| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing anhydrous gypsum suitable as a raw material for cement composition from gypsum waste material. SOLUTION: The method for manufacturing the anhydrous gypsum by calcining the gypsum waste material in a kiln is characterized by manufacturing the anhydrous gypsum containing II anhydrous gypsum of >=80 wt.%, a total of hemihydrate and III anhydrous gypsum of <=5 wt.%, CaO of <=5 wt.% and carbon of <=0.3 wt.% by controlling the calcination temperature to be at 600-1200 deg.C, calcination period to be 10 minutes or longer, charge ratio of the gypsum waste material in the kiln to be <=15 vol.% and oxygen concentration in combustion gas at the inlet of the kiln to be >=5 vol.%.
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