Thermodynamic Analysis on Effects of Chemical Composition on Mineral Composition in Medium-titanium Blast Furnace Slag

The equilibrium mineral components in the crystallization process of medium-titanium blast furnace slag are calculated by using FACTSage 7.0 thermodynamics software,and the influence of different chemical composition on mineral precipitation process and mineral composition of medium-titanium blast furnace slag are analyzed. The results show that in the cooling process of medium titanium blast furnace slag,the precipitation phases mainly are melilite,perovskite,spinel and diopside. There is no single perovskite phase existing in the slag when alkalinity is low（R＜0.93）; when the basicity is more than 1.03 and continues to increase,the content of melilite increases,however,the content of spinel is lower.The higher alkalinity is more conducive to form the perovskite. Due to the increase of TiO₂ content,the content of melilite on medium-titanium slag decreases with increasing perovskite content. And with the temperature decreasing,the titanium enriches into titania spinel firstly,and finally moves into perovskite phase. The mineral precipitation process becomes more complicated with the increase of MgO or Al₂O₃ content in the slag,which has an significant influence on the precipitation of titanium.