CARBONATE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is related to and claims priority to U.S. Provisional Serial No. 62/573,452, filed October 17, 2017, pending, and U.S. Provisional Serial No. 62/573,526, filed October 17, 2017, pending, the entire contents of each of which are hereby incorporated by reference in their entirety.

BACKGROUND DISCLOSURE

TECHNICAL FIELD

[0002] The present disclosure relates to a mu Iti-batch process for forming precipitated calcium carbonate from a C02 source and a calcium source.

DESCRIPTION OF THE RELATED ART

[0003] The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

[0004] Given the global demand for paper, paper producing industries are a necessity of modern life. However, the processes to produce paper from wood chips require the use of strong chemical agents, producing a waste effluent which is toxic unless otherwise treated. In the treatment of waste effluents from paper mills or deinking processes, components involved in the industrial processes may furthermore be recovered and reused in the paper mill or diverted to other uses. One of these components is calcium carbonate, which may be solubilized and precipitated.

[0005] Precipitated calcium carbonate (PCC) may be used widely as a filler in sheet molding compounds, bulk molding compounds, adhesives, caulks, sealants, rubber products, paper, paper fillers, paper coatings, 3D printing media, tires, or concrete. PCC is produced through a reaction process that utilizes a calcium source, a carbon dioxide, and water. This precipitation reaction is capable of producing three distinct polymorphs (calcite, aragonite and vaterite) as well as an amorphous morphology, depending on the reaction conditions used. For some uses, it is desirable to use PCC having more than one structure or more than one morphology. Reaction conditions of a single reactor may be carefully tuned to produce a desired distribution of properties, however, in some cases a multi-batch process allows for a higher level of control, and also makes it possible to recycle excess reagents for reaction or to divert a portion of PCC product to use in seeding a reaction.

[0006] in view of the forgoing, one objective of the present disclosure is to provide a multi-batch process for forming precipitated calcium carbonate from a CO ₂ source and a calcium source with additional means of forming multi-structured and polymorphous products.

BRIEF SUMMARY

[0007] The present disclosure relates to multi-batch processes for forming precipitated calcium carbonate using one or more reaction vessels. A CO ₂ source and a calcium source are reacted in water partially or completely to form calcium carbonate, which may be separated from the water as a precipitated calcium carbonate product having single or multiple modes, structures, and/or morphologies. In other embodiments, more than one reactor may be used to react similar or different CO ₂ sources and calcium sources to form more than one PCC product having similar or different properties. These PCC products may be combined. In addition, one or more steps of a multi-batch process may have a dopant, a seed, a fatty acid or fatty acid derivative salt, and/or a dispersant added to influence the properties of the resulting PCC product. In some embodiments of the multi-batch process, one or more reactors may have an output stream of PCC or excess reagents diverted to feed into one or more reactors. The diverted output stream may be concentrated or modified by other means.

[0008] The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0010] Fig. 1 is a multi-batch process for generating PCC, with optional water phase recycling. [0011] Fig. 2 is a two-reactor multi-batch process for generating PCC, where a seed and/or a dopant may be added to either or both reactors.

[0012] Fig. 3 is a serial three-reactor multi-batch process for generating PCC.

[0013] Fig. 4 is a serial three-reactor multi-batch process for generating PCC, with an optional recycling step.

[0014] Fig. 5 is a three-reactor process for generating PCC, which involves diverting portions of product and/or reagent from the first reactor to the second and third reactors.

[0015] Fig. 6 is another three-reactor process for generating PCC, and involves diverting portions of product and/or reagent from the first reactor to the second reactor, and from the second reactor to the third reactor, and ultimately combining the products from all three reactors.

[0016] Fig. 7 is another three-reactor process for generating PCC, and involves diverting portions of product and/or reagent from the first reactor to the second reactor, and from the second reactor to the third reactor, and ultimately combining the products from the first and second reactors.

[0017] Fig. 8 is another two-reactor multi-batch process for generating PCC.

[0018] Fig. 9 is a three-reactor process for generating PCC, and involves diverting portions of product and/or reagent from the first reactor to the second reactor, and ultimately combining the products from all three reactors following an optional fatty acid, fatty acid derivative salt, and/or dispersant treatment.

[0019] Fig. 10 is another three-reactor process for generating PCC, and involves ultimately combining the products from all three reactors following an optional fatty acid, fatty acid derivative salt, and/or dispersant treatment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the disclosure are shown.

[0021] The present disclosure will be better understood with reference to the following definitions. As used herein, the words "a" and "an" and the like carry the meaning of "one or more." Within the description of this disclosure, where a numerical limit or range is stated, the endpoints are included unless stated otherwise. Also, all values and subranges within a numerical limit or range are specifically included as if explicitly written out. [0022] In addition, the present disclosure is intended to include all isotopes of atoms occurring in the present compounds and complexes. Isotopes include those atoms having the same atomic number but different mass numbers. By way of general example and without limitation, isotopes of hydrogen include deuterium and tritium. Isotopes of carbon include ^l3 C and ¹⁴ C. Isotopically-labeled compounds of the disclosure can generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those described herein, using an appropriate isotopically-labeled reagent in place of the non-labeled reagent otherwise employed.

[0023] As used herein, "dopant" refers to a small amount of an impurity that is intentionally added to another material, such as an impurity intentionally added to a carbonate matrix.

[0024] As used herein, "precipitated calcium carbonate" or "PCC" refers to a synthetically manufactured calcium carbonate material that can be tailor-made with respect to its compositional forms, purity, morphology, particle size, and other characteristics (e.g. particle size distribution, surface area, cubicity, etc.) using various precipitation techniques and methods. Precipitated calcium carbonate (PCC) thus differs from natural calcium carbonate or natural calcium carbonate-containing minerals (marble, limestone, chalk, dolomite, shells, etc.) or ground calcium carbonate (natural calcium carbonate which has been ground) in terms of both methods of manufacture as well as the various composition/characteristics mentioned above, and which will be described more fully hereinafter. See WO20161 15398 Al, WO2010142859 Al, US20020172636 Al, US6251356 Bl, EP2238077 Al, US20020176813 Al, US7048900 B2, EP2632855 Al, US2962350 A, and US3920800 A - each incorporated herein by reference in its entirety.

[0025] In one embodiment, the term "waste stream" refers to a waste stream, which can be aqueous, which can come from either a paper mill, such as one using the kraft process (also known as kraft pulping or sulfate process), or from a deinking process. The kraft process is a process for the conversion of wood into wood pulp, which consists of almost pure cellulose fibers, the main component of paper. The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide, and sodium sulfide that breaks the bonds in the wood that link lignin, hemicellulose, and cellulose. This mixture may be called white liquor or white water, due to its white opaque color. Besides sodium hydroxide and sodium sulfite, the white water also contains sodium carbonate, sodium sulfate, sodium thiosulfate, sodium chloride, calcium carbonate and other accumulated salts and non-process elements, and the waste streams can also include the components. Waste streams similar to the waste streams from either a paper mill or from a deinking process as described above may be produced by other industrial processes, such as other paper making processes and deinking processes. To reduce the environmental impact of such waste streams and similar paper mill waste effluents, it is possible to recycle the components or process the effluent in a treatment plant, to substantially reduce its toxicity.

[0026] Here, the present disclosure relates to a process for regenerating the calcium carbonate of a waste stream as precipitated calcium carbonate (PCC). This involves the steps of filtering the waste stream to produce a solid waste material; calcining the solid waste material to produce a calcined material; mixing the calcined material with water and an inorganic salt to form a solution of calcium and water; carbonating the solution with a CO ₂ source to produce a mixture of calcium carbonate and water; and filtering the mixture to produce PCC and a water phase. This PCC may be reused in a paper making process or used for other purposes. Certain related methods have been described in the art. See US8771621, US4115188- each incorporated herein by reference in its entirety.

[0027] In some embodiments, the waste stream may undergo a pretreatment before the filtering, in order to increase the efficiency of the reactions and/or the recovery yield of the regenerated PCC. For example, in one embodiment, the waste stream is exposed to UV light before the filtering. Here, the UV light may be in the form of a xenon and/or mercury vapor gas discharge lamp. Preferably the UV light is of a wavelength and power density that it is able to degrade organic materials in the waste stream, thus increasing the efficiency of regenerating the PCC, as well as its purity, by removing more contaminants at earlier stages of the process.

[0028] In another embodiment the pretreatment involves lowering the pH of the waste stream to 4.0 or less, preferably 3.5 or less, more preferably 3.0 or less, and then raising the pH to 10.0 or greater, preferably 10.4 or greater, more preferably 10.8 or greater. However, in some embodiments, the pH may be lowered to 4.0 - 6.0, preferably 4.0 - 5.0, or the pH may already be at 4.0 or lower without any adjustment necessary. The pH may be lowered by mixing an acid into the solution, such as H2SO4, HC1, HNO3, and/or HBr. Preferably the acid is H2SO4. Following the pH lowering, the pH may be raised as described by the addition of a base, such as LiOH, NaOH, KOH, RbOH, CsOH, and/or Mg(OH) ₂ . Preferably the base is NaOH. These changes in the pH help to coagulate the suspended material of the waste stream so that the coagulated solids can be easily filtered, thus increasing the recovery yield of the calcium carbonate.

[0029] The solid waste material may be washed before the calcining, to removing excess soluble compounds. In one embodiment, the solid waste material is calcined at a temperature above 1100 °C, preferably above 1150 °C, more preferably above 1200 °C, even more preferably above 1250 °C for a time sufficient to develop fractures extending from the surface of the calcined particle to the interior thereof. These fractures increase substantially the surface area of the calcined particle over that of a non-calcined particle. Typically temperature and time are controlled to attain the maximum number of fractures and surface area for a particular solid waste material. In general, the preferred calcining temperature is above 1500° C. This temperature can vary somewhat with different solid waste materials and paper mill processes. The calcining procedure when operating at ambient atmospheric pressure, i.e., substantially 760 mm Hg, produces the calcined material. Here, the calcining may be at about 1500 °C, at about 760 mm Hg, for 1 - 6 h, preferably 2 - 5 h, more preferably 2.5 - 4 h. Here, the calcining may be in air. In other embodiments, subatmospheric pressure calcining may be used, where at a given temperature, the calcining time is markedly decreased. Desirably, the calcining oven operates at a vacuum of less than about 25 mm Hg. Under these vacuum conditions, at about 1500° C, the calcining time is on the order of 5-30 min, preferably 8-25 min, more preferably 10-20 min. For example, solid waste material may be calcined at about 1500° C, at about 10 mm Hg, for about 15 minutes.

[0030] In one embodiment, the above calcining parameters may also be applied to producing a calcined clay and/or a pozzolan from the waste stream, which may be separated from the calcined material. In one embodiment, a calcined clay and/or a pozzolan produced from the waste stream may be used in cement.

[0031] As defined here, pozzolans are members of a broad class of siliceous or siliceous and aluminous materials which, in themselves, possess little or no cementitious value but which will, in finely divided form and in the presence of water, react chemically with calcium hydroxide to form compounds possessing cementitious properties. Pozzolans may be added to cement for three main advantages: (1) the economic gain obtained by replacing a substantial part of the Portland cement by cheaper, pollution free, natural pozzolans or industrial by-products, (2) the lowered emission of greenhouse gases during Portland cement production, and (3) increased durability of the end product [0032] The addition of pozzolans to Portland cement offers the opportunity to convert waste (e.g. fly ash or a waste stream) into durable construction materials. A reduction of up to 40 wt% of Portland cement in the concrete mix is usually possible when replaced with a combination of pozzolans. Pozzolans can be used to control setting, increase durability, reduce cost and reduce pollution without significantly reducing the final compressive strength or other performance characteristics. The properties of these blended cements are strongly related to the development of the binder microstructure, i.e., to the distribution, type, shape and dimensions of both reaction products and pores. The beneficial effects of pozzolan addition in terms of higher compressive strength, performance and greater durability are mostly attributed to the reaction in which calcium hydroxide is consumed to produce additional C-S-H and C-A-H reaction products. These reaction products fill in pores and result in a refining of the pore size distribution or pore structure. This results in a lowered permeability of the binder.

[0033] The contribution of the pozzolanic reaction to cement strength is usually developed at later curing stages, depending on the pozzolanic activity. In the large majority of blended cements initial lower strengths can be observed compared to the parent Portland cement. However, especially in the case of pozzolans finer than the Portland cement, the decrease in early strength is usually less than what can be expected based on the dilution factor. This can be explained by the filler effect, in which small SCM grains fill in the space between the cement particles, resulting in a much denser binder. The acceleration of the Portland cement hydration reactions can also partially accommodate the loss of early strength.

