Nonisothermal Gravimetric Investigation on Kinetics of Reduction of Magnesia by Aluminum

An investigation of the reduction of magnesia by aluminum was carried out using a nonisothermal gravimetric technique under an argon atmosphere, in the temperature range from 1273 to 1873 K. The mixture (if magnesia and aluminum powders was formed into a pellet under various isostatic pressures. It was found that magnesia is reduced by aluminum to form magnesium and spinel at first, and then the excess aluminum reacts with spinel slowly. The temperature at which the reaction starts increases with an increasing heating rate. The reaction rate is also affected by pellet-forming conditions. A kinetic model is proposed to explain the experimental results. The activation energy of the reduction of magnesia by aluminum is 151.2 kJ/mol. Good agreement between calculated and experimental results is obtained.