Selective leaching of iron and vanadium with concurrent titanium enrichment from vanadium-titanium magnetite via wet grinding activation and acid leaching

A process integrating wet grinding activation and hydrochloric acid (HCl) selective leaching was developed to achieve efficient separation of Fe as well as V and directional Ti enrichment from Panzhihua vanadium-titanium (V-Ti) magnetite concentrate. The effects of wet grinding time, grinding ball size distribution, ball-to-powder mass ratio, HCl concentration, liquid–solid ratio, and leaching time on leaching performance were systematically investigated. The optimal activation conditions were identified as a grinding time of 2 h, a ball-to-powder mass ratio of 20:1, and the exclusive use of Φ25 mm balls. Under these conditions, and with 8 mol/L HCl, a liquid–solid ratio of 12:1, and a leaching time of 2.5 h, the leaching rates of Fe and V reached 88.1% and 84.2%, respectively, while the leaching rate of Ti remained as low as 4.15%. In comparison with direct acid leaching without activation, wet grinding increased the leaching rates of Fe and V by 10.2% and 9.1%, respectively, and significantly enhanced the selectivity of Fe and V over Ti. Results of SEM, DLS, and XRD analyses revealed that wet grinding transformed the initially coarse, dense particles into fine and porous structures, increasing the specific surface area from 0.23 m 2 /g to 25.4 m 2 /g. Notably, lattice distortion and partial amorphization were triggered after wet grinding. After acid leaching, the magnetite phase was essentially dissolved, while ilmenite was retained and enriched, resulting in a leaching residue enriched with ~38% TiO₂ grade and 95.85%TiO₂ recovery. This study developed a synergistic process that utilizes mechanical chemical activation to overcome the kinetic obstacles of V-Ti magnetite, achieving highly selective separation of Fe/V and Ti under mild conditions.