Influence of SiO₂-Adding on the Thermophysical Properties and Crystallization Behavior of Ladle Slags

The thermophysical properties (viscosity, density, and surface tension) of the secondary metallurgical slags with various CaO/Al2O3 ratios (0.56-1.99) and SiO2 (1-20 wt%) contents are investigated. The results show that the addition of SiO2 increases the viscosity of the cleanness and desulfurization slags (CaO/Al2O3 ratios & GE;1). In slag with a higher Al2O3 content (CaO/Al2O3 < 1) and constant CaO content, the viscosity shows a first decreased and then increased phenomenon with the addition of SiO2. Moreover, the breakpoints of the viscosity are strongly lowered with the addition of SiO2. Both the density and surface tension of slags show a decreasing tendency with the SiO2 addition. Moreover, the single hot thermocouple technique method is applied to investigate the crystallization process of the slags, and the result shows that with high SiO2 contents, glassy layers are formed on the molten slags.