Phase Diagrams and Thermodynamic Properties of the FeO–SiO2–V2O3 Systems

The phase diagrams of FeO–SiO2–V2O3 systems as the main components of vanadium slag are assessed on the basis of the existing literature models and experimental studies to modify partial parameters by FactSage thermodynamic software. The results show that the eutectic and peritectic reactions for the FeO–V2O3 system happen at about 1626 and 1985 K, respectively. The eutectic and monotectic reactions for the V2O3–SiO2 system happen at about 1935 and 1963 K, respectively. According to the actual blowing temperature of the vanadium-extraction converter, the isothermal section at 1573, 1623, and 1672 K of the FeO–SiO2–V2O3 ternary system is calculated, and the isothermal section at 1573 and 1623 K has seven phase regions, which are the liquid + spinel + tridymite, liquid + wustite + spinel, spinel + tridymite + karelianite, liquid + tridymite, liquid + spinel, liquid + wustite, and liquid, respectively. But liquid + wustite and liquid + wustite + spinel regions disappear at 1673 K. Meanwhile, two ternary eutectic points are determined to be at 1470 and 1476 K, respectively. Peritectic reaction of phase wustite, karelianite, and silica (tridymite and cristobalite) occurs at 1702 and 1750 K, respectively.