Title:
PRODUCTION OF ALPHA-TYPE HEMIHYDRATE GYPSUM
Document Type and Number:
Japanese Patent JP3245436
Kind Code:
B2
Abstract:
PURPOSE: To improve quality of the subject gypsum by reacting slurry of dihydrate gypsum having a specific concentration with steam in a condition controlled at definite temperature and detecting a time when the reaction is finished by lowering of flow rate of heated steam.
CONSTITUTION: Dihydrate gypsum is mixed with a habit modifier in a raw material slurry preparing tank 1 to prepare slurry having 40-65wt.% dihydrate gypsum concentration and steam 7 is blown into the slurry to retain the slurry temperature to ≥90°C. Then the slurry is transferred into a reactional tank 2 and the slurry is charged so that apparent volume of the produced a type hemihydrate gypsum (hereinafter referred to as a gypsum) becomes equal to basket volume of a solid liquid separator 3 and steam 7 is blown into the slurry to control the reactional tank 2 to 110-150°C. A steam amount is controlled so that temperature in the reactional tank 2 retains to prescribed temperature and α-gypsum forming reaction is finished at the time when steam amount is lowered. Lowering of flow rate of the steam 7 is detected by opening and closing degree of a control valve 8. The produced α-gypsum slurry is cooled and taken out to a solid liquid separator 3 and α-gypsum cake is washed with warm water so as to remove the habit modifier to provide the high-purity objective α-gypsum.
Inventors:
Akira Yamazaki
Yoshihiko Kudo
Yoshihiko Kudo
Application Number:
JP33522091A
Publication Date:
January 15, 2002
Filing Date:
December 18, 1991
Export Citation:
Assignee:
Kureha Chemical Industry Co., Ltd.
Kureha Techno Engineering Co., Ltd.
Kureha Techno Engineering Co., Ltd.
International Classes:
C04B11/032; C01F11/46; (IPC1-7): C04B11/032; C01F11/46
Attorney, Agent or Firm:
Yoshio Kawaguchi (3 outside)