Oxidation Mechanism of Vanadium Slag with High MgO Content at High Temperature

Based on two considerations of making full use of the residual heat of vanadium slag and exploring a novel green vanadium extraction process, this article employs vanadium slag with high MgO content as raw material, blowing oxygen into the molten vanadium slag and using the residual heat of the vanadium slag to carry out high-temperature roasting experiments. XRD and SEM/EDS were used to characterize the phase evolution and morphology of vanadium slag with high MgO content during oxidation. The results show that at a high temperature of 1723 K, the trivalent vanadium in vanadium slag can be partly transformed into acid-soluble pentavalent vanadium. Titanium-bearing spinel was oxidized into a large amount of strip pseudobrookite Fe₂TiO₅. After oxidation, vanadium existed in the form of the solid solution of magnesium pyrovanadate (Mg, Mn, Ca)₂V₂O₇. The leaching rate of roasted vanadium slag with high MgO content is significantly higher than that of industrial vanadium slag. With the increase of oxygen blowing time from 10 to 30 minutes, the leaching rate of roasted vanadium slag with high MgO content increases from 23.19 to 53.69 pct.