THE EFFECTS OF MECHANICAL ACTIVATION AND SODIUM CARBONATE ON KINETICS OF CARBOTHERMIC REDUCTION OF MOLYBDENITE

In this research, kinetics of carbothermic reduction of molybdenite in the presence of different amounts of sodium carbonate has been studied. Mixed powders consisting of molybdenite, graphite and sodium carbonate with three mole-ratios of 1:4:2,1:4:3 and 1:4:4 were mechanically activated for 40 hours. The results of X-ray diffraction on activated samples showed that no reaction occurrs in different samples during milling. The effect of mechanical activation on reduction of molybdenite particle size in three mixtures having different amounts of sodium carbonate was investigated by the Williamson-Hall method. The results indicated that the grain size of molybdenite increases with increasing the amount of sodium carbonate in different samples. To study the kinetics of carbothermic reduction of molybdenite in the presence of different amounts of sodium carbonate, simultaneous thermal analysis (STA) with heating rates of 10, 15 and 20 C/min was carried out on activated samples. The results were evaluated using the Friedman, Kissinger and Ozawa approaches and it was found that the temperature and activation energy of molybdenite carbothermic reduction in the presence of sodium carbonate increase with an increase in the amount of sodium carbonate in different samples. Key Word Molybdenite, Carbothermic reduction, Kinetics, Sodium Carbonate, Mechanical activation.