ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Dehydration of gypsum in the water suspension

J. Kazimír

Research institute of Civil Engineering, 894 13 Bratislava

Abstract: The dehydration of gypsum   in aq. suspensions in an autoclave proceeds through hemihydrate  to insol. anhydrite, giving metastable sol. anhydrite as an intermediate as previously proposed. Dehydration under hydrothermal conditions proceeds according to the reaction CaSO₄.2H₂O(112°) → α-CaSO₄.O.5H₂O(250°) → α-CaSO₄ III (270°) → CaSO4 II. The endothermic peaks at 130 and 235° indicate the formation of α-CaSO₄.O.5H₂O and α-CaSO₄ III, resp., and a small exothermic peak for the formation of CaSO₄ II is observable. The chemism of the dehydration as proposed by M. Sekiya (1963) was not confirmed.

Full paper in Portable Document Format: 302a167.pdf

Chemical Papers 30 (2) 167–169 (1976)