Kinetic study of carbonation of MgO slurries

Carbonation of MgO slurries at atmospheric pressure using natural magnesite from Navarra, Spain, was studied. Two processes were observed: the formati on of a magnesium bicarbonate solution and the precipitation of magnesium c arbonate. Under different conditions, each process was favoured so as to fi nd the optimum conditions to produce the Mg(HCO3)(2) solution that acts as raw material in the production of basic magnesium carbonate. In the absence of precipitation, the kinetic data were examined according to the plot of rate equation 1 - (1 - X MgO)(1/3) against time. The activation energy of 2 9.1 kJ/mol suggested a chemical reaction controlling step. A mechanism for carbonation is proposed. The effect of specific surface area on the MgO con version, as a function of time and temperature of calcination, was also inv estigated. (C) 1999 Elsevier Science B.V. All rights reserved.