Abstract:Thermal decomposition model of magnesite was investigated by TG-DSC analysis with magnesite (900 μm) as raw material. The result shows magnesite begins to decompose at about 800 K and completely decomposes at around 950 K. DSC curve shows one downward peak corresponding to weight loss process, indicating that decomposition reaction of magnesite is one-step and endothermic. With increase of heating rate, magnesite needs higher temperature to achieve the same degree of decomposition. Average activation energy of thermal decomposition of magnesite is 260.54 kJ/mol calculated by Flynn-Wall-Ozawa Method and Kissinger Method. Magnesite decomposition reaction model was discussed by Malek Method. Thermal decomposition reaction of magnesite is two-dimensional phase boundary reaction as cylindrical symmetric model. The kinetic equation of magnesite is G(α)= .