| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for recovering high purity gypsum of a large average particle diameter which can be used in usual application of gypsum obtained by desulfurizing flue gas, for example, to raw material of a plaster board, a cement setting regulating agent, etc., as it is, from waste gypsum obtained from a waste plaster board, etc. SOLUTION: The method for treating waste gypsum comprises: wet-grinding slurry containing waste gypsum; incorporating an alkali salt of a 4-6C oxycarboxylic acid into the resulting slurry containing gypsum dihydrate; heat-treating this slurry under pressure to convert the gypsum dihydrate to hemihydrate gypsum; and obtaining gypsum dihydrate of a regulated particle diameter from the hemihydrate gypsum. COPYRIGHT: (C)2007,JPO&INPIT
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