Anosovite-dominated slag design for Fe-V-Ti separation in electric-furnace smelting of vanadium titanomagnetite

This study elucidates the influence of the CaO/MgO mass ratio and quaternary basicity (R 4 (CaO + MgO)/(SiO 2 /Al 2 O 3 )) on slag-phase evolution and element partitioning during electric-furnace smelting of pre-reduced vanadium titanomagnetite pellets. Thermodynamic calculations were employed to delineate a Ti-rich pseudobrookite-type slag domain that is amenable to subsequent acid-leaching processing for TiO 2 extraction. Smelting experiments under optimized conditions revealed that a balanced slag composition can simultaneously achieve high Ti enrichment in the slag and efficient Fe/V recovery in the metal phase, while suppressing the formation of CaTiO 3 . At 1600 °C with a holding time of 30 min and a carbon addition of 2 wt%, the combination of CaO/MgO = 0.5 and R 4  = 0.9 was identified as an optimal operating condition, yielding recovery rates of 99.82% for Fe, 93.12% for V, and 94.64% for TiO 2 . XRD and EPMA results show that the resulting slag is predominantly composed of anosovite, with subordinate diopside and magnesium titanium spinel, confirming the effective retention of Ti in the slag and the preferential partitioning of Fe and V into the metal phase. Collectively, these findings define a viable composition window for the design of acid-soluble titanium-bearing slags within the direct-reduction/electric-furnace processing route for vanadium titanomagnetite.