Influences of Al2O3 and TiO2Content on Viscosity and Structure of CaO–8%MgO–Al2O3–SiO2–TiO2–5%FeO Blast Furnace Primary Slag

Abstract

In view of the fact that Ti–bearing blast furnace primary slag has been explored limitedly and its viscosity–structural property is not fully understood, the phase compositions, viscosity and structure of CaO–8%MgO–Al2O3–SiO2–TiO2–5%FeO slag are investigated by X-ray diffractometer, rotating cylinder method, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy respectively, considering the effect of Al2O3 and TiO2. The critical temperature that is defined as the temperature below which the viscosity of slag increases quickly, could be explained by the relative amount of perovskite to melilite from phase compositions analysis. The slag viscosity first increases with increasing Al2O3 content from 10 to 15 mass%, and then decreases with the further increase of Al2O3 to 18 mass%. Increasing TiO2 content continuously lowers the viscosity. FTIR and Raman spectra results show that increasing Al2O3 or decreasing TiO2 content leads to complex Si–O and Ti–O networks structure, corresponding to the slag viscosity variation. The effect of weak linkages of Si–O–Al is more dominant when Al2O3exceeds 15 mass%, which results in the decrease of viscosity.