Roasting oxidation behaviors of ReS2 and MoS2 in powdery rhenium-bearing, low-grade molybdenum concentrate
(School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The oxidation roasting process of molybdenum concentrate has significant advantages in industrial applications. However, utilization of low-grade mineral has many problems because it is more complex than the standard concentrate. In this study, the oxidation behaviors of powdery rhenium-bearing low-grade molybdenum concentrate were investigated through thermodynamic calculation, roasting experiments, thermogravimetric analysis, and phase analysis. The results obtained show that oxidation of MoS2 begins at 450 °C, and MoO3 reacts with metal-oxide forming molybdate at 600 °C. Finally, MoO3 can be dissolved in ammonia with a maximum content of approximately 80%. The volatile speed of Re was considerably slower than the oxidation speed of MoS2 because the nonvolatile products ReO2 and ReO3 were generated in reactions among MoS2, SO2, and Re2O7. The final volatilization rate of Re was almost 70%. This study determined the problems related to the roasting of low-grade molybdenum concentrate, which lays the scientific foundations for subsequent enhancement of molybdenum and rhenium extraction.
Key words: low-grade molybdenum; rhenium; oxidation roasting; thermodynamics; phase evolution