Process for continuous production of alpha-calcium sulphate hemihydrate from calcium sulphate dihydrate

摘要

Continuous prodn. of alpha -CaSO4 semihydrate comprises continuously adding finely divided CaSO4 dihydrate as water suspension into stirred autoclave subjected to vapour. Partial conversion to alpha -CaSO4 semihydrate occurs by the pressurised wet process, the residual conversion to alpha -CaSO4 semihydrate being completed in a 2nd dry autoclave subjected to vapour pressure. Residual conversion takes place by a pressurised dry process.