Transformation Behavior of Fe, V and Ti in Pre–Reduced Vanadium–Titanium Magnetite During Electric Furnace Smelting

Vanadium–titanium magnetite is an important global strategic resource, with proven reserves exceeding 40 billion tons. Currently, the direct reduction–electric furnace route is regarded as the most promising process for VTM treatment. However, the transformation mechanisms of Fe, V and Ti remain insufficiently understood, constraining industrial implementation. In this study, the transformations of Fe, V and Ti during reduction smelting were systematically clarified, and the effects of MgO, CaO and semi–coke were evaluated. MgO addition promoted the formation of MgAl2O4, (Ti,V)2O3 and (Mg,V)xTi3–xO5, hindering slag–alloy separation. In contrast, with CaO as a modifier, FeTiO3 in the raw material was reduced by C to yield Fe and VxTi3–xO5, which was further reduced to (Ti,V)2O3. The added CaO reacted with (Ti,V)2O3 to generate CaTiO3 and (VxOy), chemically dissolved V. Concurrently, CaO reacted with silicates to produce CaAl2Si2O8, facilitating the sedimentation of the Fe–V alloy. Under the optimal conditions of 1873 K, a holding time of 20 min and additions of 2.5 wt% semi–coke and 12 wt% CaO, the recoveries of V, Fe and Ti reached 94.56%, 99.61% and 98.87%. In comparison, conventional processes typically achieved Fe and V recoveries of only approximately 90% and 70%. These findings support the industrial application of pre–reduced VTM.