Establishment And Properties Of FeO-SiO₂-V₂O₃ Systems Phase Diagrams

The purpose of this work is to calculate phase diagram of FeO-V2O3-SiO2 ternary system of converter vanadium-recovering.Base on the silicate melt structure,using the modified quasi-chemical solution model to describe the Gibbs free energy of solution phase,combined with the experimental data of thermodynamic and phase diagram,model of the FeO-V2O3-SiO2 system was structured.By the Gibbs free energy minimum principle of equilibrium system,binary phase diagrams and ternary phase diagrams related to the FeO-V2O3-SiO2 ternary oxide system were calculated by FactSage thermodynamic package.Then relations between phases and temperature in FeO-V2O3-SiO2 system were discussed.The main research results are as follows:(1)The compound(Fe2SiO4)of the FeO-SiO2 system at about 1206? was produced.The eutectic reactions happened with the 27 mol%and 42 mol%SiO2,respectively.The results of phase diagram calculation agreed with the experimental results and the tested phase diagram and the maximum error of liquid temperature is less than 20 ?.(2)The eutectic reactions of the FeO-V2O3 system happened with the 5 mol%V2O3 at about 1353?.FeV2o4 was produced with the 50 mol%V2O3 and decomposed at about 1712?.(3)The monotectic and eutectic reactions of the SiO2-V2O3 system happened with the 55.7 mol%and 99.6 mol%SiO2 at about 1690?and 1662?,respectively.Liquid immiscibility happened above 1662? including two saturated solutions,one of which was produced for SiO2 in V2O3 phase and the another of which was produced for V2O3 in SiO2 phase.The compound wasn't produced in the SiO2-V2O3 system.(4)According to the actual blowing temperature of the extraction-vanadium converter,the isothermal section at about 1300? 1350?,1400? and the projection diagram of the FeO-SiO2-V2O3 system were calculated.For the projection diagram at 1300? and 1350?,three ternary phase regions,two binary phase regions and one liquid phase region were existed in the FeO-SiO2-V2O3 system,including Liquid+Spinel+Tridymite?Liquid+FeO+Spinel?Spinel+Tridymite +V2O3?Liquid+ Tridymite?Liquid+Spinel?Liquid+FeO ?Liquid.When the temperature increased from 1300 ? to 1400 ?,the liquid phase region of the isothermal section extended gradually,but the ternary and binary phases regions were shrank.The phase regions of Liquid+FeO+Spinel and Liquid+FeO were shrank when FeO was melted at 1400?.(5)The eutectic point Pa with the composition of 76.85 mol%FeO,20.29 mol%SiO2 and 2.86 mol%V2O3 at temperature 1197? was established among liquid,FeO and FeV2O4 phase fields.The temperature of another ternary eutectic point PB for phases liquid,SiO2 and FeV2O4 was verified at 1203 ? with composition of 55.96 mol%FeO,42.32 mol%SiO2 and 1.72 mol%V2O3.Peritectic reaction of phase FeO,V2O3 and SiO2(S4 and S6)took place at 1429?(Pc)and 1477 ?(PD),respectively.