Blast Furnace Ironmaking Process with Super-High TiO 2 in the Slag: Viscosity and Melting Properties of the Slag

To increase the utilization fraction of vanadium titano-magnetite in the blast furnace burden to > 80 pct, a new slag zone with high MgO was found. The effect of the TiO2 content and MgO/CaO mass ratio on the viscosity and liquidus temperature of the high TiO2-bearing blast furnace slag was investigated in the present work. The results indicated that at a fixed CaO/SiO2 ratio of 1.1, the viscosity decreases with increasing TiO2 content at a range of 20 to 34 mass pct. Conversely, increasing the MgO/CaO ratio from 0.32 to 0.65 causes a slight increase in the slag viscosity. The activation energy may show a concomitant variation corresponding to the viscosity of slag. The liquidus temperature first increases and then slightly decreases with TiO2 content. However, the liquidus temperature first decreases and then increases with the MgO/CaO ratio, similar to the variation of the thermodynamic calculation using FactSage software. Various viscosity models were employed to predict the viscosity, and Yan’s model was found to be the most reliable in predicting the viscosity in the present study. In addition, the iso-viscosity distribution diagram was obtained using Yan’s model calculation. It may have potential for application in the blast furnace ironmaking process with super-high (> 80 pct) vanadium titano-magnetite. A suitable slag composition was found to satisfy the smelting process in a blast furnace with super-high TiO2 content at low temperature by using more MgO and less CaO content.