Synergic Acid Leaching of Vanadium from Sodium Vanadium Extraction Tailings

The content of V₂O₅ in sodium vanadium extraction tailings is much higher than that in vanadium-titanium magnetite concentrate and it has high utilization value. In this paper, a synergistic acid leaching method for vanadium extraction from sodium vanadium extraction tailings was proposed, which can realize secondary vanadium extraction from vanadium extraction tailings. Taking sulfuric acid as the leaching agent, CaF₂ and MnO₂ as the leaching aid agent, this paper researches the sulfuric acid concentration, particle size of vanadium extraction tailings, the liquid-solid ratio, types of the leaching aid agent and impats of additive amount on vanadium leaching rate. The results show that in CaF₂-sulfuric acid leaching system, CaF₂ is beneficial to open the structure of vanadium extraction tailings, the vanadium leaching rate can reach 85.43% at the conditions that the CaF₂ additive amount is 7%, the sulfuric acid concentration is 450 g/L, the temperature is 95 ℃, and the leaching time is 2 h. In MnO₂-sulfuric acid leaching system, MnO₂ can dissolve and oxidize vanadium, the vanadium leaching rate can reach 78.35% at the conditions that MnO₂ additive amount is 10%, the sulfuric acid concentration is 450 g/L, the temperature is 95 ℃, and the leaching time is 2 h. In the CaF₂-MnO₂-sulfuric acid leaching system, the vanadium leaching rate can reach 86.45% at the conditions that CaF₂ additive amount is 7%, MnO₂ additive amount is 10%, the sulfuric acid concentration is 300 g/L, the temperature is 95 ℃, and the leaching time is 2 h owing to the synergistic effect of CaF₂ and MnO₂ in vanadium extraction process. In single sulfuric acid leaching system and synergic leaching system, the vanadium leaching behavior can achieve the removal of sodium from vanadium extraction tailings simultaneously, the removal rate of sodium can reach 90%.