Effect of Atmosphere on the Pyrolysis Process of Basic Calcium Carbonate

The pyrolysis process of basic calcium carbonate (BCC) in air was studied by TG-DTA and high temperature X-ray diffractometry, and obtained results were compared with our previous results in a flowing N2 gas. The decomposition of Ca(OH)2 and calcite was observed at higher temperatures than those in a flowing N2 gas. An exothermic peak appeared in DTA around 370°C before the decomposition of Ca(OH)2. The difference between the results in air and in a flowing N2 gas was caused by carbonation of intermediate products by a slight amount of CO2 in air. The carbonation was promoted by H2O. The exothermic peak around 370°C was attributed to the crystallization of CaCO3.