Dissolution Behavior of Calcium Vanadates and Magnesium Vanadates in Sulfuric Acid

The dissolution efficiency of vanadium is the key to improve the recovery of vanadium from vanadium-bearing converter slag by calcification roasting-acid leaching process. An improved process, which involves roasting with calcium–magnesium salts, followed by acid leaching, was found to have a positive effect on the vanadium recovery. In this process, CaO–MgO–V₂O₅ is the basic system in the roasting step. In this study, the dissolution behavior of calcium vanadates (CaV₂O₆, Ca₂V₂O₇, and Ca₃V₂O₈) and magnesium vanadates (MgV₂O₆, Mg₂V₂O₇, and Mg₃V₂O₈) in sulfuric acid was investigated. The effect of parameters, such as stirring speed, solid/liquid ratio, and pH value, on the dissolution behavior of vanadates were determined. The results shown that both of solid/liquid ratio and pH value have significantly effects on the dissolution efficiency of vanadium, while stirring speed has a relatively minor effect under the studied conditions. Furthermore, the dissolution efficiency of magnesium vanadates has been found much higher than that of calcium vanadates.