and embodiments, the fossil fuel substitute input includes biomass and / or hydrogen. In some embodiments of the foregoing aspect and embodiments, the first gas stream contains less than about 25 volume % carbon dioxide. In some embodiments of the foregoing aspect and embodiments, the first gas stream contains greater than about 20% of at least one component selected from the group consisting of: SOx; thermal NOx; carbon monoxide; metals; volatile organic compounds; particulate matter; and combinations thereof.

[0029] In some embodiments of the foregoing aspect and embodiments, the process further comprises treating a slipstream or all of the mixture containing lime with air, and allowing carbon dioxide from the air to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0030] In some embodiments of the foregoing aspect and embodiments, the process further comprises treating a slipstream or all of the mixture containing lime with natural water, and allowing carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0031] In some embodiments of the foregoing aspect and embodiments, the process further comprises treating a slipstream or all of the mixture containing lime with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with the first gas stream containing less than about 25 volume % carbon dioxide to produce a precipitate containing calcium carbonate.

[0032] In some embodiments of the foregoing aspects and embodiments, the process further includes treating a second gas stream comprising greater than about 90 volume % carbon dioxide, wherein the treating includes cooling, compressing, and / or storing. In some embodiments of the foregoing aspects and embodiments, the storing includes geologically sequestering a second gas stream comprising greater than about 90 volume % carbon dioxide.

[0033] In some embodiments of the foregoing aspects and embodiments, the second gas stream comprising greater than about 90 volume % carbon dioxide does not contain gaseous or non-gaseous components from the combustion of fossil fuels. In some embodiments of the foregoing aspects and embodiments, the second gas stream comprises between about 90 volume % and 100 volume % carbon dioxide. In some embodiments of the foregoing aspects and embodiments, the gas stream comprises about 99 volume % carbon dioxide.

[0034] In one aspect, there is provided a system for carbon dioxide sequestration, the system comprising:

[0035] a first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture comprising lime and a gas stream comprising greater than about 30 volume % carbon dioxide; and

[0036] a sequestration system operably connected to the first calcination system and configured to treat the mixture comprising lime with the atmosphere and allow carbon dioxide from the atmosphere to react with the mixture and form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

[0037] In one aspect, there is provided a system for carbon dioxide sequestration, the system comprising:

[0038] a first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture comprising lime and a gas stream comprising greater than about 30 volume % carbon dioxide; and

[0039] a sequestration system operably connected to the first calcination system and configured to treat the mixture comprising lime with natural water and allow the carbon dioxide dissolved in the natural water to react with the mixture to form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

[0040] In some embodiments of the foregoing aspects and embodiments, the sequestration system is a conveyor belt and / or a transport vehicle.

[0041] In some embodiments of the foregoing aspects and embodiments, the system further includes a treatment system operably connected to the first calcination system and configured to treat the gas stream comprising greater than about 30 volume % carbon dioxide. In some embodiments of the foregoing aspects and embodiments, the treatment system includes a cooler, a compressor, and / or a geological injector.

[0042] In some embodiments of the foregoing aspects and embodiments, the gas stream comprises greater than about 90 volume % carbon dioxide.

[0043] In some embodiments of the foregoing aspects and embodiments, the system further comprises:

[0044] A processing reactor operably connected to the first calcination system, the processing reactor being configured to receive a slipstream of a mixture comprising lime and being configured to dissolve the mixture comprising lime in a nitrogen-containing salt solution to produce an aqueous solution comprising a calcium salt; and

[0045] A contact reactor operably connected to the processing reactor and the first calcination system, and being configured to receive a slipstream of the aqueous solution comprising a calcium salt and a gas stream comprising greater than about 30 volume % carbon dioxide, and being configured to treat the aqueous solution comprising a calcium salt with the gas stream to form a precipitate comprising calcium carbonate.

[0046] In some embodiments of the foregoing aspects and embodiments, the system further comprises:

[0047] A second calcination system configured to calcine a limestone feed using a fossil fuel and produce a gas stream comprising less than about 25 volume % carbon dioxide;

[0048] A processing reactor operably connected to the first calcination system, the processing reactor being configured to receive a slipstream of a mixture comprising lime and being configured to dissolve the mixture comprising lime in a nitrogen-containing salt solution to produce an aqueous solution comprising a calcium salt; and

[0049] A contact reactor operably connected to the processing reactor and the second calcination system, and being configured to receive the aqueous solution comprising a calcium salt from the processing reactor and the gas stream comprising less than about 25 volume % carbon dioxide from the second calcination system, and being configured to treat the aqueous solution comprising a calcium salt with the gas stream to form a precipitate comprising calcium carbonate.

[0050] Drawings

[0051] The features of the invention are particularly pointed out in the appended claims. A better understanding of the features and advantages of the invention will be obtained by reference to the following detailed description and drawings, which set forth illustrative embodiments that utilize the principles of the invention, in which:

[0052] Figure 1A Illustrate some process and system embodiments provided herein.

[0053] Figure 1B Illustrate some process and system embodiments related to the indirect heating of limestone provided herein.

[0054] Figure 2 Illustrates some of the process and system implementations provided herein.

[0055] Figure 3 Illustrates some of the process and system implementations provided herein.

[0056] Figure 4 Illustrates some of the process and system implementations provided herein.

[0057] Description

[0058] To reduce global warming, it may become necessary to actively remove CO2 from the atmosphere. The oceans cover 70% of the Earth's surface and affect weather and climate by absorbing solar radiation, distributing heat and moisture throughout the oceans and globally, and driving the global weather system. The oceans also absorb approximately 30% of all anthropogenic CO2 emissions and trap more than about 90% of the excess heat in the biosphere caused by CO2 pollution. Cement is an important contributor to global carbon dioxide emissions, with more than 1.5 billion metric tons emitted annually, corresponding to approximately 8% of total emissions. More than 50% of cement emissions may be caused by the release of carbon dioxide from the decomposition of limestone raw materials in conventional kilns (CaCO3 --> CaO + CO2). Another 40% of cement emissions may come from fuel combustion in high-temperature conventional kilns, which are units that may not be needed or can be replaced by fossil fuel alternatives according to some embodiments of the present invention. Examples of conventional kilns are kilns such as rotary kilns and shaft kilns. Multiple embodiments relate to refining the emitted CO2 (i.e., increasing the purity and concentration of CO2), recapturing CO2 back into the process or sequestering and storing or disposing of it underground (which can be greater than 20% or greater than 25% or greater than 60% or close to 100% capture), avoiding the use of conventional coal-burning kilns, reducing capital expenditure by reducing absorber size and ventilation systems, capturing CO2 from air and / or natural water, and improving the kinetics of calcium carbonate formation, such as in the form of vaterite. Embodiments of the present invention eliminate more than 50% or more than 80% or close to 100% of cement carbon dioxide emissions.

[0059] Multiple embodiments are provided for capturing high-concentration or relatively pure CO2 from limestone calcination, capturing CO2 from air (e.g., direct air capture or DAC), and / or capturing CO2 from natural water (e.g., direct ocean capture or DOC) in a cost-effective, robust, and economically viable technology.

[0060] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0061] Calcining limestone using a fossil fuel substitute input to form a mixture containing lime and an air stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein); and

[0062] a) Treating a slipstream or all of the mixture containing lime with air, and allowing carbon dioxide from the air to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0063] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0064] a) Calcining limestone using a fossil fuel substitute input to form a mixture containing lime and an air stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein); and

[0065] b) Treating a slipstream or all of the mixture containing lime with natural water, and allowing carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

[0066] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0067] a) Calcining limestone using a fossil fuel substitute input to form a mixture containing lime and an air stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein); and

[0068] b) Treating a slipstream or all of the mixture containing lime with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with an air stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein) to produce a precipitate containing calcium carbonate.

[0069] In one aspect, a carbon dioxide sequestration process is provided that includes:

[0070] a) Calcining limestone using a fossil fuel substitute input to form a mixture containing lime and a first gas stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein); and treating a slipstream or all of the mixture containing lime with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with a second gas stream containing less than 25 vol% carbon dioxide or less than 20 vol% carbon dioxide to produce a precipitate containing calcium carbonate.

[0071] In some embodiments of the foregoing aspects, the gas stream or second gas stream containing less than 25 vol% carbon dioxide is obtained from the calcination of limestone in a cement plant using a fossil fuel.

[0072] In one aspect, a carbon dioxide sequestration process is provided, the process comprising:

[0073] a) Calcining limestone using a fossil fuel substitute input to form a mixture containing lime and a first gas stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein); and

[0074] b) Treating a slipstream or all of the mixture containing lime with the atmosphere and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof, and / or

[0075] c) Treating a slipstream or all of the mixture containing lime with natural water and allowing the carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof, and / or

[0076] d) Treating a slipstream or all of the mixture containing lime with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with a first gas stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein) to produce a precipitate containing calcium carbonate, and / or

[0077] e) Treating a slipstream or all of the mixture containing lime with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with a second gas stream containing less than 25 vol% carbon dioxide or less than 20 vol% carbon dioxide to produce a precipitate containing calcium carbonate.

[0078] In some embodiments of the foregoing aspect, a second gas stream comprising less than 25% by volume carbon dioxide is obtained from the calcination of limestone in a cement facility using fossil fuels.

[0079] In one aspect, a system for carbon dioxide sequestration is provided, the system comprising:

[0080] A first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture comprising lime and a gas stream comprising greater than 25% by volume carbon dioxide or greater than 30% by volume carbon dioxide or greater than 50% by volume carbon dioxide or greater than 80% by volume carbon dioxide or greater than 90% by volume carbon dioxide (or higher concentrations as provided herein); and

[0081] A sequestration system operably connected to the first calcination system and configured to treat a slipstream or all of the mixture comprising lime with the atmosphere and allow carbon dioxide from the atmosphere to react with the mixture and form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

[0082] In one aspect, a system for carbon dioxide sequestration is provided, the system comprising:

[0083] A first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture comprising lime and a gas stream comprising greater than 25% by volume carbon dioxide or greater than 30% by volume carbon dioxide or greater than 50% by volume carbon dioxide or greater than 80% by volume carbon dioxide or greater than 90% by volume carbon dioxide (or higher concentrations as provided herein); and

[0084] A sequestration system operably connected to the first calcination system and configured to treat a slipstream or all of the mixture comprising lime with natural water and allow the carbon dioxide dissolved in the natural water to react with the mixture to form a composition comprising calcium carbonate, calcium bicarbonate, or a combination thereof.

[0085] In one aspect, a system for carbon dioxide sequestration is provided, the system comprising:

[0086] A first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture comprising lime and a first gas stream comprising greater than 25% by volume carbon dioxide or greater than 30% by volume carbon dioxide or greater than 50% by volume carbon dioxide or greater than 80% by volume carbon dioxide or greater than 90% by volume carbon dioxide (or higher concentrations as provided herein);

[0087] A treatment reactor operably connected to a first calcination system, the treatment reactor being configured to receive a slipstream or all of a mixture containing lime and being configured to dissolve the mixture containing lime in a salt solution containing N to produce an aqueous solution containing a calcium salt; and

[0088] A contact reactor operably connected to the treatment reactor and the first calcination system and configured to receive an aqueous solution containing a calcium salt and a first gas stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein), and configured to treat the aqueous solution containing the calcium salt with the gas stream to form a precipitate containing calcium carbonate.

[0089] In one aspect, a system for carbon dioxide sequestration is provided, the system comprising:

[0090] A first calcination system configured to calcine a limestone feed using a fossil fuel substitute input to form a mixture containing lime and a first gas stream containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein);

[0091] A second calcination system configured to calcine a limestone feed using a fossil fuel and produce a second gas stream containing less than 25 vol% carbon dioxide or less than 20 vol% carbon dioxide;

[0092] A treatment reactor operably connected to the first calcination system and configured to receive a slipstream or all of the mixture containing lime, and further configured to dissolve the mixture containing lime in a salt solution containing N to produce an aqueous solution containing a calcium salt; and

[0093] A contact reactor operably connected to the treatment reactor and the second calcination system and configured to receive the aqueous solution containing the calcium salt from the treatment reactor and the second gas stream containing less than 25 vol% carbon dioxide or less than 20 vol% carbon dioxide from the second calcination system, and configured to treat the aqueous solution containing the calcium salt with the gas stream to form a precipitate containing calcium carbonate.

[0094] In some embodiments of the above aspect, a gas stream or a slipstream thereof containing greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentrations as provided herein) obtained from calcining limestone using a fossil fuel substitute input is subject to the disposal as further described herein.

[0095] Some embodiments of the above aspects have been illustrated in the accompanying drawings and are further described in detail herein. It should be understood that the steps illustrated in the drawings can be modified according to the desired results, or the order of the steps can be changed, or more steps can be added or deleted. It should also be understood that some steps described in the specification may not be illustrated in the drawings.

[0096] Calcining limestone using a fossil fuel substitute input

[0097] A process and system for calcining limestone using a fossil fuel substitute input to form a mixture containing lime are as Figure 1A and Figure 1B illustrated in Step I of Figure 1B An embodiment is illustrated in which the fossil fuel substitute input is indirectly heated, as will be further described. Figure 1A is an illustration of some embodiments and includes feeding limestone 110 with a fossil fuel substitute 120 for calcination to form a mixture 130 containing lime. The mixture is then used to capture CO2 152 from the air, or CO2 154 from natural water, or a dissolution process 156. These processes can in turn produce calcium carbonate and / or calcium bicarbonate 160. Referring to Figure 1B , in some embodiments, limestone 162 is directed into a kiln 170 and subjected to indirect heating 164 to form a mixture 172 containing lime. The mixture is then used to capture CO2 182 from the air, or CO2 184 from natural water, or a dissolution process 186. These processes can in turn produce calcium carbonate and / or calcium bicarbonate 190.

[0098] As Figure 1A and Figure 1B illustrated in Step I of

[0099] Calcination or calcining is a heat treatment process used to thermally decompose limestone. The "limestone" as used in the embodiments of the present invention has the chemical formula CaCO3 and may also include other impurities commonly present in limestone. In some embodiments, the limestone also contains magnesium or magnesium oxide. Limestone is a naturally occurring mineral. The chemical composition of limestone may vary from region to region and between different deposits within the same region. Therefore, the lime containing calcium oxide and / or calcium hydroxide obtained by calcining limestone from each natural deposit can be different. Limestone can contain calcium carbonate (CaCO3), magnesium (e.g., magnesium carbonate (MgCO3)), silica (SiO2), alumina (Al2O3), iron (Fe), sulfur (S), or other trace elements and compositions.

[0100] Limestone deposits can vary greatly. Limestones from various deposits may differ in physical and chemical properties and can be classified according to their chemical composition, texture, and geological structure. Limestone can be classified into the following types: high-calcium limestone, in which the carbonate content may mainly contain calcium carbonate and the magnesium carbonate content is not more than 5%; magnesian limestone, which contains a magnesium carbonate content of about 5% - 35%; or dolomitic limestone, which may contain between 35% - 46% of magnesium carbonate, with the balance being calcium carbonate. Limestones from different sources may vary significantly in chemical composition and physical structure. It should be understood that the embodiments of the present invention are applicable to all cement equipment for calcining various limestones from the above or any commercially available source. Quarries include, but are not limited to: quarries associated with cement kilns, quarries of limestone for aggregates in concrete, quarries of limestone for other purposes (roadbeds), and / or quarries associated with lime kilns.

[0101] Limestone calcination is a decomposition process, and the chemical reaction used to decompose limestone is:

[0102] CaCO3 → CaO + CO2(g).

[0103] This step is illustrated in Figure 1A and Figure 1B as step I of calcining limestone to form a mixture containing lime and greater than 25 volume% carbon dioxide or greater than 30 volume% carbon dioxide or greater than 50 volume% carbon dioxide or greater than 80 volume% carbon dioxide or greater than 90 volume% carbon dioxide (or higher concentrations or purities as provided herein).

[0104] In some embodiments, the limestone contains between about 1% and 70% magnesium. Optionally or additionally, a magnesium-containing mineral is mixed with the limestone prior to calcination, where the magnesium-containing mineral contains between about 1% and 70% magnesium. In some embodiments, upon calcination, the magnesium forms magnesium oxide. In some embodiments, the magnesium-containing mineral can include magnesium carbonate, magnesium salts, magnesium hydroxide, magnesium silicate, magnesium sulfate, or combinations thereof. In some embodiments, the magnesium-containing mineral can include, but is not limited to, dolomite, magnesite, brucite, carnallite, talc, olivine, hydromagnesite, nesquehonite, lansfordite, dypingite, barringonite, natroxalate, or combinations thereof.

[0105] As used in various embodiments, the term "lime" refers to calcium oxide and / or calcium hydroxide. The presence and amount of calcium oxide and / or calcium hydroxide in the lime can vary depending on the conditions under which the lime is formed. The lime can be in a dry form, i.e., calcium oxide, and / or in a wet form, such as calcium hydroxide, depending on the conditions. The lime can be calcium oxide in solid form from a dry kiln / cement process and / or can be a combination of calcium oxide and calcium hydroxide in slurry form in a wet kiln / cement process. Calcium oxide can exist in its hydrated form when wet (which can also be referred to as a basic anhydride that converts to its hydroxide form in water), such hydrated forms including, but not limited to, calcium hydroxide. While calcium hydroxide (also referred to as slaked lime) is the common hydrated form of calcium oxide, other intermediate hydrated complexes and / or hydrated complexes can also be present in the slurry and are all included within the scope of the embodiments of the present invention. It should be understood that while lime is illustrated as CaO in some of the figures of the present disclosure, it can exist as Ca(OH)2 or as a combination of CaO and Ca(OH)2. A mixture containing lime can also contain calcium hydroxide formed by dissolving calcium oxide in water. Both calcium oxide and / or calcium hydroxide can act as a source of divalent cations (Ca 2+ ) and a proton remover and react with carbon dioxide to form calcium carbonate, calcium bicarbonate, or combinations thereof.

[0106] The production of lime can depend on the type of kiln, the conditions of calcination, and the nature of the raw material, i.e., limestone. At relatively low calcination temperatures, the product formed in the kiln may contain both unburned carbonate and lime and can be referred to as underburned lime. As the temperature increases, lightly burned lime or highly reactive lime can be produced. At even higher temperatures, dead burned lime or low reactive lime can be produced. Lightly burned lime can be produced when the reaction front reaches the core of the charged limestone and converts all of the carbonate present into lime. Such a highly reactive product can be relatively soft, can contain small lime microcrystals, and can have an open porous structure with an interior that is easy to evaluate. Such lime can have properties of high reactivity, high surface area, and low bulk density.

[0107] Increasing the degree of calcination beyond this stage may cause the lime microcrystals to become larger, agglomerate, and sinter. This can lead to a decrease in surface area, porosity, and reactivity and an increase in bulk density. Such a product is referred to as dead burned lime or low reactive lime. Without being bound by any theory, embodiments of the present invention utilize any one or combination of the above lime phases. In some embodiments, the lime is dead burned lime. In some embodiments, the lime is lightly burned lime. In some embodiments, the lime is underburned lime. In some embodiments, the lime is dead burned lime, lightly burned lime, underburned lime, or a combination thereof.

[0108] In various embodiments, calcining limestone using a fossil fuel replacement feedstock produces a mixture comprising greater than 10 wt%, or greater than 20 wt%, or greater than 30 wt% lime. In some embodiments, calcining limestone produces a mixture comprising greater than 40 wt% lime, or greater than 50 wt% lime, or greater than 60 wt% lime, or greater than 70 wt% lime, or greater than 80 wt% lime, or greater than 90 wt% lime, or lime between 30 wt% - 95 wt%, or lime between 40 wt% - 95 wt%, or lime between 50 wt% - 95 wt%, or lime between 60 wt% - 95 wt%, or lime between 70 wt% - 95 wt%, or lime between 80 wt% - 95 wt%, or lime between 30 wt% - 90 wt%, or lime between 40 wt% - 90 wt%, or lime between 50 wt% - 90 wt%, or lime between 60 wt% - 90 wt%, or lime between 70 wt% - 90 wt%, or lime between 80 wt% - 90 wt%, or lime between 30 wt% - 80 wt%, or lime between 40 wt% - 80 wt%, or lime between 50 wt% - 80 wt%, or lime between 60 wt% - 80 wt%, or lime between 70 wt% - 80 wt%, or lime between 40 wt% - 50 wt%, or lime between 50 wt% - 60 wt%. In some embodiments, the lime is dead burned lime. In some embodiments, the lime is lightly burned lime. In some embodiments, the lime is under burned lime. In some embodiments, the lime is dead burned lime, lightly burned lime, under burned lime, or a combination thereof. In some embodiments, the lime is lightly burned lime, under burned lime, or a combination thereof. In some embodiments, the lime is dead burned lime, lightly burned lime, or a combination thereof. In some embodiments, the lime is dead burned lime, under burned lime, or a combination thereof.

[0109] Without being bound by any theory, embodiments of the present invention can produce and / or utilize any one or combination of lime phases. Calcination using a fossil fuel replacement feedstock provides the advantage of finer control of the calcination temperature, which results in better control of producing lightly burned lime relative to dead burned lime or relative to under burned lime, and vice versa.

[0110] In some embodiments, the lime-containing mixture obtained after calcining limestone using a fossil fuel replacement feedstock may also contain limestone or impurities that decompose limestone. These impurities can be present as solids along with the lime-containing mixture. For example, in some embodiments, the mixture containing lime may also contain sulfur, depending on the source of the limestone. Sulfur compounds can include any compound containing a sulfur ion.

[0111] As used in some embodiments, the term "fossil fuel replacement input" can include any fuel input that can be an alternative source to fossil fuels. Examples include but are not limited to electric kilns, renewable electricity, hydrogen, biofuels, solar heating, indirect heating, etc. or combinations thereof. In some embodiments, renewable electricity can include solar, wind, geothermal, and / or hydroelectric power. By way of example only, biofuels can contain biomass. Examples of biomass include but are not limited to torrefied biomass, lignin, and / or shredded biomass. Upgraded biomass can be produced by thermochemical processes such as torrefaction, which can be a mild pyrolysis process that occurs at atmospheric pressure in the absence of oxygen. Torrefaction can increase the energy density of biomass, reduce its moisture content, and make it hydrophobic and brittle. Fossil fuel replacement inputs can be produced from available biomass residues or can be produced using renewable electricity. The processing of wood typically produces biomass residues such as bark, branches, and fines. The amount of residue depends on the process, wood type, and local conditions.

[0112] In some embodiments, biomass residues can be pretreated, whether the residues are gasified, torrefied, or shredded, for fuel use. Pretreatment can reduce problems in the fuel feed system and improve the efficiency of the conversion or combustion process. Unwanted elements such as sand and metal can be removed to prevent problems in the equipment during processing. In some embodiments, biomass pretreatment includes but is not limited to drying, shredding, and grinding to achieve a desired moisture content and particle size, which can vary depending on the conversion process selected.

