KINETICS OF HYDRATION OF MAGNESIUM-OXIDE IN AQUEOUS SUSPENSION .1. METHOD OF MEASUREMENT AND EVALUATION OF EXPERIMENTAL-DATA

Magnesium oxide in aqueous suspension is hydrated by the ''via solutio n'' mechanism In the initial stage, there arise brucite nuclei on acti ve centres of the surface of MgO, and this is associated with a rapid increase in the specific surface area of the solid phase. In the subse quent stage the specific surface area decreases as a result of a slowi ng down of the nucleation rate, probably due to inactivation of the fr ee active centres that become overgrown by the forming brucite crystal s. The time course of the entire process is described by the equation ln (1/(1-y)) = (kt)(n) where y is the rate of conversion, (t) under ba r t is time, (k) under bar k is the rate constant and (n) under bar n is a constant of the empirical equation, having the value of 2/3. The temperature dependence of the rate constant conforms to the Arrhenius equation and has the activation energy (E) under bar E = 54.7 kJ mol(- 1).