Reaction Mechanism of Magnesium in Roasting of Vanadium Slag

Abstract

The influence of magnesium on roasting vanadium slag was investigated by simulating the roasting process of vanadium by mixing V₂O₅ and MgO. The calcination products of V₂O₅ reacted with MgO at different temperatures which were characterized by X-ray diffraction (XRD), Thermogravimetry-differential scanning calorimetry (TG-DSC) and scanning electron microscope (SEM). There were two mass loss intervals, three endothermic peaks and one exothermic peak appearing during the reaction by the integrated thermal analysis as the temperature increased from room temperature to 1273.15 K. The samples of mixed V₂O₅ and MgO began to melt at 573.15 K and reacted at 773 K, and the shape of the particles changed from block to ovoid or irregular sphere at 773.15 K. With increasing the reaction temperature from 973.15 to 1073.15 K, the intermediate of VO₂ was produced, and MgV₂O₆ was partially decomposed at 1073.15 K. During this process, the particle shape gradually returned to block shape. The conversion rate of vanadium is 99.4% with MgO of 1.65%.

Key words
vanadium slag; roasting; simulation; magnesium