level in the gypsum calcining mill, the gypsum is simultaneously calcined. ... Grinding and calcining of gypsum with Pfeiffer grinding plants TEXT Eckhard Sander, Gebr. Pfeiffer SE, Kaiserslautern/Germany ... x ½ H 2 O are obtained. GPSE Gypsum powder raw gypsum calcium sulphate dihydrate CaSO 4 · 2H 2 O a) natural gypsum b) synthetic gypsum ...