ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 38, (3) 173 - 177 (1994)


THE INFLUENCE OF MAGNESIUM CHLORIDE CONCENTRATION IN THE LIQUID PHASE ON THE HYDROTHERMAL DEHYDRATION OF GYPSUM
 
Kostič-Pulek Aleksandra, Marinkovic Slobodanka, Tomanec Rudolf, Logar Mihovil
 
University of Belgrade, Faculty of Mining and Geology, 11000 Belgrade, P. O. Box 162

The thermal treatment of gypsum in boiling 1M, 2M, 3M, 4M and 4.5M solutions of magnesium chloride, at atmoshperic pressure, in order to obtain α-CaSO₄.0.5H₂O was performed. Three mechanism of α-hemihydrate formation were identified in solutions of different concentrations. Gypsum transformation into α-hemihydrate operated in solid phase, through an intermediate product, β-hemihydrate, in solutions of low concentrations (1 and 2M), direct in solutions of high concentrations (3 and 4M) and in solid phase in the solution of the highest concentration (4.5M). Specific surface areas of the obtained products indicated that slow transformation processes (regardless ol the mechanism involved) gave products of small surface areas, or high usability.


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