[0113] In some embodiments, hydrogen can be produced from water using water electrolysis. Alkaline electrolyzers are a commercially available technology and can be used for hydrogen production. In an electrolyzer, water can be decomposed into hydrogen and oxygen as shown in the following reaction:

[0114] 2H2O(l) → 2H2(g) + O2(g).

[0115] In some embodiments, water electrolysis can be integrated with hydrogen combustion in a lime kiln according to some embodiments.

[0116] In some embodiments, indirect heating includes using a heat input to calcine limestone, where the gas stream from the heat input is separated from the gas stream containing greater than about 30 volume % carbon dioxide. Figure 1B is an illustrative example of indirect heating as a fossil fuel replacement input.

[0117] As Figure 1B illustrated, the heat input for providing indirect heating to limestone (in Figure 1BShown as X) can be any system in which fuel emissions from a thermal input (e.g., fuel emissions containing less than 25 volume % or even less carbon dioxide and containing other pollutants) are not allowed to be mixed with gaseous emissions from limestone heating (containing greater than 25 volume % carbon dioxide or greater than 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide (or higher concentrations or purities as provided herein)), and the limestone is only exposed to heating. The thermal input can be obtained using any fuel, such as but not limited to fossil fuels or fossil fuel alternative inputs, such as biomass or hydrogen fuels.

[0118] For example, in some embodiments, the thermal input can be implemented using a double - walled tube or double - walled duct (e.g., Figure 1B X) in or an array of double - walled tubes or double - walled ducts, where the space between the outer wall and the inner wall of the tube can include a fuel or source for heating the inner wall of the tube or duct. Emissions from the fuel or heat source are collected separately (shown as Figure 1B <25 volume % CO2) in. The limestone is indirectly heated in the space within the inner wall of one or more tubes, and the gas stream from the heated or calcined limestone can be collected separately (shown as Figure 1B >30 volume % CO2) in. The mixture containing lime obtained from the calcined limestone can be subjected to Figure 1A or Figure 1B the various processes illustrated in and described herein.

[0119] In some embodiments, a carbon dioxide sequestration process is provided, the process comprising:

[0120] burning a fuel to generate heat and a first gas stream; and

[0121] indirectly heating and calcining limestone using heat from the thermal input to form a mixture containing lime and a second gas stream containing greater than about 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide, or 100 volume % carbon dioxide (or any concentration or purity),

[0122] wherein the first gas stream from the thermal input is separated from the second gas stream.

[0123] In some embodiments, the heat input can be a fossil fuel input or a fossil fuel alternative input. In some embodiments, the fossil fuel input or fossil fuel alternative can be switched for grid load balancing and / or economic reasons. For example, the fossil fuel can be used during periods of lower utility electricity rates (such as at night), and the fossil fuel alternative input can be used during periods of higher utility electricity rates (such as during the day). In some embodiments, the fossil fuel alternative input can comprise biomass and / or hydrogen.

[0124] In some embodiments, the first gas stream comprises less than about 25 volume % carbon dioxide. In some embodiments, the first gas stream comprises greater than about 1% or greater than about 20% of an element or compound, such as SOx, thermal NOx, carbon monoxide, metals, volatile organic compounds, particulate matter, or combinations thereof.

[0125] In some embodiments, the process can further comprise treating a slipstream or all of the lime-containing mixture with air, and allowing carbon dioxide from the air to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or combinations thereof.

[0126] In some embodiments, the process further comprises treating a slipstream or all of the lime-containing mixture with natural water, and allowing the carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing calcium carbonate, calcium bicarbonate, or combinations thereof.

[0127] In some embodiments, the process further comprises treating a slipstream or all of the lime-containing mixture with an N-containing salt solution to produce an aqueous solution containing a calcium salt; and contacting the aqueous solution containing the calcium salt with a first gas stream containing less than about 25 volume % carbon dioxide to produce a precipitate containing calcium carbonate.

[0128] In some embodiments, the process can further comprise disposing of a second gas stream containing greater than about 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide or 100 volume % carbon dioxide (or any concentration or purity), wherein the disposal can include cooling, compressing, and / or storing.

[0129] In some embodiments, the storing can include geologically sequestering the second gas stream.

[0130] In some embodiments, the second gas stream containing greater than about 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide or 100 volume % carbon dioxide (or any concentration or purity) does not contain gaseous or non-gaseous components that would otherwise be produced by the combustion of fossil fuels.

[0131] In some embodiments, the second gas stream comprises between about 90 vol% - 100 vol% carbon dioxide.

[0132] In some embodiments, the gas stream comprises about 99 vol% carbon dioxide.

[0133] In some embodiments according to the present invention, any lime kiln used in cement production can be replaced with a kiln operating on a fossil fuel replacement input. Production of lime by calcining limestone can be carried out using various types of kilns operating on fossil fuel replacement inputs, such as but not limited to shaft kilns or rotary kilns. The use of electric kilns in calcination and the associated advantages have been described in U.S. Application No. 17 / 363,537, filed Jun. 30, 2021, which is hereby incorporated by reference in its entirety. The suitability of each fossil fuel replacement input can depend on local conditions, the price of fossil fuels, and the price of electricity.

[0134] Replacing the fossil fuel used in a limestone kiln with a fossil fuel replacement input at a cement facility, especially if lime and a CO2 stream are used according to some embodiments of the present invention, can render the cement production operation almost fossil fuel-free. In addition to the fossil fuel-free operation, the integration of the fossil fuel replacement input according to the embodiments of the present invention provides additional benefits, such as increased kiln capacity and production of by-products (such as vaterite, described in some embodiments below).

[0135] The embodiment system of the present invention for calcining limestone is suitable for calcining limestone in the form of lumps with diameters ranging from a few millimeters to several tens of millimeters. The cement facility waste streams can include waste streams from both wet and dry processes, and different facilities can employ shaft kilns, rotary kilns, electric kilns, or combinations thereof. The cement facility can also include a pre-calciner, and all of these components can operate on a fossil fuel replacement input according to the embodiments of the present invention. Different facilities can each burn a single fossil fuel replacement input, or can burn two or more of the same or different fossil fuel replacement inputs sequentially or simultaneously.

[0136] According to some embodiments, calcining limestone using a fossil fuel replacement feedstock provides several advantages associated with a high purity and high concentration of the emitted carbon dioxide. In some embodiments, calcining limestone using a fossil fuel replacement feedstock produces a gas stream comprising greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentration or purity). In some embodiments, calcining limestone using a fossil fuel replacement feedstock produces a gas stream comprising greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentration or purity), wherein the gas stream does not include gaseous or non-gaseous components that would otherwise be produced by the combustion of a fossil fuel. In some embodiments, the carbon dioxide comprising greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentration or purity) comprises carbon dioxide gas that is free of contaminants present in the flue gas from the combustion of a fossil fuel. The contaminants caused by the combustion of a fossil fuel can be gaseous contaminants such as, but not limited to, SOx, NOx, carbon monoxide, and / or any other non-carbon dioxide gas. Additionally, these contaminants caused by the combustion of a fossil fuel can be non-gaseous contaminants such as, but not limited to, metals, volatile organic compounds, particulate matter, and / or dust. Although the gas stream comprising greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentration or purity) does not contain gaseous or non-gaseous components caused by the combustion of a fossil fuel, it should be understood that some of the gaseous or non-gaseous components described above may be present in the gas stream from the fossil fuel replacement process but not in the gaseous or non-gaseous components produced by the combustion of a fossil fuel. For example, the gas stream can comprise one or more of the gaseous or non-gaseous components obtained from the decomposition or calcination of limestone. As described above, limestone can contain several impurities such as magnesium carbonate (MgCO3), silica (SiO2), alumina (Al2O3), iron (Fe), sulfur (S), or other trace elements or compounds. The decomposition of limestone can result in the formation of one or more components (gaseous or non-gaseous components) including SOx, carbon monoxide, metals, volatile organic compounds, particulate matter, and combinations thereof. Some thermal NOx can also be formed by the oxidation of molecular nitrogen present in the combustion air. One or more of these gaseous or non-gaseous components obtained from the decomposition or calcination of limestone can be present in the gas stream comprising greater than 25 vol% carbon dioxide or greater than 30 vol% carbon dioxide or greater than 50 vol% carbon dioxide or greater than 80 vol% carbon dioxide or greater than 90 vol% carbon dioxide (or higher concentration or purity).Although some non-gaseous components obtained from the decomposition of limestone may remain in the mixture containing lime, some gaseous or non-gaseous components may be present in the gas stream. However, the amount of such gaseous or non-gaseous components present in the gas stream will be much lower or negligible compared to the carbon dioxide obtained by calcining limestone in a conventional kiln burning fossil fuels.

[0137] In some embodiments, calcining limestone using a fossil fuel replacement input produces less than 20% of at least one of the following components: the components include SOx, thermal NOx, carbon monoxide, metals, volatile organic compounds, particulate matter, or combinations thereof, which are otherwise produced by the combustion of fossil fuels. In some embodiments, a gas stream containing greater than 25 volume % carbon dioxide or greater than 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide (or higher concentration or purity) contains less than 20% of any one of SOx, thermal NOx, carbon monoxide, metals, volatile organic compounds, particulate matter, or combinations thereof. In some embodiments, a gas stream containing greater than 25 volume % carbon dioxide or greater than 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide (or higher concentration or purity) contains less than 20%, or less than 18%, or less than 15%, or less than 12%, or less than 10%, or less than 8%, or less than 6%, or less than 5%, or less than 3%, or less than 2%, or less than 1%, or between about 0% - 20%, or between about 1% - 19%, or between about 1% - 18%, or between about 1% - 5%, or between about 1% - 2% of any one of SOx, thermal NOx, carbon monoxide, metals, volatile organic compounds, particulate matter, or combinations thereof.

[0138] Since there are no gaseous or non-gaseous components from fossil fuel combustion in the embodiments of the present invention, the carbon dioxide in the gas stream has high purity and high concentration. For example, compared to conventional kilns that produce about or less than 25 vol% of CO2 or about or less than 20 vol% of CO2, embodiments of the present invention using fossil fuel substitutes as inputs produce a gas stream containing CO2 between about 25 vol% - 100 vol%.In some embodiments, the gas stream obtained using a fossil fuel replacement feedstock contains between about 25 vol% and 100 vol% carbon dioxide, or between about 25 vol% and 95 vol% carbon dioxide, or between about 25 vol% and 90 vol% carbon dioxide, or between about 25 vol% and 80 vol% carbon dioxide, or between about 25 vol% and 70 vol% carbon dioxide, or between about 25 vol% and 60 vol% carbon dioxide, or between about 25 vol% and 50 vol% carbon dioxide, or between about 25 vol% and 40 vol% carbon dioxide, or between about 25 vol% and 30 vol% carbon dioxide, or between about 30 vol% and 100 vol% carbon dioxide, or between about 30 vol% and 95 vol% carbon dioxide, or between about 30 vol% and 90 vol% carbon dioxide, or between about 30 vol% and 80 vol% carbon dioxide, or between about 30 vol% and 70 vol% carbon dioxide, or between about 30 vol% and 60 vol% carbon dioxide, or between about 30 vol% and 50 vol% carbon dioxide, or between about 30 vol% and 40 vol% carbon dioxide, or between about 40 vol% and 100 vol% carbon dioxide, or between about 40 vol% and 95 vol% carbon dioxide, or between about 40 vol% and 90 vol% carbon dioxide, or between about 40 vol% and 80 vol% carbon dioxide, or between about 40 vol% and 70 vol% carbon dioxide, or between about 40 vol% and 60 vol% carbon dioxide, or between about 40 vol% and 50 vol% carbon dioxide, or between about 50 vol% and 100 vol% carbon dioxide, or between about 50 vol% and 95 vol% carbon dioxide, or between about 50 vol% and 90 vol% carbon dioxide, or between about 50 vol% and 80 vol% carbon dioxide, or between about 50 vol% and 70 vol% carbon dioxide, or between about 50 vol% and 60 vol% carbon dioxide, or between about 60 vol% and 100 vol% carbon dioxide, or between about 60 vol% and 95 vol% carbon dioxide, or between about 60 vol% and 90 vol% carbon dioxide, or between about 60 vol% and 80 vol% carbon dioxide, or between about 60 vol% and 70 vol% carbon dioxide, or between about 70 vol% and 100 vol% carbon dioxide, or between about 70 vol% and 95 vol% carbon dioxide, or between about 70 vol% and 90 vol% carbon dioxide, or between about 70 vol% and 80 vol% carbon dioxide, or between about 80 vol% and 100 vol% carbon dioxide, or between about 80 vol% and 95 vol% carbon dioxide, or between about 80 vol% and 90 vol% carbon dioxide, or between about 90 vol% and 100 vol% carbon dioxide, or between about 90 vol% and 95 vol% carbon dioxide, or about 99 vol% carbon dioxide in high purity and / or high concentration.

[0139] In some embodiments, the gas stream obtained using a fossil fuel substitute input contains between about 80 volume % and 100 volume % carbon dioxide, or between about 80 volume % and 95 volume % carbon dioxide, or between about 80 volume % and 90 volume % carbon dioxide, or between about 90 volume % and 100 volume % carbon dioxide, or between about 90 volume % and 95 volume % carbon dioxide, or about 99 volume % carbon dioxide, or about 99.9 volume % carbon dioxide, or between about 90 volume % and 99.9 volume % carbon dioxide, or about 100 volume % carbon dioxide.

[0140] Compared to processes that use fossil fuels to calcine limestone, which can produce about 20 volume % or less than 25 volume % or less than 20 volume % CO2 and relatively large amounts of pollutants, embodiments using fossil fuel substitute inputs offer several advantages, including but not limited to a gas stream containing greater than 30 volume % carbon dioxide or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide and substantially free of pollutants or containing fewer pollutants or containing less than 1 % pollutants or less than 5 % pollutants or less than 20 % pollutants, and a high concentration of carbon dioxide in the gas stream having greater than 30 volume % CO2 or CO2 between 30 volume % and 100 volume %. Additionally, these embodiments do not produce or substantially do not produce impurities in the CO2 that typically come from the combustion of coal (such as in a conventional kiln), and offer improved economics by: reducing the capital expenditure of equipment (e.g., no gas scrubber is required), and / or having less sulfur or no sulfur or less than 5 %, or less than 2 %, or less than 1 %, or less than 0.1 % sulfur in the lime and thus providing purer lime, which is placed on land to capture CO2 from the air or placed in natural water to react with dissolved carbon dioxide.

[0141] In some embodiments, a gas stream containing greater than about 25 volume % carbon dioxide, or greater than about 30 volume % carbon dioxide, or greater than about 40 volume % carbon dioxide, or greater than about 50 volume % carbon dioxide, or greater than about 60 volume % carbon dioxide, or greater than about 70 volume % carbon dioxide, or greater than about 80 volume % carbon dioxide, or greater than about 90 volume % carbon dioxide, or greater than about 99 volume % carbon dioxide, or carbon dioxide between about 30 volume % - 99 volume % or 30 volume % - 100 volume % obtained using a fossil fuel substitute input can be disposed of.

[0142] It should be understood that while the gas stream from calcination is for illustrative purposes in Figure 1A and Figure 1Bis depicted as greater than 30 volume % carbon dioxide, but in embodiments of the present invention higher percentages including and up to 100 volume % carbon dioxide can be achieved and are fully within the scope of these embodiments.

[0143] In various embodiments, the carbon dioxide in the gas stream obtained from the calcination of the fossil fuel replacement input can be disposed of or stored in a variety of ways to prevent carbon dioxide emissions into the atmosphere. In some embodiments, the carbon dioxide is stored for future use in other products. In some embodiments, the carbon dioxide is disposed of via injection into specific underground geological locations. In some embodiments, the carbon dioxide is deposited into underwater storage reservoirs such as the seabed. In some embodiments, the carbon dioxide is stored in long-term storage locations, which can be underground, above ground, or underwater. In different embodiments, the duration of carbon dioxide storage can vary from a few hours to several centuries depending on the given situation or use. In some embodiments, when the carbon dioxide has a high concentration, it can be sequestered underground. Certain aspects of some of these embodiments are shown in FIG. 1, denoted as CCS (carbon capture and storage) or CCUS (carbon capture, utilization, and storage).

[0144] Due to the high concentration of carbon dioxide in the gas stream obtained from the calcination of the fossil fuel replacement input according to embodiments of the present invention, CCS may not require separation and purification of the carbon dioxide gas prior to disposal, which is a significant cost savings.

[0145] In some embodiments, the disposal process can include but is not limited to cooling, compression, and / or storage. For example, in some embodiments, the carbon dioxide is compressed and transported via a sequestration system such as a pipeline, road vehicle, or ship to a storage location where the carbon dioxide can be injected into a deep underground geological location for permanent storage. In some embodiments, possible storage locations for the carbon dioxide can include saline aquifers or depleted oil and gas reservoirs, which can be, for example, 0.62 miles (1 km) or deeper underground.

[0146] The costs and energy requirements can vary depending on the type of technology and whether the captured CO2 is to be stored geologically or used immediately at low pressure. In some embodiments, the CO2 may need to be compressed at high pressure to inject it into a geological formation. This step may require equipment such as compressors. The captured CO2 can be disposed of by injecting it deep underground for sequestration in certain geological formations or used in various products and applications as described in the various embodiments.

[0147] In some embodiments, the net amount of carbon benefit or permanently stored carbon used in a product can depend on the product. By way of example only, use in products such as concrete or plastics can provide long-term sequestration (for decades or even centuries). Various embodiments relate to capturing gas streams containing greater than 30 volume % carbon dioxide or higher concentrations during a dissolution process. In some embodiments, jet fuel (synthetic fuel produced using pure CO2 formed according to embodiments of the present invention) can be an alternative to emission-intensive fossil fuels.

[0148] Embodiments of the present invention provide several advantages, including reducing the carbon footprint, the amount of energy used, and / or the amount of CO2 generated for sequestering gas streams containing greater than 25 volume % CO2 or greater than 50 volume % carbon dioxide or greater than 80 volume % carbon dioxide or greater than 90 volume % carbon dioxide (or higher concentrations) from fossil fuel alternatives.

[0149] Capturing CO2 from air

[0150] In some embodiments, a slipstream or the entire mixture of the lime-containing mixture obtained from limestone calcination ( Figure 1A or Figure 1B I in) is used to directly or indirectly capture CO2 from the atmosphere or ambient air ( Figure 1A or Figure 1B II in), to reduce the amount of CO2 in the air and thus reduce the greenhouse effect. The reaction that occurs between lime and CO2 in the air can be shown as follows:

[0151] CaO + CO2(g) --> CaCO3(s)

[0152] Ca(OH)2 + CO2(g) --> CaCO3(s) + H2O.

[0153] As can be seen from these equations, in these reactions, according to embodiments of the present invention, some calcium bicarbonate can be formed. Capturing CO2 from the atmosphere as a carbon removal option provides several benefits, including but not limited to limited land and water footprint and the feasibility of locating the equipment on non-arable land near suitable storage sites, eliminating the need for long-distance CO2 transportation. The location selection can also be based on the energy required to operate the equipment. By way of example only, a fossil fuel alternative input for limestone calcination can provide a lower cost for capturing each ton of CO2 from the atmosphere.

[0154] In some embodiments, a carbon dioxide sequestration process is provided that includes calcining a limestone feed using a fossil fuel substitute input to form a mixture containing lime and an air stream containing greater than 25 volume % carbon dioxide, or greater than 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide (or higher concentration); and treating the mixture with the atmosphere and allowing carbon dioxide in the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof. In some embodiments, the process may further include cooling, compressing, and / or storing the air stream containing greater than 25 volume % or greater than 30 volume % or greater than 50 volume % or greater than 80 volume % or greater than 90 volume % carbon dioxide (or higher concentration). In some embodiments, after the mixture reacts with CO2 in the air, the remaining portion of the air is partially or completely free of CO2, thereby mitigating climate change.

[0155] In different embodiments, the step of treating the mixture with the atmosphere and allowing carbon dioxide in the atmosphere to react with the mixture can be carried out in various ways. For example, in some embodiments, the mixture containing lime is placed on a piece of land where the mixture is exposed to the atmosphere, allowing carbon dioxide in the atmosphere to react with the mixture. For example, in some embodiments, the mixture is spread on a sequestration system such as a conveyor belt, where the lime reacts with CO2 in the atmosphere to form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof, which can solidify and harden. In some embodiments, the hardened material can be crushed into gravel or aggregate and used in building materials.

[0156] In some embodiments, the CO2 in the atmosphere after reacting with the mixture can be permanently stored in or on a deep geological formation.

[0157] In some embodiments, the CO2 in the atmosphere is passed through the mixture containing lime (optionally under pressure) to allow carbon dioxide in the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof. In some embodiments, the atmosphere can be pushed through a filter to capture the CO2 and then treated with the mixture. In some embodiments, the stored CO2 in the composition containing calcium carbonate, calcium bicarbonate, or a combination thereof can be regenerated by calcining the composition, and thereby regenerate an air stream containing greater than 50 volume % or greater than 90 volume % CO2, and the air stream is disposed of as described in various embodiments. The process in turn produces a mixture containing lime, which can then be used again to capture carbon dioxide from the air. The process can be repeated any number of times to capture carbon dioxide from the air.

[0158] In some embodiments, a carbon dioxide sequestration process is provided that includes using a fossil fuel substitute input to calcine limestone to form a mixture containing lime and an air stream containing greater than 20 volume % carbon dioxide, or greater than 25 volume % carbon dioxide, or greater than 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide (or higher concentration);

[0159] Treating a slipstream or all of the mixture with the atmosphere and allowing carbon dioxide in the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof, and

[0160] Using a fossil fuel substitute input to calcine or heat the composition to form a mixture containing lime and an air stream having greater than 20 volume % carbon dioxide, or greater than 25 volume % carbon dioxide, or greater than 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide (or higher concentration).

[0161] In some embodiments, the sequestration process further includes disposing of the air stream. In some embodiments, the sequestration process further includes reusing the mixture to capture carbon dioxide from the atmosphere.

[0162] Capturing CO2 from natural water

[0163] In some embodiments, a slipstream or the entire mixture of the lime-containing mixture obtained by calcining limestone in the process ( Figure 1A or Figure 1B I in) is used to directly or indirectly capture CO2 from natural water ( Figure 1A or Figure 1B III in) to reduce the CO2 dissolved in natural water and thus mitigate the greenhouse effect. The term "natural water" as used in various embodiments includes any natural water body. Examples include but are not limited to oceans or sea water, lakes, rivers, streams, etc. "Ocean water" or "ocean" or "sea water" all include water from the ocean or sea. The reaction that occurs between lime and the CO2 dissolved in natural water can be shown as follows:

[0164] CaO + CO2 --> CaCO3(s)

[0165] Ca(OH)2 + CO2 --> CaCO3(s) + H2O.

