Phase Relations of “FeO”–SiO2–CaO–V2O3 System: Basic Research on Vanadium Slag
摘要
The lack of thermodynamic data on vanadium slag, the main raw material for vanadium extraction, limits the efficient extraction of vanadium from vanadium slag. According to the composition and smelting process of industrial vanadium slag, this study firstly investigated the phase equilibria of the “FeO”–SiO2–CaO–16 wt pctV2O3 system at 1673 K and 1473 K under oxygen partial pressure of 10−10 atm via XRD, SEM and EPMA, based on which the phase diagrams of that at 1673 K and 1473 K were constructed. The results showed that the vanadium-enriched phases mainly consisted of V2O3, Fe2VO4, and Ca3[Fe,V]2(SiO4)3, where Ca3[Fe,V]2(SiO4)3 was generated due to the replacement of a large amount of Fe3+ by V3+ in Ca3Fe2(SiO4)3. On this basis, the phase relations of the “FeO”–SiO2–CaO–16 wt pctV2O3 system were further discussed. It was found that the decrease in temperature promoted the crystallization of Fe2VO4 and Ca3[Fe,V]2(SiO4)3, but had an inhibitory effect on the crystallization of V2O3. And Fe2VO4 was transformed to V2O3 or Ca3[Fe,V]2(SiO4)3 by decreasing Fe/Si (Mass fraction of “FeO” and SiO2). This study supplements the thermodynamic data for vanadium slag and provides a theoretical basis for the recovery of vanadium from vanadium slag.