(57) Gypsum derived from waste gypsum boards is calcined and converted into gypsum granules including hemihydrate and/ or anhydrous type III gypsum. The calcined gypsum granules are dropped into water to prepare a gypsum slurry. Then, dihydrate gypsum particles are crystalized in the slurry. The temperature of the gypsum granules just before being dropped into the water is 90° C or higher.
(71) Tokuyama Corporation, Shunan-shi (JP)