US 2020/0123055 A1

Recycling method of dihydrate gypsum from waste gypsum boards

(22) 22.10.2019

(43) 23.04.2020

(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)

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