New insight into the contribution of Ca, Mn, and Mg component to vanadium extraction from vanadium slag

The contribution of Ca, Mn, and Mg component to vanadium extraction from vanadium slag after calcium roasting−acid leaching was rarely investigated. In this study, vanadium slag was adopted to explore the vanadium extraction behavior, contribution of calcium, manganese and magnesium component to vanadium extraction in blank roasting and calcium roasting by X-ray diffraction analysis (XRD), Scanning electron microscope (SEM), and inductively coupled plasma (ICP). Furthermore, quantitative analysis of different vanadate was clarified in calcium roasting process. The results show that Ca2V2O7, Mn2V2O7, and Mg2V2O7 were mainly generated in blank roasting and calcium roasting. For blank roasting, 79.17 % of vanadium, 60.03 % of manganese and 44.33 % of magnesium was maximally extracted after roasting at 850℃ and leaching with pH of 2.2. The contribution of calcium, manganese, and magnesium component to vanadium extraction namely the ratio of vanadium dissolved by corresponding vanadate to total vanadium in leachate occupied 26.39 %, 49.61 %, and 24.00%. For calcium roasting, after roasting at 900℃ for 1.5 h with n(CaCO3)/n(V2O3) of 1 (molar ratio), vanadium leaching efficiency was 91.23 %. The contribution of calcium, manganese, and magnesium component to vanadium extraction occupied 61.37 %, 28.37 %, and 10.26 %. At least 55.99 %, 25.88 %, and 9.36 % of vanadium generated as calcium vanadate, manganese vanadate, and magnesium vanadate during roasting process.