[0166] In these reactions, some calcium bicarbonate may be formed, which may or may not be converted to calcium carbonate. Some of the dissolved CO2 may be in the form of carbonic acid.

[0167] Processes for capturing CO2 directly or indirectly from natural water as described in these embodiments offer the potential for offshore deployment, which provides various useful benefits such as reducing competition for land, allowing access to ocean CO2 storage sites that are currently only reachable by pipeline, and directly reversing ocean acidification caused by anthropogenic CO2 emissions.

[0168] Some embodiments provide a carbon dioxide sequestration process that includes calcining a limestone feed using a fossil fuel substitute input to form a mixture containing lime and an air stream containing greater than 25 volume % carbon dioxide, or greater than 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide (or higher concentration), and treating the mixture with natural water and allowing the carbon dioxide in the natural water to react with the mixture and form calcium carbonate, calcium bicarbonate, or a combination thereof. In some embodiments, the process further includes disposing of the air stream, such as cooling, compressing, and / or storing the air stream, the air stream containing greater than 25 volume % carbon dioxide, or greater than 30 volume % carbon dioxide, or greater than 50 volume % carbon dioxide, or greater than 80 volume % carbon dioxide, or greater than 90 volume % carbon dioxide (or higher concentration), as described in the embodiments of the present invention. In some embodiments, after the mixture containing lime reacts with CO2 from natural water, the remaining natural water is partially or completely free of CO2, thereby mitigating climate change.

[0169] In some embodiments, treating the mixture in natural water is accomplished by directly sealing the mixture in natural water. In some embodiments, the mixture is transported using pipes, tanks, and / or vessels to seal the mixture in natural water, such as but not limited to lakes, rivers, and oceans, where the mixture captures CO2 in the natural water and forms calcium carbonate, calcium bicarbonate, or a combination thereof. In some embodiments, calcium carbonate, calcium bicarbonate, or a combination thereof settles at the bottom of the natural water body. In some embodiments, calcium carbonate, calcium bicarbonate, or a combination thereof forms coral reefs in natural water.

[0170] In some embodiments, the calcium carbonate, calcium bicarbonate, or a combination thereof formed according to the embodiments of the present invention is pH-neutral.

[0171] In some embodiments, treating the mixture with natural water includes blending the mixture with cooling natural water at a power generation facility and sealing the blend back into natural water. In some embodiments, the calcining facility is integrated with the power generation facility such that the mixture from the calcining facility is blended with the natural water used to cool the power generation facility. The natural water can be sealed back into the water body together with the mixture and form calcium carbonate, calcium bicarbonate, or a combination thereof in the water body such as the ocean, thereby capturing CO2 from the natural water.

[0172] In some embodiments, the natural water is seawater, and treating the mixture with seawater involves blending the mixture with concentrated brine from the ocean at a desalination facility and sequestering the blend back into the ocean. In some embodiments, the calcination facility is integrated with the desalination facility such that the mixture from the calcination facility is blended with concentrated brine from the ocean (obtained after seawater desalination) from the desalination facility. The concentrated brine can be sequestered back into the ocean together with the mixture that forms calcium carbonate, calcium bicarbonate, or a combination thereof in the ocean, thereby capturing CO2 from seawater.

[0173] Dissolution process

[0174] In one aspect, a slipstream or the entire mixture of the lime-containing mixture obtained by calcining limestone according to embodiments of the present invention ( Figure 1A or Figure 1B I in) undergoes a dissolution process in which the mixture is treated with an N-salt-containing solution to produce an aqueous solution containing a calcium salt, and the aqueous solution having the calcium salt is contacted with a carbon dioxide gas stream or a slipstream thereof to produce a precipitate containing calcium carbonate. In some embodiments, the carbon dioxide captured during the dissolution process can be clean or pure carbon dioxide obtained from the calcination process according to various embodiments (using fossil fuel substitutes) having greater than 25 vol% carbon dioxide, or greater than 30 vol% carbon dioxide, or greater than 50 vol% carbon dioxide, or greater than 80 vol% carbon dioxide, or greater than 90 vol% carbon dioxide (or higher concentrations); and / or in some embodiments, the carbon dioxide captured during the dissolution process is obtained from a cement facility using a conventional calcination kiln (using fossil fuel) and producing impure or less than 25 vol% carbon dioxide, or less than 20 vol% carbon dioxide.

[0175] It should be understood that the dissolution process ( Figure 1A or Figure 1B and Figures 2 - 4 the process illustrated in) can proceed spontaneously or can be combined with the process of capturing CO2 from the air ( Figure 1A or Figure 1B II in) or capturing CO2 from natural water ( Figure 1A or Figure 1B ) or a combination thereof. Any such combination can be carried out as shown in Table I below.

[0176] Table I

[0177]

[0178] In some embodiments, a slipstream of the lime-containing mixture obtained by calcining limestone ( Figure 1A or Figure 1B)Undergoes a dissolution process, where the mixture is treated with an N-containing salt solution to produce an aqueous solution containing a calcium salt, and the aqueous solution containing the calcium salt is contacted with a gas stream or a slipstream thereof (using a fossil fuel substitute input) containing greater than 25 vol% carbon dioxide, or greater than 30 vol% carbon dioxide, or greater than 50 vol% carbon dioxide, or greater than 80 vol% carbon dioxide, or greater than 90 vol% carbon dioxide (or a higher concentration as provided) to produce a precipitate containing calcium carbonate.

[0179] In some embodiments, a slipstream of the lime-containing mixture ( Figure 1A or Figure 1B ) undergoes a dissolution process, where the mixture is treated with an N-containing salt solution to produce an aqueous solution containing a calcium salt, and the aqueous solution containing the calcium salt is contacted with a gas stream or a slipstream thereof containing less than 25 vol% carbon dioxide (from a fossil fuel) to produce a precipitate containing calcium carbonate. Some of these embodiments involving the dissolution process are illustrated in Figures 2 - 4 FIG. Figure 2 FIG. is an illustration of some embodiments. It indicates a lime-containing mixture 202, dissolution 210 in an N-containing salt, solid / liquid separation 220, precipitation 230 together with the product of calcination 204, and solid / liquid separation 240, where the cake can be used to directly construct the product 250, or construct the product 280 after passing through a dryer 260 together with additional components 270. Figure 3 FIG. is an illustration of some embodiments, where a lime-containing mixture 302, dissolution 310 in an N-containing salt, solid / liquid separation 320, precipitation 330 together with the product of calcination 304, and solid / liquid separation 340 are indicated, where the cake can be used to directly construct the product 350, or construct the product 380 after passing through a dryer 360 together with additional components 370. Figure 4 FIG. is an illustration of some embodiments, where a lime-containing mixture 402, dissolution 410 in an N-containing salt, cooling 480 or solid / liquid separation 420, precipitation 430 together with the product of calcination 404 after cooling 480, and solid / liquid separation 440 are indicated, where the cake can be used to directly construct the product 452, or construct the product 454 after passing through a dryer 460 together with additional components 470.

[0180] Dissolution in an N-containing salt solution

[0181] In some embodiments, the lime-containing mixture is treated with a solubilizer such as an N-containing salt to improve its solubility, thereby producing Figures 2 - 4aqueous solutions containing calcium salts 210, 310, and 410. In some embodiments, the aqueous solution containing the calcium salt further comprises a solid, as will be further described. In some embodiments, the aqueous solution containing the calcium salt further contains ammonia and / or N-containing salts. For example, in some embodiments, the aqueous solution containing the calcium salt further contains ammonia and / or ammonium salts. For example, in some embodiments, the aqueous solution containing calcium chloride further contains ammonia and / or ammonium chloride (when the N-containing salt is ammonium chloride).

[0182] In some embodiments, the lime slurry obtained from a wet cement facility can optionally be subjected to a dehydration step (not shown in the figure), where residual water can be removed, and the dehydrated residue can be subjected to further treatment, such as dissolution with an N-containing salt. For illustrative purposes only, the N-containing salt solution is depicted in the figure as an ammonium chloride (NH4Cl) solution, and the subsequent calcium salt is depicted as calcium chloride (CaCl2). Various examples of N-containing salts have been provided in various embodiments and are all within the scope of the embodiments of the present invention.

[0183] In various embodiments, the N-containing salt is an N-containing inorganic salt or an N-containing organic salt or a combination thereof. The term "N-containing salt" as used in various embodiments is a salt that solubilizes or dissolves a calcium compound, in part or completely or substantially, from a mixture containing lime. The calcium compound can be calcium oxide, calcium hydroxide, any other derivative of calcium, or a combination thereof.

[0184] The "N-containing inorganic salt" as used in various embodiments can include any inorganic salt containing nitrogen. Examples of N-containing inorganic salts can include, but are not limited to, ammonium halides (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. Such chemicals are commercially available.

[0185] The "N-containing organic salt" as used in various embodiments can include any salt of an organic compound containing nitrogen. Examples of N-containing organic compounds can include, but are not limited to, aliphatic amines, alicyclic amines, heterocyclic amines, and combinations thereof. Such chemicals are commercially available.

[0186] The "aliphatic amine" as used in various embodiments can include any alkylamine of the formula (R) n -NH 3-n where n is an integer from 1 - 3, and R is independently a straight-chain or branched, substituted or unsubstituted alkyl group between C1 - C8. Examples of corresponding salts of the alkylamine of the formula (R) n -NH 3-n are (R) n -NH 4-n + Cl -and (R) n -NH 4-n + Br - 。In some embodiments, when R is a substituted alkyl group, the substituted alkyl group is independently substituted by halogen, hydroxyl, acid and / or ester.

[0187] In some embodiments, when R is (R) n -NH 3-n the alkyl group in, the alkylamine can be a primary alkylamine, by way of example only, such as methylamine, ethylamine, butylamine, pentylamine, etc. The alkylamine can be a secondary amine, by way of example only, such as dimethylamine, diethylamine, methylethylamine, etc. The alkylamine can also be a tertiary amine, by way of example only, such as trimethylamine, triethylamine, etc.

[0188] In some embodiments, when R is a substituted alkyl group substituted by hydroxyl in (R) n -NH 3-n the substituted alkylamine can be an alkanolamine, including but not limited to monoalkanolamine, dialkanolamine or trialkanolamine, such as monoethanolamine, diethanolamine or triethanolamine, etc.

[0189] In some embodiments, when R is a substituted alkyl group substituted by halogen in (R) n -NH 3-n the substituted alkylamine can be, for example, chloromethylamine, bromomethylamine, chloroethylamine, bromoethylamine, etc.

[0190] In some embodiments, when R is a substituted alkyl group substituted by acid in (R) n -NH 3-n the substituted alkylamine can be, for example, an amino acid. In some embodiments, the aforementioned amino acid can have a polar uncharged alkyl chain, and examples thereof can include but not limited to serine, threonine, asparagine, glutamine, or a combination thereof. In some embodiments, the aforementioned amino acid has a charged alkyl chain, and examples thereof can include but not limited to arginine, histidine, lysine, aspartic acid, glutamic acid, or a combination thereof. In some embodiments, the aforementioned amino acid can be glycine, proline, or a combination thereof.

[0191] As used in various embodiments, the term "alicyclic amine" can include any alicyclic amine of the formula (R) n -NH 3-n wherein n is an integer from 1 - 3, and wherein R is independently one or more all-carbon rings, which can be saturated or unsaturated and do not have aromatic characteristics. The alicyclic compound can have one or more aliphatic side chains attached. Examples of corresponding salts of the alicyclic amine of the formula (R) n -NH 3-n are (R) n-NH 4-n + Cl - Examples of alicyclic amines can include, but are not limited to, cycloalkylamines: cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, and the like.

[0192] As used in various embodiments, the term "heterocyclic amine" includes at least one heterocyclic aromatic ring attached to at least one amine. Examples of heterocycles can include, but are not limited to, pyrrole, pyrrolidine, pyridine, pyrimidine, etc. Such chemicals may be commercially available.

[0193] In various embodiments, under one or more dissolution conditions, a mixture containing lime is treated or dissolved or solubilized with an N-containing salt such as an aqueous ammonium chloride solution ( Figures 2 - 4 step A in), to produce an aqueous solution containing a calcium salt. "Treat" or "solvate" or "solubilize" or any grammatical equivalent can be used interchangeably and includes dissolving the mixture containing lime in an aqueous medium.

[0194] As Figures 2 - 4 illustrated in step A of, the N-containing salt is exemplified as ammonium chloride (NH4Cl). It should be understood that NH4Cl is for illustrative purposes only, and any other N-containing salt can be used in the embodiments of the present invention, including any other ammonium salt. One or more steps may be omitted or modified, or the order of the steps may be changed. By treating with an N-containing inorganic salt such as NH4Cl (new and recycled as further explained below), the lime containing calcium oxide is solvated or solubilized, and the possible reactions are:

[0195] CaO(s) + 2NH4Cl(aqueous solution) → 2NH3(aqueous solution) + CaCl2(aqueous solution) + H2O(l).

[0196] Similarly, when the base is an N-containing organic salt, the reaction can be shown as follows:

[0197] CaO(s) + 2NH3RCl → CaCl2(aqueous solution) + 2NH2R + H2O(l).

[0198] In some embodiments, an N-containing salt such as, but not limited to, an ammonium chloride solution, can be supplemented with anhydrous ammonia or an aqueous ammonia solution to maintain an optimal level of ammonium ions in the solution.

[0199] In some embodiments, the amount of the N-containing salt is in excess of the lime-containing mixture by 20% or 30%. In some embodiments, the molar ratio of the N-containing salt to the lime-containing mixture is between 0.5:1 and 4:1 by weight (N-containing salt: mixture, or N-inorganic salt: mixture, or N-organic salt: mixture, or ammonium chloride: mixture), or between 0.5:1 and 3:1 by weight, or 0.5:1 and 2:1, or 0.5:1 and 1.5:1, or 1:1 and 1.5:1, or 2:1 and 4:1, or 2:1 and 3:1, or 2.5:1 and 3:1, or 3:1 and 4:1, or 1.5:1, or 2:1, or 2.5:1, or 3:1, or 3.5:1, or 4:1. In some embodiments, the above ratios are molar ratios or wt% ratios.

[0200] In some embodiments of the processes described herein, no polyhydroxy compound is used to form the precipitate material and / or product according to the embodiments.

[0201] In some embodiments, one or more dissolution conditions are selected, including a temperature between about 20°C and 200°C, or between about 20°C and 150°C, or between about 20°C and 100°C, or between about 20°C and 75°C, or between about 20°C and 50°C, or between about 20°C and 30°C, or between about 30°C and 200°C, or between about 30°C and 150°C, or between about 30°C and 100°C, or between about 30°C and 75°C, or between about 30°C and 50°C, or between about 30°C and 40°C, or between about 40°C and 200°C, or between about 40°C and 150°C, or between about 40°C and 100°C, or between about 40°C and 75°C, or between about 40°C and 50°C, or between about 50°C and 200°C, or between about 50°C and 150°C, or between about 50°C and 100°C; and a pressure between about 0.5 atm and 50 atm, or between about 0.5 atm and 10 atm, or between about 0.5 atm and 20 atm; and an N-inorganic salt or organic salt between about 0.5% and 50% by wt% in water, or between about 0.5% and 25% by wt%, or between about 0.5% and 10% by wt%; or a combination thereof.

[0202] In some embodiments, agitation can be used to effect the treatment of lime, e.g., by eliminating hot and cold spots. In some embodiments, the concentration of lime in water can be between 1 g / L and 10 g / L, between 10 g / L and 20 g / L, between 20 g / L and 30 g / L, between 30 g / L and 40 g / L, between 40 g / L and 80 g / L, between 80 g / L and 160 g / L, between 160 g / L and 320 g / L, between 320 g / L and 640 g / L, or between 640 g / L and 1280 g / L. To optimize the purification / solvation of calcium oxide, according to some embodiments, high-shear mixing, wet milling, and / or sonication can be used to break up the calcium oxide.

[0203] Processing of Solids

[0204] In some embodiments, the solids in the lime-containing mixture (obtained from limestone impurities and / or from the decomposition of limestone as explained above) are further processed and can be present as insoluble or partially soluble impurities in the aqueous solution containing the calcium salt. In some embodiments, the solids may or may not be removed from the aqueous solution before treating the aqueous solution containing the calcium salt with carbon dioxide in the process. The solids can optionally be removed from the aqueous solution by filtration and / or centrifugation techniques. In some embodiments, the solids are not removed from the aqueous solution, and the aqueous solution containing the calcium salt and the solids is contacted with carbon dioxide in step C to form a precipitate. In such embodiments, the precipitated material also contains the solids.

[0205] In some embodiments, the solids (shown as the solids in Figures 2 - 4 are calcium-depleted solids and can be used as a cement substitute (such as a substitute for Portland cement). In some embodiments, the solids can include impurities carried from limestone and / or the decomposition of limestone and include, but are not limited to, silicates, iron oxides, alumina, other particulate matter, and combinations thereof. In some embodiments, the solids in the precipitated material containing vaterite, aragonite, calcite, or combinations thereof provide a pozzolanic phase when mixed with OPC and enhance the binding with cement.

[0206] In some embodiments, in the aqueous solution containing the calcium salt, in the precipitated material, in the vaterite composition, or in combinations thereof, the solids are between about 1 wt% - 80 wt%, or between about 1 wt% - 70 wt%, or between about 1 wt% - 60 wt%, or between about 1 wt% - 50 wt%, or between about 1 wt% - 40 wt%, or between about 1 wt% - 30 wt%, or between about 1 wt% - 20 wt%, or between about 1 wt% - 10 wt%, or between about 1 wt% - 5 wt%, or between about 1 wt% - 2 wt%.

[0207] Contacting an aqueous solution with CO2

[0208] In various embodiments, an aqueous solution containing a calcium salt can also be treated with carbon dioxide. In an embodiment, a gas stream containing greater than 25 vol% carbon dioxide, or greater than 30 vol% carbon dioxide, or greater than 50 vol% carbon dioxide, or greater than 80 vol% carbon dioxide, or greater than 90 vol% carbon dioxide (or higher concentrations as provided) is sequestered for storage or for disposal (as described above). The aqueous solution containing the calcium salt can be treated with carbon dioxide from a power generation facility or from a cement facility or from any other commercial process (e.g., a gas stream containing less than 25 vol% carbon dioxide).

[0209] The high purity (less contaminants) and high concentration of CO2 (greater than 50 vol% carbon dioxide, or greater than 80 vol% carbon dioxide, or greater than 90 vol% carbon dioxide or higher concentrations provided in the gas stream compared to limestone calcination in a conventional kiln using CO2 that produces less than 25 vol%, or about 20%, or less than 20% contamination) results in significant savings due to the fact that less gas recycling or no gas recycling is required for absorption. In some embodiments, it is not necessary to wash the CO2 prior to absorption in the contact / absorption reactor. Some embodiments provide a zero-emission process when all of the CO2 emitted during calcination of limestone using a fossil fuel substitute input is sequestered for storage or disposal or is used in product manufacturing, where no CO2 is emitted to the atmosphere, thus providing a CO2 capture of nearly 95% to 100%. In some embodiments, due to the high purity and high concentration of CO2, the process is more than 40%, or more than 50%, or more than 60%, or more than 70%, or more than 80%, or more than 90%, or about 95%, or about 99% effective in capturing CO2 compared to a process using a conventional kiln operating on a fossil fuel.

[0210] Due to the provision of high purity and high concentration of CO2, some embodiments have several advantages such as, but not limited to, reduced blower power requirements, resulting in reduced blower capital expenditure; reduced capital expenditure for the piping system; greater absorber depth (if required), which translates to a higher capacity per footprint area; smaller absorber vessels, resulting in capital expenditure savings; reduced absorber agitation requirements (volume related); and reduced absorber vent scrubbing and ammonia losses in cases where a small-scale purge may be required.

[0211] Due to the presence of greater than 25 vol% CO2 or greater than 30 vol% CO2 (or higher purity) in the gas stream, embodiments of the present invention require less gas recirculation, do not require a scrubber, do not require absorber vents, require less blower power, require less blower capital expenditure, and / or require less piping system capital expenditure, etc., thereby improving the economics and efficiency of the system.

[0212] In some embodiments, an aqueous solution containing a calcium salt is contacted with a gas stream containing carbon dioxide under one or more precipitation conditions to produce a precipitate product containing vaterite, aragonite, calcite, or a combination thereof.

[0213] In some embodiments, a portion of the carbon dioxide is sequestered for storage or disposal, and the remaining portion of the carbon dioxide (e.g., a slipstream) is contacted with an aqueous solution containing a calcium salt under one or more precipitation conditions to produce a precipitate product containing vaterite, aragonite, calcite, or a combination thereof.

[0214] As Figures 2 - 4 illustrated in step C of

[0215] CaCl2 (aqueous solution) + 2NH3 (aqueous solution) + CO2 (g) + H2O --> CaCO3 (s) + 2NH4Cl (aqueous solution).

[0216] In embodiments of the present invention, the term "contact" can be used interchangeably with "absorb" or "precipitate".

[0217] In embodiments of the present invention, absorbing CO2 in an aqueous solution containing a calcium salt produces a CO2-bearing water containing carbonic acid, which is a substance in equilibrium with both bicarbonate and carbonate. The precipitate material is prepared under one or more precipitation conditions suitable for forming calcium carbonate (including vaterite, aragonite, calcite, or a combination thereof) or PCC material.

[0218] In some embodiments, the process further includes removing and optionally recovering an ammonia-containing gas stream during the dissolution process.

[0219] Certain aspects of various embodiments are illustrated in Figure 3 wherein a CO2-containing gas stream obtained from calcination and an NH3-containing gas stream obtained from dissolution are recycled to a contact / absorption reactor for forming a precipitate material. Figure 3 The remaining steps ofFigure 2 is the same as the steps of. It should be understood that Figure 2 and Figure 3 the processes of both can also occur simultaneously, such that the nitrogen-containing salts including nitrogen-containing inorganic salts or nitrogen-containing organic salts and optionally ammonia can be partially present in the aqueous solution and partially present in the gas stream.

[0220] In these embodiments, the reactions occurring in the contacting reactor can be as shown below:

[0221] CaCl2 (aqueous solution) + 2NH3 (g) + CO2 (g) + H2O -> CaCO3 (s) + 2NH4Cl (aqueous solution).

[0222] In some embodiments, the gas stream containing ammonia can have supplemental ammonia from an external source and / or be recycled only from dissolution and recovery in the nitrogen-containing salts.

[0223] In some embodiments, dissolving a mixture containing lime in some of the nitrogen-containing organic salts may not result in the formation of ammonia gas, or the amount of ammonia gas formed may not be substantial. In these embodiments, Figure 2 the process illustrated in is applicable, where the aqueous solution containing the calcium salt is treated with carbon dioxide gas. In such embodiments, the organic amine salt can remain in the aqueous solution in a fully or partially dissolved state, or can be separated into an organic amine layer, as shown in the following reaction:

[0224] CaO (s) + 2NH3R + Cl - → CaCl2 (aqueous solution) + 2NH2R + H2O.

