Effect and Mechanisms of Oxidative Roasting Mineral Phase Reconstruction with MgO and Leaching in Direct Extraction of V from Titanomagnetite Concentrate

Abstract

The technology for directly extracting vanadium from titanomagnetite concentrate boasts low energy consumption, a streamlined process, and a high recovery rate, thereby holding immense significance for advancements in various fields, including Ti-Al-V alloys, vanadium catalysts, and all-vanadium redox flow batteries. Research findings on the oxidative roasting and V leaching process of magnesium compounds within this concentrate revealed optimal conditions for hydrochloric acid/sulfuric acid leaching: an acid concentration of 1.5 mol/L, a leaching temperature of 55℃, and a liquid-to-solid ratio of 8, when the leaching duration was set at 2 hours. Under these parameters, the introduction of 3 wt.% MgO, MgCO3, and Mg(OH)2 to titanomagnetite concentrate oxidative roasting led to ore phase reconstruction, subsequently enhancing the V leaching efficiency by 5.19%, 2.92%, and 4.21%, respectively. The highest V leaching efficiency of 64.4% was achieved with the addition of MgO for mineral phase reconstruction. This enhancement was attributed to the local shrinkage and pore-forming mechanisms within the lattice structure facilitated by MgO. Furthermore, calculations on the variations in the concentrations of 12 V-related ions in the V-H2O system across different pH values indicated that V predominantly existed in the form of VO2+ in the leachate. The H-free large ion in the V-H2O system, V10O286–, comprised 31.4% V at pH 6 and exhibited a tendency towards precipitation. The stable generation of this ion occurred within pH 5-6.3, which could be deemed as the optimal pH range for V precipitation in the V-H2O system.