| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for obtaining gypsum hemihydrate or anhydrous gypsum, which is reduced in the mixing amount with paper flour, from a wet gypsum board waste material difficult heretofore. SOLUTION: The gypsum board waste material, wherein board raw paper is adhered to the surface of a gypsum body, is heated to a temperature not baking the board raw paper in a state that the board raw paper is adhered to the gypsum body to convert the surface layer part of the gypsum body being in contact with the board raw paper to gypsum hemihydrate or anhydrous gypsum. Thereafter, the gypsum body is supplied to a crusher along with the board raw paper to apply crushing treatment to the gypsum body of which the surface part is converted to gypsum hemihydrate or anhydrous gypsum and the obtained gypsum powder and board raw paper are subsequently separated. COPYRIGHT: (C)2011,JPO&INPIT
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