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