[0034] The inorganic salt may be ammonium chloride, ammonium nitrate, tetramethyl ammonium chloride, or some other ammonium salt. In one embodiment, the inorganic salt is ammonium chloride.

[0035] In one embodiment, the mixing and the carbonating may be performed in the same reaction vessel. In other embodiments, the mixing and the carbonating may be performed in different locations.

[0036] In one embodiment, a weight percentage of the PCC produced by the process or a variation (such as a multi-reactor process) is 60 - 90 wt%, preferably 67 - 87 wt%, more preferably 70 - 85 wt%, even more preferably 72 - 85 wt% with respect to a total weight of calcium carbonate in the solid waste material. A weight percentage of PCC of 100 wt% corresponds to a complete conversion of calcium carbonate from the waste material to the PCC product. In other embodiments, a weight percentage of the PCC produced may be less than 60 wt% or greater than 90 wt%.

[0037] According to another aspect, the present disclosure relates to a two- reactor process for regenerating precipitated calcium carbonate (PCC) from a waste stream. This process comprises the steps of filtering the waste stream (aqueous) to produce a solid waste material; calcining the solid waste material to produce a calcined material; mixing the calcined material with water, a CCh source, and an inorganic salt in a first reactor to form a first mixture of calcium carbonate and water; feeding the first mixture, a calcium source, and a second CO ₂ source to produce a second mixture of calcium carbonate and water; and filtering the second mixture to produce PCC and a water phase, wherein the PCC is multi-modal, multi-polymorph, and/or multi-structure.

[0038] In one embodiment, the process further comprises a step of feeding the water phase to the first reactor, wherein the water phase comprises the inorganic salt. As stated previously, the inorganic salt may be an ammonium salt, preferably ammonium chloride.

[0039] In one embodiment, the PCC may comprise nanoparticles clustered together as agglomerates. As used herein, the term "agglomerates" refers to a clustered particulate composition comprising primary particles, the primary particles being aggregated together in such a way so as to form clusters thereof, with at least SO volume percent of the clusters having a mean diameter that is at least 2 times the mean diameter of the primary particles, and preferably at least 90 volume percent of the clusters having a mean diameter that is at least S times the mean diameter of the primary particles.

[0040] In one embodiment, the PCC may be synthesized and formed into a variety of morphologies and shapes including, but not limited to, nanoparticles, nanosheets, nanoplatelets, nanocrystals, nanospheres, nanowires, nanofibers, nanoribbons, nanorods, nanotubes, nanocylinders, nanogranules, nanowhiskers, nanoflakes, nanofoils, nanopowders, nanoboxes, nanostars, tetrapods, nanobelts, nanoflowers, etc. and mixtures thereof.

[0041] The present disclosure relates to multi-batch processes for forming PCC of single and multi-modal types, while allowing the addition of additives and treatment with other compounds to influence the PCC properties. Reactor streams may be combined or recycled in order to seed reactions, provide a variety of PCC structures and/or morphologies, or to use excess reactants. [0042] PCC exists in different phases and morphologies, for example, vaterite, calcite, and aragonite. PCC may also be amorphous, or exist as a combination of more than one phase. Vaterite is a metastable phase of calcium carbonate at ambient conditions at the surface of the earth and belongs to the hexagonal crystal system. Vaterite is less stable than either calcite or aragonite, and has a higher solubility than either of these phases. Therefore, once vaterite is exposed to water, it may convert to calcite (for example, at low temperature) or aragonite (for example, at high temperature: ~60°C). There are other pathways and methods for conversion of one to the other as well, and the above are presented merely as examples. The vaterite form is uncommon because it is generally thermodynamically unstable.

[0043] The calcite form is the most stable form and the most abundant in nature and may have one or more of several different shapes, for example, rhombic and scalenohedral shapes. The rhombic shape is the most common and may be characterized by crystals having approximately equal lengths and diameters, which may be aggregated or unaggregated. Calcite crystals are commonly trigonal-rhombohedral. Scalenohedral crystals are similar to double, two-pointed pyramids and are generally aggregated.

[0044] The aragonite form is metastable under ambient temperature and pressure, but can be converted to calcite, for example, at elevated temperatures and pressures. The aragonite crystalline form may be characterized by acicular, needle- or spindle-shaped crystals, which can be aggregated and which typically exhibit high length-to-width or aspect ratios. For instance, aragonite may have an aspect ratio ranging from about 3:1 to about 15:1. Aragonite may be produced, for example, by the reaction of carbon dioxide with slaked lime.

[0045] In one embodiment, the PCC from a reactor may comprise PCC with a hybrid structure. In the present disclosure, a "hybrid structure" refers to a PCC component bound to at least a portion of a surface of a seed component. For example, the PCC component may be chemically bound to the seed component, such as, for example, through ionic, coordinate covalent (dative), or van der Waals bonds. According to some embodiments, the PCC component may physically bond or attach to the seed component. According to some embodiments, the PCC component may be adsorbed or physisorbed to the seed component. According to some embodiments, the PCC component may form a carbonate layer over the seed component during the carbonate addition step. For example, the PCC component may form a carbonate layer, shell, or coating that covers at least a portion of, majority of, or substantially all of the seed component. According to some embodiments, the PCC component may coat, enclose, or encapsulate substantially all of the seed component. According to some embodiments, the hybrid structure may include a PCC component, a seed component, and/or an interfacial component. The interfacial component may be, for example, a boundary region between the PCC component and the seed component. The interfacial component may include a chemical composition containing elements of the carbonate component and the second component For example, when the hybrid structure includes a calcium carbonate as the PCC component and a magnesium carbonate as the seed component, an interfacial region may include calcium and/or magnesium diffusing into the other component, or a region containing a mixture of calcium carbonate and magnesium carbonate. An interfacial region may occur, for example, upon thermal treatment (e.g., sintering) of the hybrid structure.

[0046] A structure described as "amorphous" herein refers to no short or long chain order and a crystalline structure refers to at least some level of order. Materials that may be described as semi-crystalline may therefore be considered crystalline in the present disclosure. The products herein are typically not 100% crystalline or 100% amorphous or non-crystalline, but rather exist on a spectrum between these points. In some embodiments, the PCC may be predominantly amorphous or a combination of an amorphous phase and a crystalline phase (such as calcite, vaterite, or aragonite).

[0047] In one embodiment, PCC produced may be single monodisperse PCC, where "monodisperse PCC" is defined herein as PCC having a PSD steepness (d3o/d70*100) of greater than 30. In one embodiment, monodisperse PCC may be formed using one or more reactors, in which the reagents in each may fully or partially react.

[0048] In one embodiment, PCC produced may be single or multi-structured. Structures of PCC include needles, rhombic blocks, needle clusters, rhombic block clusters, spheres, and combinations thereof.

[0049] In another embodiment, PCC produced may be a mixture of monodisperse PSDs of a single polymorph and structure.

[0050] In another embodiment, PCC produced may be a mixture of monodisperse PSDs of two or more polymorphs and/or structures of PCC.

[0051] In another embodiment, PCC produced may be a mixture of monodisperse PSDs of multiple structures that have the same polymorph of calcium carbonate.

[0052] In other embodiments, any combination of morphologies, phases, densities, and structures of PCC formed by the present disclosure may be possible. [0053] In one embodiment, the PCC may have a second layer of precipitated calcium carbonate due to the PCC being exposed to a second calcium carbonate precipitation reaction in the same or different reactor. This second layer may comprise PCC of a different structure or polymorphology, or the second layer may comprise a different material. In another embodiment, the second layer may be PCC of a similar structure and polymorphology, but contains an additive between itself and the PCC core. In one embodiment, the second coating may contain or comprise a second dopant.

[0054] In one embodiment, the PCC produced may be a combination of a PCC having a second layer of precipitated calcium carbonate due to the PCC being exposed to a second calcium carbonate precipitation reaction in the same or different reactor and at least one other PCC produced separately from the second calcium carbonate precipitation reaction in the same or different reactor. The second layer may comprise PCC of a different structure or polymorphology, or the second layer may comprise a different material. In another embodiment, the second layer may be PCC of a similar structure and polymorphology, but contains an additive between itself and the PCC core. In one embodiment, the second coating may contain or comprise a second dopant. The other PCC produced separately may comprise PCC of a different structure or polymorphology to that of the PCC having a second layer. In another embodiment, the other PCC produced separately may be PCC of a similar structure and polymorphology to that of the PCC having a second layer.

[0055] In one embodiment, the PCC has a surface area of 20 - 300 m ² /g, preferably 30 - 250 m ² /g, more preferably 40 - 200 m ² /g, even more preferably 60 - 180 m ² /g. However, in some embodiments, the surface area may be smaller than 20 m ² /g or greater than 300 m ² /g. Here, the surface area may be measured by BET theory, which refers to the Brunauer-Emmett- Teller theory explaining the physical adsorption of gas molecules on a solid surface.

[0056] In the present disclosure, the methods of producing a PCC composition may be varied to yield different polymorphs of calcium carbonate, such as, for example, vaterite, calcite, aragonite, amorphous calcium carbonate, or combinations thereof. The methods may be modified by varying one or more of the reaction rate, the pH of the mixtures, the reaction temperature, the reaction time, the stirring rate, the agitation rate, the shear rate, calcium salt type and concentration, dopant(s) type and concentration, reaction vessel pressure, reaction vessel volume, reaction vessel geometry, retention time in each reaction vessel, additives (treatment type and level, dispersant chemistry), flow rates, points of introduction for calcium, carbonation source, dopant, additive, and/or seeds. Reaction controls for PCC generation, polymorph, particle size, and structure are well known in the art, and can be applied to these processes by a person having ordinary skill in the art. See USRE38301 El , WO2016174309 Al , WO2016115386 Al, US5164172 A, US6156286 A, US5290353 A, US20050106110 Al, US6022517 A, US3320026 A, and WO2013142473 Al - each incorporated herein by reference in its entirety.

[0057] A multi-batch process may include preferably at least 2 reaction vessels. In one embodiment, the multi-batch process may have 2 - 15 reaction vessels, preferably 2 - 10, more preferably 3 - 8. The reaction vessels may be cylindrical, cuboid, frustoconical, or some other shape. The vessel walls may comprise a material including, but not limited to, glass, stainless steel polypropylene, polyvinyl chloride, polyethylene, and/or polytetrafluoroethylene, and the vessel walls may have a thickness of 0.1 - 3 cm, preferably 0.1 -2 cm, more preferably 0.2 - 1.5 cm. In one embodiment, for small scale or benchtop PCC production, one or more reaction vessels may have a volume of 100 rnL - 50 L, preferably 1 L - 20 L, more preferably 2 L - 10 L. In another embodiment, for instance, for pilot plant PCC production, one or more reaction vessels may have a volume of 50 L - 10,000 L, preferably 70 L - 1,000 L, more preferably 80 L - 2,000 L. In another embodiment, for instance, industrial plant-scale PCC production, one or more reaction vessels may have a volume of 10,000 L - 500,000 L, preferably 20,000 L - 400,000 L, more preferably 40,000 L - 100,000 L.

[0058] A reaction vessel may have one or more devices to measure and record the physical and/or chemical properties of its contents. Examples of these devices include, but are not limited to, pressure gauges, flowmeters, conductivity meters, pH meters, thermometers, and spectrophotometers. Recorded data from a device may allow a user skilled in the art to calculate parameters, such as efficiency, product recovery, reaction rate, and particle size distribution.

[0059] In one embodiment, a reaction in a reaction vessel may react fully to completion, meaning that the greatest possible amount of PCC is produced. In other embodiments, the reaction may only proceed partially, for instance, producing only 30 - 90 wt%, preferably 60 - 85 wt%, more preferably 65 - 82 wt% theoretical yield of PCC. The extent of the reaction may be influenced by the chemical species or other chemical reaction conditions as discussed previously. In other embodiments, one or more reagents may be added in excess, and exist in the reaction vessel or product stream throughout the reaction process. In one embodiment, the extent of reaction may be controlled by limiting the reaction time. [0060] In some embodiments, one or more compounds from a reaction vessel may be fed into another reaction vessel. The compound may be a PCC product, inorganic salt, water, unreacted CO ₂ source, unreacted dopant, unreacted seed, or unreacted calcium source. Where the compound is PCC product, the compound may work as a seed to form more PCC. Where the compound is an unreacted compound, it may react when fed into the other reaction vessel. In some embodiments, this may be considered "recycling" a compound or product. In a related embodiment, one or more compounds from a single reactor may be fed into one or more other reactors.

