Recovery of Molybdenum from Spent Lubricant

Abstract

The recovery of Mo from spent lubricant by applying carbothermic reduction was investigated. The carbothermic reduction of CaCO₃–MoS₂–C, CaCO₃–MoS₂–Fe₂O₃–C and the spent lubricant–CaCO₃–Fe₃O₄–C mixtures at 1073 K, 1173 K, 1273 K, 1373 K and 1473 K were carried out to investigate the reduction mechanism of MoS₂ under various conditions. The reduction process was anlayzed by using quadruple mass spectroscopy (QMS) analysis, differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis. Based on the investigated reaction mechanism, the carbothermic reduction of the spent lubricant–CaCO₃–Fe₃O₄–C mixtures at 1773 K was carried out to confirm the feasibility of the Mo recovery from the spent lubricant. Mo in the spent lubricant was found to be fully recovered as molten Fe–Mo alloy by the reaction, MoS₂(s) + 2CaO(s) + 2C(s) → 2CaS(s) + 2CO(g) + Mo. The recovered Fe–Mo alloy contained about 40 mass% Mo and 4.3 mass% C. Thus, Mo recovery from the spent lubricant by carbothermic molten reduction is promising.