Roles of MgO and Al2O3 on the Viscous and Structural Behavior of Blast Furnace Primary Slag, Part 1: C/S = 1.3 Containing TiO2

Abstract

This research provides fundamental insight into the roles of MgO and Al2O3 on the viscous and structural behaviors of CaO−SiO2−MgO−Al2O3−10 mass% TiO2−5 mass% FeO (CaO/SiO2 = 1.3) system primary blast furnace slag. The slag viscosity is measured by the rotating cylinder method, which is essential to the efficient and stable operation of a blast furnace. The network structure characterization of the quenched vitreous samples was conducted using Fourier Transformation Infrared (FTIR) and Raman spectroscopy. Unusual viscous behaviors (that the slag viscosity and the activation energy decrease or increase with increasing MgO or Al2O3 content) were observed, corresponding to changes in the network structure certified by FTIR and Raman analyses. It seems that the addition of MgO and Al2O3 prefers to modify the Si−O and Ti−O network in the present slag. When the slag composition reaches 10% MgO and 12% Al2O3, unexpected viscous behaviors (that MgO increases viscosity and Al2O3 decreases viscosity) are discovered. The roles of MgO and Al2O3 could be interpreted by changes in the arrangement structure of ions in liquid, corresponding to changes in the primary equilibrium phase region determined in phase diagrams and variation in the difference between the experimental and liquidus temperature, respectively.