Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

Provided is a continuous preparation method of composite particles for capturing carbon dioxide which, in a process of using sea water as water, that is, a process of converting sea water into water, contribute to carbon neutrality by fixing carbon dioxide through mineralization of ions in sea water which is supply water or effluent water of the process.

The present invention is directed to a process for producing an aqueous suspension of precipitated calcium carbonate, wherein a milk of lime is prepared by mixing water, a calcium oxide containing material, at least one water-soluble polymer having a molecular weight M.sub.w in the range from 200 to 6500 g/mol, and at least one slaking additive, and subsequently, the milk of lime is carbonated to form an aqueous suspension of precipitated calcium carbonate.

Provided is a method for preparing a stable amorphous calcium carbonate (ACC), which can be obtained either in suspension or as a powder. The method comprises stepwise combination of a soluble calcium salt, a soluble carbonate, a first and second stabilizer, and a water miscible organic solvent as described herein. The present invention further relates to stable ACC suspensions and dry powders produced by the method of the present invention.

A process, apparatus, and cyclopropenimine (CPI) material for generating metal carbonates are disclosed. Generating the metal carbonates comprises reacting carbon dioxide (CO.sub.2) with CPI. Generating the metal carbonates also comprises forming a reaction mixture comprising water, metal cations, and a product of the reacting.

The present disclosure relates to methods for producing hydrogen and calcium- or magnesium-bearing carbonates by capturing, converting, and storing carbon dioxide. The methods may include providing one or more calcium- or magnesium-bearing compounds; providing one or more water-soluble oxygenates; providing a plurality of catalysts; and reacting one or more calcium- or magnesium-bearing compounds and one or more water-soluble oxygenates with plurality of catalysts under conditions to produce hydrogen and calcium- or magnesium-bearing carbonates. The methods may include providing one or more calcium- or magnesium-bearing silicates; providing carbon monoxide; providing water vapor; and reacting one or more calcium- or magnesium-bearing silicates, carbon monoxide, and water vapor. The methods may include providing one or more calcium- or magnesium-bearing compounds; providing one or more water-soluble oxygenates; providing a catalyst; and reacting one or more calcium- or magnesium-bearing compounds and one or more water-soluble oxygenates with said catalyst.

A process is provided for the production of precipitated single-phase crystalline 1-D nanoscaled calcite (CaCO3). This process utilizes natural plant extracts, specifically from Hyphaene thebaica fruit, as a chelating agent. The method involves combining a source of calcium cations, typically calcium chloride (CaCl2), with a source of carbon dioxide (CO2) in a solvent of water (H2O). The natural extract acts as a bio-catalyst, facilitating the formation of crystalline CaCO3 with unique properties. The process is distinguished by its avoidance of synthetic chelating agents, pH control chemicals, and additional thermal treatments, making it a green and sustainable approach to CaCO3 production. The calcite demonstrates notable shape anisotropy and elevated porosity, attributes that are beneficial in various applications.

Provided herein are methods and systems to form calcium carbonate comprising vaterite, comprising dissolving limestone in an aqueous base solution under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant solution, wherein the calcium carbonate comprises vaterite.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

Provided are carbon dioxide capture composite particles which contribute to carbon neutrality by fixing carbon dioxide in seawater or an aqueous solution in which calcium ions are dissolved through mineralization, and a method of producing the same. More particularly, provided are carbon dioxide capture composite particles which capture carbon dioxide in seawater to form calcium carbonate particles, preferably aragonite type calcium carbonate, and a method of producing the same. In an exemplary embodiment, a method of producing carbon dioxide capture composite particles including: immersing polyamidoamine particles in seawater or an aqueous solution in which calcium ions are dissolved and maintaining the solution at room temperature under normal pressure to produce carbon dioxide capture composite particles in which aragonite type calcium carbonate particles are formed on a surface of the polyamidoamine particles is provided.