Effect of Chlorine on the Fluidity and Thermal Stability Properties of High-Titanium Slags

The fluidity and thermal stability properties of melting slag are closely related to the smooth production of the blast furnace. In this study, the viscosity and thermal stability properties of the chlorine-containing high-titanium melting slag (CaO–SiO2–MgO–Al2O3–TiO2–CaCl2) are investigated. The concept of “Extreme Heat Release of Slag” (EHRS) is proposed to quantitatively express the change in the thermal stability of the melting slag. Fourier transform infrared (FTIR) and Raman spectroscopy is used to analyze the structure evolution. The results indicate that chlorine can reduce the viscosity and simplify the structure of melting slag. Due to the evaporation of chlorine at high temperatures, the chlorine content decreases slightly in the viscosity test process. The changing trend of viscous flow activation energy is similar to that of viscosity. Increasing chlorine content could reduce the heat capacity but increase EHRS. The larger the EHRS is, the smaller the viscosity fluctuation. In addition, the [SiO4]-tetrahedral structures and Ti–O–(Ti or Si) bonds would be destroyed. The relative area fractions of Q2 and Q3 units transform to the Q0 and Q1 units, resulting in the decrease in the degree of polymerization of melting slag.