Precisely sized precipitated calcium carbonate (PCC) crystals of preselected crystal habit, manufactured using pressure carbonation

• US 20020009410A1
• Filed: 02/22/2001
• Published: 01/24/2002
• Est. Priority Date: 07/21/1999
• Status: Abandoned Application

• Current Assignee: G.R. International, Inc.
• Original Assignee: G.R. International, Inc.
• Inventors: Mathur, Vijay K.
• Application Number:
  US09/791,433
• Publication Number:
  US 20020009410A1
• Time in Patent Office: Days
• US Class Current: 423/430
• CPC Class Codes: C01F 11/181 Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/30 extending in three dimensions
• CPC Class Codes: C01P 2004/39 parallelepiped-like
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: D21H 17/675 Oxides, hydroxides or carbonates

Abstract

Precipitated calcium carbonate crystals of selected crystal habit. A pressure carbonation process is used to manufacture precipitated calcium carbonate. A slurry of calcium hydroxide is agitated in a pressurized reactor, and carbon dioxide is provided to a reactor to produce calcium ions and carbonate ions that react under pressure to produce precipitated calcium carbonate at a high reaction rate. Control of process conditions such as pressure, temperature, and hydroxide slurry concentration, enables production of (1) a desired crystal habit (including sclenohedral, rhombohedral, stacked rombohedral, or aragonite calcium carbonate crystal structures), (2) a desired crystal size, or (3) a desired crystal aspect ratio. The precipitated calcium carbonate produced by the process is useful as either a paper filler or as an ingredient in paper coatings, and provides a paper product with improved properties.

Claims

1. A precipitated calcium carbonate having sclenohedral crystal structure, said sclenohedral crystal structure, said rhomboheral crystal structure precipitated at a pressure greater than atmospheric pressure, and comprising a surface area of approximately 28,200 cm²/gram (measured by Blaine method), and a GE brightness of at least 96.7.

2. A precipitated calcium carbonate having rhombohedral crystal structure, said rhombohedral crystal structure precipitated at a pressure greater than atmospheric pressure, and having an aspect ratio of approximately 1:

1, said rhombohedral crystal structure comprising a surface area of approximately 40,000 cm²/gram (measured by Blaine method), and a GE brightness of at least 92.1.

3. A precipitated calcium carbonate having rhombohedral crystal structure, said rhombohedral crystal structure precipitated at a pressure greater than atmospheric pressure, and having an aspect ratio of approximately 1:

1.5, said rhombohedral crystal structure comprising a surface area of approximately 21,500 cm²/gram (measured by Blaine method), and a GE brightness of at least 98.6.

4. A precipitated calcium carbonate having rhombohedral crystal structure, said rhombohedral crystal structure precipitated at a pressure greater than atmospheric pressure, and having an aspect ratio from approximately 1:

1 to approximately 1;

1.5, said rhombohedral crystal structure comprising a surface area of approximately from approximately 40,000 cm²/gram to approximately 21,500 cm²/gram (measured by Blaine method), and a GE brightness of at least 92.1.

5. A precipitated calcium carbonate produced having stacked rhombohedral crystal structure, said stacked rhombohedral crystal structure precipitated at a pressure greater than atmospheric pressure, and comprising a surface area of approximately 16,400 cm²/gram (measured by Blaine method), and a GE brightness of at least 87.3.

6. A precipitated calcium carbonate having an aragonite crystal structure, said aragonite crystal structure precipitated at a pressure greater than atmospheric pressure, and comprising a surface area of approximately 23,500 cm²/gram (measured by Blaine method), and a GE brightness of at least 95.0.