[0225] The nitrogen-containing organic salts or nitrogen-containing organic compounds remaining in the supernatant solution after precipitation can be referred to as residual nitrogen-containing organic salts or residual nitrogen-containing organic compounds. Multiple embodiments describe how to recover these residual compounds from the precipitate and the supernatant solution.

[0226] Some embodiments also include recovering the gas stream containing carbon dioxide and the gas stream containing ammonia, and subjecting the gas streams to a cooling process under one or more cooling conditions to condense a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonium carbamate, ammonia, or a combination thereof. In some embodiments, the process also includes treating the aqueous solution containing the calcium salt with the second aqueous solution under one or more precipitation conditions to form a precipitated material.

[0227] Some aspects of these embodiments are illustrated in Figure 4 where the gas stream containing CO2 and the gas stream containing NH3 from calcination are recycled to the cooling reactor for forming carbonate and bicarbonate solutions, as shown in the following reaction.Figure 4 The remaining steps can be the same as those of Figure 2 and Figure 3 .

[0228] In some embodiments, the gas stream containing CO2 and / or the gas stream containing NH3 further contains water vapor. In some embodiments, the gas stream containing CO2 and / or the gas stream containing NH3 further contains between about 20% - 90%; or between about 20% - 80%; or between about 20% - 70%; or between about 20% - 60%; or between about 20% - 55%; or between about 20% - 50%; or between about 20% - 40%; or between about 20% - 30%; or between about 20% - 25%; or between about 30% - 90%; or between about 30% - 80%; or between about 30% - 70%; or between about 30% - 60%; or between about 30% - 50%; or between about 30% - 40%; or between about 40% - 90%; or between about 40% - 80%; or between about 40% - 70%; or between about 40% - 60%; or between about 40% - 50%; or between about 50% - 90%; or between about 50% - 80%; or between about 50% - 70%; or between about 50% - 60%; or between about 60% - 90%; or between about 60% - 80%; or between about 60% - 70%; or between about 70% - 90%; or between about 70% - 80%; or between about 80% - 90% water vapor.

[0229] In some embodiments, no external water is added to the cooling process. It should be understood that the cooling process may be similar to the condensation of a gas in existing water vapor (but may not be similar to the absorption of a gas), such that the gas is not absorbed by water but is cooled together with the water vapor. Condensing the gas into a liquid stream can provide process control advantages compared to absorbing the vapor. By way of example only, condensing the gas into a liquid stream can allow pumping the liquid stream to a precipitation step. The cost of pumping the liquid stream may be lower than the cost of compressing the vapor stream into an absorption process.

[0230] In some embodiments, an intermediate step in the cooling reaction / reactor can include forming ammonium carbonate and / or ammonium bicarbonate through the following reactions:

[0231] 2NH3 + CO2 + H2O → (NH4)2CO3

[0232] NH3 + CO2 + H2O → (NH4)HCO3.

[0233] For N-containing organic salts, similar reactions can be shown:

[0234] 2NH2R + CO2 + H2O → (NH3R)2CO3

[0235] NH2R + CO2 + H2O → (NH3R)HCO3.

[0236] Then, in contact / absorption / precipitation reaction / reactor C, a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonium carbamate, ammonia, or a combination thereof (exiting the Figure 4 cooling reaction / reactor therein) is treated with an aqueous solution containing a calcium salt from the treatment reaction / reactor to form a precipitated material comprising vaterite, aragonite, calcite, or a combination thereof:

[0237] (NH4)2CO3 + CaCl2 → CaCO3 + 2NH4Cl

[0238] (NH4)HCO3 + NH3 + CaCl2 → CaCO3 + 2NH4Cl +

[0239] (NH4)HCO3 + CaCl2 → CaCO3 + 2NH4Cl +

[0240] H2O + CO2.

[0241] Irrespective of any intermediate steps, in some embodiments, the combination of reactions results in the following overall process chemistry:

[0242] CaCO3 (limestone) → CaCO3 (vaterite, aragonite, calcite, or a combination thereof).

[0243] In some embodiments, one or more cooling conditions include a temperature between about 0 - 100 °C, or between about 0 - 80 °C, or between about 0 - 60 °C, or between about 0 - 50 °C, or between about 0 - 40 °C, or between about 0 - 30 °C, or between about 0 - 20 °C, or between about 0 - 10 °C, or between about 10 °C - 100 °C, or between about 10 °C - 80 °C, or between about 10 °C - 60 °C, or between about 10 °C - 50 °C, or between about 10 °C - 40 °C, or between about 10 °C - 30 °C, or between about 20 °C - 100 °C, or between about 20 °C - 80 °C, or between about 20 °C - 60 °C, or between about 20 °C - 50 °C, or between about 20 °C - 40 °C, or between about 20 °C - 30 °C, or between about 30 °C - 100 °C, or between about 30 °C - 80 °C, or between about 30 °C - 60 °C, or between about 30 °C - 50 °C, or between about 30 °C - 40 °C, or between about 40 °C - 100 °C, or between about 40 °C - 80 °C, or between about 40 °C - 60 °C, or between about 50 °C - 100 °C, or between about 50 °C - 80 °C, or between about 60 °C - 100 °C, or between about 60 °C - 80 °C, or between about 70 °C - 100 °C, or between about 70 °C - 80 °C.

[0244] In some embodiments of the aspects and embodiments provided herein, one or more cooling conditions include a pressure between about 0.5 atm - 50 atm, or between about 0.5 atm - 25 atm, or between about 0.5 atm - 10 atm.

[0245] It should be understood that although Figure 4 FIG. shows a separate cooling reaction / reactor 480, the processing / dissolution reaction / reactor 410 can be integrated with the cooling reaction / reactor. For example, the processing / dissolution reactor can be integrated with a condenser. Various examples of integrated dissolution and cooling reactors have been described in U.S. Application Serial No. 17 / 184,933, filed on February 25, 2021, which is incorporated herein by reference in its entirety. When forming an aqueous solution containing a calcium salt, both a mixture containing lime and a mixture of an N-salt solution (illustrated as NH4Cl in the figure) are supplied to the processing / dissolution reaction / reactor. The solution can optionally contain solid impurities, which can remain at the bottom of the processing / dissolution reactor 410. The aqueous solution containing the calcium salt is removed from the processing / dissolution reaction / reactor for further processing for precipitation. A gas stream containing carbon dioxide, ammonia, and water vapor passes through the upper section of the processing / dissolution reactor, where the gas stream is cooled to condense into a second aqueous solution. The second aqueous solution is collected using one or more trays.

[0246] As Figures 2 - 4 illustrated in step C of Figure 4 , the aqueous solution containing a calcium salt is contacted with CO2 and optionally NH3 at any time before, during or after subjecting the aqueous solution containing a calcium salt to one or more precipitation conditions (i.e., conditions that allow precipitation of the precipitated material), and the aqueous solution containing a calcium salt is from the treatment of a mixture containing lime with an N-containing salt such as an ammonium salt or ammonium halide in an embodiment of the present invention. Similarly, as

[0247] illustrated in step C of Figure 3 , the aqueous solution containing a calcium salt is contacted with a second aqueous solution containing ammonium bicarbonate, ammonium carbonate, ammonium carbamate, ammonia or a combination thereof from a cooling reaction / reactor at any time before, during or after subjecting the aqueous solution containing a calcium salt to one or more precipitation conditions (i.e., conditions that allow precipitation). Figure 4 Figure 3 Figure 4 Figure 3 Figure 4 Figure 3 Figure 4

[0248] Thus, in some embodiments, the aqueous solution containing a calcium salt is contacted with CO2 (and optionally NH3 as seen in Figure 3 or the second aqueous solution as seen in Figure 4 ), and then the aqueous solution is subjected to one or more precipitation conditions conducive to the formation of a precipitated material containing calcium carbonate, the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite or a combination thereof or PCC. In some embodiments, the aqueous solution containing a calcium salt is contacted with CO2 (and optionally NH3 as seen in Figure 3 or the second aqueous solution as seen in Figure 4 ), while the aqueous solution is subjected to one or more precipitation conditions conducive to the formation of a precipitated material containing calcium carbonate, the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite or a combination thereof or PCC. In some embodiments, the aqueous solution containing a calcium salt is contacted with CO2 (and optionally NH3 as seen in Figure 3 or the second aqueous solution as seen in Figure 4 ), and then and simultaneously the aqueous solution is subjected to one or more precipitation conditions conducive to the formation of a precipitated material containing calcium carbonate, the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite or a combination thereof or PCC. In some embodiments, after subjecting the aqueous solution containing a calcium salt to one or more precipitation conditions conducive to the formation of a precipitated material containing calcium carbonate, the aqueous solution is contacted with CO2 (and optionally NH3 as seen in Figure 3 or the second aqueous solution as seen in Figure 4 ), the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite or a combination thereof or PCC.

[0248] In some embodiments, contacting an aqueous solution containing a calcium salt with carbon dioxide and optionally ammonia or a second aqueous solution is achieved by contacting the aqueous solution using a convenient protocol (precipitation conditions) as described herein to reach and maintain a desired pH range, a desired temperature range, and / or a desired divalent cation concentration.

[0249] In some embodiments, the contacting / precipitation of the aqueous solution containing a calcium salt can occur in a contacting / precipitation reactor, where the amount of the added aqueous solution containing a calcium salt is sufficient to raise the pH to a desired level (e.g., the pH that induces precipitation of the precipitation material), such as pH 7 - 8.5, pH 7 - 8, pH 7.5 - 8, pH 8 - 8.5, pH 9 - 14, pH 10 - 14, pH 11 - 14, pH 12 - 14, or pH 13 - 14. In some embodiments, when contacting with carbon dioxide and optionally NH3 or a second aqueous solution, the pH of the aqueous solution containing a calcium salt is maintained between 7 - 8.5, or between 7.5 - 8.5, or between 7 - 8, or between 7.6 - 8.5, or between 8 - 8.5, or between 7.5 - 9.5, so as to form a precipitation material containing calcium carbonate, and the calcium carbonate contains stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC.

[0250] In some embodiments, the aqueous solution can be recycled more than once, where the first precipitation cycle removes vaterite, aragonite, calcite, or a combination thereof, and leaves an alkaline solution, and an additional aqueous solution containing a calcium salt can be added to the alkaline solution. Carbon dioxide, when contacting the recycled aqueous solution, enables precipitation of more vaterite, aragonite, calcite, or a combination thereof. It should be understood that in these embodiments, after the first precipitation cycle, the aqueous solution can contact CO2 before, during, and / or after the addition of the aqueous solution containing a calcium salt. In these embodiments, water can be recycled or freshly introduced. Thus, the addition order of CO2 and the aqueous solution containing a calcium salt can vary. For example, the aqueous solution containing a calcium salt can be added to, for example, brine, seawater, or fresh water, followed by the addition of CO2. In another example, CO2 can be added to, for example, brine, seawater, or fresh water, followed by the addition of the aqueous solution containing a calcium salt.

[0251] An aqueous solution containing a calcium salt can be contacted with CO2 in a contacting reactor using any convenient scheme according to an embodiment of the present invention. The contacting schemes of interest can include, but are not limited to, direct contact (e.g., bubbling CO2 gas through the aqueous solution), co-current contact (i.e., contact between a unidirectionally flowing gas phase stream and a liquid phase stream), counter-current contact (i.e., contact between a reversely flowing gas phase stream and a liquid phase stream), and others. Thus, in various embodiments, contact can be achieved by using an injector, a bubbler, a fluidic Venturi reactor, a sprayer, a gas filter, an atomizer, a tray, or a packed column reactor and the like in a precipitation reactor. In some embodiments, gas-liquid contact is achieved by forming a liquid sheet of the solution with a flat nozzle, wherein the CO2 gas and the liquid sheet move in a counter-current direction, a co-current direction, or a cross-current direction or in any other suitable manner. In some embodiments, gas-liquid contact is achieved by contacting droplets of the solution having an average diameter of 500 microns or less, such as 100 microns or less, with the CO2 gas.

[0252] In some embodiments, substantially (e.g., 80% or more or 90% or 99.9% or 100%) all of the CO2 and optionally the NH3 stream produced in the process illustrated in the figure are used for the precipitation of the precipitation material. In some embodiments, a portion of the CO2 and optionally the NH3 stream is used for the precipitation of the precipitation material and can be 75% or less of the gas stream, such as 60% or less, and including 50% or less.

[0253] Any combination of the methods of the gas-liquid contacting schemes described in these embodiments can be used. Continue the gas-liquid contact until the pH of the precipitation reaction mixture is optimal. A variety of optimal pH values have been described in embodiments of the present invention to form a precipitation material containing, for example, reactive vaterite, aragonite, calcite, or a combination thereof, and then allow the precipitation reaction mixture to be stirred. The rate of pH decrease can be controlled by adding more aqueous solution containing the calcium salt during the gas-liquid contact. Additional aqueous solution can be added after spraying to raise the pH back to the alkaline level used for the precipitation of some or all of the precipitation material. In any case, the precipitation material can be formed when protons are removed from certain substances (e.g., carbonic acid, bicarbonate, hydronium bicarbonate) in the precipitation reaction mixture. Then the precipitation material containing carbonate can be separated and optionally further processed.

[0254] In some embodiments, the rate of pH decrease can be controlled by adding additional supernatant or aqueous solution containing the calcium salt during the gas-liquid contact. Additional supernatant or aqueous solution containing the calcium salt can be added after the gas-liquid contact to raise the pH back to the alkaline level used for the precipitation of some or all of the precipitation material (e.g., between 7-9 or between 7-8.5 or between 7-8).

[0255] In various embodiments, an aqueous solution containing a calcium salt, when contacted with a gas stream containing CO2 gas, results in the precipitation of calcium carbonate comprising vaterite, aragonite, calcite, or a combination thereof, which are polymorphs of calcium carbonate. Precipitation conditions that result in the formation of stable vaterite or reactive vaterite or PCC in this process are described in different embodiments. In some embodiments, the precipitated material comprises stable vaterite and / or reactive vaterite or PCC. "Stable vaterite" or its grammatical equivalents as used in the embodiments of the present invention include vaterite that does not transform into aragonite or calcite during and / or after the dissolution-reprecipitation process in water. "Reactive vaterite" or "activated vaterite" or its grammatical equivalents as used in the embodiments of the present invention include vaterite that results in the formation of aragonite and / or calcite during and / or after the dissolution-reprecipitation process in water. "Precipitated calcium carbonate" or "PCC" as used in the embodiments of the present invention includes conventional PCC with high purity having particle sizes of 1 micron or less. The PCC can be in any polymorphic form of calcium carbonate, including but not limited to vaterite, aragonite, calcite, or a combination thereof. In some embodiments, the PCC has a particle size measured in nanometers or between 0.001 microns and 5 microns.

[0256] In an embodiment of the present invention, an aqueous solution containing water infused with CO2, produced by contacting an aqueous solution containing a calcium salt with a gas stream containing CO2 (and optionally a second gas stream containing ammonia), is subjected to one or more of the precipitation conditions sufficient to produce a precipitated material containing calcium carbonate and a supernatant (i.e., the portion of the precipitation reaction solution remaining after the precipitation of the precipitated material) (step C), the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC. In some embodiments, one or more of the precipitation conditions favor the production of a precipitated material containing stable vaterite or reactive vaterite or PCC.

[0257] Precipitation conditions include those that condition the environment of a CO₂-charged precipitation reaction mixture to produce a desired calcium carbonate-containing precipitate material, the calcium carbonate including stable vaterite, reactive vaterite, aragonite, calcite, or combinations thereof or PCC. Such one or more precipitation conditions suitable for forming a precipitate material including stable vaterite, reactive vaterite, aragonite, calcite, or combinations thereof or PCC that can be used in embodiments of the present invention include, but are not limited to, temperature, pH, pressure, ionic ratios, precipitation rate, presence of additives, presence of ionic species, concentration of additives and ionic species, agitation, residence time, mixing rate, agitation form such as ultrasonic, presence of seed crystals, catalysts, membranes, substrates, dehydration, drying, ball milling, etc. In some embodiments, the average particle size of stable vaterite or reactive vaterite or PCC can also depend on one or more precipitation conditions used in the precipitation of the precipitate material. In some embodiments, the percentage of stable vaterite or reactive vaterite in the precipitate material can also depend on one or more precipitation conditions used in the precipitation process.

[0258] For example, the temperature of the CO₂-charged precipitation reaction mixture can be raised to a point where precipitation of the desired precipitate material occurs. In such embodiments, the temperature of the CO₂-charged precipitation reaction mixture can be raised to, for example, from 20 °C to 80 °C, or 20 °C to 50 °C, or 30 °C to 50 °C, or 40 °C to 50 °C, or 50 °C to 60 °C, and including values from 25 °C to 45 °C. While a given set of precipitation conditions can have a temperature in the range from 0 °C to 100 °C, in certain embodiments the temperature can be raised to produce the desired precipitate material. In certain embodiments, energy from a low carbon dioxide emission source or zero carbon dioxide emission source such as solar energy, wind energy, hydroelectric energy, waste heat from the flue gas of a carbon emitter, etc. is used to raise the temperature of the precipitation reaction mixture.

[0259] In some embodiments, the pH of the CO2-charged precipitation reaction mixture can also be increased to an amount suitable for the precipitation of the desired precipitation material. In such embodiments, the pH of the CO2-charged precipitation reaction mixture is increased to an alkaline level for precipitation, where carbonate is preferred over bicarbonate. In some embodiments, the pH of an aqueous solution containing a calcium salt in contact with carbon dioxide gas has an effect on the formation of reactive vaterite, aragonite, calcite, or a combination thereof or PCC. In some embodiments, the precipitation conditions required to form a precipitation material comprising reactive vaterite or PCC include a pH above 7 or 8 or between 7.1 - 8.5 or between 7.5 - 8 or between 7.5 - 8.5 or between 8 - 8.5 or between 7.6 - 8.4, and a contact step of carbon dioxide with an aqueous solution containing a calcium salt to form reactive vaterite or PCC. In some embodiments, the pH can be increased to pH 9 or higher, such as pH 10 or higher, including pH 11 or higher or pH 12.5 or higher.

[0260] Adjusting the major ion ratio during precipitation may affect the properties of the precipitation material. The major ion ratio may have a significant effect on polymorph formation. For example, as the magnesium:calcium ratio in water increases, aragonite can become the major polymorph of calcium carbonate in the precipitation material instead of low-magnesium vaterite. At low magnesium:calcium ratios, low-magnesium calcite can become the major polymorph. In some embodiments, in the presence of both Ca 2+ and Mg 2+ , the ratio of Ca 2+ to Mg 2+ in the precipitation material (i.e., Ca 2+ :Mg 2+ ) is from 1:1 to 1:2.5, 1:2.5 to 1:5, 1:5 to 1:10, 1:10 to 1:25, 1:25 to 1:50, 1:50 to 1:100, 1:100 to 1:150, 1:150 to 1:200, 1:200 to 1:250, 1:250 to 1:500, or 1:500 to 1:1000. In some embodiments, the ratio of Mg 2+ to Ca 2+ in the precipitation material (i.e., Mg 2+ :Ca 2+ ) is from 1:1 to 1:2.5, 1:2.5 to 1:5, 1:5 to 1:10, 1:10 to 1:25, 1:25 to 1:50, 1:50 to 1:100, 1:100 to 1:150, 1:150 to 1:200, 1:200 to 1:250, 1:250 to 1:500, or 1:500 to 1:1000.

[0261] The precipitation rate may also have an impact on the formation of the compound phase, where the fastest precipitation rate is achieved by seeding the solution with the desired phase. In the absence of seeding, rapid precipitation can be achieved by rapidly increasing the pH of the precipitation reaction mixture, which may result in a greater amorphous component. The higher the pH, the faster the precipitation, which may lead to a more amorphous precipitate material.

[0262] The residence time of the reaction mixture after contacting the aqueous solution with CO2 may also have an impact on the formation of the compound phase. For example, in some embodiments, a longer residence time can result in the conversion of reactive vaterite in the reaction mixture to aragonite / calcite. Too short a residence time may result in incomplete formation of reactive vaterite in the reaction mixture. Thus, the residence time may be crucial for the precipitation of reactive vaterite. In addition, the residence time can also affect the particle size of the precipitate. For example, an overly long residence time may result in aggregation of the particles, forming large-sized particles, which is undesirable for PCC formation. Thus, in some embodiments, the residence time of the reaction is between about 10 min and 1 hour, or between about 15 min - 60 min, or between about 15 min - 45 min, or between about 15 min - 30 min, or between about 30 min - 60 min.

[0263] In some embodiments, the set of precipitation conditions for producing the desired precipitate material from the precipitation reaction mixture can include temperature and pH, and in some cases, the concentration of additives and ionic species in the water. The presence and concentration of the additives can also facilitate the formation of stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC. In some embodiments, a medium-chain fatty acid ester or a long-chain fatty acid ester can be added to the aqueous solution during precipitation to form PCC. Examples of fatty acid esters include, but are not limited to, celluloses such as carboxymethyl cellulose, sorbitol, citrates such as sodium citrate or potassium citrate, stearates such as sodium stearate or potassium stearate, phosphates such as sodium phosphate or potassium phosphate, sodium tripolyphosphate, hexametaphosphate, EDTA, or combinations thereof. In some embodiments, a combination of stearate and citrate can be added during the contacting step of the process to form PCC.

[0264] The precipitation conditions can also include factors such as the mixing rate, the form of agitation such as ultrasound, the presence of seeds, catalysts, membranes, or substrates. In some embodiments, the precipitation conditions include supersaturation, temperature, pH, and / or concentration gradients, and cycling or varying any of these parameters. The protocol for preparing the precipitate material according to the embodiments of the present invention can be batch, semi-batch, or continuous. In various embodiments, the precipitation conditions can be different to produce a given precipitate material in a continuous flow system as compared to a semi-batch system or a batch system.

[0265] In some embodiments, the gas exiting the contact / absorber / precipitation reaction / reactor, Figures 2 - 4 shown as the "scrubbing gas" in the figure, is transferred to a gas treatment unit for the scrubbing process. Although not shown in the figure, the treatment unit can be used in any of the processes and systems described in the embodiments of the present invention. The mass balance and equipment design of the gas treatment unit may depend on the nature of the gas. In some embodiments, the gas treatment unit can incorporate an HCl scrubber for recovering a small amount of NH3 in the waste gas stream, and the small amount of NH3 can be carried by the gas from the CO2 absorption and precipitation steps. NH3 can be captured by the HCl solution through:

[0266] NH3(g) + HCl(aqueous solution) →

[0267] NH4Cl(aqueous solution).

[0268] The NH4Cl(aqueous solution) from the HCl scrubber can be recycled back to the solvation step A.

