Kinetics of gypsum dehydration

Abstract

A systematic study was conducted to investigate the correlation between the dehydration of gypsum and the time and temperature of calcination as well as the grain size of the starting material.It was found that the proposed formula ▪ may be considered as a real expression of the dehydration raction throughtout the major part of α. However, the initial and final stages of dehydration revealed a slight shift due to the induction period and the residual amount of water retained by the soluble anhydrite crystal lattice, respectively. The dehydration reaction at 160°C is nearly double that at 100°C and four times that at 70°C, using one particle size. Generally, as the grain size of gypsum becomes less than about 0.13 mm an abrupt increase in the dehydration process occurs with any slight decrease in diameter. A moderate change occurs, however, as the grain size changes over 0.13 mm.