Effect of TiO2 and MnO on viscosity of blast furnace slag and thermodynamic analysis

Abstract

The effect of TiO2 and MnO on the viscous behavior and structure of CaO–SiO2–MgO–Al2O3–TiO2–MnO slags were studied using rotating cylinder method and FTIR spectroscopic analysis. Furthermore, the heat capacity and enthalpy change of the slag were calculated to clarify the influence of TiO2 and MnO on the heat quantity of the slag at elevated temperatures, and then the equilibrium temperatures and corresponding viscosities of the slag under various fixed heat quantities were also analyzed. The higher TiO2 and MnO contents resulted in lower viscosity. The FTIR results revealed that TiO2 and MnO depolymerized the slag by modifying the silicate network structure and breaking the linkage between the silicate and aluminate structure, while have little effect on aluminate structure of the slag. In the temperature range of interest, the enthalpy change of the slag increased with increasing TiO2 content, but remained basically unchanged with MnO additions. The fluctuations of the slag heat quantity had a significant influence on the slag temperature and viscosity. With the increase of TiO2 content, the equilibrium temperature of the slag at fixed heat quantity decreased and the corresponding viscosity increased. However, as the MnO content increased, the equilibrium temperature of the slag at fixed heat quantity was almost constant and the corresponding viscosity decreased.