Selective leaching of vanadium over iron from vanadium slag

A new comprehensive utilization of vanadium slag (VS) method focusing on inhibiting leaching of iron (Fe) during the leaching of vanadium (V) using sulfuric acid (SA) was proposed. In this process, Cr₂O₃ was added to VS to conjugate with Fe in the VS to form (Fe_x,Cr_1-x)₂O₃ which is insoluble in SA, resulting in the decrease of leaching ratio (LR) of Fe to avoid the subsequent separation difficulty of V in leachate. The phase evolutions of VS during the roasting and SA leaching process, and the influences of roasting temperature, roasting time, and addition of Cr₂O₃ on the LR of V, Fe and chromium (Cr) from VS were studied. When the addition of Cr₂O₃ is 12 wt.%, the mass concentration of V in the leachate is 1 order magnitude higher than Fe and the mass ratio of V to Fe reaches 18.34. The LR of V, Fe and Cr are 91% 1.39% and 0.28%, respectively. The leaching residue can be reused as ironmaking raw material. More importantly, the (Fe_x,Cr_1-x)₂O₃ and Fe₂TiO₅ can be separated from the leaching residue and recycled as raw materials for black ceramic pigments and titanium dioxide production by mineral processing technology, respectively.