Primary Study of the Phase Relationship in the MgO-"V2O3" System at 1873 K and pO2=10-11 atm

Abstract: Vanadium can be found in some iron ores as an impurity. Since vanadium is a valuable alloy element there lies an interest in development of a stable and economic way for extraction of it. For this, knowledge about the thermodynamics behind the V-O system combined with other elements, like Mg, is indispensable. A transitional metal like vanadium exists in multiple valences which makes it difficult to study. When vanadium oxide is mixed with other metal oxides the vanadium tends to concentrate in spinels. To investigate the types of phases formed in the Mg-O-V system at 1873 K and an oxygen partial pressure of 10-11 atm, multiple samples containing MgO and V2O3 in different proportions were equilibrated under these conditions. The samples were examined using SEM/EDS and XRD. A three, one and two phase region were found during analysis. In the three phase region MgV2O4, Mg2VO4 and an unidentified solid solution were found when the fraction of V2O3 was 0,234 and 0,448. In the one phase region only MgV2O4 was found at a V2O3 fraction interval of 0,500-0,530. Lastly in the two phase region MgV2O4 and V2O3 was found within the V2O3 fraction interval of 0,549-0,799. In conclusion when there was a higher amount of V2O3 more vanadium rich spinels were formed until a certain point where the spinel was saturated.