초록 ▼

A process for the production of precipitated calcium carbonate. A slurry of calcium hydroxide is agitated in a pressurized reactor, and carbon dioxide is provided under pressure to the reactor to produce precipitated calcium carbonate at a high reaction rate. Carbon dioxide is utilized at a high eff

A process for the production of precipitated calcium carbonate. A slurry of calcium hydroxide is agitated in a pressurized reactor, and carbon dioxide is provided under pressure to the reactor to produce precipitated calcium carbonate at a high reaction rate. Carbon dioxide is utilized at a high efficiency. Solubilized calcium ions and carbonate ions react to produce a calcium carbonate precipitate. Control of process conditions such as temperature, slurry concentration, and pressure, enables production of a desired crystal habit (including sclenohedral, rhombohedral, stacked rombohedral, or aragonite crystal structures), crystal size, or crystal aspect ratio. The precipitated calcium carbonate produced by the process under pressure is useful as either a paper filler or as an ingredient in paper coatings, and provides a paper product with improved preselected properties, which properties include opacity, density, and/or brightness.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for the production of precipitated calcium carbonate, said method comprising:(a) providing a source of calcium ions;(b) mixing said source of calcium ions with a solvent to create a slurry, said slurry comprising (i) an undissolved portion of said source of cal

[ What is claimed is:] [1.]1. A method for the production of precipitated calcium carbonate, said method comprising:(a) providing a source of calcium ions;(b) mixing said source of calcium ions with a solvent to create a slurry, said slurry comprising (i) an undissolved portion of said source of calcium ions, and (ii) a solution comprising calcium ions;(c) feeding said slurry to a reactor;(d) bubbling a gas stream comprising carbon dioxide through said slurry while maintaining said reactor at a pressure above atmospheric pressure, to produce carbonate ions from said carbon dioxide, and then reacting said carbonate ions with said calcium ions to form a calcium carbonate precipitate;(e) agitating the contents of said reactor,(f) wherein the acts of creation of said slurry and reaction of said slurry are performed sequentially, and(g) wherein the time required for the act of reacting said slurry is approximately the same as the time required for act of creating said slurry.