Studies in the system calcium sulphate–water. Part I. Kinetics of dehydration of calcium sulphate dihydrate

The kinetics of dehydration of synthetic calcium sulphate dihydrate have been studied between 80° and 152°, at partial pressures of water vapour between 10–5 and 45 mm. The products of reaction are controlled by both temperature and partial pressure. At temperatures greater than 110° the dehydration is controlled by a diffusion mechanism, but at lower temperatures the reaction is complex and both nucleation of product and boundary control are important. Activation energies for some of the processes have been calculated.