KINETICS OF THERMAL-DECOMPOSITION OF HYDROMAGNESITE

The thermal decomposition of hydromagnesite has been studied using thermogravimetric analysis. The experiments were conducted in a nitrogen atmosphere with pellets of hydromagnesite in the temperature range 300 to 550 degrees C, and also with powder samples under non-isothermal conditions at a heating rate of 10 degrees C/min. It is found that the reaction proceeds in two stages: dehydration followed by decomposition. The dehydration reaction is controlled by external mass transfer whilst the decomposition reaction is controlled by both external and internal mass transfer. The activation energy for the dehydration reaction was found to be 2.67 x 10(7) J/kmol. From the non-isothermal analysis the activation energy for the decomposition of magnesium carbonate was found to be 1.62 x 10(8) J/kmol.