Abstract:The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium, vanadium leaching and preparation of vanadium pentoxide. By adding Ca(OH)₂ and ball milling, not only the V in the solution can be selectively precipitated, but also the leaching kinetics of the precipitate is significantly improved. The precipitation efficiency of V is 99.59% by adding Ca(OH)₂ according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature, while the content of Cr in the precipitate is 0.04%. The leaching rate of V reaches 99.35% by adding NaHCO₃ into water according to NaHCO₃/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature. The crystals of NH₄VO₃ are obtained by adjusting the leaching solution pH to be 8.0 with CO₂ and then adding NH₄HCO₃ according to NH₄HCO₃/NaVO₃ molar ratio of 1:1 and stirring for 8 h at room temperature. After filtration, the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates, and the leaching efficiency of V is >99% after stirring for 1 h at room temperature. Finally, the product of V₂O₅ with purity of 99.6% is obtained by calcining the crystals at 560 °C for 2 h.

Key words: chromium-containing vanadate solution; calcium salt precipitating vanadium; sodium bicarbonate leaching; ammonium salt precipitating vanadate; cyclic metallurgical process