Recovery of Valuable Elements from Molten Vanadium Slag Through High-Temperature Reduction

To shorten the wet-extraction process of vanadium slag and reduce the loss of a large number of valuable elements—such as iron, manganese, and chromium—this study directly used molten vanadium slag to smelt alloys. Vanadium slag with 16 wt.% carbon, 20 wt.% CaO (R = 0.97), and 5 wt.% Al₂O₃ was reduced at 1550°C for 2 h, and a Fe-V-(Cr-Mn) alloy with Fe-V as the matrix was obtained, which could be used as a raw material for vanadium alloy steel. The valuable elements of iron, vanadium, and chromium in the slag were almost completely reduced. The tailing was mainly composed of Ca₃Si₃O₉, Ca(Mg,Mn)(Si,Al)₂O₆, and CaAl₂SiO₆, which are primarily silicates and aluminates. To obtain a better reduction rate of elements, the appropriate reduction temperature, reduction agent, and modification agent were 1500°C, 16–20 wt.% C, and 20 wt.% CaO (R = 0.97), respectively. In addition, by effectively controlling the process parameters, the recovery rate of iron and vanadium could reach as high as 98%, and the recovery rate of chromium and manganese could reach > 90% and 70%, respectively, which could effectively recover valuable elements in vanadium slag and the sensible heat, shorten the vanadium extraction process, and decrease the amount of the three waste types.