Thermodynamic and experimental study of C-S system and C-S-Mo system

In order to better utilize the low-grade molybdenite concentrates and obtain high quality products, thermodynamic analysis and experimental study of vacuum smelting process of molybdenite concentrates were carried out in detail. The possible reactions of the C-S system were analyzed, and the indirect reduction reactions and direct reduction reactions of MoS2 were discussed. To clarify the reaction mechanism under vacuum condition, the Mo-S-C system was also studied by thermodynamic and experimental methods. The results indicated that vacuum decomposition reactions and equilibrium reactions of Mo-S-C system were carried out simultaneously in the vacuum smelting process. Temperature and pressure are the main factors affecting the vacuum smelting process. There is reaction equilibrium of C, CS, CS2 and S2 in the vacuum smelting process and molybdenum sulfides can be easily reduced to Mo, Mo2C, Mo3C2 and MoC. The contents of carbon and sulfur in the product have relationship with the reaction equilibrium of Mo-S-C system. The CS generated in carbon sulfidation reaction(C + CS2→2CS) may accelerate the reaction rates in the vacuum smelting process. When the grade of molybdenite concentrates is 48%, the optimum content of carbon added in the molybdenite concentrates is about 4%, and the content of Mo in the metal molybdenum products can reach 92%, and the content of sulfur and residual carbon are all low.