Thermal Decomposition Mechanism of MgCl2 • 6H2O

The thermal decomposition mechanism and the intermediate morphology of MgCl2 center dot 6H(2)O before and after calcination by a resistance furnace, were studied using integrated thermal analysis, X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrum and chemical analysis. The results showed that there were six steps in the thermal decomposition of MgCl2 center dot 6H(2)O, producing MgCl2 center dot 4H(2)O at 69 degrees C, MgCl2 center dot 2H(2)O at 129 degrees C, MgCl2 center dot nH(2)O (1 <= n.<= 2) and MgOHCl at 167 degrees C, and the MgC12 center dot nH(2)O (1 <= n <= 2) converted to Mg(OH)Cl center dot 0.3H(2)O with dehydration and hydrolysis simultaneously at 203 degrees C, Mg(OH)Cl center dot 0.3H(2)O dehydrated to MgOHCl at 235 degrees C, MgOHCl directly converted to MgO at 415 degrees C. The MgOHCl particle was irregular with porous structure, while Mg(OH) C1 center dot 0. 3H(2)O particle had relatively flat surface.