Viscosity Measurement of CaO–SiO₂–Fe_xO Foaming Slag at 1673 K

Abstract

Foaming slag generated in the steelmaking process, especially in hot-metal pretreatment and electric arc furnaces, is a gas-liquid coexistent fluid with CO gas generated by the interfacial reaction between slag containing iron oxide and hot metal or carbonaceous materials. In addition, it is essential to understand the flow behavior of foaming slag during slag-tapping and the sedimentation behavior of iron particles, which affects iron yield, and to expand our knowledge of the viscosity of gas-liquid coexisting fluids for CFD modeling of these phenomena. In the present study, the apparent viscosity of a foaming slag was systematically investigated, which was generated by reacting CaO–SiO₂–Fe_xO slag with Fe–C alloy and varying the composition, gas phase ratio, and shear rate of the slag. By adding Fe–C alloy powder to the slag, bubbles were continuously generated in the molten slag, and foaming slag suitable for viscosity measurement could be prepared. It was found that the higher the amount of Fe–C alloy powder, the larger the gas phase ratio of the foaming slag due to an increase in the number of bubbles generated. The relative viscosity of the foaming slag was found to increase with the gas phase ratio. The higher the rotation speed, the smaller the relative viscosity of the foaming slag indicating shear-thinning characteristics. The relationship between shear rate and shear stress calculated from the viscosity of the foaming slag did not show general non-Newtonian fluid behavior.