Effect of MgO on solidification and crystallization properties of ultrahigh-basicity mold flux

Abstract

The effect of MgO on the solidification and crystallization properties of ultrahigh-basicity mold flux was analyzed (i.e., comprehensive basicity R = 1.75). Results showed that with the increase of MgO content (0–6 wt%), the viscosity, melting temperature and break temperature decreases firstly, and then increases. The change of slag viscosity caused by the change of composition is indistinct, but the variation trend of melting temperature and break temperature is obvious. With the increase of MgO content, the crystallization temperature of ultrahigh-basicity slag decreases gradually, while the crystallization rate decreases firstly, and then increases. When the MgO content reaches 3%, the crystallization rate is the minimum. Research found that Ca4Si2F2O7 is the main precipitated phase in the slag, and as the MgO content continues to increase, the new phases of CaF2 and Ca3MgSi2O8 appear gradually.