[0061] In another embodiment, the products from a reactor may be combined or kept separate. For example, Fig. 7 shows an embodiment where the PCC 48 from the first reactor 20 and the second reactor 38 is combined, but the PCC from the third reactor 46 is kept separated.

[0062] In one embodiment, bi- or tri- modal PCC may be formed from two or more reactor vessels, through partial reaction reactor; with or without seeding at least the second reactor in series with product from previous reactor(s), adjusting the retention time in the reactors, adjusting stir rate, or by the addition of surfactant or dispersant to control reaction rate and thus PCC particle size, polymorph and/or structure.

[0063] In one embodiment, bi- or tri- modal PCC may be rendered partially or fully hydrophobic through the addition of a dispersant, fatty acid, fatty acid salt derivative, dispersant and/or surfactant. This treatment can be performed before, during and/or after formation of the PCC, as desired.

[0064] In one embodiment, calcium carbonate may be precipitated onto one or more secondary materials, to yield a chemically-bound combination of products having specific characteristics. In a related embodiment, PCC may be formed in one reactor and then used as a template or a seed for additional PCC generation in a second reactor.

[0065] In one embodiment, high purity PCC may be produced having low aluminum and fluoride content. This involves the use of ammonium chloride or some other calcium chloride-generating intermediate for dissolving the calcium, and subsequent filtration. Such is known in the art to produce PCC of low (<10 ppm) aluminum, and low (<20 ppm) fluoride content. See Patent EP0673879 Al - incorporated herein by reference in its entirety.

[0066] In one embodiment, the addition of additives prior to carbonation may result in PCC with notable properties. Such additives may include fatty acids, fatty acid salts, dispersants such as fully or partially neutralized sodium polyactylate-based chemistries and/or maleic acid/maleic anhydride copolymers, biomolecules such as amino acids, lactic acid, or polylactic acid, sugar, starch, and/or cellulose. These properties may include lower density PCC, including, but not limited to, vaterite, aragonite, scalenohedral and rhombic calcite.

[0067] In one embodiment, target PSD ranges include 20 nm to 20 μπι and all subranges. Depending on the final application, PCC products can be further screened to modify the PSD range. One such example is the production of 10 nm PCC having a topcut of 20 nm. Such may find use in transparent films and polymers, where, when loaded below CPVC, transparency is retained in the polymer or film. Such small PSD may be achieved by controlling shear rate, concentration of calcium salt, use of additives, temperature and reaction pH. For example, use of high shear rate in the reactor during reaction, with high concentration of calcium salt for reaction with short reaction time, and with or without additive such as dispersant for small PSD. Likewise, carbonation may also be controlled, as to be performed in-situ with calcium ion dissolution to generate small particles. Reaction time, pH modification, temperature and/or high shear rate can be used to slow the rate and likelihood of particle agglomeration.

[0068] According to some embodiments, the PCC compositions may have a top-cut (dw) particle size less than about 25 microns ( μm ),, such as, for example, less than about 17 microns, less than about IS microns, less than about 12 microns, or less than about 10 microns. According to some embodiments, the PCC compositions may have a top-cut particle size in a range from about 2 microns to about 25 microns, such as, for example, in a range from about 15 microns to about 25 microns, from about 10 microns to about 20 microns, or from about 3 microns to about 15 microns.

[0069] According to some embodiments, the PCC compositions may have a bottom- cut (dio) particle size less than about 4 microns, such as, for example, less than about 2 microns, less than about 1 micron, less than about 0.7 microns, less than about 0.5 microns, less than 0.3 microns, or less than 0.2 microns. According to some embodiments, the PCC compositions may have a bottom-cut particle size in a range from about 0.1 micron to about 4 microns, such as, for example, in a range from about 0.1 micron to about 1 micron, from about 1 micron to about 4 microns, or from about 0.5 microns to about 1.5 microns.

[0070] The PCC compositions may additionally be characterized by their BET surface area. As used herein, BET surface area refers to the Brunauer-Emmett-Teller (BET) explaining the physical adsorption of gas molecules on a solid surface. It refers to multilayer adsorption, and usually adopts non-corrosive gases (i.e. nitrogen, argon, carbon dioxide and the like) as adsorbates to determine the surface area data. The BET surface area may vary according to the morphology of the PCC. According to some embodiments, the PCC may have a BET surface area less than 80 m ² /g, such as, for example, less than SO m ² /g, less than 20 m ² /g, less than 15 m ² /g, less than 10 m ² /g, less than 5 m ² /g, less than 4 m ² /g, or less than 3 m ² /g. In some embodiments, the calcite PCC composition particles may have a BET surface area in a range from 1 to 30 m ² /g, such as, for example, from 2 to 10 m ² /g, from 3 to 6.0 m ² /g, from 3 to 5.0 m ² /g. In other embodiments, calcite PCC may have a BET surface area in a range from 1 to 6 m ² /g, from 1 to 4 m ² /g, from 3 to 6 m ² /g, or from 1 to 10 m ² /g, from 2 to 10 m ² /g, or from 5 to 10 m ² /g. According to some embodiments, calcite PCC may have a BET surface area less than or equal to 30 m ² /g. Vaterite PCC may have a BET surface area in a range from 5 to 75 m ² /g. In certain embodiments, the vaterite PCC composition particles have a BET surface area in a range from 7 to 18 m ² /g, from 5 to 20 m ² /g, or from 7 to 15 m ² /g. In some embodiments, aragonite PCC may have a BET surface area in the range from 2 to 30 m ² /g.

[0071] The PCC compositions may additionally be characterized by the ratio of BET surface area to dso. In a certain embodiment, the vaterite PCC composition particles have a ratio of BET surface area to dso of 1-6.5, 2-5.5, or 2.5-5. In another embodiment, the calcite PCC composition particles have a ratio of BET surface area to dso of 0.6-2, 0.7-1.8, or 0.8-1.5.

[0072] In some embodiments, the PCC may have a specific gravity in a range having a lower limit of about 2.6, 3, 4, 4.5, 5, or 5.5 to an upper limit of about 20, 15, 10, 9, 8, or 7, and permutations thereof.

[0073] The PCC compositions may additionally be characterized by their stearic acid uptake surface area. As used herein, stearic acid uptake surface area refers to a surface treatment of the PCC compositions with stearic acid. Under controlled conditions, the stearic acid may form a monolayer on the surface of the PCC and thus provide information regarding the surface area via adsorption or uptake of stearic acid. The stearic acid uptake surface area may vary according to the morphology of the PCC. According to some embodiments, the PCC may have a stearic acid uptake surface area less than 80 m ² /g, such as, for example, less than 75 m ² /g, less than 50 m ² /g, less than 20 m ² /g, less than 15 m ² /g, less than 10 m ² /g, less than 5 m ² /g, less than 4 m ² /g, or less than 3 m ² /g.

[0074] In some embodiments, the yield of PCC using the multi-batch processes herein is greater than 50%, greater than 60%, greater than 80%, or greater than 90%. [0075] The PCC compositions of the present disclosure may be in any desired form, including but not limited to, powders, crystalline solids, or in dispersed form, i.e., the PCC compositions may be dispersed in a liquid, such as in an aqueous medium. In one embodiment, the dispersed PCC composition comprises at least about 50% PCC by weight relative to the total weight of the dispersion, at least about 70% PCC by weight

[0076] In some embodiments, a size reduction method is employed either in situ or on the product after recovery. A size reduction method may include sonication or grinding. Since the products appear to exhibit "substructure" that is most likely interpretable as aggregation, a size reduction method may break apart the aggregates into their constituent building blocks. According to some embodiments, ultrasound may be used to break down agglomerates

[0077] The PCC compositions of the present disclosure may optionally comprise at least one added pigment Suitable pigments are those now known or that may be hereafter discovered. Exemplary pigments include organic pigments and inorganic pigments, including, but are not limited to, carbon black, Nigrosine dyes, black iron oxide, Naphthol Yellow S, HANSA Yellow (10G, 5G and G), Cadmium Yellow, yellow iron oxide, loess, chrome yellow, Titan Yellow, polyazo yellow, Oil Yellow, HANSA Yellow (GR, A, RN and R), Pigment Yellow L, Benzidine Yellow (G and GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G and R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazane Yellow BGL, isoindolinone yellow, red iron oxide, red lead, orange lead, cadmium red, cadmium mercury red, antimony orange, Permanent Red 4R, Para Red, Fire Red, p-chloro-o-nitroaniline red, LITHOL Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL and F4RH), Fast Scarlet VD, Vulcan Fast Rubine B, Brilliant Scarlet G, LITHOL RUBINE GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, BON Maroon Light, BON Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarine Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, PYRAZOLONE Red, polyazo red, Chrome Vermilion, Benzidine Orange, perynone orange, Oil Orange, cobalt blue, cerulean blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, INDANTHRENE BLUE (RS and BC), Indigo, ultramarine, Prussian blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, cobalt violet, manganese violet, dioxane violet, Anthraquinone Violet, Chrome Green, zinc green, chromium oxide, viridian, emerald green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, titanium oxide, zinc oxide, lithopone, titanium dioxide, calcined clays, delaminated clays, talc, calcium sulfate, other calcium carbonate, kaolin clays, calcined kaolin, satin white, plastic pigments, aluminum hydrate, and mica.

[0078] The pigment may be present in the PCC compositions of the present disclosure in an amount less than about 70% by weight relative to the total weight of the composition. It is to be understood that the skilled artisan will select any amounts of the optional at least one second PCC form and the optional at least one pigment in such a way so as to obtain various desired properties without affecting, or without substantially affecting, the advantageous properties of the PCC compositions disclosed herein.

[0079] In the present disclosure, the monodispersity of the product refers to the uniformity of crystal size and polymorphs. The steepness (d3o/d7o ^x 100), as defined above, refers to the particle size distribution bell curve, and is a monodispersity indicator. In the present disclosure, the preferred PCC product is monodisperse with a steepness greater than 30, or greater than 40, or greater than SO, and less than 60, or even less than 65. According to some embodiments, the PCC may have a steepness in a range from about 30 to about 100, such as, for example, in a range from about 34 to about 100, from about 42 to about 77. In some embodiments, the steepness may vary according to the morphology of the PCC. For example, calcite may have a different steepness than vaterite.

[0080] The present disclosure enables the generation of varied PSD (dso) and polymorphs of the PCC product, which can be formed as vaterite, aragonite, calcite (e.g., rhombic or scalenohedral calcite), or amorphous calcium carbonate, as well as any desired mixtures of these, by control of the various conditions used in the multiple reactors, and the reactor configuration used. In general, lower reaction temperature yields smaller/finer, higher surface area vaterite 'balls'. In general, lower excess of an ammonium source yields smaller/ finer crystals within aggregates, and higher surface area products often comprised of a calcite/vaterite blend.

[0081] In one embodiment, the PCC composition of the present disclosure is characterized by a single vaterite crystal polymorph content of greater than or equal to 30% by weight relative to the total weight of the composition, greater than or equal to 40% by weight, greater than or equal to 60% by weight, greater than or equal to about 80% by weight, or greater than or equal to about 90% by weight.

[0082] In one embodiment, the vaterite PCC has a geometry comprising spherical coral, elliptical coral, rhombic, flower-shaped or mixtures thereof.

[0083] In another embodiment, the vaterite PCC has a PSD (dso) ranging from 2.0- 7.0, 2.4-6.0, or 2.6-5.5 microns.

[0084] In another embodiment, the vaterite PCC has a steepness

ranging from 30-100, 37-100, 40-83, 42-71.

[0085] In another embodiment, the vaterite PCC has a BET surface area ranging from 5-25, 10-17, or 10.4-16.1 m ² /g.

[0086] In another embodiment, the vaterite PCC may have an amount of hydrophobizing agent in a range from about 5 m ² /g to about 25 m ² /g to coat the particles.

[0087] In one embodiment, the PCC produced by the multi-batch process of the present disclosure may have a calcite polymorph. The calcite precipitated calcium carbonate described within has improved structural characteristics, such as particle size distribution (PSD), steepness, and BET surface area, as compared to heretofore known calcite precipitated calcium carbonate.

[0088] In one embodiment, the PCC composition of the present disclosure is characterized by a single calcite crystal polymorph content of greater than or equal to 30% by weight relative to the total weight of the composition, greater than or equal to 40% by weight, greater than or equal to 60% by weight, greater than or equal to about 80% by weight, or greater than or equal to about 90% by weight.

