Phase evolution mechanism exploration of vanadium slag during magnesiation roasting by atomic atmosphere method

Abstract

Magnesiation roasting-acid leaching technique, whose industrial application is hindered by the unknown phase evolution mechanism during magnesiation roasting. Herein, the “atomic atmosphere” method was proposed to explore the phase evolution mechanism at the atomic scale. At the initial roasting stage, FeV2O4 transformed into Fe2O3•V2O3. Then Fe2SiO4 matrix participated in the reaction, resulting in the exposure of V-bearing crystals. The structure of Fe2SiO4 was completely destroyed at 15 min. At 30 min, all V-bearing crystals transformed into vanadate crystals. Then the vanadate crystals continued to grow and the overall vanadium extraction efficiency showed an upward trend. The vanadium atoms changed from the mixture of V4+/V5+ to V5+. At 90 min, V5+, Mg2+, Mn2+, and O2− ions combined to generate Mg2V2O7 and Mn2V2O7. The explored atomic-scale phase evolution mechanism of vanadium slag during magnesiation roasting impels the industrial application of this technique, which can boost green extraction techniques of other resources.