METHOD FOR THE PRODUCTION OF ALPHA-CALCIUM SULFATE HEMIHYDRATE FROM CALCIUM SULFATE DIHYDRATE

Disclosed is a method for producing alpha-calcium sulfate hemihydrate fro m calcium dihydrate. Said method has the following features: a) calcium dihy drate is fed to an agitated autoclave (1); b) the agitated autoclave (1) is indirectly heated; c) water is added and incorporated in a controlled manner ; d) the feedstock is prevented from adhering to surfaces of the reaction ch amber by means of moved chains (3) that are mounted on the paddles and/or th e drive shaft (16) of the agitated autoclave (1); e) the pressure in the rea ction chamber is regulated at intervals or in a continuous manner by dischar ging vapor when a certain pressure has been reached in the interior, the vap or being conducted via a centrifugal separator (17) and a control valve (18) ; f) cold air is delivered for residual drying purposes; g) the process mate rial is removed. Also disclosed is a corresponding apparatus for carrying ou t said method.