Cumulative leaching behavior in sustainable vanadium extraction from V-slag using Ba-Slag

Abstract

This study explores a sustainable “waste-to-value” approach that employs barium slag (Ba-slag), a byproduct of BaCO₃ production, as a roasting additive for vanadium extraction from V-slag. Key challenges addressed include isolating a pure V product from a multi-component leachate, explaining the leaching characteristics, and managing the tailings. In this work, a roasted mixture of Ba-slag and V-slag was leached under optimized conditions, yielding a leachate from which V₂O₅ with 99.50 % purity was recovered via precipitation and calcination. Tailings were repurposed into foamed ceramics, achieving a maximum compressive strength of 4.05 MPa as a potential structural component. Optimal leaching parameters, 30 wt% H₂SO₄, 80 °C, and a holding time of 90 min, resulted in a peak V leaching efficiency of 90.67 %. The leaching efficiency increased initially but declined under excessive leaching conditions due to cumulative effects. Elemental migration, crystal phase evolution, and morphology and elemental distribution analyzes revealed that Ba₃V₂O₈ acts as the intermediate for V concentration, with newly formed small BaSO₄ particles on the tailings surface confirmed cumulative effects. Further, a novel method for calculating kinetic parameters was proposed to elucidate the cumulative characteristics. The cumulative rate constant (k_d) ranged from 0.0009 to 0.006, while the activation energy (Ea) ranged from 22.4 to 32.53kJ/mol, aligning with reported values and validating the reliability of the proposed calculation method.