Process for the production of suitable as building material calcium sulfate alpha-hemihydrate from wet finely divided flue gas desulfurization gypsum and its use

摘要

The invention relates to a process for the treatment of calcium sulphate alpha -hemihydrate present essentially in the form of primary grain, the latter being brought to a fineness corresponding to the strength evolution required in the intended application and fines being removed by screening and at least one fruit acid and/or salt(s) thereof being admixed as retarder and plasticiser, in order to obtain a product having a sufficiently retarded start of stiffening, rapid evolution of strength and a high strength level, which can be used especially as a spraying plaster.