Viscosity of Slag Suspensions with a Polar Liquid Matrix

Abstract

Under the operating temperatures employed in steelmaking, most slags and fluxes often contain solids, such as undissolved CaO and its reaction products; thus, they are more viscous than their fully liquid states. However, few studies have considered the dielectric interactions of solid particles with the liquid matrix in such systems. In the present study, the viscosity of suspensions of dispersed particles consisting of polyethylene beads in a matrix of silicone oil or aqueous glycerol at room temperature was measured. Then, empirical models for estimating the viscosity based on the Einstein–Roscoe equation were proposed. Furthermore, the viscosity of suspensions of CaO and MgO particles dispersed in a matrix of CaO–Al2O3–SiO2–MgO slag at 1773 K was measured, and the feasibility of the proposed viscosity equations was investigated. As expected, the viscosities of the suspensions of polyethylene beads dispersed in silicone oil and glycerol increased with an increasing bead volume fraction. Under comparable measurement conditions, the viscosities of the glycerol suspensions were higher than those of the silicone oil suspensions. The proposed viscosity models based on the Einstein–Roscoe equation and the capillary number reproduced the viscosity of the silicone oil suspensions but underestimated that of the glycerol suspensions. The trend of increasing viscosity of the molten slag suspensions with dispersed CaO and MgO particles was similar to that of the room-temperature suspensions, exhibiting Bingham non-Newtonian behavior. The viscosity model composed with the results from the glycerol aqueous suspensions underestimated the slag viscosity, which can be attributed to the repulsive forces in the high-polarity liquid matrix.