Rapid Vanadium Extraction from Roasted Vanadium Steel Slag via a H₂SO₄-H₂O₂ System: Process and Mechanism

A H₂SO₄-H₂O₂ system was developed to enhance the efficacy of vanadium extraction from roasted vanadium steel slag. The optimum parameters and the behavior of vanadium extraction were investigated systematically. When 1 mL of H₂O₂ per gram of vanadium slag was added to a leaching mixture at 50 °C, along with 30% H₂SO₄, 80.5% of vanadium extraction was achieved within 15 min. However, without H₂O₂, only 58.5% of vanadium extraction was achieved at the same leaching time. The H₂SO₄-H₂O₂ system facilitated the dissolution of metallic ions in a short time and then triggered the production of strong oxidizing substances, such as HO^• and O₂ ^-•, via the Fenton reaction and Fenton-like reaction. Subsequently, the low-valence vanadium, existing in the leaching solution or located on the surface of the particle, was converted to pentavalent vanadium by strongly oxidizing substances, such as H₂O₂ and its derivatives HO^• and O₂. The complex oxides on the surface of the particle were destroyed, after which the vanadium inside the particle was gradually exposed to the acid leaching solution. The vanadium was oxidized to pentavalent vanadium, which then entered the leaching solution. Finally, a pathway of vanadium extraction via the H₂SO₄-H₂O₂ system was proposed to gain insight into rapid vanadium leaching.