Gypsum-base structural material - contg calcium sulphate capable of setting, produced by partly dehydrating calcium sulphate dihydrate

摘要

Compsn. for a structural material contg. calcium sulphate capable of setting, produced from natural or synthetic CaSO4.2H2O is improved that only a part of CaSO4.2H2O is converted in calcium sulphate capable of setting, pref. by treatment with steam in a centrifuge or filter press, or in a rotary calciner by (in)direct heating. If synthetic gypsum is used, neutralisation is carried out after the removal of a major part of water. Investment costs are reduced by 30-40%; the operational costs are also diminished. The compsn. is suitable for moulding under pressure and for granulation. Waste gypsum e.g. from the prodn. of H3PO4 by the wet method can be utilised economically.