Fe3O4-FeV2O4 solid solution magnetization: An innovative strategy for the efficient enrichment of vanadium from stone coal vanadium ore

Owing to its low grade and complex dissemination, the efficient recovery of vanadium from stone coal vanadium ore remains highly challenging. To address this issue, this study proposes a novel approach, referred to as "narrow particle-fraction wüstite (Fe 1- x O) solid solution magnetization," which enables highly efficient vanadium enrichment from stone coal vanadium ore through the use of precisely controlled narrow particle-fraction Fe 1- x O. During roasting under a reducing atmosphere, vanadium-bearing components are thermally activated and diffuse into the Fe–O lattice of residual granular Fe 1- x O through the product layer, resulting in the formation of a ferrimagnetic Fe 3 O 4 –FeV 2 O 4 (Fe 3- x V x O 4 ) solid solution. Subsequently, the Fe 3- x V x O 4 phase is separated using low-intensity magnetic separation. Taken the stone coal vanadium ore with a V 2 O 5 content of 0.95 wt% as the raw material, under optimized Fe 1- x O particle size fractions and roasting parameters, the magnetic separation process yielded over 87% vanadium recovery in the concentrate, with a V 2 O 5 grade exceeding ten times that of the raw tailings, the processing volume required for the subsequent hydrometallurgical vanadium extraction process reduced by nearly 90%. Mechanistic analyses (SEM–EDS, EPMA, VSM, CLSM, and XRD) confirmed that the in situ-formed Fe 3- x V x O 4 solid solution served as an efficient magnetic carrier for vanadium in stone coal vanadium ore. Therefore, this approach provides a sustainable pathway for the efficient conversion of stone coal vanadium ore.