A method for the production of settable calcium sulfates of finely divided calcium sulfates

摘要

The calcium sulphate pieces are stored after immersion in water and before the second roasting. The calcium sulphate pieces for the first and second roasting operations are placed in two layers on a roasting belt so that the hot gases in the roasting zone first contact the layer for the second roasting operation and then the layer for the first roasting operation. The once roasted calcium sulphate pieces are divided into two parts, the first part is roasted to calcium sulphate hemihydrate in a roasting oven, and is used exclusively for the prodns. of calcium sulphate pieces, and the second part is immersed in water, roasted again and ground. The calcium sulphate pieces have a size of 10-25 pref. 14-20 mm. The two layers of calcium sulphate pieces on the roasting belt each have a thickness of 30 cm.