[0269] In some embodiments, the waste gas stream containing ammonia (shown as the "scrubbing gas") can undergo a scrubbing process, where the waste gas stream containing ammonia is scrubbed together with water and carbon dioxide from an industrial process to produce a solution of ammonia. The inlet of the scrubber can be carbon dioxide (CO2(g)), the reactor off-gas containing ammonia (NH3(g)), and fresh make-up water (or some other dilution water stream). The outlet can be a slip stream of the scrubber recycle fluid (such as H3N-CO 2(水溶液) or carbamate), which can optionally be returned to the main reactor for contact with carbon dioxide and precipitation. The pH of the system can be controlled by adjusting the flow rate of CO2(g) entering the scrubber. The conductivity of the system can be controlled by adding diluted make-up water to the scrubber. The volume can be kept constant by using a level detector in the scrubber or its reservoir. Although ammonia is a basic gas, carbon dioxide gas is an acidic gas. In some embodiments, the acidic gas and the basic gas can ionize each other to increase their solubility.

[0270] Therefore, in some embodiments, and without being limited by any theory, the following reaction can occur:

[0271] NH3(aqueous solution) + CO2(aqueous solution) + H2O --> HCO3 - + NH4 + .

[0272] In some embodiments, the system includes a source of an aqueous solution containing a calcium salt from a cement plant and a structure having an inlet for the aqueous solution. For example, the system may include a pipe or a feed for the aqueous solution. The aqueous solution may be brine, seawater, or fresh water. The system may also include an inlet for CO2 from the cement plant, and components for combining these sources with water (optionally an aqueous solution such as water, brine, or seawater) before or in a contacting / precipitation reactor. In some embodiments, the gas-liquid contactor is configured to contact sufficient CO2 to produce more than 1 ton, 10 tons, 100 tons, 1,000 tons, or 10,000 tons of precipitate material per day.

[0273] In some embodiments, the system further includes a contacting / precipitation reactor that subjects the water introduced into the contacting / precipitation reactor to one or more of the precipitation conditions (as described herein) and produces a precipitate material and a supernatant. In some embodiments, the contacting / precipitation reactor is configured to hold sufficient water to produce more than 1 ton, 10 tons, 100 tons, 1,000 tons, or 10,000 tons of precipitate material per day. The contacting / precipitation reactor may also be configured to include any of a number of different components, such as a temperature modulation component configured to heat the water to a desired temperature, a chemical addition component configured to introduce additives, etc. into the precipitation reaction mixture, an automation component, and the like.

[0274] In various embodiments, the gas stream containing CO2 can be provided to the precipitation site from the cement plant in different ways. In some embodiments, the gas stream is provided with a gas conveyance (e.g., a conduit) running from a location on the cement plant site to one or more locations on the precipitation site. The gas stream source can be a distal location relative to the precipitation site such that the gas stream source is a location 1 mile or more, such as 10 miles or more (including 100 miles or more) from the precipitation location. For example, the gas stream containing CO2 may have been conveyed from a remote cement plant to the precipitation site via a CO2 gas conveyance system (e.g., a pipeline). The gas may or may not be processed (e.g., other components removed) before it reaches the precipitation site (i.e., the site where precipitation and / or product generation occurs). In still other embodiments, the gas stream containing CO2 is close to the precipitation site. For example, the precipitation site may be integrated with the gas stream containing CO2, such as a cement plant that integrates a contacting / precipitation reactor for precipitating a precipitate material that can be used to produce a product.

[0275] In embodiments where the salt water source from which the system processes to produce a precipitate is seawater, the input end is in fluid communication with the seawater source, such as in cases where the input end is a pipe or a feed section that is an inlet port from seawater to a land-based system or a hull, for example, in cases where the system is part of a ship, for example, in an ocean-based system.

[0276] Some embodiments include one or more detectors configured to monitor a water source or an aqueous solution source or a carbon dioxide source (not illustrated in the figures). Monitoring can include, but is not limited to, collecting data on the pressure, temperature, and composition of water or carbon dioxide gas. The detector can be a device configured to monitor different physical or chemical quantities, for example, pressure sensors such as electromagnetic pressure sensors, potentiometric pressure sensors, etc., temperature sensors such as resistance temperature detectors, thermocouples, gas thermometers, thermistors, pyrometers, infrared radiation sensors, etc., volume sensors such as geophysical diffraction tomography sensors, X-ray tomography sensors, acoustic water gauges, etc., and devices for determining the chemical composition of water or carbon dioxide gas such as 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.

[0277] In some embodiments, the detector can be integrated with a computer interface configured to provide the user with the collected data on the aqueous medium, the lime-containing mixture, the aqueous solution containing calcium salts, carbon dioxide gas, the second aqueous solution, and / or ammonia. In some embodiments, the summary can be stored as a computer-readable data file or printed as a user-readable document.

[0278] In some embodiments, the detector can be a monitoring device such that it can collect real-time data (e.g., internal pressure, temperature, etc.). In some embodiments, the detector can be one or more detectors configured to determine parameters at regular time intervals, such as determining the composition every 1 minute, every 5 minutes, every 10 minutes, every 30 minutes, every 60 minutes, every 100 minutes, every 200 minutes, every 500 minutes, or some other time interval.

[0279] Separation of the precipitated material

[0280] Some embodiments also include separating (e.g., dehydrating) the precipitated material from the aqueous solution by dehydration, optionally rinsing, and optionally drying, thereby forming a calcium carbonate cake, as Figures 2 - 4as shown in steps 240, 340, and 440 thereof. The precipitated material can then be used to prepare a gelled product or a non-gelled product ( Figures 2 - 4 shown in

[0281] as products 250, 350, 380, 452, and 454). After being produced from the precipitation reaction mixture, the precipitated material is separated from the reaction mixture to produce a separated precipitated material (e.g., a wet cake) and a supernatant, as Figures 2 - 4 illustrated in step D of

[0282] In some embodiments, the separation step can be carried out in a separation station. The precipitated material can be stored in the supernatant for a period of time (e.g., by drying) after precipitation and before separation. For example, the precipitated material can be stored in the supernatant at a temperature in the range from 1 °C to 40 °C, such as from 20 °C to 25 °C, for a period of time in the range from a few minutes to several hours to 1 day to 1000 days or longer, such as from 1 day to 10 days or longer. Separating the precipitated material from the precipitation reaction mixture is achieved using any one of a variety of convenient methods, including draining (e.g., gravitational settling of the precipitated material followed by draining), decantation, filtration (e.g., gravity filtration, vacuum filtration, filtration using forced air), centrifugation, pressing, or any combination thereof. Separating the bulk water from the precipitated material produces a wet cake or a dehydrated precipitated material of the precipitated material. A liquid-solid separator such as the Extrem-Separator ("ExSep") liquid-solid separator of Epuramat, the spiral concentrator of Xerox PARC, or a modification of either the ExSep of Epuramat or the spiral concentrator of Xerox PARC can be used to separate the precipitated material from the precipitation reaction mixture.

[0283] In some embodiments related to processes involving the use of temperature and pressure, a precipitated cake that can be dried and dehydrated can be used. 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 amount of water added back, the temperature, the pressure, the combination of the exposure time, and the thickness of the cake can vary depending on the composition of the starting material and the desired result.

[0284] According to some embodiments, various different ways of exposing materials to temperature and pressure are described; it should be understood that any convenient process can be used. The thickness and size of the cake can be adjusted as needed; in some embodiments, the thickness can vary from 0.05 inches to 5 inches, such as 0.1 - 2 inches or 0.3 - 1 inch. In some embodiments, the cake can be from 0.5 inches to 6 feet or even thicker. Then, by any convenient process, such as in a plate press using heated platens, the cake is exposed to high temperature and / or high pressure for a given period of time. For example, the heat used to raise the temperature of the platen can be provided, for example, by heat from an industrial waste gas stream such as a flue gas stream. The temperature can be any suitable temperature; generally, for thicker cakes, a higher temperature is required. Examples of temperature ranges are 40°C - 150°C, such as 60°C - 120°C, such as 70°C - 110°C, or 80°C - 100°C. Similarly, the pressure can be any suitable pressure that produces the desired result; exemplary pressures include 1000 - 100,000 pounds per square inch (psi), including 2000 psi - 50,000 psi, or 2000 psi - 25,000 psi, or 2000 psi - 20,000 psi, or 3000 psi - 5000 psi. The time for which the cake is pressed can be any suitable time, such as 1 - 100 seconds, or 1 - 100 minutes, or 1 - 50 minutes, or 2 - 25 minutes, or 1 - 10,000 days. The resulting hard sheet can then optionally be cured, for example, by placing it outdoors and storing it, by curing it in a room where they experience a high level of humidity and heat, etc. These optionally cured hard sheets can then be used as building materials or crushed to produce aggregates.

[0285] Another process for providing temperature and pressure is to use a press. A suitable press, such as a plate press, can be used to provide pressure at a desired temperature (using, for example, heat provided by flue gas or by other steps of the process to produce a precipitate, such as a precipitate from an electrochemical process) for a desired period of time. A set of rollers can be used in a similar manner.

[0286] Another way to expose the cake to high temperature and pressure is through an extruder, such as a screw extruder. The barrel of the extruder can be equipped to achieve high temperature, for example, by a jacket equipped to achieve high temperature; such high temperature can be provided by, for example, flue gas or the like. Extrusion can be used as a means to preheat and dry the raw materials before the pressing operation. Such pressing can be carried out by a compression die, via rollers, via rollers with forming indentations (which can provide almost any shape of the desired aggregate), between belts that provide compression as it travels, or any other convenient process.

[0287] Optionally, the extruder can be used to extrude the material through a die, exposing the material to pressure as the material is forced through the die and giving any desired shape. In some embodiments, the carbonate precipitate is mixed with fresh water and then placed into the feed section of a rotary screw extruder. The extruder and / or the exit die can be heated to further assist the process. The rotation of the screw conveys the material along its length and compresses the material as the slice thickness of the screw decreases. The screw and barrel of the extruder can also include vents in the barrel where the decompression zone in the screw coincides with the barrel vent opening. Especially in the case of a heated extruder, these vent areas allow the release of vapors from the conveyed material and the removal of water from the material.

[0288] Then, the material conveyed by the screw can be forced through a die section that further compresses and shapes the material. Typical openings in the die can be circular, oval, square, rectangular, trapezoidal, etc., although any shape required for the final aggregate can be fabricated by adjusting the shape of the opening. The material leaving the die can be cut to any desired length by any convenient process, such as by flying knives. The use of a heated die section can further assist in the formation of the product by accelerating the transformation of the carbonate mineral into a hard and stable form. In the case of an adhesive, the heated die can also be used to harden or solidify the adhesive. Temperatures from 100°C to 600°C are typically used for the heated die section.

[0289] In some embodiments, the precipitate can be used for in-situ or in-place formed structure fabrication. For example, roads, paved areas, or other structures can be formed by applying a layer of the precipitate as described above to a substrate (such as the ground, roadbed, etc.), and then hydrating the precipitate, for example, by allowing the precipitate to be exposed to naturally applied water (such as in the form of rain), or by watering made from the precipitate. The hydration solidifies the precipitate into the desired in-situ or in-place formed structure, such as roads, paved areas, etc. (other examples of products in the figure). For example, in cases where a thicker in-situ formed structure layer is required, the process can be repeated.

[0290] In some embodiments, the resulting dehydrated precipitate material, such as a wet cake material, is used directly to prepare a product (shown in the figures as "Product"). For example, the wet cake of the dehydrated precipitate material is mixed with one or more additives described herein and spread on a conveyor belt, where the reactive vaterite or PCC in the precipitate material is converted to aragonite and / or calcite and solidifies and hardens (and the ammonium salts are thermally removed). The hardened material is then cut into the desired shape, such as the plates or panels described herein. In some embodiments, the wet cake is poured onto a sheet of paper on top of the conveyor belt. Another sheet of paper can be placed on top of the wet cake, and then the wet cake is pressed to remove excess moisture. After the precipitate material has solidified and hardened (e.g., reactive vaterite is converted to aragonite and / or calcite), the material is cut into the desired shape, such as cement wallboards and drywall. In some embodiments, the amount of one or more additives can be optimized according to the desired time required for the conversion of reactive vaterite to aragonite and / or calcite (as described below). For example, for some applications, it may be desirable for the material to convert quickly, and in other cases, a slow conversion may be desirable. In some embodiments, the wet cake can be heated on the conveyor belt to accelerate the conversion of reactive vaterite to aragonite and / or calcite. In some embodiments, the wet cake can be poured into a mold of the desired shape, and then the mold is heated in an autoclave to accelerate the conversion of reactive vaterite to aragonite and / or calcite (and to remove residual ammonium salts). Thus, continuous flow processes, batch processes, or semi-batch processes are all fully within the scope of the present invention.

[0291] In some embodiments, the calcium carbonate cake as described above may contain impurities of ammonium (NH4 + ) ions, sulfide ions, and / or chloride (Cl - ) (e.g., 1%-2% or more by weight). Although rinsing of the precipitated CaCO3 filter cake as described above can remove some or all of the ammonium salts and / or sulfur compounds, it may result in a dilute concentration of ammonium salts (in the supernatant), which may require concentration before recycling it back to the process.

[0292] In some embodiments, the resulting supernatant of the precipitation process or the slurry of the precipitated material can also be processed as needed. For example, the supernatant or slurry can be returned to step 410 of the process or another stage. In some embodiments, as described above, the supernatant can be contacted with CO2 to sequester additional CO2. For example, in embodiments where the supernatant is to be returned to the contact / precipitation reactor, the supernatant can be contacted with a stream of CO2 in a manner sufficient to increase the concentration of carbonate ions present in the supernatant. As described above, any convenient scheme can be used for the contact. In some embodiments, the supernatant has an alkaline pH, and the contact with the CO2 stream is carried out in a manner sufficient to reduce the pH to a range between pH 5 and 9, between pH 6 and 8.5, or between pH 7.5 and 8.2.

[0293] In some embodiments, the calcium carbonate slurry can undergo dehydration and optionally rinsing to form a calcium carbonate slurry (with reduced water) or a calcium carbonate cake (as Figures 2 - 4 illustrated) and water or supernatant containing the residual ammonium salt solution. The residual ammonium chloride solution obtained from the dehydration and rinse streams can optionally be concentrated and then recycled back for treatment with the lime-containing mixture (shown in Figures 2 - 4 . Additional ammonium chloride and / or ammonia (anhydrous or aqueous solution) can be added to the recycled solution to make up for the loss of ammonium chloride during the process and to optimize the concentration of ammonium chloride.

[0294] In some embodiments, residual ammonium salts such as Figures 2 - 4 the ammonium chloride solution illustrated in can be recovered from the supernatant aqueous solution and concentrated using a recovery process such as, but not limited to, thermal decomposition, pH adjustment, reverse osmosis, multistage flash evaporation, 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., with a strong base like NaOH). This may shift the equilibrium towards volatile ammonia (NH3(aq) / NH3(g)). Both the rate and the total removal rate can be increased by heating the solution.

[0295] In some embodiments, the residual ammonium salts can be separated and recovered from the calcium carbonate precipitate by a thermal decomposition process. This process can be incorporated into the Figures 2 - 4 illustrated process when separating the CaCO3 precipitate (step D) and / or after the step of drying the CaCO3 precipitate or powder (step E).

[0296] Typically, at 338 °C, solid NH4Cl can decompose into ammonia (NH3) and hydrogen chloride (HCl) gas. However, at 840 °C, solid CaCO3 decomposes into solid calcium oxide (CaO) and carbon dioxide (CO2) gas.

[0297] NH4Cl (s) ←→NH 3(g) +

[0298] HCl (g) CaCO 3(s )←→

[0299] CaO (s) +CO 2(g)

[0300] In some embodiments, residual ammonium salts in the CaCO3 precipitate and / or the dried CaCO3 precipitate, such as but not limited to ammonium chloride, ammonium sulfate, ammonium sulfite, ammonium hydrosulfide, ammonium thiosulfate, or combinations thereof, can be removed by thermal decomposition at a temperature between 338 °C and 840 °C. This can be done during the normal filter cake drying process and / or as a post-drying heat treatment. Such a temperature range is desired, which decomposes the residual ammonium salts in the precipitate while maintaining the gelling properties of the reactive vaterite in the precipitated material, such that the reactive vaterite remains as reactive vaterite after heating and, upon combination with water, successfully transforms into aragonite to form a gelled product. In some embodiments of the foregoing aspects and embodiments, the step of removing and optionally recovering residual ammonium salts from the precipitated material includes heating the precipitated material to between about 100 °C and 360 °C or between about 150 °C and 360 °C or between about 200 °C and 360 °C or between about 250 °C and 360 °C or between about 300 °C and 360 °C or between about 150 °C and 200 °C or between about 100 °C and 200 °C or between about 200 °C and 300 °C or between about 290 °C and 375 °C or between about 300 °C and 350 °C or between about 310 °C and 345 °C or between about 320 °C and 345 °C or between about 330 °C and 345 °C or between about 300 °C and 345 °C to evaporate the ammonium salts from the precipitated material and optionally recover them by concentrating the ammonium salts. In some embodiments of the foregoing aspects and embodiments, the step of removing and optionally recovering residual ammonium salts from the precipitated material includes heating the precipitated material for a duration of more than about 10 min or more than about 15 min or more than about 5 min or between about 10 min and about 1 hour or between about 10 min and about 1.5 hours or between about 10 min and about 2 hours or between about 10 min and about 5 hours or between about 10 min and about 10 hours.

[0301] Step E: Drying of the precipitate

[0302] In some embodiments, the resulting dehydrated precipitate material obtained from the separation station is dried at a drying station to produce a powder form of the precipitate material comprising calcium carbonate (step E in the figure), wherein the calcium carbonate comprises vaterite (stable vaterite or reactive vaterite), aragonite, calcite, or a combination thereof or PCC. Drying can be achieved by air-drying the precipitate material. In certain embodiments, drying is achieved by freeze-drying (i.e., lyophilization), wherein the precipitate material is frozen, the surrounding pressure is reduced, and sufficient heat is added to allow the frozen water in the precipitate material to directly sublime into a gas. In yet another embodiment, the precipitate material is spray-dried to dry the precipitate material, wherein the liquid comprising the precipitate material is dried by feeding the liquid through a hot gas (such as a gaseous waste stream from a power plant), and wherein the liquid feed is pumped into the main drying chamber through an atomizer, and the hot gas flows as a co-current or counter-current towards the direction of the atomizer.

[0303] The calcium carbonate slurry can be pumped via a pump to a drying system, which in some embodiments includes a filtration step followed by spray-drying. The water separated from the drying system can be discharged or can be recycled to the reactor. The resulting solid or powder from the drying system is used as cement or aggregate to produce building materials, effectively chelating clean CO2. The solid or powder can also be used as a PCC filler in non-cementitious products such as paper, plastics, paints, etc. The solid or powder can also be used to form shaped building materials such as drywall, cement boards, etc.

[0304] Depending on the specific drying scheme of the system, the drying station can 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, when appropriate, waste heat from a power plant or similar operation can be used to perform the drying step. For example, in some embodiments, a dried product is produced by using high temperature (e.g., waste heat from a power plant), pressure, or a combination thereof. After the precipitate material is dried, the material can then be heated at a high temperature to remove the ammonium salts as described herein, and reactive vaterite is obtained after heating. In some of the foregoing embodiments, it is desirable that the reactive vaterite in the precipitate material remains as reactive vaterite so as to maintain the cementitious properties of the material. In some embodiments, the ammonium salts evaporate from the precipitate material in the form of ammonia gas, hydrogen chloride gas, chlorine gas, or a combination thereof.

[0305] In some embodiments, the combination of the amount of the temperature and duration maintained during heating may be crucial for removing ammonium salts from the precipitated material and maintaining the gelling properties of the reactive vaterite material. Conventionally, reactive vaterite is highly unstable and prone to conversion to aragonite and / or calcite. The temperature range, optionally combined with the heating duration, can minimize the conversion of reactive vaterite while removing residual ammonium salts from the material. In some of the foregoing embodiments, the vaterite in the precipitated material remains as reactive vaterite after removal of the ammonium salts, and this reactive vaterite converts to aragonite and / or calcite (dissolution-reprecipitation process) upon combination with water, and the aragonite and / or calcite solidify and gel to form a gelled product. The gelled product thus formed has a minimal chloride content or no chloride content and no foul odor of ammonia or sulfur. In some embodiments, the chloride content is about or below the acceptable ASTM standard for the gelled product.

[0306] In some embodiments, the temperature conditions described above, optionally combined with the duration of heating, can be combined with pressure conditions that provide a driving force to improve the thermodynamics of the decomposition of the residual ammonium salts. For example, heating of the precipitated material can be carried out in a system where the headspace is at a pressure below atmospheric pressure. By reducing the partial pressure of the reactants in the gas phase, a pressure below atmospheric pressure can create a driving force for heating reactions involving gas-phase products such as, but not limited to, ammonia gas, hydrogen chloride gas, chlorine gas, or combinations thereof. Another advantage of operating under reduced pressure or vacuum may be that at lower pressures, some sublimation reactions may occur at lower temperatures, thereby improving the energy requirements of the heating reaction.

[0307] In some embodiments of the thermal decomposition process described above, the separated ammonium chloride in the form of ammonia and HCl gas can be recovered for reuse by recrystallization of the combined evolved gases or by absorption of the gases into an aqueous medium. Both of these mechanisms can result in the NH4Cl product being concentrated enough to be reused in the process as Figures 2 - 4 shown.

[0308] In some embodiments, ammonium salts can be separated and recovered by pH-regulated precipitation from ammonium salts in the processes described herein (or as Figures 2 - 4 illustrated in). When separating and / or drying the CaCO3 cake, this process can be incorporated into the process illustrated in Figures 2 - 4 herein. The final pH of the water in the filter cake can typically be about 7.5. At this pH, NH4 + (pKa = 9.25) may be the major species. Increasing the pH of this water can drive the acid-base equilibrium towards NH3 gas, as described in the following equation:

[0309] NH4+ ←→H + +NH 3(g) 。

[0310] Any source of alkalinity can be used to increase the pH of the filter cake water. In some embodiments, an aqueous solution of calcium oxide and / or hydroxide or a limestone slurry can provide a high alkalinity source. In some embodiments, the aqueous fraction of calcium oxide can be incorporated into the rinse stage (e.g., the filter cake step) of the dewatering process to increase the pH of the system and drive the evolution of NH3 gas. Since ammonia has a high solubility in water, heat and / or vacuum pressure can be applied to further drive the equilibrium towards the gas phase. Ammonia can be recovered for reuse by recrystallizing ammonia with chloride or by absorbing ammonia into an aqueous medium. Both mechanisms can result in the ammonia solution or NH4Cl product being concentrated enough to be reused in the processes described herein.

