Vanadium extraction from vanadinite and high carbon v-bearing stone coal by coupling reduction smelting and oxalic acid hydrothermal leaching

Abstract

Vanadinite and high-carbon vanadium-bearing (V-bearing) stone coals are important vanadium sources widely used in vanadium extraction. The traditional sulfuric acid leaching method for extracting vanadium consumes a large amount of acid, wastes significant amounts of lead and carbon, and causes serious environmental pollution. This study discusses the integration of reduction smelting and oxalic acid hydrothermal leaching for processing vanadinite and high-carbon V-bearing stone coals. Specifically, high-carbon V-bearing stone coal is selectively added to vanadinite to produce coarse lead blocks and V-bearing slag during reduction smelting. Then, the oxalic acid hydrothermal leaching process is employed to extract vanadium from the V-bearing slag. This approach reduces the waste of lead and carbon resources and achieves co-extraction of vanadium from both V-bearing minerals. The results show that when the mass ratio of high-carbon V-bearing stone coal to vanadinite is 25%, and smelting is conducted at 1150°C for 15 min under argon protection, a separation efficiency of 90.67% for metallic lead and V-bearing slag is achieved, the grade of V₂O₅ in vanadium slag is 12.37%, and the recovery rate is 95.64% by ICP-OES analysis. Furthermore, the leaching rate of vanadium in the V-bearing slag can reach 85.34% via oxalic acid hydrothermal leaching under conditions of a leaching temperature of 100°C, a leaching duration of 30 min, an oxalic acid concentration of 25 wt%, a liquid-to-solid ratio of 10:1 mL/g, and a stirring speed of 500 rpm. The integration of reduction smelting and oxalic acid hydrothermal leaching offers benefits such as improved resource utilization, waste reduction, cost savings, and environmental enhancements. Thus, the findings of this research can serve as references for the vanadium extraction processes of related vanadium-containing minerals.