Influence of basicity and MgO/Al2O3ratio on the viscosity of blast furnace slags containing chloride

The viscosities of CaO–SiO2–Al2O3–MgO–CaCl2 slags under conditions of CaCl2 = 0–10%, C/S = 0.90–1.30 and MgO/Al2O3 = 0.40–0.67 have been experimentally measured to elucidate the effect of chlorine, basicity and MgO/Al2O3 ratio on the viscous behavior of the blast furnace slag. Slag viscosity gradually increases with decreasing temperature, then sharply increases at the critical temperature, and it decreases with increasing chlorine content at temperatures over 1673 K. The critical temperature decreases from 1660 K to 1590 K with increasing chlorine content from 0% to 10% CaCl2; this may be attributed to the variation of chemical potential of primary solid phase caused by adding chloride. Slag viscosity diminishes with increase in basicity, while MgO/Al2O3 ratio does not significantly affect the viscosity at temperatures higher than 1645 K. The tendency of the effect of basicity on the slag viscosity corresponds closely with that of corresponding CaO–SiO2–Al2O3–MgO slags obtained from literature, while the trend of MgO/Al2O3 ratio influence is distinct from that. The activation energy of chlorine-containing slags under the range of 182.8 kJ/mol to 213.8 kJ/mol generally decreases with increasing chlorine content, basicity and MgO/Al2O3 ratio in slags. Due to the dual effect of the variation of polymerization and the primary phase by adding chloride, the MgO/Al2O3 ratio almost has no influence on the viscosity of the chlorine-containing slags at higher temperatures.