[0089] In one embodiment, the PCC composition or compositions comprises calcite. Calcite PCC has a rhombic geometry. In one exemplary embodiment, seeding calcium sulfate with crystal ized calcium carbonate consistently yields rhombic PCC. Seeding with calcite, dolomite, or magnesite yields rhombic PCC. In general, seeding with coarse scalenohedral PCC >5% yields a larger/ coarser and a higher surface area product. In one exemplary embodiment, seeding with fine rhombohedral PCC <5% yields a finer crystal size within the aggregate; >5% gives finer aggregates. In the absence of seeding, ammonium carbonate conditions can influence rhombic PCC formation.

[0090] In another embodiment, the calcite PCC has a PSD (d50) ranging from 1.8- 6.0, 2.2-5.8, or 2.8-5.6 microns. [0091] In another embodiment, the calcite PCC has a steepness

ranging from 30-100, 40-100, 50-83, 56-71, 100-40, 83-50, or 71-56.

[0092] In another embodiment, the calcite PCC has a BET surface area ranging from 3.0-7.0, 3.1-6.0, or 3.5-5.0 m ² /g,

[0093] In another embodiment, the calcite PCC may have an amount of hydrophobizing agent in a range from about 0.15 m ² /g to about 8 m ² /g to coat the particles.

[0094] The present disclosure also relates to a precipitated calcium carbonate compound with an aragonite polymorph. The aragonite precipitated calcium carbonate described within has improved structural characteristics, such as particle size distribution (PSD), steepness, and BET surface area, as compared to heretofore known aragonite precipitated calcium carbonate.

[0095] In one embodiment, the PCC compound of the present disclosure is characterized by a single aragonite crystal polymorph content of greater than or equal to 30% by weight relative to the total weight of the composition, greater than or equal to 40% by weight, greater than or equal to 60% by weight, greater than or equal to about 80% by weight, or greater than or equal to about 90% by weight.

[0096] In one embodiment, the PCC produced by the multi-batch process of the present disclosure may comprise rhombic PCC in the form of small stacked plates of 300-500 nm, forming inconsistent or consistent particle shapes, having a dso of 1-6 μπι, a steepness (d3o/d7o><100) of 91-56, and surface area 2-5 m ² /g.

[0097] According to some embodiments, after forming the PCC compound of the present disclosure, the morphology may be changed through post-processing techniques, such as aging. For example, according to some embodiments, an amorphous PCC may be used as a precursor to convert into a crystalline morphology, such as vaterite, aragonite, or calcite. According to some embodiments, a metastable PCC, such as vaterite or aragonite, may be converted to calcite through aging, such as, for example, wet aging. The amount of vaterite converted to calcite through aging may be varied by adjusting the properties of the aging conditions. For example, the aging may be varied by the presence or absence of ammonium sulfate, including the amount of ammonium sulfate, the aging temperature, and the concentration of wet cake solids. According to some embodiments, when less than about 90% vaterite is present, the vaterite will convert to calcite. When greater than or equal to about 90% vaterite is present, the vaterite can be retained in a dry powder or wet cake. The amount of retained vaterite may vary depending on the aging parameters. According to some embodiments, vaterite can be converted to calcite through a mechanical process, such as by grinding or ball milling the vaterite.

[0098] In another embodiment, the PCC produced has a PSD (dso) ranging from 1 - 40 μηι, preferably 3 - 30 μm , more preferably 5 - 15 μm ,. In another embodiment, the PCC has a steepness (d3o/d70*100) in a range from 30-100, or 53-71, or 59-63. In another embodiment, the PCC has a surface area (BET and/or stearic acid uptake) ranging from 1 - 30, or from 3 - 9 m ² /g. According to some embodiments, the PCC may have a relatively steep particle size distribution, for example, a steepness greater than about 46. According to some embodiments, the PCC may have a relatively broad particle size distribution, for example, a steepness less than about 40.

[0099] The calcium source is at least one selected from the group consisting of lime, calcium oxide, calcium hydroxide, calcium chloride, calcium carbonate, calcium sulfate (gypsum), calcium phosphate (mono-calcium phosphate, di-calcium phosphate, and/or tri- calcium phosphate), calcium lactate, calcium silicate, calcium saccharin, calcium glycerophosphate, calcium citrate, calcium malate, calcium maleate, calcium tartrate, calcium succinate, calcium gluconate, calcium lactate, calcium fumarate, calcium benzoate, calcium sorbate, or any calcium salt. In one embodiment, the calcium source is calcium chloride. In one embodiment, the calcium source contains calcium that was previously in the form of calcium carbonate.

[0100] In certain embodiments of the disclosure, the calcium source is first reacted with an inorganic salt, such as ammonium chloride, to convert it into calcium chloride prior to reaction with CO ₂ to prepare the PCC. The conversion of the various types of calcium sources into calcium chloride can be performed using conventional chemistry within the purview of one of ordinary skill in the art. In certain embodiments, once the chloride salt has been generated, the resulting composition is treated to remove impurities. These impurities can be discarded, or if desired can be recycled as a seed, dopant, or other additive, into one or more of the reactors in the multi-batch process. Prior to such use, the impurities may also be treated or modified to change their surface chemistries or effect some other change, in order to alter their additive properties.

[0101] In one embodiment, a calcium source, such as those mentioned above, is pure, meaning that 0.1 wt% or less, preferably 0.05 wt% or less, more preferably 0.01 wt% or less of the calcium source is impurities, such as salts, metals, or organic compounds, which do not contain calcium.

[0102] Calcium sources may include calcium carbonate from rich waste feeds, such as egg shells and animal bones. Calcium carbonate may come from natural sources such as limestone, talc, diatomaceous earth, marble, chalk, or dolomitic limestone, and may be mined. Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite. Dolomitic limestone is a type of rock that includes up to 50% dolomite (e.g. CaMg(CCb)2) by weight, where calcium ions present in the calcite part are replaced by magnesium ions. Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock (e.g. calcite or dolomite). Metamorphism causes variable recrystallization of the original carbonate mineral grains. Chalk is a soft, white, porous sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Chalk typically forms under deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores.

[0103] In certain embodiments of the present disclosure, the calcium source is first reacted to convert it into calcium chloride prior to reaction with CO ₂ to prepare the PCC. The conversion of the various types of calcium sources into calcium chloride can be performed using conventional chemistry within the purview of one of ordinary skill in the art. In certain embodiments, once the chloride salt has been generated, the resulting composition is treated to remove impurities. These impurities can be discarded, or if desired can be recycled as a seed, dopant, or other additive, into one or more of the reactors in the multi-batch process. Prior to such use, the impurities may also be treated or modified to change their surface chemistries or effect some other change, in order to alter their additive properties.

[0104] The CO ₂ source may be CO ₂ in solid, liquid, or gaseous forms, and/or a carbonate salt. CO ₂ in gaseous forms may be pure carbon dioxide gas, flue gas containing 15- 90 vol% carbon dioxide gas, or flue gas with enriched carbon dioxide gas (e.g., greater than 90 vol% CO) ₂ . The carbonate salt may be ammonium carbonate, ammonium bicarbonate, ammonium carbamate, sodium carbonate, ammonium uranyl carbonate, barium carbonate, beryllium carbonate, bismuth subcarbonate, caesium carbonate, cerium(III) carbonate, cobalt(II) carbonate, copper carbonate, lanthanum carbonate, lead carbonate, lithium carbonate, magnesium carbonate, manganese(II) carbonate, nickel(II) carbonate, potassium carbonate, rubidium carbonate, silver carbonate, sodium bicarbonate, sodium carbonate, sodium percarbonate, sodium sesquicarbonate, strontium carbonate, thallium(I) carbonate, thiocarbonate, uranyl carbonate, calcium carbonate, dolomite, carbonic acid, or some other carbonate salt. In a preferred embodiment, the CC¾ source is gaseous CO. ₂

[0105] Calcium carbonate may be derived from other sources such as carpet and tile backing, PVC, films, food and drink packaging, and/or paperboard, and processes where it is used as a porogen or templating agent for structure and/or porosity. Extraction from calcium carbonate-rich sources involves calcium extraction using an acid such as hydrochloric acid, separation of the calcium salt solution from insoluble waste product, and introduction of a base, such as ammonium hydroxide, to liberate the calcium for further reaction.

[0106] Calcium may also be produced from calcium oxide-rich wastes such as steel slag, biomass slag, and ash. Extraction of calcium from calcium oxide-rich wastes involves extracting calcium using ammonium chloride, and separating the dissolved calcium solution from insoluble waste for further reaction. Such processes are known in the art

[0107] In some embodiments, calcium must be extracted from such compounds through selective dissolution and extraction, though in other embodiments, the calcium source may be used directly in the reaction without extraction, or with only physical processing, such as grinding. Calcium extraction from calcium carbonate-rich sources involves calcining the sources to generate calcium oxide, which can then be reacted with ammonium chloride to generate calcium salt for further reaction. Extraction from calcium carbonate-rich sources may involve using an acid, such as hydrochloric acid, to produce a calcium salt. The calcium salt solution may be separated or filtered from the insoluble waste product. Then the calcium salt solution may be treated with a base, such as ammonium hydroxide, to liberate the calcium for further reaction.

[0108] In another embodiment, calcium may be extracted from calcium oxide-rich wastes. This involves treating the calcium oxide-rich wastes with ammonium chloride, and then separating the dissolved calcium solution from insoluble waste for further reaction. Such processes are known in the art.

[0109] In some embodiments of the multi-batch reactions, one or more steps of calcium extraction or purification from a source of calcium may be included as part of the disclosure.

[0110] In some embodiments, the residence time for calcium extraction will depend on accessibility of calcium in the calcium source. For certain calcium sources, including but not limited to dry slag, ash, and lime, the calcium source may be ground prior to water suspension and dissolution in order to increase accessibility of calcium.

[0111] Calcium sources may be purified prior to reaction by methods known in the art. Such may include full dissolution of the calcium with acid or acidic compounds, such as ammonium chloride, hydrochloric acid, or sulfuric acid and subsequent filtration to separate dissolved calcium salt from insoluble fraction. Methods for filtration are also well known in the art. Acidic compounds herein are those having a pH < 7. After filtration, the acid or acidic compound may be recycled for reuse in the reaction. The acid or acidic compound may be concentrated if needed by non-thermal means.

[0112] In addition, solvent may be added to the calcium source, slurry or suspension prior to reacting with the CO ₂ source. Suitable solvents that may be used for forming a solution, slurry, or suspension from the calcium source include aprotic polar solvents, polar protic solvents, and non-polar solvents. Suitable aprotic polar solvents may include, but are not limited to, propylene carbonate, ethylene carbonate, butyrolactone, acetonitrile, benzonitrile, nitromethane, acetonitrile, nitrobenzene, sulfolane, dimethylformamide, N-methylpyrrolidone, or the like. Suitable polar protic solvents may include, but are not limited to, water, nitromethane, and short chain alcohols. Suitable short chain alcohols may include, but are not limited to, one or more of methanol, ethanol, propanol, isopropanol, butanol, or the like. Suitable non-polar solvents may include, but are not limited to, cyclohexane, octane, heptane, hexane, benzene, toluene, methylene chloride, carbon tetrachloride, or diethyl ether. Co-solvents may also be used. In one embodiment gypsum (calcium sulfate) is the calcium source, and the solvent is water. Gypsum is moderately water-soluble (2.0-2.5 g/L at 25 °C). Therefore, to form a gypsum solution, enough water is added to fully dissolve all of the gypsum prior to reaction. To form a slurry or suspension, an amount of water is added to partially dissolve the gypsum, such that some of the gypsum is fully dissolved and some of the gypsum remains in solid form. In another embodiment, water is added to the calcium source to form a slurry, wherein the percent of solids in the slurry is 10-80%, 20-40%, or 30-35%. The water may be tap water, distilled water, bidistilled water, deionized water, deionized distilled water, reverse osmosis water, and/or some other water. In one embodiment the water is bidistilled to eliminate trace metals. Preferably the water is bidistilled, deionized, deinonized distilled, or reverse osmosis water and at 25 °C has a conductivity at less than 10 preferably less than resistivity greater than 0.1 ΜΩ-cm, preferably greater than 1 ΜΩ-cm, more preferably greater than 10 ΜΩ-cm, a total solid concentration less than 5 mg/L, preferably less than 1 mg/L, and a total organic carbon concentration less than 1000 μg/L, preferably less than 200 μg/L, more preferably less than SO Mg/L. In methods A-I, the concentration of the reacting mixture is also controlled. In a certain embodiment, the concentration is controlled by the addition or subtraction of water from the reacting solution, mixture, or slurry.

