Reduction of molybdenite with carbon in the presence of lime

The thermodynamics of the MoS₂-C-CaO system has been studied in order to understand the carbothermic reduction of molybdenite in the presence of CaO. Kinetic studies were also conducted with mixtures of MoS₂+C+CaO in the temperature range of 900 °C 1200 °C. The reduction of MoS₂ with carbon in the presence of lime proceeds through the direct oxidation of MoS₂ by CaO to form intermediate molybdenum oxidized species, MoO₂ and CaMoO₄, which subsequently undergo reduction by CO to yield mixtures of Mo, Mo₂C, and CaS. Complete conversion of MoS₂ can be obtained at 1200 °C in less than 20 minutes for molar concentrations of MoS₂:C:CaO=1:2:2. The kinetic model ln (1−X)=kt was used to determine the rate constants. The activation energy found for the temperature range studied was 218.8 kJ/mol.