محمدهاشم صدق کردار

The intrinsic kinetics of the carbonation reactions for two limestones (Havelock and Cadomin) were studied using an atmospheric thermogravimetric analyzer (ATGA) and a pressurized thermogravimetric analyzer (PTGA). A grain model was applied to measure the kinetic parameters. The order of the carbonation reaction was related to the carbon dioxide (CO2) partial pressure, changing from the first order to the zero order when the CO2 partial pressure exceeded ~0.7 atm for both limestones. The rate of carbonation reaction increased with increasing temperature up to 675°C and decreased with further increases. No significant effect of particle size was found on the rate of carbonation reaction. Thermodynamic and kinetic simulations of the carbonation reaction using the Aspen Plus simulator was performed, obtaining the optimal temperature of 650°C. The activation energies were 32.1 and 20.3 kJ/mol for the tested Havelock and Cadomin limestones, respectively. The simulation results from the kinetic model were in good agreement with the experimental data, showing the reversible characteristic of the carbonation reaction. The shift in the mechanism of the carbonation reaction with temperature and the shift in the reaction order with CO2 partial pressure were demonstrated by both the experiments and simulation.