[0113] In one embodiment, the PCC may be a nanocomposite. A nanocomposite is a multiphase solid material where one of the phases or polymorphs has one, two, or three dimensions of less than 100 nm, or the nanocomposite comprises structures with nanoscale repeat distances between the different phases that make up the material. In general, the mechanical, electrical, thermal, optical, electrochemical, and/or catalytic properties of a nanocomposite will differ from that of its component materials.

[0114] In one embodiment, structures, such as hematite, may be added to a reactor for reacting calcium carbonate onto the surface. The particle size and coverage on the structure may be varied between multiple reactors, by modifying concentrations, reaction time, temperature, or pH. More than one reactor may be used, such that the structure is only partially coated with PCC or fully coated with PCC. The thickness of the PCC layer and polymorph may be tuned by changing reaction conditions.

[01 IS] In one embodiment, one or more additives may be added at any stage of the process (before, during, and/or after PCC formation) including one or more of a dopant, a seed, a buffer, a thickener, an anticaking agent, a defoamer, a rheology agent, a dispersant, a wetting agent, a co-solvent, a brightness enhancer or dampener, a pigment, citric acid, phosphoric acid, ammonium sulfate, sodium thiosulfate, a fatty acid, or a fatty acid derivative salt. In one embodiment, the weight % of the additive ranges from 0.5% to 10% relative to the PCC. The choice of additive and timing of addition (before, during or after carbonation and/or PCC formation) can result in differing properties of the final PCC product, and can be used to fine tune a set of properties desired in the product.

[0116] In one embodiment, additive may be a fatty acid or fatty acid salts (ex. stearic acid, ammonium stearate, sodium stearate, palmitic acid, and others), a dispersant, another acid, an ammonium phosphate (as di- or tri- ammonium phosphate to co-generate hydroxyapatite).

[0117] In one embodiment, a seed is added and is one or more of ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), dolomite, dolomitic carbonate, magnesium carbonate, sodium carbonate, or some other carbonate salt or form of calcium carbonate as mentioned earlier. The seed may be dissolvable in dilute acid, such as, for example, hydrochloric acid (HC1).

[0118] In one embodiment, the seed does not exceed 10 wt% relative to the total weight of the calcium source in the reaction mixture. In an alternative embodiment, the seed is at least 10 wt% relative to the total weight of the calcium source in the reaction mixture.

[01 19] In one embodiment, a dopant may be added. The dopant may be a mineral or salt including but not limited to a sodium salt, a magnesium salt, a potassium zinc salt, a cesium salt, an iron salt, or a manganese salt. The dopant may be an organic compound, including but not limited to ascorbic acid, folic acid, and pantothenic acid.

[0121] The additive may be, but is not limited to, a buffer, a dispersant, a thickener, an anticaking agent, a defoamer, a rheology agent, a wetting agent, a crystal seed, a co-solvent, a brightness enhancer, or any agent that affects crystal morphology/geometry of the product. Examples of additives include, but are not limited to, citric acid, phosphoric acid, a sugar, BaCl ₂ , MgO, MgC0 ₃ , H ₂ S0 ₄ , H3PO4, HC1, various phosphates, sodium hexametaphosphate, ammonium sulfate, sodium thiosulfate, and NO3 compounds. Examples of brightness enhancers include, but are not limited to, fluorescent brightening agents. According to some embodiments, when the additive is an acid, such as, for example, citric acid, the surface area of a resulting PCC morphology may be increased. The selection of the acid, such as, for example, phosphoric acid, may be used in varying amounts to control the shape, particle size, and/or surface area of the PCC. In one embodiment, a calcite polymorph is produced when the mixture further comprises citric acid, phosphoric acid, ammonium sulfate, or sodium thiosulfate. In one embodiment, the weight % of the additive ranges from 0.1% to 20%, or 0.5% to 10%, or 1% to 6% relative to the total weight of the calcium source.

[0122] The PCC compositions of the present disclosure may be in any desired form, including but not limited to, powders, crystalline solids, or in dispersed form, i.e., the PCC compositions may be dispersed in a liquid, such as in an aqueous medium. In one embodiment, the dispersed PCC composition comprises at least about 50% PCC by weight relative to the total weight of the dispersion, preferably at least about 70% PCC by weight. The dispersed PCC composition may comprise at least one dispersing agent, which may be chosen from dispersing agents now known in the art or hereafter discovered for the dispersion of PCC. Examples of suitable dispersing agents include, but are not limited to: polycarboxylate homopolymers, polycarboxylate copolymers comprising at least one monomer chosen from vinyl and olefinic groups substituted with at least one carboxylic acid group, and water soluble salts thereof. Example of suitable monomers include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, isocrotonic acid, undecylenic acid, angelic acid, and hydroxyacrylic acid. The at least one dispersing agent may be present in the dispersed PCC composition in an amount ranging from about 0.01 wt% to about 2 wt%, preferably from about 0.02 wt% to about 1.5 wt% relative to the total weight of the dispersion

[0123] In one embodiment, single monodisperse PCC may be rendered partially or fully hydrophobic by treating with a dispersant (for example, maleic acid or maleic anhydride based) and/or surfactant.

[0124] In one embodiment, PCC may be surface treated with stearic acid, other stearate or hydrocarbon species, other dispersants, other fatty acids, and/or other fatty acid derivative salts to yield a specific level of hydrophobicity. Hydrophobicity may be measured using a moisture uptake (MPU) technique, in which a PCC powder is exposed to a high relative humidity atmosphere for 24h or longer and the weight change due to water sorption is recorded. In general, the maximum reduction in MPU achievable by surface treatment is particularly advantageous. Hydrophobicity may also be measured by contact angle, in which a droplet of a test liquid (e.g. water) is placed on a PCC powder and is observed to see whether the droplet is absorbed (wets) or gives a stable droplet with a measurable contact angle. Surface treatments may involve dry or wet coating with a C6-C22 fatty acid or fatty acid derivative salt. Such treatments are well-known in the art, and in addition to stearic acid, include such materials as ammonium stearate, sodium stearate, palmitic acid, and others. The fatty acid/ fatty acid salt is provided in sufficient quantity to coat at least a portion of the surface of the majority of PCC particles, in some embodiments a substantial portion of the surface of the majority of PCC particles. The amount of hydrophobizing agent needed to form the desired coating level of the PCC surface is related to the PCC surface area. In one embodiment, a calcite PCC of this disclosure requires 0.5-1.0% hydrophobizing agent to coat the surface. In another embodiment, a vaterite PCC requires 2.0-3.0% hydrophobizing agent to coat the surface. Treated and untreated PCC or blends thereof, of single or blended size distributions can be used in a variety of applications, including adhesives and sealants as a rheology modifier, in paints and ink for opacity and as an extender, as a paper filler, for surface finishing and brightness, a functional filler in plastics and as an extender. According to some embodiments, the hydrophobizing agent may form a monolayer on the surface of the PCC. According to some embodiments, the amount of hydrophobizing agent may be in a range from about 0.15 m ² /g to about 18 m ² /g to coat the particles, such as, for example, in a range from about 0.15 mVg to about 8 m ² /g or from about 10 m ² /g to about 17 m ² /g. The amount of hydrophobizing agent may be dependent on the morphology of the PCC. For example, calcite PCC may have an amount of hydrophobizing agent in a range from about 0.15 m ² /g to about 20 rrr/g to coat the particles, and vaterite PCC may have an amount of hydrophobizing agent in a range from about 10 m ² /g to about 80 m ² /g to coat the particles.

[0125] In one embodiment, PCC may be fully or partially hydrophobized. Fully hydrophobized PCC has a theoretical monolayer of hydrophobizing coating (fatty acid, or fatty acid derivative salt) required for coating the entire surface of the calcium carbonate. In one embodiment, this may range from 0.5 wt% - 10 wt% surface treatment.

[0126] In one embodiment, mineral dopants may provide a form of PCC for different applications. Such may include the use of magnesium to produce a calcium-magnesium carbonate product, which may have advantageous impact on reaction behavior during polymer cure, or improved compatibility in ion-sensitive materials. Furthermore, reaction conditions, such as reaction vessel pressure, may be modified to generate precipitation of combined mineral crystal structures, such as the formation of dolomite instead of co-precipitated magnesium carbonate and calcium carbonate. Mineral-doped PCC may have use in food and pharmaceutical applications. Inorganic, biologically desirable agents, such as ascorbic acid, folic acid, pantothenic acid, and inorganics such as sodium fluoride may be added to the calcium source prior to carbonation. The PSD, structure and polymorph desired for the final PCC will dictate which reactor the dopant is provided. Sodium fluoride may prove beneficial in toothpaste. Aforementioned acids are vitamin compounds useful in food fortification and supplementation.

[0127] Dopants may include organic or inorganic pigment to impart specific uses to PCC. PCC may also serve to modify dispersion behavior of inorganic pigments, decrease the total amount of pigment needed in a given system, and provide unique color enhancement to final application. Dopant may be ammonium phosphate to co-generate hydroxyapatite with PCC. Hydroxyapatite may be surface bound and/or encapsulated with PCC, and is also useful as a biological agent, such as for bone generation and in bone scaffolds.

[0128] Dopants may also include taggants, for example, fluorescent compounds. Such doped PCCs and additional dopants are known in the art and are incorporated herein by reference. See PCT/US2017/022466, published as WO2017/160950 - incorporated herein by reference in its entirety.

[0129] In one embodiment, a dopant and/or a seed is added to the water before or during the mixing.

[0130] Single or multiple reagents, dopants, seeds, or any other additive or combination thereof, may be added to any reactor in bulk, portion-wise, or by a slow-addition process to control the PCC product characteristics. The rate of addition of these components also controls the changes in the reacting mixture concentration. Reagents such as mineral acid, ammonium carbonate, calcite, aragonite, calcium carbonate, dolomite, ammonium bicarbonate, ammonium carbamate, ammonium hydroxide, carbon dioxide, dopant, seed, or any other additive or carbonate source or combination thereof is added as a solution, a solid, a suspension or slurry, a gas, or a neat liquid. In terms of adding a gas, the gas may be bubbled into a solution to an effective concentration, or may be used to purge or pressurize the reaction vessel until a desired effective concentration is reached.

[0131] During the preparation, the nucleation rate and crystal size of calcium carbonate can be controlled through control of the reaction time and temperature. In a certain embodiment, the carbon dioxide, or carbon dioxide equivalent is equimolar or greater to the calcium source. The reaction time may be 0.2-10 hours, or 0.5-3 hours, and the temperature may be in a range from 8-90° C, or from 10-98°C. According to some embodiments, a CC¾- containing gas, such as a flue gas, may be continuously added during the reaction period [0132] In one embodiment, additives may be added prior to carbonation to generate lower density PCC.

[0133] In one embodiment, additives may be added prior to carbonation to generate lower density PCC having a needle shape. PCC in this form would have high surface area and would be useful in tires and rubber products, 3D printing, and in other applications to be discussed later in this application.

[0134] The processes for forming precipitated calcium carbonate may further include at least one method selected from the group consisting of dewatering, drying, ageing, surface treating, size reducing, and beneficiating. Reactions may be batch, semi-batch, combination of batch and semi-batch, or may be continuous or combination of all reactions, such as a cascade reaction.

[0135] In some embodiments, the precipitated calcium carbonate may be between about 10% and about 25% by weight of the combined calcium carbonate and additive(s), such as, for example, between about 10% and about 15% by weight, between about 15% and about 20% by weight, between about 20% and about 25% by weight, between about 12% by weight and about 18% by weight, or between about 18% by weight and about 23% by weight of the combined calcium carbonate and additive(s).

[0136] The pH of any reaction mixture in the process may be controlled. In one embodiment, the reacting mixture may be acidic (pH less than 6.5), neutral (pH 6.5-7.5), or basic (pH greater than 7.5). In regards to the process of the present disclosure, the ionic strength of the mixtures may also be controlled. The ionic strength, /, of a solution is a function of the concentration of all ions present in that solution.

[0137] where C _i is the molar concentration of ion i (M, mol/L), z\ is the charge number of that ion, and the sum is taken over all ions in the solution. In one embodiment, the ionic strength is controlled by the stoichiometry of ionizable reactants. In another embodiment, the ionic strength is controlled by the addition of ionic additives. These ionic additives may be a participating reactant, a spectator ion (i.e. a non-participating reactant), and/or a total ionic strength adjustment buffer. In another embodiment, the ionic strength is controlled by the use of deionized (DI) water. [0138] The PCC production process of Example Setup 1 of the present disclosure aims to produce only one form of PCC. However, a small amount of an alternative polymorph is often present, and can be readily tolerated in most end uses. Thus, the PCC compositions comprising mixtures of crystalline forms (e.g., aragonite and calcite) can be readily employed in coating formulations. Even in the case of PCC compositions predominantly comprising one form (predominately vaterite, for example), the compositions are likely to contain a small amount of at least one other crystal PCC structure (e.g., calcite). As a result, the PCC compositions of the present disclosure may optionally comprise at least one second PCC form that differs from the main PCC form. In contrast, the PCC production processes of Example Setups 2 - 10 aim to produce more than one form of PCC.

