Abstract:Metallurgical extraction of vanadium from a mixed vanadium concentrate obtained from beneficiation was studied applying compound salt roasting and weak alkali leaching process. V2O5 grade in mixed concentrate is 1.738%, about 70% vanadium exists in the form of low-price (V3+) with a tight structure as refractory mineral. Effects of additives, particle size of concentrate, roast temperature, roast time, leaching temperature, and leaching concentration of alkali liquor on vanadium leaching rate were investigated. Vanadium leaching rate is 78.52% under the conditions including additives of 16.0% NaCl+7.5% Na2CO3+1.5% halide-A, particle size of concentrate of -0.075 mm of 86.2%, pellet size of ~10 mm, charging temperature of 200 ℃, roasting temperature of 830 ℃, roasting time of 2.5 h, L/S of leaching of 2, alkali liquor concentration of 0.2 mol/L, leaching temperature of 60 ℃, and stirring time of 2.0 h.