Viscosity of Highly Basic Slags

Abstract

The viscous behavior of CaO–SiO2–FeO–MgO slags saturated with dicalcium silicate (2CaO·SiO2) with 8 mass% MgO at 1873 K, and CaO–SiO2–FeO–Al2O3–MgO slags are measured under the conditions of highly basic slag compositions with regard to the fluidity of BOF slag and slag coating technology. The experiment shows that slag viscosities increase with decreasing temperature for almost all the slags that have been investigated over a range of temperature range, and the slag viscosity has exhibited different behavior in the temperature range lower and higher than 1773 K. The viscosity of the present slag systems has decreased with increasing FeO content. The viscosities depended on Al2O3 and FeO contents more strongly than on MgO content. The slag basicity has a more significant effect on increasing slag viscosity. A thermodynamic approach for the constants of the Einstein–Roscoe equation has resulted in a reasonable relationship between the relative viscosity and the volume fractions of solid phases estimated from the slag compositions. Thus, the present study confirms that the viscosities of highly basic slags can be estimated in terms of the slag compositions by predicting the fraction of solid phases in the slags for the stable BOF operation and the reliable coating of vessel lining.