Semi-quantitative Analysis of Phase Conversion of Vanadium Slag in Sodium Calcination Process

Using sodium carbonate as additive,experimental studies of oxidation roasting of vanadium slag were conducted.The content of sodium vanadate was detected through XRD semi quantitative method and the factors influencing the formation of sodium vanadate were investigated.The phase transitions and their corresponding temperatures of vanadium slag during the roasting process with sodium carbonate（Na₂CO₃） presence were studied by some assistant methods （e.g.SEM and TG）.Experimental results show that the oxidation roasting process mainly consists of the decomposition of olivine and spinel phases,as well as the formation of vanadates,chromates,silicates,sodium titanate,sodium aluminate and sodium ferrite.The mass fraction of sodium vanadate in products increases with the increase of V₂O₅ and Na₂CO₃ content with 730 ℃ of the optimal reaction temperature and 80 min of optimal reaction time when the content of sodium vanadate （Na₄V₂O₇） in vanadium phases is up to 98.09% and other vanadium phases are mainly CrVO₃ and CrVO₄ and FeVO₄.