Ceramics-Silikáty 18, (4) 287 - 293 (1974)

The dissolution kinetics of gypsum monocrystals in water was studied at a constant speed of stirring within the 25 to 100 °C temperature range. Throughout this range, the transport process having an activation energy of 3300 kcal/mol, was found to be the rate controlling process. A comparison of the rate of dissolution of gypsum with the rate of growth of hemihydrate crystals shows that within the temperature range of 100-117 °C dehydration of gypsum in aqueous solution may proceed by the "through solution" mechanism. When the surface area of dehydrate is equal to or larger than that of hemihydrate, the rate of hemihydrate growth from a solution almost saturated with dihydrate is the rate controlling process.