Patent Number: 6,251,356

Title: High speed manufacturing process for precipitated calcium carbonate employing sequential perssure carbonation

Abstract: 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.

Inventors: Mathur; Vijay K. (Federal Way, WA)

Assignee: G. R. International, Inc.

International Classification: C01F 11/18 (20060101); C01F 11/00 (20060101); D21H 17/00 (20060101); D21H 17/67 (20060101); C01F 011/18 ()

Expiration Date: 06/26/2018