[0139] In one embodiment, after separating the PCC from the water phase, the PCC may be washed with water or some other solvent to remove unreacted products. In a related embodiment, the PCC may be dried, with or without previous washing. The drying of the PCC may contribute to the resulting crystal product polymorph. In certain embodiments of the present disclosure, the PCC reaction product is a first composition after the reaction, prior to drying, with a solids content of at least 70%. The PCC reaction product may convert to a second composition after the drying stage. The drying stage may convert any amorphous PCC product of a first composition to a crystalline polymorph of a second composition (and different drying methods may make different polymorphs). The product of a first composition may be aged and seeded. A dried product may also be aged. Similar to the drying process, aging may also change the polymorph composition. The reaction to form PCC, the seeding, the drying, and the aging may all be employed in a batch process, or a continuous process (e.g. in a tubular reactor with inline static mixers or cascade mixers). In one embodiment, the drying is performed at a temperature range of 30-150°C for 1-15 hours.

[0140] In some embodiments, the addition of additives or seed materials may affect the structure of the PCC. For example, adding citric acid to the PCC formation step may increase the surface area of a formed PCC product. Altering the pH, such as through the use of an acidic additive, such as an acid (e.g., phosphoric acid), may be used to control or vary the shape, particle size, or surface area of the PCC, and in particular to vary the morphology of a PCC. In some embodiments, the seed composition may be used to control the resulting PCC morphology. For example, using greater than about 5 wt% coarse scalenohedral PCC (relative to the weight of the feed material) as a seed material may yield a larger or coarser PCC product, and may result in a greater surface area. For example, using less than about 5% of a fine rhombohedral PCC as a seed material yields a PCC product with a finer crystal size within a PCC aggregate, whereas greater than about 5% of the fine rhombohedral PCC seed material yields a finer-sized aggregate of the PCC produced. Further, under seeding conditions where a pure calcite seed (where dolomite or magnesium levels are <2%) is added to the reacting mixture, the resulting PCC product is formed with a rhombic geometry. Similarly, seeding with magnesite or dolomite also yields rhombic PCC.

[0141] In the present disclosure, the crystalline content of a PCC composition may be readily determined through visual inspection by use of, for example, a scanning electron microscope or by X-ray diffraction. Such determination may be based upon the identification of the crystalline form and is well known to those of skill in the art.

[0142] The PCC compositions of the present disclosure are characterized by a single crystal polymorph content of greater than or equal to 30% by weight relative to the total weight of the composition, greater than or equal to 40% by weight, greater than or equal to 60% by weight, greater than or equal to about 80% by weight, or greater than or equal to about 90% by weight. Alternatively, and as desired, the multi-batch processes of the present disclosure may produce varied mixtures of polymorphs by selection of the operating conditions of the various reaction vessels in the process, thus forming complex mixtures of polymorphs to take advantage of the unique combination of properties such complex mixtures may provide.

[0143] The PCC compositions may also be characterized by their particle size distribution (PSD). As used herein and as generally defined in the art, the median particle size (also called dso) is defined as the size at which 50 percent of the particle weight is accounted for by particles having a diameter less than or equal to the specified value.

[0144] The PCC compositions may have a dso in a range from about 0.1 microns (μπι) to about 30 microns, for example, from about 2 microns to about 14 microns, from about 2 to about 8 microns, from about 1 micron to about 4 microns, or from about 0.1 micron to about 1.5 microns. The dso may vary with the morphology of the PCC. For example, calcite PCC may have a dso in a range from about 1 to about 28 microns, such as, for example, from about 1 to about 2 microns, from about 1 to about 5 microns, from about 2 to about 4 microns, or from about 4 to about 6 microns. Vaterite PCC may have a dso in a range from about 0.1 microns to about 30 microns, such as, for example, from about 0.1 to about 2 microns, from about 1 to about 5 microns, or from about 2 to about 8 microns. [0145] According to some embodiments, between about 0.1 percent and about 60 percent of the PCC particles are less than about 2 microns in diameter. In other embodiments, between about 55 percent and about 99 percent of the PCC particles are less than 2 microns in diameter. According to some embodiments, less than about 1 percent of the PCC particles are greater than 10 microns in diameter, such as, for example, less than 0.5 percent of the PCC particles are greater than 10 microns in diameter, or less than 0.1% of the PCC particles are greater than 10 microns in diameter.

[0146] Alternatively, and as desired, the multi-batch processes of the present disclosure may produce varied mixtures of particle size distributions (multi-modal distributions) by selection of the operating conditions of the various reaction vessels in the process, thus forming complex multi-modal mixtures to take advantage of the unique combination of properties such complex mixtures may provide.

[0147] The PCC compositions may be further characterized by their aspect ratio. As used herein, aspect ratio refers to a shape factor and is equal to the largest dimension (e.g. length) of a particle divided by the smallest dimension of the particle orthogonal to it (e.g. width). The aspect ratio of the particles of a PCC composition may be determined by various methods. One such method involves first depositing a PCC slurry on a standard SEM stage and coating the slurry with platinum. Images are then obtained and the particle dimensions are determined, using a computer based analysis in which it is assumed that the thickness and width of the particles are equal. The aspect ratio may men be determined by averaging fifty calculations of individual particle length-to-width aspect ratios.

[0148] The PCC compositions may also be characterized in terms of their cubicity, or the ratio of surface area to particle size (i.e., how close the material is to a cube, rectangular prism, or rhombohedron). In certain embodiments of the present disclosure, a lower surface area is advantageous. Smaller particles typically have much higher surface area, but small particle size is advantageous for many different applications. Thus PCC products with small particle size material and lower than "normal" surface area are particularly advantageous. Rhombic crystal forms are generally preferred in terms of cubicity.

[0149] According to some embodiments, the cubic nature of the PCC compositions may be determined by the "squareness" of the PCC particles. A squareness measurement generally describes the angles formed by the faces of the PCC particle. Squareness, as used herein, can be determined by calculating the angle between adjacent faces of the PCC, where the faces are substantially planar. Squareness may be measured using SEM images by determining the angle formed by the edges of the planar faces of the PCC particle when viewed from a perspective that is parallel to the faces being measured. Fig. 41 shows an exemplary measurement of squareness. According to some embodiments, the PCC compositions may have a squareness in a range from about 70 degrees to about 1 10 degrees.

[0150] In the present disclosure, the monodispersity of the product refers to the uniformity of crystal size and polymorphs. The steepness (d3o/d7o* 100) refers to the particle size distribution bell curve, and is a monodispersity indicator. d _x is the equivalent spherical diameter relative to which x% by weight of the particles are finer. According to some embodiments, the PCC compositions may have a steepness in a range from about 30 to about 100, such as, for example, in a range from about 33 to about 100, from about 42 to about 76, from about 44 to about 75, from about 46 to about 70, from about 50 to about 66, from about 59 to about 66, or from about 62 to about 65. According to some embodiments, the PCC compositions may have a steepness in a range from about 20 to about 71, such as, for example, in a range from about 25 to about 50. In some embodiments, the steepness may vary according to the morphology of the PCC. For example, calcite may have a different steepness than vaterite.

[0151] According to some embodiments, the PCC product and PCC compositions may be used as a filler for various applications. Exemplary applications include, but are not limited to, fillers or additives for plastics, paper coatings, adhesives, sealants, caulks, paper, moldings, coatings, paint, rubber products, and concrete. For example, the PCC compositions may be used as a filler or additive for polyvinylchloride (PVC), plasticized PVC (pPVC), polypropylene (PP), rubber, coatings, paint, ceramics, paper, or concrete. Some exemplary uses include use as a filler or additive for PVC pipes or moldings, pPVC, paint (e.g., exterior paint or road paint), tile coatings (e.g., ceiling tile coatings), decorative coatings, moldings (e.g., PVC moldings, pPVC moldings, or PP moldings), sheet molding compounds, bulk molding compounds, adhesives, caulks, sealants, rubber products, paper, paper fillers, paper coatings, or concrete. According to some embodiments, the relatively lower surface area of the PCC compositions may be suitable as a filler and may have improved dispersibility. The PCC compositions may, in general, have relatively low brightness (e.g. 65 ISO brightness) to relatively high brightness (e.g., greater than 90 ISO brightness) and may have a consistent brightness, which may improve the color of a given product in an application. The PCC compositions disclosed herein may have a relatively low surface area when compared to other calcium carbonate products, such as, for example, ground calcium carbonate (GCC). The relatively low surface area may contribute to low adsorption of additives by the PCC, reduced amounts of additives to treat a surface of the PCC, and/or low moisture pick-up by the PCC. According to some embodiments, the relatively lower surface area may contribute to a relatively lower viscosity of the material to which the PCC is added and/or a greater amount of "active" particles when used as a filler or additive, such as, for example, in polymer films. According to some embodiments, a broad particle size distribution of the PCC may increase particle packing, whereas a steep or narrow particle size distribution of the PCC may decrease particle packing. According to some embodiments, a relatively smaller PCC particle size may improve the gloss of a coating, such as, for example, a paper coating or paint, containing the PCC composition. A relatively smaller particle size may also improve the impact resistance of a material, such as, for example, a molded product or coating, containing the PCC composition.

[0152] According to some embodiments, a PCC composition can be prepared having a high surface area/low density PCC, by treating the starting mixture with one or more of the additives such as fatty acid, fatty acid derivative salt, and/or dispersant, prior to treatment with CO ₂ (carbonation).

[0153] According to some embodiments, the PCC compositions, such as the vaterite PCC compositions, may be used for various applications, including but not limited to drug delivery, medical devices, biosensing, encapsulation, tracing, polymer fillers, cavitation enhancement in films, heavy metal sequestration, as a nucleation agent (for example, a foam nucleation agent), an abrasive, FGD feeds, synthetic paper component, or emulsion systems filler. In some embodiments, the PCC, such as vaterite PCC, may be used as a drug delivery agent or component. For example, vaterite may be used as a platform for small molecule or protein absorption or adsorption, such as into the pores of the vaterite. Vaterite may also be used, in some embodiments, as a microparticle or microcapsule for drug encapsulation or drug delivery, for example, vaterite may be used to encapsulate molecules including, but not limited to, insulin, bovine serum albumin, and lysozymes. In some embodiments, encapsulation may occur during a phase transition of the PCC from vaterite to calcite. Such encapsulation may promote controlled release of the encapsulated molecules. In some embodiments, encapsulation may occur through absorption or adsorption of the molecules into the pores of the vaterite. In other embodiments, encapsulation may occur through direct encapsulation during the formation of the PCC particles. In other embodiments, encapsulation may occur through hollow-centered PCC particles.

[0154] According to some embodiments, the PCC, such as vaterite may be used as a controlled release agent. For example, vaterite may be exposed to highly acidic environments to control release. Vaterite exposed to such environments may break down, thereby releasing the encapsulant or encapsulated, absorbed, or adsorbed molecules. According to some embodiments, the vaterite may serve as a template protein structure to control release of a molecule. According to some embodiments, the vaterite may be used as a template for cross- linking polymer, such as, for example, biopolymers. In some embodiments, the polymers may be cross-linked using the vaterite as a template. Subsequent removal of the vaterite may result in a cross-linked polymer having a structure similar to the vaterite template (e.g., spherical).

[0155] According to some embodiments, the PCC, such as vaterite, may be used in medical devices, such as, for example, implantable medical devices. In some embodiments, vaterite may exhibit rapid bioabsorption, for example, due to vaterite's high surface area. Because of rapid absorption, vaterite may be used as a calcium source for biological applications, such as, for example, bone regeneration. Vaterite may also assist in the generation of bone minerals, such as phosphate bone minerals, such as hydroxyapatite. In some embodiments, the hydroxyapatite or other small molecules may be encapsulated by the vaterite or PCC, or may be bound (either chemically or physically) to the surface of the vaterite. Conversion of the vaterite to calcite, in some embodiments, may also promote binding of the PCC to bone.

[0156] According to some embodiments, the PCC, such as vaterite, may be used in biosensing applications. For example, vaterite may be used in biosensing of pH changes or ion sensing. In some embodiments, a fluorescent pH sensor may be encapsulated by the vaterite, such as, for example, in tracing applications.

