The feasibility of vanadium recovery from black shale was investigated using sulfuric acid and hydrofluoric acid solutions. The chemical characterization of black shale from Guizhou, China showed that vanadium mainly existed in free oxide and mica. According to E-pH diagram for V-H(2)O at 25 degrees C, the dissolved species of vanadium in aqueous solution mainly present in form of VO(2+) and VO(2)(+) at high potential and low pH value. The effects of leaching time, sulfuric acid concentration, hydrofluoric acid concentration, sodium hypochlorite concentration, temperature and liquid to solid ratio on the vanadium leaching were studied. The optimum parameters obtained were a reaction time of 6 h, sulfuric acid concentration of 87.5 g/L, hydrofluoric acid concentration of 15 g/L, sodium hypochlorite concentration of 1 g/L (added after a reaction time of 3 h), leaching temperature of 95 degrees C and a liquid to solid ratio of 4 mL/g. Under these conditions, up to 86% vanadium was recovered. HF has an important role in the leaching vanadium process. Compared to our previous two-step countercurrent leaching, the vanadium recovery only decreased 4% despite the leaching temperature was decreased from 150 degrees C for the previous tests to 95 degrees C for the present work. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.