Mechano-thermal reduction of molybdenite (MoS2) in the presence of Sulfur scavenger: New method for production of molybdenum carbide

Abstract

In this research, carbothermic reduction of molybdenite in the presence of sodium carbonate as sulfur scavenger by mechanical activation and heat treatment was studied. Mechanical activation of the mixed powders of molybdenite, graphite and sodium carbonate with 1:4:2 mol ratios were carried out by ball milling process under argon atmosphere for 10,20,40,50 and 70 h. The X-ray diffraction (XRD) patterns of samples revealed that no reaction occurred in the mill even after 70 h of milling. In order to study the mechanism of carbothermic reduction of molybdenite in the presence of sodium carbonate, simultaneous thermal analysis (STA) under heating rate of 10, 15 and 20 °C/min was carried out on the activated samples. XRD patterns and thermodynamic analysis of reaction products indicated that carbothermic reduction of molybdenite in the presence of sodium carbonate was advanced through the formation of intermediate phases Na2MoO4, MoO2 in which the final products were Mo2C, Na2S. For separation of these two products, leaching by HCl and hot water was used. The XRD patterns of leached products were shown that molybdenum carbide with high purity was produced. The kinetics of reduction reaction was investigated and it was found that mechanical activation lowered the reaction temperature and activation energy.