[0157] According to some embodiments, the PCC, such as vaterite may be used as a filler for polymers. For example, the vaterite may be used in polymer films, such as, for example, cavitation enhancement. In some embodiments, the vaterite may promote more uniform cavitation of pores and may increase the breathability of the film.

[0158] According to some embodiments, PCC, such as vaterite, may encapsulate metals, such as heavy metals. For example, encapsulation may occur through a phase change from vaterite to calcite. According to some embodiments, the PCC, such as vaterite, may be used as a nucleating agent. In some embodiments, the vaterite may act as a foam nucleating agent.

[0159] According to some embodiments, the PCC, such as vaterite, may be used as an abrasive, such as, for example, a cleaning abrasive. PCC can be precipitated from aqueous solution in one or more different compositional forms: vaterite, calcite, aragonite, amorphous, or a combination thereof. Generally, vaterite, calcite, and aragonite are crystalline compositions and may have different morphologies or internal crystal structures, such as, for example, rhombic, orthorhombic, hexagonal, scalenohedral, or variations thereof.

[0160] In some embodiments, PCC may find application in powder coatings and other surface energy-sensitive applications.

In alternative embodiments, the processes of the present disclosure may be adapted to produce other calcium salts, such as calcium phosphate or calcium silicate. In some embodiments, the present disclosure may be adapted to produce a mixture of calcium carbonate and at least one other calcium salt.

[0161] In the present disclosure, generating PCC can be accomplished with Example Setups 1-10, or a combination thereof. Other reactor setups are also possible within the scope of the present disclosure, with reactors in serial or parallel arrangements, combinations thereof, and differing reaction conditions and starting materials being supplied to different reactors to achieve products having unique combinations of modality, polymorphs, etc. Reaction conditions, as discussed above, particularly enable control of the precipitated calcium carbonate structure, such as crystalline polymorph and particle size.

[0162] Furthermore, combinations of processes and produced PCC are possible and within the scope of this application. For example, any two or more products may be combined in final vessel or mixer to generate combinatorial products of desirable properties for a given application. Without limitation, this may include combining multiple monodisperse PCCs to yield multi-modal PSD of single polymorph and structure of calcium carbonate; combining multiple monodisperse PCCs to yield multi-modal PSD of single polymorph with multiple structures of calcium carbonate; combining multiple monodisperse PCCs to yield multi-modal PSD of multiple polymorphs with similar structure of calcium carbonate; combining multiple monodisperse PCCs to yield multi-modal PSD of multiple polymorphs with multiple structures of calcium carbonate; and/or combining multiple PCCs generated to yield varied degrees of hydrophobicity to any of the above. Such combination of products would involve generating untreated and/or treated PCCs prior to combining, then combining in varied ratios.

[0163] In one embodiment, multiple products may be combined to provide a tailored combination of products, such as previously forming a magnesium carbonate or sodium carbonate, separately forming calcium carbonate, and then combining two or more products in varied ratios to yield a single product.

[0164] In one embodiment, multiple products may be combined to provide a tailored combination of products, such as previously forming a PCC doped with biologically desirable components such as vitamins or proteins, separately forming undoped calcium carbonate, and combining two or more products in varied ratios to yield a single product

[016S] The following is a general description of Example Setups 1-10, and is in reference to the following drawings, in which some, but not all embodiments of the present disclosure are shown.

Example Setup 1

[0166] A multi-batch process for generating PCC is illustrated in Fig. 1. Here, a CCh source 10, a calcium source 12, water 14, and optionally, a dopant 16 and/or seed 18 are fed into a first reactor 20. These components react to produce a mixture of calcium carbonate in water 22, which may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24 in a separate batch or location away from the first reactor. In other embodiments, the fatty acid, fatty acid derivative salt, and/or dispersant may be added to the first reactor before, during, and/or after the formation of the calcium carbonate. The mixture of calcium carbonate in water 22 is filtered 32 to produce PCC 28 and a water phase 30. In one embodiment, the PCC is single- modal or multi-modal. In one embodiment, the PCC has a single morphology or may have more than one morphology. In one embodiment, the PCC has a single structure or may have more than one structure. The water phase 30 may contain small amounts of precipitated calcium carbonate, or unreacted or excess CO3 source, calcium source, seed, and/or dopant. In one embodiment, a portion or all of the water phase 30 may be recycled 26, being fed back into the first reactor. In a further embodiment, where a portion of the water phase 30 is recycled 26, one or more components of the water phase (precipitated calcium carbonate, or unreacted or excess CO ₂ source, calcium source, seed, and/or dopant as mentioned previously) may be concentrated before being fed into the first reactor 20. In one embodiment, the water phase comprises an acid or an acidic compound which is recycled back into the first reactor, with or without concentrating. In one further embodiment, this acid or acidic compound is the dopant.

Example Setup 2

[0167] A two-reactor multi-batch process for generating PCC is illustrated in Fig. 2. Here, a CO ₂ source 10, a calcium source 12a, water 14, and optionally, a dopant 16 and/or seed 18 are fed into a first reactor 20. These partially react to produce a mixture of calcium carbonate 40, water 14, and potentially unreacted calcium source 12a, which is fed into a second reactor 38 with a second CO ₂ source 10 and optionally a second calcium source 12b, a second dopant 34 and/or a second seed 36. These components react to produce a calcium carbonate 42 which is mixed with calcium carbonate 40 in water 14, and which may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24 in a separate batch or at a location away from the first reactor vessel. In other embodiments, the fatty acid, fatty acid derivative salt, and/or dispersant may be added to the first reactor before the formation of the calcium carbonate. The mixture of calcium carbonates 40 and 42 in water 14 is filtered 32 to produce PCC 44 and a water phase 30, with the water phase 30 being optionally recycled into either or both of the reactors (not shown). In one embodiment, the PCC 44 is multi-modal, multi-polymorph, and/or multi-structure. In one embodiment, either or both reactors may have more than one dopant and/or more than one seed added.

Example Setup 3

[0168] A serial triple-reactor process for generating PCC is illustrated in Fig. 3. Here, a CO ₂ source 10, a calcium source 12a, and water 14, are fed into a first reactor 20. These partially react to produce a mixture of calcium carbonate 40, water 14, and potentially unreacted calcium source 12a, which is fed into a second reactor 38 with a second CO ₂ source 10 and optionally a second calcium source 12b, and/or a first dopant 16. These components partially react to produce a mixture of calcium carbonate 40 and 42 and an unreacted calcium source 14 which is fed into a third reactor 46 with a third CO ₂ source 10 and optionally a third calcium source 12c, and/or a second dopant 34. These components react to produce a calcium carbonate 43 which is mixed with calcium carbonates 40 and 42 and water 14, forming mixture 22 and which may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24 in a separate batch or location away from the first reactor vessel. In other embodiments, the fatty acid, fatty acid derivative salt, and/or dispersant may be added to any of the reactors, before, during and/or after reaction with CO ₂ in the particular reactor. The mixture 22 is filtered 32 to produce PCC 44 and a water phase 30. In one embodiment, the PCC 44 is multi-modal, multi- polymorph, and/or multi-structure.

[0169] Another serial triple-reactor process for generating PCC is illustrated in Fig. 4. Here, a CCh source 10, a calcium source 12a, and water 14, are fed into a first reactor 20. These react to produce a mixture of calcium carbonate 40 in water 14, which is fed into a second reactor 38 with a second CO ₂ source 10, water 14, and a second calcium source 12b. These components react to produce a mixture of calcium carbonate 40 and 42 and water 14, which is fed into a third reactor 46 with a third CO ₂ source 10, water 14, a third calcium source 12c, and optionally a dopant 16. These components react to form calcium carbonate 49 in mixture with calcium carbonates 40 and 42, and water 14, forming mixture 50, and a portion of the third reactor 46 contents may be fed into the second reactor 38, through recycle line 52. The contents of the recycle stream may comprise any or all of precipitated calcium carbonates 40, 42, or 49, or unreacted or excess CO ₂ source, calcium source, and/or dopant as mentioned previously, and may be concentrated before being fed into the second reactor 38. The calcium carbonates 40, 42, and 49 in mixture 50 may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24 in a separate batch or location away from the third reactor. The mixture 50 is filtered 32 to produce PCC 48b and a water phase 30b. In addition, a mixture of calcium carbonate 40 in water 22 from the first reactor 20 may optionally be treated with an additive (which may be one or more of fatty acid, fatty acid derivative salt, dispersant, dopant, and/or seed) 24 in a separate batch or location away from the first reactor, then further reacted with additional CCh (not shown) to produce additional calcium carbonate in mixture with calcium carbonate 40, and then filtered 32 to produce PCC 48a and a water phase 30a. The PCC 48a or 48b from either route may be treated or untreated. The PCC from the two routes may be combined to form PCC 44 that is multi-modal, multi-polymorph, and/or multi-structure. In one embodiment, the product routes from the first reactor 20 may be divided by selective filtering. Fully dissolved compounds such as CaCl ₂ may be screened by PCC PSD, and calcium compounds not fully dissolved may be screened by PSD. In these embodiments, calcium sources 12a, 12b, and 12c, water phases 30a and 30b, and PCCs 48a and 48b may be the same or different from one another. [0170] A three-reactor process for generating PCC is illustrated in Fig. 5. Here, a CO ₂ source 10, a calcium source 12a, and water 14, are fed into a first reactor 20. These react to produce a mixture of calcium carbonate 40 in water 14. A portion of the calcium carbonate 40 from the first reactor may be fed into a second reactor 38 and a third reactor 46, each of which are fed with a second and third CO ₂ source 10, water 14, and a second and third calcium source 12b and 12c, respectively wherein calcium carbonates 40b and 40c are produced, respectively. The third reactor may optionally be fed with a dopant 16 and/or seed 18. Each of the three reactors produces mixtures of PCC in water 22a, 22b, and 22c, respectively, each of which may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c, respectively, in a separate batch or location away from each reactor, and each mixture is filtered 32 to produce PCC (treated or untreated) 48a, 48b, and 48c, respectively, and water phase 30a, 30b, and 30c, respectively. The PCC from each of the three reactors may be combined to form PCC 44 that is multi-modal, multi-polymorph, and/or multi-structure. In these embodiments, calcium sources 12a, 12b, and 12c; PCCs 48a, 48b, and 48c; mixtures of PCC in water 22a, 22b, and 22c; and fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c may be the same or different from one another within each set.

[0171 ] A three-reactor process for generating PCC is illustrated in Fig. 6. Here, a CO ₂ source 10, a calcium source 12a, 12b, and 12c, and water 14, are fed into a first reactor 20, a second reactor 38, and a third reactor 46, respectively, with an optional dopant 16 added to the third reactor 46. In addition, PCC 40 from the first reactor 20 is fed into the second reactor 38, and PCC 42 from the second reactor 38 is fed into the third reactor 46. These transfers between the reactors may also include unreacted or excess products including PCC 40, 42 and 58, as discussed previously. Water 14 and PCC 54/56/58 from each reactor 20/38/46, respectively, may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c, respectively, in a separate batch or location away from each respective reactor, and filtered 32 to produce PCC (treated or untreated) 48a, 48b, and 48c, respectively, and a water phase 30a, 30b, and 30c. The PCC from each of the three streams 60/62/64 may be combined to form PCC 44 that is multi-modal, multi-polymorph, and/or multi-structure. In these embodiments, calcium sources 12a, 12b, and 12c; PCCs 48a, 48b, and 48c; mixtures of PCC in water 22a, 22b, and 22c; water phases 30a, 30b, and 30c; and fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c may be the same or different from one another within each set.

[0172] A similar three-reactor process for generating PCC is illustrated in Fig. 7. Here, a CO?, source 10, a calcium source 12a, 12b, and lie, and water 14, are fed into a first reactor 20, a second reactor 38, and a third reactor 46, respectiveiy, with an optional dopant 16 and/or seed 18 added to the third reactor 46, and an optional dopant 16 added to the second reactor 38. In addition, PCC 40 from the first reactor 20 is fed into the second reactor 38, and PCC 42 from the second reactor 38 is fed into the third reactor 46. These transfers between the reactors may aiso include unreacted or excess products, including PCC 40, 42 and 58 as discussed previously. Water 14 and PCC 54/56/58 from each reactor may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c, respectiveiy, in a separate batch or location away from each respective reactor, and filtered 32 to produce PCC (treated or untreated) 48a, 48b, and 48c, respectively, and a water phase 30a, 30b, and 30c, respectively. The PCC from the first two streams 60/62 may be combined to form PCC 44 that is multi-modal, multi-polymorph, and/or multi-structure. The PCC originating from the third reactor may also be multi-modal, multi-polymorph, and/or multi-structure. In these embodiments, calcium sources 12a, 12h, and 12c; PCCs 48a. 48b, and 48c; mixtures of PCC in water 22a, 22b, and 22e; water phases 30a, 30b, and 30c; and tatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c may be the same or different from one another within each set.

