Crystallization behavior and crystal characterization of V-spinel in vanadium slag via in situ separation: displacement mechanism of V and Ti

Vanadium (V) is often transferred into vanadium slag from the smelting of vanadium titano-magnetite ore, however, basic data for the crystallization behavior and crystal structure of V-spinel are lacking, which limits the efficient recovery of V resources from vanadium slag. In this study, the crystallization behavior of V-spinel in vanadium slag was investigated, and in situ separation of high-purity V-spinel crystals from vanadium slag was conducted via super-gravity at 1673 K. It was found that TiO2 content of 12 wt% in vanadium slag was the most conducive to the crystallization of V-spinel. On this basis, the crystal structures of various V-spinel crystals were characterized, by which the displacement mechanism of V and Ti in V-spinel was verified. Namely, V3+ in the octahedron sites was gradually replaced by Ti4+ with the increase of Ti content, while an equal amount of Fe3+ in the tetrahedron sites was replaced by Fe2+. This study provides some necessary theoretical basis for the efficient recovery of V resources in vanadium slag.