[0311] In one aspect, the system provided herein further includes a recovery system to recover residual ammonium salts from the aqueous solution for recycling back to the contact reactor. The recovery system is a system configured to perform thermal decomposition, reverse osmosis, multistage flash evaporation, multiple effect distillation, vapor recompression, distillation, and combinations thereof.

[0312] The calcium carbonate cake (e.g., vaterite or PCC) can be sent to a dryer ( Figures 2 - 4 step E therein) to form a calcium carbonate powder comprising stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC. The powder form of the precipitated material comprising stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC can be further used in applications to form products as described herein. Any drying technique known in the art can be used to dry the cake, such as but not limited to a fluidized bed dryer or a vortex fluidizer. The resulting solid powder is then mixed with additives to make the different products described herein. In some embodiments, the slurry form with reduced water or the cake form of the precipitated material is directly used to form products, such as building panels, as described herein.

[0313] In some embodiments, the production of the precipitated material and the product is carried out in the same facility. In some embodiments, the precipitated material is produced in one facility and transported to another facility to prepare the final product. The precipitated material can be transported in the form of a slurry, a wet cake, or a dry powder.

[0314] In some embodiments of the foregoing aspects and embodiments, the vaterite composition or the precipitated material containing vaterite (after precipitation in step C, after separation in step D, and / or after drying in step E) comprises at least 10% w / w vaterite, or at least 20% w / w vaterite, or at least 30% w / w vaterite, or at least 40% w / w vaterite, or at least 50% w / w vaterite, or at least 60% w / w vaterite, or at least 70% w / w vaterite, or at least 80% w / w vaterite, or at least 90% w / w vaterite, or at least 95% w / w vaterite, or at least 99% w / w vaterite, or from 10% w / w to 99% w / w vaterite, or from 10% w / w to 90% w / w vaterite, or from 10% w / w to 80% w / w vaterite, or from 10% w / w to 70% w / w vaterite, or from 10% w / w to 60% w / w vaterite, or from 10% w / w to 50% w / w vaterite, or from 10% w / w to 40% w / w vaterite, or from 10% w / w to 30% w / w vaterite, or from 10% w / w to 20% w / w vaterite, or from 20% w / w to 99% w / w vaterite, or from 20% w / w to 95% w / w vaterite, or from 20% w / w to 90% w / w vaterite, or from 20% w / w to 75% w / w vaterite, or from 20% w / w to 50% w / w vaterite, or from 30% w / w to 99% w / w vaterite, or from 30% w / w to 95% w / w vaterite, or from 30% w / w to 90% w / w vaterite, or from 30% w / w to 75% w / w vaterite, or from 30% w / w to 50% w / w vaterite, or from 40% w / w to 99% w / w vaterite, or from 40% w / w to 95% w / w vaterite, or from 40% w / w to 90% w / w vaterite, or from 40% w / w to 75% w / w vaterite, or from 50% w / w to 99% w / w vaterite, or from 50% w / w to 95% w / w vaterite, or from 50% w / w to 90% w / w vaterite, or from 50% w / w to 75% w / w vaterite, or from 60% w / w to 99% w / w vaterite, or from 60% w / w to 95% w / w vaterite, or from 60% w / w to 90% w / w vaterite, or from 70% w / w to 99% w / w vaterite, or from 70% w / w to 95% w / w vaterite, or from 70% w / w to 90% w / w vaterite, or from 80% w / w to 99% w / w vaterite, or from 80% w / w to 95% w / w vaterite, or from 80% w / w to 90% w / w vaterite, or from 90% w / w to 99% w / w vaterite, or 10% w / w vaterite, or 20% w / w vaterite, or 30% w / w vaterite, or 40% w / w vaterite, or 50% w / w vaterite, or 60% w / w vaterite, or 70% w / w vaterite,or 75% w / w vaterite, or 80% w / w vaterite, or 85% w / w vaterite, or 90% w / w vaterite, or 95% w / w vaterite, or 99% w / w vaterite. The above vaterite may be stable vaterite or reactive vaterite and / or PCC. In some embodiments, the balance may be aragonite, calcite, or a combination thereof.

[0315] In some embodiments, the precipitated material comprising vaterite (after precipitation in step C, after separation in step D, and / or after drying in step E) is a particulate composition having an average particle size of 0.1 micrometer to 100 micrometers. The average particle size (or average particle diameter) can be determined using any conventional particle size determination process, such as but not limited to multi-detector light scattering or laser diffraction or sieving. In certain embodiments, there is a unimodal distribution or a multimodal distribution, such as a bimodal distribution or other distributions. A bimodal distribution can allow the surface area to be minimized, thus allowing a lower liquid / solid mass ratio when the vaterite composition is mixed with water, while providing smaller reactive particles for early reactions. In some embodiments, the vaterite composition or precipitated material provided herein is an average particle size of 0.1 micrometer to 1000 micrometers, or 0.1 micrometer to 500 micrometers, or 0.1 micrometer to 100 micrometers, or 0.1 micrometer to 50 micrometers, or 0.1 micrometer to 20 micrometers, or 0.1 micrometer to 10 micrometers, or 0.1 micrometer to 5 micrometers, or 1 micrometer to 50 micrometers, or 1 micrometer to 25 micrometers, or 1 micrometer to 20 micrometers, or 1 micrometer to 10 micrometers, or 1 micrometer to 5 micrometers, or 5 micrometers to 70 micrometers, or 5 micrometers to 50 micrometers, or 5 micrometers to 20 micrometers, or 5 micrometers to 10 micrometers, or 10 micrometers to 100 micrometers, or 10 micrometers to 50 micrometers, or 10 micrometers to 20 micrometers, or 10 micrometers to 15 micrometers, or 15 micrometers to 50 micrometers, or 15 micrometers to 30 micrometers, or 15 micrometers to 20 micrometers, or 20 micrometers to 50 micrometers, or 20 micrometers to 30 micrometers, or 30 micrometers to 50 micrometers, or 40 micrometers to 50 micrometers, or 50 micrometers to 100 micrometers, or 50 micrometers to 60 micrometers, or 60 micrometers to 100 micrometers, or 60 micrometers to 70 micrometers, or 70 micrometers to 100 micrometers, or 70 micrometers to 80 micrometers, or 80 micrometers to 100 micrometers, or 80 micrometers to 90 micrometers, or 0.1 micrometer, or 0.5 micrometer, or 1 micrometer, or 2 micrometers, or 3 micrometers, or 4 micrometers, or 5 micrometers, or 8 micrometers, or 10 micrometers, or 15 micrometers, or 20 micrometers, or 30 micrometers, or 40 micrometers, or 50 micrometers, or 60 micrometers, or 70 micrometers, or 80 micrometers, or 100 micrometers particulate composition. For example, in some embodiments, the vaterite composition or precipitated material provided herein is an average particle size of 0.1 micrometer to 20 micrometers, or 0.1 micrometer to 15 micrometers, or 0.1 micrometer to 10 micrometers, or 0.1 micrometer to 8 micrometers, or 0.1 micrometer to 5 micrometers, or 1 micrometer to 25 micrometers, or 1 micrometer to 20 micrometers, or 1 micrometer to 15 micrometers, or 1 micrometer to 10 micrometers, or 1 micrometer to 5 micrometers, or 5 micrometers to 20 micrometers, or 5 micrometers to 10 micrometers particulate composition.In some embodiments, the vaterite composition or precipitate material includes two or more, or three or more, or four or more, or five or more, or ten or more, or 20 or more, or 3 - 20, or 4 - 10 different sized particles in the composition or precipitate material. For example, the vaterite composition or precipitate material can include two or more, or three or more, or between 3 - 20 particles that are in the range from 0.1 micron - 10 microns, 10 microns - 50 microns, 50 microns - 100 microns, 100 microns - 200 microns, 200 microns - 500 microns, 500 microns - 1000 microns, and / or sub - micron size. In some embodiments, the PCC in the precipitate material can have an average particle size of less than 0.1 micron, such as between 0.001 micron and 1 micron or greater. In some embodiments, the PCC can be in nano - particle size. The reactive vaterite is converted to aragonite and / or calcite.

[0316] As Figures 2 - 4 As illustrated, the process produces a precipitate material (in wet form, slurry form, or dry form) that contains stable vaterite, reactive vaterite, aragonite, calcite, or a combination thereof or PCC. "Composition", "precipitate", and "precipitate material" are used interchangeably herein. As described herein, the precipitate material formed in the process and system after optionally removing residual ammonium salts contains vaterite, aragonite, calcite, or a combination thereof or PCC. "Stable vaterite" includes vaterite that does not convert to aragonite and / or calcite during and / or after the dissolution - reprecipitation process. "Reactive vaterite" or "activated vaterite" includes vaterite that results in the formation of aragonite and / or calcite during and / or after the dissolution - reprecipitation process. In some embodiments, the PCC formed is in vaterite form. In some embodiments, the precipitate material contains vaterite and also contains aragonite, calcite, or a combination thereof. In some embodiments, the precipitate material contains aragonite and also contains vaterite, calcite, or a combination thereof. In some embodiments, the precipitate material contains calcite and also contains vaterite, aragonite, or a combination thereof. In some embodiments, the precipitate material contains vaterite, where the vaterite is stable vaterite and / or reactive vaterite. In some embodiments, the precipitate material contains aragonite. In some embodiments, the precipitate material contains calcite.

[0317] In some embodiments, the process described herein further includes contacting the precipitate material (in dry form or wet form) with water and converting the reactive vaterite to aragonite and / or calcite. In some embodiments, the stable vaterite does not convert to aragonite when contacted with water and remains in vaterite form or converts to calcite over a long period of time.

[0318] In some embodiments, a precipitated material comprising reactive vaterite (optionally including solids) undergoes a transformation (dissolution-reprecipitation) to aragonite and / or calcite upon contact with water and solidifies and hardens into a gelled product (shown as “product” in Figures 2 - 4 ).

[0319] In some embodiments, solids (such as described herein) can be incorporated into calcite. In some embodiments, solid impurities do not adversely affect the strength of the gelled product (such as compressive strength or flexural strength). In fact, it has been anticipated that impurities from limestone such as silica constituting the solid can promote pozzolanic properties during the gelling process.

[0320] The transformation of a precipitated material comprising aragonite or reactive vaterite to aragonite can endow the product with one or more unique properties, including but not limited to high compressive strength, complex microstructure network, neutral pH, etc. In some embodiments, vaterite in the precipitated material can be formed under suitable conditions such that the vaterite is stable and used as a filler in various applications. In some embodiments, PCC in the precipitated material can be formed under suitable conditions such that the PCC is of high purity and very small-sized particles.

[0321] Typically, upon precipitation of calcium carbonate, amorphous calcium carbonate (ACC) can initially precipitate and transform into one or more of its three more stable phases (vaterite, aragonite, or calcite). There may be a thermodynamic driving force for the transformation from the unstable phase to the more stable phase. For this reason, the calcium carbonate phases transform in the following order: ACC to vaterite, aragonite, and calcite, where intermediate phases may or may not be present. This inherent energy can be utilized to generate a strong aggregation tendency and surface interactions, which may lead to aggregation and solidification or gelling.

[0322] The processes and systems provided herein produce or separate a precipitated material comprising vaterite, aragonite, calcite, or a combination thereof or in the form of PCC, which can exist in the form of vaterite, aragonite, or calcite. The precipitated material can be in a wet form, slurry form, or dry powder form. Such a precipitated material can have a stable vaterite form that is not easily transformed into any other polymorph, or can have a reactive vaterite form that transforms into aragonite and / or calcite form. The aragonite form may not further transform into the more stable calcite form. Products containing precipitates in the aragonite form exhibit one or more unexpected properties, including but not limited to high compressive strength, high porosity (low density or light weight), neutral pH (usable as an artificial reef as described below), microstructure network, etc.

[0323] Other minor polymorphic forms of calcium carbonate that may be present in the precipitated material include, but are not limited to, amorphous calcium carbonate, precursor phases of vaterite, precursor phases of aragonite, intermediate phases less stable than calcite, polymorphic forms between these polymorphs, or combinations thereof.

[0324] Vaterite can exist in a monodisperse form or an aggregated form and can be spherical, ellipsoidal, plate-like in shape, or hexagonal. Vaterite typically has a hexagonal crystal structure and forms polycrystalline spherical particles upon growth. The precursor form of vaterite contains nanoclusters of vaterite, and the precursor form of aragonite contains submicron to nanoclusters of aragonite needles. Aragonite, if present in the composition, can be in the form of needles, columns, or orthorhombic crystals. Calcite, if present in the composition, can be in the form of cubes, spindles, or hexagonal crystals. Intermediate phases less stable than calcite can be phases between vaterite and calcite, between the precursor of vaterite and calcite, between aragonite and calcite, and / or between the precursor of aragonite and calcite.

[0325] The transformation between calcium carbonate polymorphs can occur via solid-state transformation, can be solution-mediated, or both. In some embodiments, the transformation is solution-mediated because it may require less energy than thermally activated solid-state transformation. Vaterite is metastable, and the difference in the thermodynamic stability of calcium carbonate polymorphs can manifest as a difference in solubility, where the least stable phase is the most soluble (Ostwald, supra). Thus, vaterite can readily dissolve in solution and advantageously transform towards more stable polymorphs such as aragonite. In a polymorphic system like calcium carbonate, two kinetic processes may occur simultaneously in solution: dissolution of the metastable phase and growth of the stable phase. In some embodiments, when vaterite undergoes dissolution in an aqueous medium, aragonite crystals can grow.

[0326] In some embodiments, a precipitated material containing vaterite, such as prepared by the processes described herein, is transformed into aragonite and solidifies and hardens after treatment with an aqueous medium under one or more suitable conditions. The aqueous medium includes, but is not limited to, fresh water, or brine, optionally containing additives. In some embodiments, one or more suitable conditions include, but are not limited to, temperature, pressure, the period of time for solidification, the ratio of the aqueous medium to the composition, and combinations thereof. The temperature may be related to the temperature of the aqueous medium. In some embodiments, the temperature ranges from 0 °C to 110 °C, or 0 °C to 80 °C, or 0 °C to 60 °C, or 0 °C to 40 °C, or 25 °C to 100 °C, or 25 °C to 75 °C, or 25 °C to 50 °C, or 37 °C to 100 °C, or 37 °C to 60 °C, or 40 °C to 100 °C, or 40 °C to 60 °C, or 50 °C to 100 °C, or 50 °C to 80 °C, or 60 °C to 100 °C, or 60 °C to 80 °C, or 80 °C to 100 °C. In some embodiments, the pressure is atmospheric pressure or above atmospheric pressure. In some embodiments, the period of time for the cement product to solidify is from 30 minutes to 48 hours, or 30 minutes to 24 hours, or 30 minutes to 12 hours, or 30 minutes to 8 hours, or 30 minutes to 4 hours, or 30 minutes to 2 hours, 2 hours to 48 hours, or 2 hours to 24 hours, or 2 hours to 12 hours, or 2 hours to 8 hours, or 2 hours to 4 hours, 5 hours to 48 hours, or 5 hours to 24 hours, or 5 hours to 12 hours, or 5 hours to 8 hours, or 5 hours to 4 hours, or 5 hours to 2 hours, or 10 hours to 48 hours, or 10 hours to 24 hours, or 24 hours to 48 hours.

[0327] In one aspect, reactive vaterite can be activated such that the reactive vaterite results in an aragonite pathway rather than a calcite pathway during the dissolution-reprecipitation process. In some embodiments, a composition containing reactive vaterite is activated in such a way that after the dissolution-reprecipitation process, the formation of aragonite is enhanced and the formation of calcite is inhibited. The activation of a composition containing reactive vaterite can lead to the control of the formation and crystal growth of aragonite. The activation of a composition containing vaterite can be achieved by various processes. Multiple examples of the activation of vaterite are described herein, such as, but not limited to, nuclear activation, thermal activation, mechanical activation, chemical activation, or combinations thereof. In some embodiments, vaterite is activated by multiple processes such that the formation of aragonite and its morphology and / or crystal growth can be controlled when the composition containing vaterite reacts with water. The aragonite formed results in a product formed from reactive vaterite having higher tensile strength and fracture tolerance.

[0328] In some embodiments, reactive vaterite can be activated by mechanical means, as described herein. For example, a composition comprising reactive vaterite can be activated by creating surface defects on the vaterite composition such that aragonite formation is accelerated. In some embodiments, the activated vaterite is ball-milled reactive vaterite or reactive vaterite having surface defects such that the aragonite formation pathway is promoted.

[0329] Compositions comprising reactive vaterite can also be activated by providing chemical activation or nucleation activation to the vaterite composition. Such chemical activation or nucleation activation can be provided by one or more of aragonite seeds, inorganic additives, or organic additives. The aragonite seeds present in the compositions provided herein can be obtained from natural sources or synthetic sources. Natural sources include, but are not limited to, reef sand; limestone; the hard skeletal materials of certain freshwater and marine invertebrate organisms, including brachiopods, gastropods, mollusk shells, and the calcareous endoskeletons of warm-water and cold-water corals; pearls; rocks; sediments; ore minerals (such as serpentine) and the like. Synthetic sources include, but are not limited to, precipitated aragonite, such as aragonite formed from sodium carbonate and calcium chloride; or aragonite formed by the transformation of vaterite to aragonite, such as the transformed vaterite described herein.

[0330] In some embodiments, the inorganic additives or organic additives in the compositions provided herein include, but are not limited to, 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, dextrose, 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, sodium citrate dehydrate, sodium bicarbonate, magnesium sulfate, magnesium acetate, sodium polystyrene sulfonate, sodium dodecyl sulfate, polyvinyl alcohol, or combinations thereof. In some embodiments, the inorganic additives or organic additives in the compositions provided herein include, but are not limited to, taurine, creatine, poly(n-vinyl-1-pyrrolidone), lauric acid, sodium salt of lauric acid, urea, magnesium chloride, acetic acid, sodium salt of acetic acid, strontium chloride, magnesium sulfate, magnesium acetate, or combinations thereof. In some embodiments, the inorganic additives or organic additives in the compositions provided herein include, but are not limited to, magnesium chloride, magnesium sulfate, magnesium acetate, or combinations thereof.

[0331] Without being bound by any theory, it is expected that activating vaterite by ball milling or by adding vaterite seeds, inorganic additives, or organic additives, or combinations thereof, can result in controlling the formation of aragonite during the dissolution-precipitation process of the activated reactive vaterite, including controlling properties such as, but not limited to, polymorph, morphology, particle size, crosslinking, agglomeration, coagulation, aggregation, deposition, crystallography, inhibiting growth along a certain face of the crystal, allowing growth along a certain face of the crystal, or combinations thereof. For example, vaterite seeds, inorganic additives, or organic additives can selectively target the morphology of aragonite, inhibit calcite growth, and promote the formation of aragonite, the formation of which may generally be kinetically unfavorable.

[0332] In some embodiments, one or more inorganic additives can be added to promote the transformation of vaterite to aragonite. One or more additives can be added during any step of the process. For example, one or more additives can be added during the contact of the first aqueous solution with the stream containing clean carbon dioxide; after the contact of the first aqueous solution with the stream containing clean carbon dioxide; during the precipitation of the precipitated material, in the slurry after the precipitated material has precipitated, in the slurry after the precipitated material has been dehydrated, in the powder after the slurry has been dried, in the aqueous solution to be mixed with the powdered precipitated material, or in the slurry made from the powdered precipitated material and water, or any combination thereof. In some embodiments, the water used in the process of preparing the precipitated material 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.

[0333] In some embodiments, in the foregoing process, 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 greater than 4.5% by weight, or greater 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 0.5% - 2% by weight, or 0.5% - 1% by weight, or 1% - 3% by weight, or 1% - 2.5% by weight, or 1% - 2% by weight, or 1.5% - 2.5% by weight, or 2% - 3% by weight, or 2.5% - 3% by weight, or 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, in the foregoing process, 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.

[0334] In some embodiments, the precipitated material or vaterite composition is in powder form. In some embodiments, the precipitated material or vaterite composition is in dry powder form. In some embodiments, the precipitated material or vaterite composition is disordered or not in an ordered array or is in powder form. In still some embodiments, the precipitated material or vaterite composition is in a partially hydrated form or a fully hydrated form. In still some embodiments, the precipitated material or vaterite composition is in salt water or fresh water. In still some embodiments, the precipitated material or vaterite composition is in water containing sodium chloride. In still some embodiments, the precipitated material or vaterite composition is in water containing alkaline earth metal ions such as, but not limited to, calcium, magnesium, etc. In some embodiments, the precipitated material or vaterite composition is non-medical or not used in medical procedures. A product is formed from the precipitated material.

[0335] Precipitated materials containing calcium carbonate (in the form of a wet cake or dry form) can be combined with other materials to form a composition that can be used to form a product, and the calcium carbonate includes vaterite, aragonite, calcite, or a combination thereof. Products made from the compositions or precipitated materials provided herein (also shown in the drawings) exhibit one or more properties such as high compressive strength, high durability, high porosity (light weight), high flexural strength, and lower maintenance costs. In some embodiments, the composition or precipitated material has a compressive strength of at least 3 MPa (megapascals), or at least 7 MPa, or at least 10 Mpa, or in some embodiments between 3 MPa and 30 MPa, or between 14 MPa and 80 MPa, or between 14 MPa and 35 MPa when combined with water, solidified, and hardened (e.g., reactive vaterite transforms into aragonite and / or calcite).

[0336] Products produced by the processes described herein can be aggregates or building materials or prefabricated materials or formed building materials. In some embodiments, products produced by the processes described herein include non-cementitious materials such as paper, paint, PVC, etc. In some embodiments, products produced by the methods described herein include artificial reefs. These products have been described herein.

[0337] In some embodiments of the foregoing aspects and foregoing embodiments, the precipitated material comprising calcium carbonate (comprising vaterite, aragonite, calcite, or a combination thereof) has a compressive strength of at least 3 MPa, at least 7 MPa, at least 14 MPa, or at least 16 MPa, or at least 18 MPa, or at least 20 MPa, or at least 25 MPa, or at least 30 MPa, or at least 35 MPa, or at least 40 MPa, or at least 45 MPa, or at least 50 MPa, or at least 55 MPa, or at least 60 MPa, or at least 65 MPa, or at least 70 MPa, or at least 75 MPa, or at least 80 MPa, or at least 85 MPa, or at least 90 MPa, or at least 95 MPa, or at least 100 MPa, or from 3 - 50 MPa, or from 3 - 25 MPa, or from 3 - 15 MPa, or from 3 - 10 MPa, or from 14 - 25 MPa, or from 14 - 100 MPa, or from 14 - 80 MPa, or from 14 - 75 MPa, or from 14 - 50 MPa, or from 14 - 25 MPa, or from 17 - 35 MPa, or from 17 - 25 MPa, or from 20 - 100 MPa, or from 20 - 75 MPa, or from 20 - 50 MPa, or from 20 - 40 MPa, or from 30 - 90 MPa, or from 30 - 75 MPa, or from 30 - 60 MPa, or from 40 - 90 MPa, or from 40 - 75 MPa, or from 50 - 90 MPa, or from 50 - 75 MPa, or from 60 - 90 MPa, or from 60 - 75 MPa, or from 70 - 90 MPa, or from 70 - 80 MPa, or from 70 - 75 MPa, or from 80 - 100 MPa, or from 90 - 100 MPa, or from 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 after being combined with water, solidified, and hardened (i.e., reactive vaterite is transformed into aragonite and / or calcite), or after stable vaterite is mixed with cement and water and solidified and hardened to form a product. For example, in some embodiments of the foregoing aspects and foregoing embodiments, the composition 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 after solidifying and hardening to form a product. 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.

