Phase control in vanadium recovery via matrix-introduced interfacial atomic diffusion

Controlling product selectivity in high-temperature solid-solid reactions remains challenging in metallurgy, as exemplified by roasting vanadium slag with CaO, where multiple calcium vanadates readily form and complicate vanadium recovery. We introduce a matrix-introduced interfacial atomic diffusion (MIIAD) strategy to selectively stabilize the most leachable phase, CaV₂O₆. To elucidate the MIIAD mechanism, an Fe₂O₃ matrix was inserted between V₂O₅ and CaO to suppress molecular mixing and enforce diffusion-controlled interfacial reactions, thereby narrowing the disparity between Ca and V diffusivities at high temperatures. Multiscale characterization identified a CaV₂O₆ interfacial layer, while DFT calculations revealed lower diffusion barriers for Ca, V, and O in Fe₂O₃ than in CaV₂O₆, accounting for the selective stabilization of CaV₂O₆. Replacing Fe₂O₃ with Fe₂O₃-rich leaching residue enables practical implementation through a pellet architecture containing numerous MIIAD interfaces. Under insufficient leaching conditions, the MIIAD pellet achieves 74.17% vanadium extraction compared with 53.36% for conventional powder mixtures, highlighting its energy-saving potential.