Effect of Cr₂O₃ Addition on Viscosity and Structure of Ti-bearing Blast Furnace Slag

Abstract

The viscous flow of CaO–SiO₂–MgO–TiO₂–Al₂O₃–Cr₂O₃ slag (CaO/SiO₂=0.9–1.3, Cr₂O₃=0–4 mass%) were investigated to promote understanding of the effect of Cr₂O₃ addition and basicity (CaO/SiO₂) on the viscous behavior of slag containing TiO₂. The viscosity of slag was found to significantly increase with increasing Cr₂O₃ content at a fixed basicity. The increase in basicity could alleviate the viscosity of the slag to a particular extent. And this study involved the use of theoretical calculations and experiments to prove that Cr₂O₃ in the BF slag could easily react with MgO and Al₂O₃ to generate spinel phase (MgCr₂O₄, MgCrAlO₄) with high melting points, there increasing the viscosity of the slag. The perovskite phase with high melting points is easily crystallized out at high temperatures with increasing Cr₂O₃ content and basicity which makes the viscosity of the slag increase sharply with increasing the CaO/SiO₂ ratio. In addition, this study analyzed the silicate structure of the slag via infrared spectroscopy. The addition of Cr₂O₃ has little effect on the silicate structure of the slag. The increasing basicity enabled the slag to become simple in structure. However, the viscosity of the slag increased rapidly because of the precipitation of the high melting phase perovskite.