GYPSUM WHEREIN ELUTED FLUORINE IS REDUCED

摘要

PROBLEM TO BE SOLVED: To provide gypsum wherein eluted fluorine is reduced. SOLUTION: The gypsum wherein eluted fluorine is reduced can be obtained by adding an alkali to gypsum slurry to increase its pH up to≥9 and then adding phosphoric acids and/or an acid to the resultant gypsum slurry to adjust its pH so that the pH is decreased by≥1 and up to≥6. Suppression of eluted fluorine is further promoted by adding calcium phosphate to the gypsum slurry. COPYRIGHT: (C)2003,JPO