Example Setup8

[0173] A two-reactor multi-batch process for generating PCC is illustrated in Fig. 8, and is similar to Example Setup 2. Here, a CQ¾ source 10, a calcium source 12a, and water 14 are fed into a first reactor 20. These partially react to produce a mixture of calcium carbonate 40, water 14, and a potentially unreacted calcium source 12a, which is fed into a second reactor 38 with a second CO? source 19 and optionally a second calcium source 12b. These components react to produce a mixture of calcium carbonate 42 in water 14, which may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24 in a separate batch or at a location away from the first reactor vessel. In other embodiments, the fatty acid, fatty acid derivative salt, and/or dispersant may be added to the first reactor before the formation of the calcium carbonate. The mixture of calcium carbonates 40 and 42 in water 14 is filtered 32 to produce PCC 44 and a water phase 30, with the water phase 30 being optionally recycled into either or both of the reactors (not shown). In one embodiment, the PCC 44 is multi-modal, multi- polymorph, and/or multi-structure. In one embodiment, either or both reactors may have more than one dopant and/or more than one seed added.

Exampfe, Setup ¾

[0174] Another three-reactor process for generating PCC is illustrated in Fig. 9. Here, a CO ₂ source 10, a calcium source 12a, 12b, and 12c, and water 14, are fed into a first reactor 20, a second reactor 38, and a third reactor 46, respectively, with an optional dopant 16 and/or seed 18 added to the third reactor 46. In addition, PCC 40 from the first reactor 20 is fed into the second reactor 38. This material transfer from the first reactor 20 to the second reactor 38 may also include unreacted or excess products, as discussed previously. Water 14 and PCC 22a, 22b, and 22c from each reactor may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c, respectively, in a separate batch or at a location away from each respective reactor, and filtered 32 to produce PCC (treated or untreated) 48a, 48b, and 48c, respectively, and a water phase 30a, 30b, and 30c, respectively. The PCC 48a, 48b, and 48c from the three streams may be combined to form PCC 44 that is multi-modal, multi- polymorph, and/or multi-structure. In these embodiments, calcium sources 12a, 12b, and 12c; PCCs 48a, 48b, and 48c; mixtures of PCC in water 22a, 22b, and 22c; water phases 30a, 30b, and 30c; and fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c may be the same or different from one another within each set.

[0175] Another three-reactor process for generating PCC is illustrated in Fig. 10. Here, a CO ₂ source 10, a calcium source 12a, 12b, and 12c, and water 14, are fed into a first reactor 20, a second reactor 38, and a third reactor 46, respectively, with an optional dopant 16 and/or seed 18 added to the third reactor 46. Water 14 and PCC 22a, 22b, and 22c from each reactor may optionally be treated with a fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c, respectively, in a separate batch or at a location away from each respective reactor, and filtered 32 to produce PCC (treated or untreated) 48a, 48b, and 48c, respectively, and a water phase 30a, 30b, and 30c, respectively. The PCC 48a, 48b, and 48c from the three streams may be combined to form PCC 44 that is multi-modal, multi-polymorph, and/or multi- structure. In these embodiments, calcium sources 12a, 12b, and 12c; PCCs 48a, 48b, and 48c; mixtures of PCC in water 22a, 22b, and 22c; water phases 30a, 30b, and 30c; and fatty acid, fatty acid derivative salt, and/or dispersant 24a, 24b, and 24c may be the same or different from one another within each set.

[0176] The foregoing examples are not intended to be limiting, and are presented merely for illustrative purposes. It is to be understood that the various reactor setups can be performed in a wide array of configurations, with dopants, additives, seeds, etc being used in any reactor as desired, and conditions within each reactor being set independently of any other reactor in the set of reactors in a particular configuration. This provides the present disclosure with the ability to generate multi-modal, multi-polymorph and/or multi-structure PCCs in any desired form.

[0177] The following are exemplary embodiments of the present disclosure:

[0178] Embodiment 1: A multi-batch process for generating precipitated calcium carbonate (PCC), comprising:

[0179] reacting a CCh source, a calcium source, and water in a first reactor to produce a mixture of calcium carbonate and water; and

[0180] filtering the mixture to produce PCC and a water phase.

[0181] Embodiment 2: The multi-batch process of Embodiment 1, wherein the calcium source is converted to calcium chloride prior to reaction with CCh.

[0182] Embodiment 3: The multi-batch process of Embodiment 1 or 2, wherein the calcium source is converted to calcium chloride in the first reactor prior to addition of the CO ₂ source.

[0183] Embodiment 4: The multi-batch process of Embodiment 1 or 2, wherein the calcium source is converted to calcium chloride in the first reactor in the presence of the CO ₂ source.

[0184] Embodiment 5: The multi-batch process of any one of Embodiments I to 3, further comprising treating the mixture with a fatty acid, a fatty acid derivative salt, and/or a dispersant, wherein the treating is performed before, during and/or after the reacting.

[0185] Embodiment 6: The multi-batch process of any one of Embodiments 1 to 4, further comprising feeding the water phase to the first reactor.

[0186] Embodiment 7: The multi-batch process of Embodiment 6, wherein the water phase comprises an acid or an acidic compound.

[0187] Embodiment 8: The multi-batch process of any one of Embodiments 1 to 7, further comprising adding a dopant and/or a seed before, during, and/or after the reacting. [0188] Embodiment 9: The multi-batch process of any one of Embodiments 1 to 8, wherein the PCC is at least one selected from the group consisting of single-modal, single- polymorph, and single-structure.

[0189] Embodiment 10: The multi-batch process of any one of Embodiments 1 to 8, wherein the PCC is at least one selected from the group consisting of multi-modal, multi- polymorph, and multi-structure.

[0190] Embodiment 11: The multi-batch process of any one of Embodiments 1 to 10, wherein the process is performed in from 2 to 15 reactors.

[0191] Embodiment 12: The multi-batch process of Embodiment 11, wherein the 2 to IS reactors may be operated in series or in parallel, wherein each reactor may have the same or different operating conditions, and the same or different starting materials, relative to other reactors in the process.

[0192] Embodiment 13: A two- reactor process for generating precipitated calcium carbonate (PCC), comprising:

[0193] feeding a first CCh source, a first calcium source, and water to a first reactor to produce an unreacted calcium source and a first mixture of calcium carbonate and water;

[0194] feeding at least a portion of the first mixture, the unreacted calcium source and/or a second calcium source the same as or different from the first calcium source, and a second CCh source to a second reactor to produce a second mixture of calcium carbonate and water; and

[0195] filtering at least a portion of the second mixture to produce PCC and a water phase,

[0196] wherein the PCC is multi-modal, multi-polymorph, and/or multi-structure.

[0197] Embodiment 14: The two-reactor process of Embodiment 13, further comprising adding a dopant and/or a seed to the first reactor and/or to the second reactor.

[0198] Embodiment 15: The two- reactor process of Embodiment 13 or 14, further comprising treating the first mixture and/or the second mixture with a fatty acid, a fatty acid derivative salt, and/or a dispersant, wherein the treating is before, during and/or after the feeding step for the specified mixture.

[0199] Embodiment 16: A serial triple-reactor process for generating precipitated calcium carbonate (PCC), comprising: [0200] feeding a first CO ₂ source, a first calcium source, and water to a first reactor to produce a first unreacted calcium source and a first mixture of calcium carbonate and water;

[0201 ] feeding at least a portion of the first mixture, the first unreacted calcium source and/or a second calcium source the same as or different from the first calcium source, and a second CO ₂ source to a second reactor to produce a second unreacted calcium source and second mixture of calcium carbonate and water;

[0202] feeding at least a portion of the second mixture, the second unreacted calcium source and/or a third calcium source the same as or different from either or both of the first and second calcium sources, and a third CO ₂ source to a third reactor to produce a third mixture of calcium carbonate and water; and

[0203] filtering at least a portion of the third mixture to produce PCC and a water phase,

[0204] wherein the PCC is multi-modal, multi-polymorph, and/or multi-structure.

[0205] Embodiment 17: The serial triple-reactor process of Embodiment 16, further comprising filtering a fully reacted mixture of calcium carbonate and water from the first reactor to produce a second PCC and a second water phase, wherein the second PCC is multi-modal, multi-polymorph, and/or multi-structure.

[0206] Embodiment 18: The serial triple-reactor process of Embodiment 16 or 17, further comprising treating the the first, second, and/or third mixture with a fatty acid, a fatty acid derivative salt, and/or a dispersant, wherein the treating is performed before, during and/or after feeding the specified mixture.

[0207] Embodiment 19: The serial triple-reactor process of any one of Embodiments 16 to 18, further comprising adding a dopant and/or a seed to the first, second, and/or third reactor.

[0208] Embodiment 20: The serial triple-reactor process of any one of Embodiments 16 to 19, further comprising feeding a product from the third reactor to the second reactor.

[0209] Embodiment 21 : The serial triple-reactor process of any one of Embodiments 16 to 20, further comprising treating the third mixture of calcium carbonate and water with a fatty acid, a fatty acid derivative salt, and/or a dispersant before, during, or after reacting in the third reactor.

[0210] Embodiment 22: A triple-reactor process for generating precipitated calcium carbonate (PCC), comprising: [021 1 ] feeding a first CO ₂ source, a first calcium source, and a first water source to a first reactor to produce a first mixture of calcium carbonate and water;

[0212] filtering at least a portion of the first mixture to produce a first PCC and a first water phase;

[0213] feeding a second CO ₂ source, a second calcium source, and a second water source to a second reactor to produce a second mixture of calcium carbonate and water;

[0214] filtering at least a portion of the second mixture to produce a second PCC and a second water phase

[0215] feeding a third CO ₂ source, a third calcium source, and a third water source to a third reactor to produce a third mixture of calcium carbonate and water; and

[0216] filtering at least a portion of the third mixture to produce a third PCC and a third water phase,

[0217] wherein the first PCC, the second PCC, and/or the third PCC is multi-modal, multi-polymorph, and/or multi-structure.

[0218] Embodi ment 23 : The triple-reactor process of Embodiment 22, wherein

[0219] a fatty acid, fatty acid derivative salt, and/or a dispersant is added to the first mixture, the second mixture, and/or the third mixture; and/or

[0220] a dopant and/or a seed is added to the first, second, and/or third reactor.

[0221] Embodiment 24: The triple-reactor process of Embodiment 22 or 23, further comprising feeding the second reactor with a product from the first reactor.

[0222] Embodiment 25: The triple-reactor process of any one of Embodiments 22 to 24, wherein

[0223] a fatty acid, fatty acid derivative salt, and/or dispersant is added to the first mixture, the second mixture, and/or the third mixture; and/or

[0224] a dopant and/or a seed is added to the first, second, and/or third reactor.

[0225] It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

[0226] As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as "Γ. [0227] Disclosure of values and ranges of values for specific parameters (such as temperatures, molecular weights, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if parameter X is exemplified herein to have values in the range of 1-10 it is also envisioned that Parameter X may have other ranges of values including 1-9, 2-9, 3-8, 1- 8, 1-3, 1-2, 2-10, 2.5-7.8, 2-8, 2-3, 3-10, and 3-9, as mere examples.

[0228] As used herein, the words "preferred" and "preferably" refer to embodiments of the technology that afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the technology.

[0229] As referred to herein, all compositional percentages are by weight of the total composition, unless otherwise specified. As used herein, the word "include," and its variants, is intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that may also be useful in the materials, compositions, devices, and methods of this technology. Similarly, the terms "can" and "may" and their variants are intended to be non- limiting, such that recitation that an embodiment can or may comprise certain elements or features does not exclude other embodiments of the present disclosure that do not contain those elements or features.

[0230] Although the terms "first" and "second" may be used herein to describe various features/elements (including steps), these features/elements should not be limited by these terms, unless the context indicates otherwise. These terms may be used to distinguish one feature/element from another feature/element. Thus, a first feature/element discussed below could be termed a second feature/element, and similarly, a second feature/element discussed below could be termed a first feature/element without departing from the teachings of the present disclosure. [0231] Nothing in the above description is meant to limit the scope of the claims to any specific composition or structure of components. Many substitutions, additions, or modifications are contemplated within the scope of the present disclosure and will be apparent to those skilled in the art. The embodiments described herein were presented by way of example only and should not be used to limit the scope of the claims.