Title:
MANUFACTURE OF CALCIUM SULFATE ANHYDRITE AND CALCIUM SULFATE ANHYDRITE THEREBY
Document Type and Number:
Japanese Patent JPS5580720
Kind Code:
A
Abstract:
The invention relates to a process for the preparation of calcium sulphate anhydrite in which calcium sulphate dihydrate is recrystallized at elevated temperature using concentrated sulphuric acid.
?>The recrystallization is performed using sulphuric acid at an H2SO2-concentration of 40-65 wt. %, calculated relative to the quantity of liquid phase in the recrystallization mixture. A temperature of between 40 and 90 DEG C and a residence time of 5-30 minutes is applied for the preparation of calcium sulphate anhydrite with an average particle size of 0.5-3 mu , and a temperature of between 20 and 45 DEG C and a residence time of 30 minutes to 3 hours is applied for the preparation of calcium sulphate anhydrite with an average particle size of 10-20 mu .
?>According to the invention a very pure calcium sulphate anhydrite is obtained, which is suitable for industrial application, for example in the building or paper industry.
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Inventors:
KOONERISU ANTONIASU MARIA UETE
YOUHANESU ANNA YANSEN
YOUHANESU ANNA YANSEN
Application Number:
JP15905079A
Publication Date:
June 18, 1980
Filing Date:
December 07, 1979
Export Citation:
Assignee:
STAMICARBON
International Classes:
C01F11/46; C04B11/02; C04B11/05; C09C1/02; (IPC1-7): C01F11/46