Recovery of Vanadium from Rapid-Cooling Converter Vanadium Slag by Sodium Roasting and Water Leaching

Rapid-cooling converter vanadium slag (CVS) is a raw material for the extraction of vanadium which can improve the productivity of the industry, but little research work has been carried out in this respect. The investigation of rapid-cooling CVS is essential for the industrial production of vanadium. In this study, a process for the extraction of vanadium from rapid-cooling CVS by sodium roasting-water leaching was investigated, including the factors that affect the vanadium extraction efficiency and phase transformation mechanisms of roasting and leaching. The analysis of the raw material indicates that the rapid-cooling CVS contains spinel, olivine, and glass phases. The vanadium-rich spinel is tightly enveloped by the other phases, forming a stable structure. After roasting with Na2CO3 at 800 degrees C for 1.5 h, the vanadium is converted to soluble sodium metavanadate (NaVO3), and the other phases are oxidized to Fe2O3, Fe2TiO5, and NaAlSi3O8, respectively. Under the optimum leaching conditions (liquid to solid ratio of 4:1 mL/g, 80 degrees C, 2 h), more than 93% of the vanadium is extracted. The experimental result shows that the recovery of vanadium from rapid-cooling CVS not only requires low production cost but also has a high efficiency of vanadium extraction.