Acid Leaching of Vanadium from a Vanadium Residue

A process has been developed at the laboratory scale for leaching of vanadium from a vanadium residue using mixed hydrofluoric and sulfuric acid solutions, and NaClO as an oxidant. The extraction studies were carried out using various acid concentrations, liquid/solid ratios, addition of oxidant, reaction temperatures and leaching times. The optimum leaching conditions were then determined. Characterization of the leach residues was carried out by SEM and EDS analysis. Results indicate that the silicates can be effectively destroyed by HF, and the vanadium contained in the vanadium-iron spinel can be leached by the mixed acid solutions. The addition of NaClO enhanced the leaching process by the oxidation of V3+(s) to V4+ and V5+. The leaching efficiency was also improved by raising the leaching temperature, prolonging the reaction rime and using a higher liquid/solid ratio. A vanadium recovery of 81.8% was obtained by the direct acid leaching process