Process for the preparation of alpha-hemihydrate from calcium sulphate dihydrate in a reactor

摘要

The invention relates to a process for the preparation of calcium sulphate hemihydrate in the ALPHA-configuration from calcium sulphate dihydrate, it being possible for all the necessary process steps to proceed one after the other, preferably within one reactor. According to the invention, fine granular raw material is charged to the reactor. Good heat transfer and a uniform temperature distribution are obtained by an intensive mixing motion of the solids bed. The conversion process and the subsequent drying proceed under control and in accordance with a preselected time curve.