[0338] In some embodiments, the precipitated material produced by the processes described herein is used as a construction material (e.g., a construction material for certain types of man-made structures such as buildings, roads, bridges, dams, and the like), such that CO2 is effectively sequestered in the built environment. Any man-made structure, such as a foundation, parking structure, house, office building, commercial office, government building, infrastructure (e.g., sidewalks; roads; bridges; overpasses; walls; footings for gates, fences, and utility poles; and the like) is considered part of the built environment. Mortar finds application in binding construction blocks (e.g., bricks) together and filling the gaps between construction blocks. Mortar can also be used to secure existing structures (e.g., to replace sections where the original mortar has become damaged or eroded) and for other uses.

[0339] In some embodiments, the aggregate is produced from the resulting precipitated material. In such embodiments, little to no additional processing is required to produce the aggregate if the drying process yields particles of the desired size. In still other embodiments, further processing of the precipitated material is carried out to produce the desired aggregate. For example, vaterite in dry form can be combined with fresh water in a manner sufficient to cause the vaterite to form a solid product, where the reactive vaterite is converted to aragonite and / or calcite. By controlling the water content of the wet material, the porosity as well as the final strength and density of the resulting aggregate can be controlled. Typically, the wet cake can be 40 vol% - 60 vol% water. For denser aggregates, the wet cake can be <50% water, and for less dense cakes, the wet cake can be >50% water. After hardening, the resulting solid product can then be mechanically processed, e.g., crushed or otherwise broken and sorted, to produce an aggregate with desired properties such as size, specific shape, etc.

[0340] In these processes, the setting step and the mechanical processing step can be carried out in a substantially continuous manner or at separate times. In certain embodiments, large quantities of compositions containing vaterite, aragonite, calcite, or combinations thereof can be stored in an open environment where the composition is exposed to the atmosphere. For the setting step, the vaterite can be watered with fresh water in a convenient manner or allowed to be rained on naturally in order to produce a set product. The set product can then be mechanically processed as described above. After the production of vaterite, the vaterite is processed to produce the desired aggregate. In some embodiments, the vaterite can be left outdoors where rainwater can be used as a source of fresh water to cause the atmospheric water stabilization reaction to occur, hardening the precipitate to form the aggregate.

[0341] In some embodiments, the compositions provided herein comprise a precipitated material comprising calcium carbonate and ordinary Portland cement (OPC) or Portland cement clinker, wherein the calcium carbonate comprises vaterite, aragonite, calcite, or a combination thereof. The amount of the Portland cement component can vary and is in the range from 10% w / w to 95% w / w, or 10% w / w to 90% w / w, or 10% w / w to 80% w / w, or 10% w / w to 70% w / w, or 10% w / w to 60% w / w, or 10% w / w to 50% w / w, or 10% w / w to 40% w / w, or 10% w / w to 30% w / w, or 10% w / w to 20% w / w, or 20% w / w to 90% w / w, or 20% w / w to 80% w / w, or 20% w / w to 70% w / w, or 20% w / w to 60% w / w, or 20% w / w to 50% w / w, or 20% w / w to 40% w / w, or 20% w / w to 30% w / w, or 30% w / w to 90% w / w, or 30% w / w to 80% w / w, or 30% w / w to 70% w / w, or 30% w / w to 60% w / w, or 30% w / w to 50% w / w, or 30% w / w to 40% w / w, or 40% w / w to 90% w / w, or 40% w / w to 80% w / w, or 40% w / w to 70% w / w, or 40% w / w to 60% w / w, or 40% w / w to 50% w / w, or 50% w / w to 90% w / w, or 50% w / w to 80% w / w, or 50% w / w to 70% w / w, or 50% w / w to 60% w / w, or 60% w / w to 90% w / w, or 60% w / w to 80% w / w, or 60% w / w to 70% w / w, or 70% w / w to 90% w / w, or 70% w / w to 80% w / w. For example, the vaterite composition comprises a blend of 75% OPC and 25% vaterite, or 80% OPC and 20% vaterite, or 85% OPC and 15% vaterite, or 90% OPC and 10% vaterite, or 95% OPC and 5% vaterite.

[0342] In certain embodiments, the composition comprises a precipitated material comprising calcium carbonate and an aggregate, the calcium carbonate comprising vaterite, aragonite, calcite, or a combination thereof. The aggregate can be included in the composition or the precipitated material to provide a mortar comprising fine aggregate and a concrete further comprising coarse aggregate. Fine aggregate is material that passes almost entirely through a No. 4 sieve (ASTM C 125 and ASTM C 33), such as silica sand. Coarse aggregate is material that is retained primarily on a No. 4 sieve (ASTM C 125 and ASTM C 33), such as silica, quartz, crushed round marble, glass spheres, granite, limestone, calcite, feldspar, alluvial sand, sand, or any other durable aggregate and mixtures thereof. Thus, the term "aggregate" is used broadly to refer to both many different types of coarse-grained and fine-grained materials, including but not limited to sand, gravel, crushed stone, slag, and recycled concrete. The amount and nature of the aggregate can vary widely. In some embodiments, the amount of aggregate can range from 25% w / w to 80% w / w of the total composition consisting of both the composition and the aggregate, such as 40% w / w to 70% w / w, and including 50% w / w to 70% w / w.

[0343] During mixing of the composition or the precipitated material comprising calcium carbonate (the calcium carbonate comprising vaterite, aragonite, calcite, or a combination thereof) with an aqueous medium (e.g., for converting reactive vaterite to aragonite and / or calcite), the precipitate can be subjected to a high-shear mixer. After mixing, the precipitate can be dehydrated again and placed in a preformed mold to produce a shaped building material, or can be used to produce a shaped building material using processes well known in the art or as described herein. Alternatively, the precipitate can be mixed with water and allowed to solidify. The precipitate can solidify over a period of several days and can then be placed in an oven for drying, e.g., at 40 °C, or from 40 °C - 60 °C, or from 40 °C - 50 °C, or from 40 °C - 100 °C, or from 50 °C - 60 °C, or from 50 °C - 80 °C, or from 50 °C - 100 °C, or from 60 °C - 80 °C, or from 60 °C - 100 °C. The precipitate can be cured at elevated temperatures, such as from 50 °C - 60 °C, or from 50 °C - 80 °C, or from 50 °C - 100 °C, or from 60 °C - 80 °C, or from 60 °C - 100 °C, or 60 °C, or 80 °C - 100 °C, at high humidity, such as at 30%, or 40%, or 50%, or 60% humidity.

[0344] In some embodiments, the composition comprises a precipitated material in wet or dry form, which is mixed with one or more admixtures to impart one or more properties to the product, including but not limited to strength, flexural strength, compressive strength, porosity, thermal conductivity, etc. The amount of the admixture used can vary depending on the nature of the admixture. In some embodiments, the amount of one or more admixtures ranges from 1% w / w to 50% w / w, such as 1% w / w - 30% w / w, or 1% w / w - 25% w / w, or 1% w / w - 20% w / w, or 2% w / w - 10% w / w. Examples of admixtures include but are not limited to setting accelerators, setting retarders, air-entraining agents, foaming agents, defoaming agents, alkali reactivity reducers, adhesion admixtures, dispersants, coloring admixtures, corrosion inhibitors, moisture-proof admixtures, gas-forming agents, permeability reducers, pumping aids, shrinkage-compensating admixtures, fungicidal admixtures, bactericidal admixtures, insecticidal admixtures, rheology modifiers, finely divided mineral admixtures, pozzolans, aggregates, wetting agents, strength enhancers, waterproofing agents, reinforcing materials such as fibers, and any other admixtures. When using an admixture, the composition or precipitated material into which the admixture raw material is introduced is mixed for a sufficient time to disperse the admixture raw material relatively uniformly throughout the composition.

[0345] Setting accelerators can be used to accelerate the setting and early strength development of cement. Examples of setting accelerators that can be used include but are not limited to non-chloride type setting accelerators and / or calcium nitrite-based corrosion inhibitors, both of which are sold under the above trademarks by BASF Admixtures Inc. of Cleveland, Ohio, USA. Setting retardation, also known as delayed setting or hydration control, admixtures are used to retard, delay, or slow down the setting rate of cement. Most setting retarders can also act as low-level water reducers and can also be used to entrain some air into the product. An example of a retarder is An air entrainer includes any substance that entrains air in a composition. Some air entrainers can also reduce the surface tension of a composition at low concentrations. Air entraining admixtures are used to purposefully entrain minute air bubbles into cement. Air entrainment can increase the workability of the mixture while eliminating or reducing segregation and bleeding. Materials used to achieve these desired effects can be selected from wood resins, natural resins, synthetic resins, sulfonated lignin, petroleum acids, protein 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 and mixtures thereof. A certain amount of air entrainer is added to produce a desired level of air in the gelling composition. Examples of air entrainers that can be used in an admixture system include, but are not limited to, MB AE 90, MB VR, and all of which are available from BASF Admixtures Inc., Cleveland, Ohio, USA.

[0346] In some embodiments, a precipitating material is mixed with a foaming agent. The foaming agent incorporates a large number of voids / pores and helps to reduce the density of the material. Examples of foaming agents include, but are not limited to, soaps, detergents (alkyl ether sulfates), millifoam TM (alkyl ether sulfates), cedepal TM (ammonium alkyl ethoxysulfate), witcolate TM 12760 and the like.

[0347] As an admixture, defoamers are also of interest. Defoamers are used to reduce the air content in a gelling composition. As an admixture, dispersants are also of interest. Dispersants include, but are not limited to, polycarboxylate dispersants with or without polyether units. The term dispersant also means chemicals that also serve as plasticizers, water reducers such as high range water reducers, fluidizing agents, anti-flocculants or superplasticizers for the composition, such as lignosulfonates, salts of sulfonated naphthalene sulfonate condensates, salts of sulfonated melamine sulfonate condensates, β-naphthalenesulfonates, sulfonated melamine formaldehyde condensates, naphthalene sulfonate formaldehyde condensate resins, e.g. Dispersant (Cognis Inc., Cincinnati, Ohio, USA), polyaspartates or oligomeric dispersants. Polycarboxylate dispersants can be used, which means that the dispersant has a carbon backbone with side chains having side groups, at least a portion of which are attached to the backbone through carboxyl groups or ether groups.

[0348] For aesthetic and safety reasons, natural and synthetic admixtures can be used to color the product. These coloring admixtures can contain pigments and include carbon black, iron oxide, phthalocyanine, umber, chromium oxide, titanium oxide, cobalt blue, and organic colorants. Also of interest as an admixture is a corrosion inhibitor. Corrosion inhibitors can be used to protect embedded steel reinforcement from corrosion. Materials commonly used to inhibit corrosion are calcium nitrite, sodium nitrite, sodium benzoate, certain phosphates or fluorosilicates, fluoroaluminates, amines, and related chemicals. Also of interest is a moisture-proof admixture. Moisture-proof admixtures reduce the permeability of products having a low cement content, a high water-cement ratio, or insufficient fines in the aggregate. These admixtures retard the penetration of moisture into the dry product and include certain soaps, stearates, and petroleum products. Also of interest is a gas-forming agent admixture. A gas former or gas-forming agent is sometimes added to the mixture to cause slight expansion prior to hardening. The amount of expansion depends on the amount of gas-forming material used and the temperature of the fresh mixture. Aluminum powder, resin soaps, and vegetable or animal gums, saponins, or hydrolyzed proteins can be used as gas-forming agents. Also of interest is a permeability reducer. Permeability reducers can be used to reduce the rate at which water is transmitted through the mixture under pressure. Silica fume, fly ash, slag powder, natural pozzolans, water reducers, and latex can be used to reduce the permeability of the mixture.

[0349] Also of interest is a rheology modifier admixture. Rheology modifiers can be used to increase the viscosity of the composition. Suitable examples of rheology modifiers include precipitated silica, colloidal silica, hydroxyethyl cellulose, starch, hydroxypropyl cellulose, fly ash (as defined in ASTM C618), mineral oil such as light naphthenic, clays such as lithium montmorillonite clay, polyoxyalkylene, polysaccharides, natural gums, or mixtures thereof. Some mineral fillers, such as but not limited to sepiolite clay, are rheology modifiers.

[0350] Also of interest is a shrinkage-compensating admixture. are examples of shrinkage reducers and are available from BASF Admixtures Inc. of Cleveland, Ohio, USA. Bacterial and fungal growth on or in the hardened product can be partially controlled by using fungicidal and bactericidal admixtures. Materials used for these purposes include but are not limited to polyhalophenols, dialdrin emulsions, and copper compounds. Also of interest in some embodiments are admixtures that improve workability. Entrained air that acts like a lubricant can be used as a workability improver. Other workability agents are water reducers and certain finely divided admixtures.

[0351] In some embodiments, for example, where a fiber-reinforced product is desired, the composition comprises a precipitated material containing vaterite, aragonite, calcite, or combinations thereof, and a reinforcing material such as fibers. The fibers can be made of a material containing zirconia, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood, fiberglass, or synthetic materials such as polypropylene, polycarbonate, polyvinyl chloride, polyvinyl alcohol, nylon, polyethylene, polyester, rayon, high-strength aramid (e.g., ) or mixtures thereof. The reinforcing material is described in U.S. Patent Application Serial No. 13 / 560,246, filed July 27, 2012, the disclosure of which is incorporated herein in its entirety by reference.

[0352] The components of the composition can be combined using any suitable scheme. Each material can be mixed during operation, or some or all of the materials can be premixed. Alternatively, some materials are mixed with water, with or without admixtures such as high-range water-reducing admixtures, and then the remaining materials can be mixed therewith. As mixing equipment, any conventional equipment can be used. For example, Hobart mixers, inclined drum mixers, Omni mixers, Henschel mixers, V-type mixers, and Nauta mixers can be employed.

[0353] The processes and systems provided herein can be carried out on land (e.g., at the location of a cement plant where limestone is calcined, or where it can be easily and economically transported), at sea, or in the ocean. In some embodiments, a cement plant that calcines limestone can be retrofitted with the systems described herein to form the precipitated material and further form products from the precipitated material.

[0354] Aspects include systems for implementing the processes described herein, the systems comprising a processing plant or factory. The systems can have any configuration capable of implementing a particular production method of interest.

[0355] As described above, the systems can be located on land or at sea. For example, the systems can be land-based systems, which are in coastal areas, e.g., near a water source such as seawater, or even inland locations where water is piped from a saltwater source such as the ocean into the system. Alternatively, the systems are water-based systems, i.e., systems that are located on or in water. Such systems can be located on ships, ocean-based platforms, etc., as needed.

[0356] In some embodiments, the system may include a control station configured to control a precipitator or charger; the amount of precipitate delivered to a separator; the amount of precipitate delivered to a drying station; and / or the amount of precipitate delivered to a refining station. The control station may include a set of manually controlled, mechanically controlled, or digitally controlled valves or a multi-valve system, or any other convenient flow regulator scheme may be employed. In some cases, the control station may include a computer interface (where the regulation is computer-aided or fully computer-controlled) configured to provide input and output parameters to a user to control the amounts, as described above.

[0357] Products formed by a dissolution process

[0358] Processes and systems are provided herein for forming various gelled and non-gelled products from a precipitated material comprising calcium carbonate, the calcium carbonate comprising stable vaterite, reactive vaterite, aragonite, calcite, or combinations thereof, the precipitated material comprising calcium carbonate being formed by the dissolution processes described herein. In some embodiments, reactive vaterite transforms to aragonite and forms cement. The products include storage-stable forms, such as materials for constructing structures such as buildings and infrastructure, and the structures themselves or formed building materials such as drywall, or non-gelled materials such as paper, paint, plastics, etc., or artificial reefs.

[0359] In some embodiments of aspects provided herein, a dissolution process is provided that includes treating a slipstream of a mixture comprising lime with an N-containing salt solution to produce an aqueous solution comprising a calcium salt, contacting the aqueous solution comprising the calcium salt with a gas stream comprising greater than 30 volume % carbon dioxide (using a fossil fuel substitute input) to produce a precipitate comprising calcium carbonate, and adding water to the precipitated material, solidifying, and hardening to form cement, gelled products, and / or non-gelled products.

[0360] In some embodiments of aspects provided herein, a dissolution process is provided that includes treating a slipstream of a mixture comprising lime with an N-containing salt solution to produce an aqueous solution comprising a calcium salt, contacting the aqueous solution comprising the calcium salt with a gas stream comprising less than 25 volume % carbon dioxide (using a fossil fuel) to produce a precipitate comprising calcium carbonate, and adding water to the precipitated material, solidifying, and hardening to form cement, gelled products, and / or non-gelled products.

[0361] The cement or gelled product may be a building material or a formed building material as described below.

[0362] "Building materials" as used herein include cementitious materials for construction. In one aspect, there is provided a structure or building material in a solidified and hardened form that includes a precipitated material such as an aragonite composition, for example, where reactive aragonite has been converted to solidified and hardened calcite and / or aragonite or PCC. Products containing precipitates that include a transformation to the form of calcite and / or aragonite exhibit one or more unexpected properties, including but not limited to high compressive strength, high porosity (low density or light weight), neutral pH (e.g., useful as an artificial reef), a microstructure network, and the like.

[0363] Examples of such structures or building materials include, but are not limited to, buildings, driveways, foundations, kitchen slabs, furniture, pavements, roads, bridges, highways, overpasses, parking structures, bricks, blocks, walls, gate, fence, or utility pole footings, and combinations thereof.

[0364] "Shaped building materials" as used herein include materials shaped (e.g., molded, cast, cut, or otherwise produced) into a structure having a defined physical shape. Shaped building materials can be precast building materials, such as precast cement or concrete products. Shaped building materials and methods of making and using shaped building materials are described in U.S. Application Serial No. 12 / 571,398, filed September 30, 2009, which is incorporated herein by reference in its entirety. Various examples of shaped building materials have been described below.

[0365] Shaped building materials can vary widely and include materials shaped (e.g., molded, cast, cut, or otherwise produced) into a structure having a defined physical shape (i.e., configuration). Shaped building materials are different from amorphous building materials (e.g., powders, pastes, slurries, etc.), which do not have a defined and stable shape but conform to the shape of the container that holds them, such as a bag or other container. Shaped building materials are also different from irregularly or imprecisely shaped materials (e.g., aggregates, bulk forms for disposal, etc.) because shaped building materials are produced according to specifications that allow for the use of shaped building materials in, for example, buildings. Shaped building materials can be prepared according to conventional manufacturing schemes for such structures, provided that the precipitated materials provided herein are used to make such materials.

[0366] In some embodiments, the processes provided herein further include solidifying and hardening a precipitated material that includes reactive aragonite, where the reactive aragonite has been converted to calcite and / or aragonite, or solidified and hardened PCC; and forming a shaped building material.

[0367] In some embodiments, the formed building material made of the precipitated material has a compressive strength or flexural strength of at least 3 MPa, at least 10 MPa, or at least 14 MPa, or between 3 MPa and 30 MPa, or between about 14 MPa and 100 MPa, or between about 14 MPa and 45 MPa; or the compressive strength of the precipitated material after solidification and hardening, as described herein.

[0368] Examples of formed building materials that can be produced by the foregoing processes include, but are not limited to, masonry units, by way of example only bricks, blocks, and tiles, including but not limited to ceiling tiles; building panels, by way of example only cement boards (boards traditionally made of cement, such as fiber cement boards) and / or drywall (boards traditionally made of gypsum); conduits; basins; beams; columns, slabs; sound barriers; insulation materials; or combinations thereof. A building panel is used in a broad sense to refer to a formed building material of any non-load-bearing structural element, which is characterized such that its length and width are substantially greater than its thickness. Thus, a panel can be a plank, a board, shingles, and / or tiles. Exemplary building panels formed from a precipitated material comprising vaterite include cement boards and / or drywall. A building panel is a polygonal structure, the dimensions of which vary widely depending on its intended use. The length of the building panel can range from 50 cm to 500 cm, including 100 cm to 300 cm, such as 250 cm; the width ranges from 25 cm to 200 cm, including 75 cm to 150 cm, such as 100 cm; and the thickness ranges from 5 mm to 25 mm, including 7 mm to 20 mm, including 10 mm to 15 mm.

[0369] In some embodiments, cement boards and / or drywall can be used to manufacture different types of boards, such as but not limited to paper-faced boards (e.g., having a surface reinforcement of cellulose fibers), fiberglass-faced boards or fiberglass mat-faced boards (e.g., having a surface reinforcement of fiberglass mat), fiberglass mesh-reinforced boards (e.g., having a surface reinforcement of fiberglass mesh), and / or fiber-reinforced boards (e.g., having a cement reinforcement of cellulose, glass, fibers, etc.). These boards can be used in a variety of applications, including but not limited to, wallboards, such as fiber cement wallboards, roofs, soffits, claddings, facades, coverboards, ceilings, shaft linings, wallboards, linings, trim, cornices, shingles, and panels, and / or underlayments.

[0370] Cement boards are traditionally made of cement, such as ordinary Portland cement (OPC), magnesia cement, and / or calcium silicate cement. Cement boards prepared by the methods provided herein are made of a precipitated material (partially or entirely when reactive vaterite transforms to aragonite) and fibers and / or fiberglass, and can have additional fiber and / or fiberglass reinforcement on both sides of the board.

[0371] Cement boards are formed building materials, and in some embodiments, the formed building materials are used as backing boards for ceramics, which can be used behind bathroom tiles, kitchen countertops, backsplashes, etc., and can have a length in the range from 100 cm to 200 cm. Cement boards can vary in physical properties and mechanical performance. In some embodiments, the flexural strength can vary, ranging between 1 MPa and 7.5 MPa, including 2 MPa to 6 MPa, such as 5 MPa. The compressive strength can also vary, ranging from 5 MPa to 50 MPa, including 10 MPa to 30 MPa, such as 15 MPa to 20 MPa. In some embodiments, cement boards can be used in environments with a large amount of exposure to moisture (e.g., commercial saunas). The compositions or precipitated materials described herein can be used to produce the desired shape and size to form cement boards. Additionally, a variety of additional components can be added to the cement boards, and these components include but are not limited to plasticizers, clays, foaming agents, accelerators, retarders, and air entrainment additives. The composition is then poured into a sheet mold, or a roller can be used to form a sheet of the desired thickness. The formed composition can be further compacted by roller compaction, hydraulic pressure, vibratory compaction, or resonant impact compaction. The sheet is then cut into the desired size of the cement board.

