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 formation of a magnesium bicarbonate solution and the precipitation of magnesium carbonate. Under different conditions, each process was favoured so as to find 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 29.1 kJ/mol suggested a chemical reaction controlling step. A mechanism for carbonation is proposed. The effect of specific surface area on the MgO conversion, as a function of time and temperature of calcination, was also investigated. (C) 1999 Elsevier Science B.V. All rights reserved.