Title:
PRODUCTION PROCESS OF HIGH-PURITY GYPSUM
Document Type and Number:
WIPO Patent Application WO2001085412
Kind Code:
A3
Abstract:
A process is provided for the production of high-purity gypsum, which comprises reacting a calcium source with a mineral acid in a water phase to have the calcium source sufficiently dissolved as a calcium salt in the water phase, separating and removing undissolved residue from a resulting water phase, adding sulfuric acid to a water phase, which has been obtained by the removal of the undissolved residue, to crystallize gypsum, and separating the crystallized gypsum from the water phase. According to the process, plate-like or short prism-like crystals of dihydrate gypsum of high purity, high whiteness, large bulk density and small aspect ratio can be efficiently obtained even when a low-purity calcium source is used. Calcination of such crystals of dihydrate gypsum can also provide calcined gypsum of high purity, which is satisfactory in spray mixing water amount, setting time, and physical properties such as tensile strength.
Inventors:
MOCHIYAMA TOKUMI (JP)
YAMAGUCHI MASATO (JP)
YAMAGUCHI MASATO (JP)
Application Number:
PCT/JP2001/003910
Publication Date:
August 22, 2002
Filing Date:
May 10, 2001
Export Citation:
Assignee:
YOSHINO GYPSUM CO (JP)
MOCHIYAMA TOKUMI (JP)
YAMAGUCHI MASATO (JP)
MOCHIYAMA TOKUMI (JP)
YAMAGUCHI MASATO (JP)
International Classes:
C01F11/46; C04B11/26; (IPC1-7): C01F11/46
Foreign References:
| JPH0867516A | 1996-03-12 | |||
| JPH1034105A | 1998-02-10 | |||
| JPH02111607A | 1990-04-24 | |||
| JPH07330329A | 1995-12-19 |
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