[0372] Another type of building panel formed from the compositions or precipitated materials described herein is a backing board. Backing boards can be used to construct interior and / or exterior floors, walls, and ceilings. In embodiments, the backing board is partially or entirely made of precipitated materials.

[0373] Another type of building panel formed from the composition or precipitated material is drywall. As used herein, "drywall" includes boards used to construct interior and / or exterior floors, walls, and ceilings. Traditionally, drywall is made of gypsum (referred to as paper-faced panels). In embodiments, the drywall is partially or entirely made of carbonate precipitated materials, thus replacing the gypsum from drywall products. In some embodiments, the drywall can include building panels prepared from a combination of aragonite cement (which solidifies and hardens when the reactive vaterite transforms to aragonite) and cellulose, fibers, and / or fiberglass, and can have additional paper, fibers, fiberglass mesh, and / or fiberglass mat reinforcements on both sides of the board. A variety of processes for manufacturing drywall products are well known in the art and are fully within the scope of the present invention. Some examples include but are not limited to the wet process, semi-dry process, extrusion process, processes, etc.

[0374] In some embodiments, drywall is a panel made of a paper liner wrapped around a core. For example, in some embodiments, during the process of preparing a drywall product from a precipitated material, a slurry of the precipitated material containing reactive vaterite is poured onto a sheet of paper. Then another sheet of paper is placed on top of the precipitated material such that the precipitated material is flanked by paper on both sides (the resulting composition is sandwiched between two outer materials such as heavy paper or fiberglass mats). The reactive vaterite in the precipitated material then transforms to aragonite (using additives and / or heating), and then the aragonite solidifies and hardens. When the core solidifies and dries in a large drying chamber, the sandwich becomes hard and strong enough to be used as a building material. The drywall sheets are then cut and separated.

[0375] The flexural strength and compressive strength of drywall formed from a precipitated material are equal to or higher than those of conventional drywall made from gypsum plaster, which is a known soft building material. In some embodiments, the flexural strength can be in the range between 0.1 MPa and 3 MPa, including 0.5 MPa to 2 MPa, such as 1.5 MPa. The compressive strength can also vary, in some cases in the range from 1 MPa to 20 MPa, including 5 MPa to 15 MPa, such as 8 MPa to 10 MPa. In some embodiments, the formed building materials produced by the methods described herein, such as building panels, such as but not limited to cement boards and drywall, have low density and high porosity, making them suitable for lightweight and insulating applications.

[0376] The high porosity and light weight of the formed building materials (merely by way of example, building panels) may be due to the development of the aragonite microstructure when reactive vaterite transforms to aragonite. The transformation of reactive vaterite during the dissolution / reprecipitation process can result in the generation of micropores, while the voids generated between the formed aragonite crystals can provide nanoscale porosity, leading to a highly porous and lightweight structure. Certain admixtures can be added during the transformation process, such as but not limited to foaming agents, rheology modifiers, and mineral fillers, such as but not limited to clay, starch, etc., which can increase the porosity in the product, because the foaming agent can entrap air in the mixture and reduce the total density, and mineral fillers such as sepiolite clay can increase the viscosity of the mixture, thus preventing the separation of the precipitated material and water.

[0377] One application of cement boards or drywall is fiber cement wall panels. The fiber - cement wall panels formed by the process provided herein include building panels prepared from a combination of aragonite cement, aggregates, interwoven cellulose, and / or polymer fibers, and can have a wood - like texture and flexibility.

[0378] In some embodiments, the formed building material is a masonry unit. A masonry unit is a formed building material used to construct load-bearing and non-load-bearing structures, which are typically assembled using mortar, grout, and the like. Exemplary masonry units formed from the composition include bricks, blocks, and tiles.

[0379] Another formed building material formed from the precipitation materials described herein is a conduit. A conduit is a tube or similar structure configured to transport gas or liquid from one location to another. A conduit can include any of a variety of different structures for transporting liquid or gas, including but not limited to pipes, culverts, box culverts, drainage channels and portals, inlet structures, intake towers, gate wells, outlet structures, and the like.

[0380] Another formed building material formed from the precipitation materials described herein is a basin. The term basin can include a container of any configuration for holding a liquid such as water. Thus, a basin can include but not limited to structures such as wells, collection boxes, sanitary manholes, septic tanks, catch basins, grease traps / separators, stormwater discharge collection reservoirs, and the like.

[0381] Another formed building material formed from the precipitation materials described herein is a beam, which generally refers to a horizontal load-bearing structure having high flexural strength and compressive strength. A beam can be rectangular cross-shaped, C-channel, L-section edge beam, I-beam, spandrel beam, H-beam, having an inverted T-shaped design, and the like. A beam can also be a horizontal load-bearing unit, which includes but not limited to joists, lintels, arches, and cantilevers.

[0382] Another formed building material formed from the precipitation materials described herein is a column, which generally refers to a vertical load-bearing structure that primarily bears loads through axial compression and includes structural elements such as compression members. Other vertical compression members can include but not limited to struts, piers, pedestals, or columns.

[0383] Another formed building material formed from the precipitation materials described herein is a concrete slab. A concrete slab is one of those building materials used to construct precast foundations, floors, and wall panels. In some cases, a concrete slab can be used as a floor unit (e.g., a hollow plank unit or a double-T design).

[0384] Another formed building material made from the precipitated materials described herein is a sound barrier, which refers to a structure used as a barrier for sound attenuation or absorption. Thus, a sound barrier can include, but is not limited to, structures such as sound-absorbing panels, reflective barriers, absorption barriers, reactive barriers, etc.

[0385] Another formed building material made from the precipitated materials described herein is a thermal insulation material, which refers to a material used to reduce or inhibit heat conduction. Thermal insulation materials can also include those that reduce or inhibit radiative heat transfer.

[0386] In some embodiments, other formed building materials such as precast concrete products include, but are not limited to, bunker silos; cattle feed bunks; cattle grids; agricultural fences; H-shaped bunks; J-shaped bunks; livestock slats; livestock watering troughs; building panel walls; cladding (brick); architectural trim; foundations; floors, including slabs on grade; walls; double-wall precast sandwich panels; aqueducts; mechanically stabilized earth panels; box culverts; three-sided culverts; bridge systems; RR crossings; RR ties; sound walls / barriers; Jersey barriers; tunnel segments; reinforced concrete boxes; utility protection structures; handholes; hollow-core products; light pole bases; meter boxes; panel vaults; pull boxes; telecommunications structures; transformer pads; transformer rooms; trenches; utility vaults; utility poles; controlled environment wells; underground wells; mausoleums; tombstones; coffins; hazardous protection pad storage containers; detention facilities; catch basins; manholes; aeration systems; distribution boxes; bulk storage tanks; dry wells; grease interceptors; leach pits; sand / oil or oil / water interceptors; septic tanks; water / sewage storage tanks; wet wells; fire reservoirs; floating docks; underwater infrastructure; decks; railings; seawalls; roof tiles; pavers; community retaining walls; reservoir retaining walls; modular closure systems; and segmented retaining walls.

[0387] In some embodiments, the processes described herein include preparing other products from the precipitated materials described herein, including but not limited to non-cementitious compositions, including paper, polymer products, lubricants, adhesives, rubber products, chalk, asphalt products, paints, abrasives for paint removal, personal care products, cosmetics, cleaning products, personal hygiene products, ingestible products, agricultural products, soil amendment products, pesticides, environmental remediation products, and combinations thereof. Such compositions have been described in U.S. Patent No. 7,829,053, issued November 9, 2010, which is incorporated herein by reference in its entirety.

[0388] In some embodiments, the non-cementitious composition is produced from a precipitated material comprising stable vaterite, where the stable vaterite acts as a filler.

[0389] In some embodiments, the processes described herein include manufacturing artificial ocean structures from the precipitation materials described herein, and the artificial ocean structures include, but are not limited to, artificial corals and artificial reefs. In some embodiments, the artificial structures can be used in aquariums or in the ocean. In some embodiments, these products are made from precipitation materials containing reactive vaterite, which, after solidification and hardening, transforms into aragonite. Aragonite cement provides a neutral or near-neutral pH, which may be beneficial for the maintenance and growth of marine life. Aragonite reefs can provide suitable habitats for marine species.

[0390] Throughout the specification, when a composition is described as having, including, or containing, comprising a particular component, or when a process and method are described as having, including, or containing, comprising a particular step, it is contemplated that there are also compositions of the invention consisting essentially of or consisting of the stated components, and processes and methods according to the invention consisting essentially of or consisting of the stated processing steps.

[0391] In this application, when an element or component is referred to as being included in and / or selected from the stated list of elements or components, it should be understood that the element or component can be any one of the stated elements or components, or the element or component can be selected from the group consisting of two or more of the stated elements or components.

[0392] Furthermore, it should be understood that the elements and / or features of the compositions or processes described herein can be combined in various ways without departing from the spirit and scope of the invention, whether explicit or implicit herein. For example, in reference to a particular composition, unless otherwise understood from the context, the composition can be used in various embodiments of the compositions of the invention and / or in the processes of the invention. In other words, in this application, the embodiments have been described and depicted in a manner that enables a clear and concise application to be written and drawn, but it is contemplated and will be understood that the embodiments can be differently combined or separated without departing from this teaching and invention. For example, it should be understood that all of the features described and depicted herein can be applied to all aspects of the invention described and depicted herein.

[0393] Where a range of values is provided, it is to be understood that every intermediate value between the upper and lower limits of that range, to one-tenth of the unit of the lower limit (unless the context clearly dictates otherwise), as well as any other stated value or intermediate value in the stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specific excluded limits in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of the included limits are also included in the invention. The terms "include", "includes", "including", "have", "has", "having", "contain", "contains", or "containing", as well as the use of their grammatical equivalents, are generally to be understood as open-ended and non-restrictive, e.g., not excluding additional unrecited elements or steps, unless specifically stated or understood from the context otherwise.

[0394] Any and all embodiments herein, or the use of exemplary language (e.g., "such as" or "including") is merely intended to better illustrate the invention and not to limit the scope of the invention otherwise claimed. Language in this specification should not be construed as indicating any non-claimed element as essential to the practice of the invention.

[0395] Certain ranges are presented herein, where the numerical values are preceded by the term "about". The term "about" is used herein to provide literal support for the exact number preceding it as well as numbers that are close to or approximate the number preceding it. As used herein, the term "about" means a difference of ±10% from the nominal value, unless otherwise stated or inferred.

[0396] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any processes and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative exemplary processes and materials of the prior art are described herein. In addition, the dates of the publications provided may be different from the actual publication dates that may need to be independently verified.

[0397] It is to be understood that, unless otherwise understood from the context and usage, the phrase "at least one of... " separately includes each of the recited objects following the phrase as well as various combinations of two or more of the recited objects. The phrase "and / or" with respect to three or more of the recited objects should be understood to have the same meaning unless the context otherwise dictates.

[0398] It should be noted that, unless the context clearly dictates otherwise, as used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents. For example, when the plural form is used for compounds, salts, and the like, this also means a single compound, salt, or the like. It should also be noted that the claims may be drafted to exclude any optional elements.

[0399] Upon reading this disclosure, it will be apparent to those skilled in the art that each of the individual embodiments described and illustrated herein has discrete components and features that can be readily separated from or combined with the features of any other several embodiments without departing from the scope or spirit of the invention. Any recited process may be carried out in the order of recited events or in any other order that is logically possible. It should be understood that the order of steps or the order for performing certain actions is immaterial so long as this application remains operable. In addition, two or more steps or acts may be carried out simultaneously.

[0400] The following examples are presented in order to provide a complete disclosure and description to those of ordinary skill in the art of how to make and use the present invention and are not intended to limit the scope of what the inventors regard as their invention, nor are they intended to represent that the following experiments are all or the only experiments performed. Efforts have been made to ensure the accuracy of the numbers used (e.g., amounts, temperatures, etc.), but some experimental error and deviation should be accounted for.

[0401] Formation and transformation of precipitated materials from calcined limestone

[0402] Dissolve NH4Cl in water. Calcinate limestone in an electric kiln at 950 °C, cool to room temperature, and add to the NH4Cl aqueous solution and mix for several hours. Decant the resulting mixture to remove any impurities. Transfer the filtered solution to an airtight container. Supply the solution through a heat exchanger that preheats the solution to 40 °C. The carbonation reactor is an acrylic cylinder equipped with baffles, a gas diffuser, a pH electrode, a thermocouple, a turbine impeller, and inlets and outlets for liquids, gases, and slurries. A mass flow controller proportions the clean CO2 (free of contaminants from fossil fuels) inlet gas. During startup, the solution in the container is pumped through the heat exchanger into the reactor. Stir the mixer while introducing clean CO2 gas through the gas diffuser. Control the continuous inlet flow of fresh reactant solution by maintaining the reactor pH at 8. Continuously collect the resulting reactive vaterite slurry into a holding container. Vacuum filter the slurry. Dry the reactive vaterite cake in an oven at 100 °C. The cake shows 100% vaterite with an average particle size of 9 μm. Recycle the clarified filtrate containing regenerated NH4Cl in subsequent experiments.

[0403] Mix the dry reactive vaterite solid into a paste. X-ray diffraction (XRD) of the paste after 1 day shows 99.9% aragonite (complete conversion of reactive vaterite to aragonite). Cast the paste into 2” x 2” x 2” cubes and solidify and harden in a humidity chamber set at 60 °C and 80% relative humidity for 7 days. Dry the cement cubes in an oven at 100 °C. Destructive testing determines the compressive strength of the cubes to be 4600 psi (∼31 MPa).

[0404] Although, for purposes of clarity of understanding, the foregoing invention has been described in some detail by way of illustration and example, it will be apparent to those of ordinary skill in the art that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. Accordingly, the foregoing merely illustrates the principles of the invention. It is to be understood that those skilled in the art will be able to devise a variety of arrangements, which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. In addition, all of the examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to further the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Accordingly, the scope of the invention is not intended to be limited to the exemplary embodiments shown and described herein. It is intended that the appended claims define the scope of the invention and thereby cover the methods and structures within the scope of these claims and their equivalents.

Claims

1. A carbon dioxide sequestration process, comprising: Calcining limestone using a fossil fuel substitute to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide; and Treating the mixture with the atmosphere and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

2. A carbon dioxide sequestration process, comprising: Calcining limestone using a fossil fuel substitute to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide; and Treating the mixture with natural water and allowing carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

3. The process according to claim 1 or 2, further comprising treating the gas stream, wherein the treatment comprises at least one of cooling, compressing, and storing.

4. The process according to claim 3, wherein the storing comprises geologically sequestering the gas stream.

5. The process according to any one of the preceding claims, wherein the gas stream does not contain gaseous or non-gaseous components from the combustion of fossil fuels.

6. The process according to any one of the preceding claims, wherein the gas stream contains more than about 90 volume % carbon dioxide.

7. The process according to any one of the preceding claims, wherein the gas stream contains carbon dioxide between about 90 volume % and 100 volume %.

8. The process according to any one of the preceding claims, wherein the gas stream contains about 99 volume % carbon dioxide.

9. The process according to any one of the preceding claims, wherein the fossil fuel substitute comprises at least one of an electric kiln, renewable electricity, hydrogen, biofuel, and indirect heating.

10. The process according to claim 9, wherein the renewable electricity comprises at least one of solar energy, wind energy, geothermal energy, and hydropower.

11. The process according to claim 9, wherein the biofuel comprises biomass.

12. The process according to claim 11, wherein the biomass comprises at least one of carbonized biomass, lignin, and shredded biomass.

13. The process according to claim 9, wherein the gas generated by heating is separated from the gas stream.

14. The process according to any one of the preceding claims, wherein the mixture contains underburned lime.

15. The process according to any one of the preceding claims, wherein the mixture contains lightly burned lime.

16. The process according to any one of the preceding claims, wherein the mixture contains dead burned lime.

17. The process according to any one of the preceding claims further comprises treating the slipstream of the mixture with an N-containing salt solution to produce an aqueous solution containing a calcium salt, and contacting the aqueous solution with the gas stream to produce a precipitate containing calcium carbonate.

18. The process according to any one of the preceding claims further comprises treating the slipstream of the mixture with an N-containing salt solution to produce an aqueous solution containing a calcium salt, and contacting the aqueous solution with a second gas stream containing less than about 25 vol% carbon dioxide to produce a precipitate containing calcium carbonate.

19. The process according to claim 18, wherein the second gas stream is obtained from limestone calcination using a fossil fuel.

20. The process according to any one of the preceding claims, wherein treating the mixture with the atmosphere comprises spreading the mixture on land and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

21. The process according to any one of the preceding claims, wherein treating the mixture containing lime in natural water comprises directly sequestering the mixture in natural water.

22. The process according to any one of the preceding claims, wherein treating the mixture in natural water comprises blending the mixture containing lime with cooled natural water at a power plant and sequestering the blend back into the natural water.

23. The process according to any one of the preceding claims, wherein the natural water is seawater, and treating the mixture containing lime in seawater comprises blending the mixture containing lime with concentrated brine at a seawater desalination plant and sequestering the blend back into the seawater.

24. The process according to any one of the preceding claims, wherein the gas stream contains less than about 20% of at least one component selected from the group consisting of SOx, thermal NOx, carbon monoxide, metals, volatile organic substances, and particulate matter.

25. The process according to any one of the preceding claims, wherein the gas stream contains greater than about 90 vol% carbon dioxide and further contains less than about 1% of at least one component selected from the group consisting of SOx, thermal NOx, carbon monoxide, metals, volatile organic substances, and particulate matter.

26. The process according to any one of the preceding claims, wherein the gas stream contains greater than about 99 vol% carbon dioxide and further contains less than about 1% of at least one component selected from the group consisting of SOx, thermal NOx, carbon monoxide, metals, volatile organic substances, and particulate matter.

27. The process according to any one of the preceding claims, wherein the composition containing calcium carbonate, calcium bicarbonate, or a combination thereof formed in seawater is pH-neutral.

28. The process according to any one of the preceding claims, further comprising depositing the composition comprising calcium carbonate, calcium bicarbonate or a combination thereof on the seabed.

29. The process according to claim 28, further comprising forming a coral reef on the composition comprising calcium carbonate, calcium bicarbonate or a combination thereof.

30. A carbon dioxide sequestration process, comprising: Burning a fuel to generate heat and a first gas stream; and Using the heat to indirectly heat and calcine limestone to form a mixture containing lime and a second gas stream containing greater than about 90 volume % carbon dioxide, wherein the first gas stream is separated from the second gas stream.

31. The process according to claim 30, wherein the fuel is at least one of a fossil fuel and a fossil fuel substitute.

32. The process according to claim 31, wherein the fuel is selected based on grid load balancing and economy.

33. The process according to claim 31 or 32, wherein the fossil fuel substitute comprises one of biomass and hydrogen.

34. The process according to any one of claims 30-33, wherein the first gas stream comprises less than about 25 vol% carbon dioxide.

35. The process according to any one of claims 30-34, wherein the first gas stream comprises greater than about 20% of at least one component selected from the group consisting of SOx, thermal NOx, carbon monoxide, metals, volatile organic substances, and particulate matter.

36. The process according to any one of claims 30-35, further comprising treating a slipstream or all of the mixture with the atmosphere and allowing carbon dioxide from the atmosphere to react with the mixture and form a composition comprising calcium carbonate, calcium bicarbonate or a combination thereof.

37. The process according to any one of claims 30-36, further comprising treating a slipstream or all of the mixture with natural water and allowing the carbon dioxide dissolved in the natural water to react with the mixture to form a composition comprising calcium carbonate, calcium bicarbonate or a combination thereof.

38. The process according to any one of claims 30-37, further comprising treating a slipstream or all of the mixture with an N-containing salt solution to produce an aqueous solution comprising a calcium salt and contacting the aqueous solution with the first gas stream to produce a precipitate comprising calcium carbonate.

39. The process according to any one of claims 30-38, further comprising disposing of the second gas stream, wherein the disposal comprises at least one of cooling, compressing, and storing.

40. The process according to claim 39, wherein the storing comprises geologically sequestering the second gas stream.

41. The process according to any one of claims 30 - 40, wherein the second gas stream does not contain gaseous or non - gaseous components from fossil fuel combustion.

42. The process according to any one of claims 30 - 41, wherein the second gas stream contains between about 90 vol% - 100 vol% carbon dioxide.

43. The process according to any one of claims 30 - 42, wherein the gas stream contains about 99 vol% carbon dioxide.

44. A system for carbon dioxide sequestration, comprising: A first calcination system configured to calcine limestone using a fossil fuel substitute to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide; and A sequestration module operably connected to the first calcination system and configured to treat the mixture containing lime with the atmosphere and allow carbon dioxide from the atmosphere to react with the mixture and form a composition containing calcium carbonate, calcium bicarbonate, or a combination thereof.

45. A system for carbon dioxide sequestration, comprising: A first calcination module configured to calcine a limestone feed using a fossil fuel substitute to form a mixture containing lime and a gas stream containing greater than about 30 volume % carbon dioxide, and A sequestration module operably connected to the first calcination module and configured to treat the mixture with natural water and allow carbon dioxide dissolved in the natural water to react with the mixture to form a composition containing at least one of calcium carbonate and calcium bicarbonate.

46. The system according to claim 44 or 45, wherein the sequestration module is one of a conveyor belt and a transportation module.

47. The system according to any one of claims 44 - 46, further comprising a disposal module operably connected to the first calcination module and configured to dispose of the gas stream.

48. The system according to claim 47, wherein the disposal module comprises a cooler, a compressor, and / or a geological injector.

49. The system according to any one of claims 44 - 48, wherein the gas stream contains more than about 90 vol% carbon dioxide.

50. The system according to any one of claims 44 - 49, further comprising: A treatment reactor operably connected to the first calcination module and configured to receive a slipstream of the mixture and dissolve the mixture containing lime in an N-containing salt solution to produce an aqueous solution containing a calcium salt; and A contact reactor operably connected to the treatment reactor and the first calcination module and configured to receive the aqueous solution and a slipstream of the gas stream and treat the aqueous solution with the gas stream to form a precipitate containing calcium carbonate.

51. The system according to any one of claims 44 - 49, further comprising: A second calcination module configured to calcine a limestone feed using a fossil fuel and produce a second gas stream containing less than about 25 volume % carbon dioxide; A treatment reactor operably connected to the first calcination module and configured to receive a slipstream of the mixture and dissolve the mixture in an N-containing salt solution to produce an aqueous solution containing a calcium salt; and A contact reactor operably connected to the treatment reactor and the second calcination module and configured to receive the aqueous solution from the treatment reactor and the gas stream from the second calcination module and treat the aqueous solution with the gas stream to form a precipitate containing calcium carbonate.

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