Evaluation of Existing Viscosity Data and Models and Developments of New Viscosity Model for Fully Liquid Slag in the SiO₂-Al₂O₃-CaO-MgO System

Metallurgical properties of slag are determined to a great extent by its viscosity. High-temperature viscosity measurements are time-consuming and expensive. It is necessary to develop an accurate viscosity model for blast furnace slag in the SiO₂-Al₂O₃-CaO-MgO system using reliable viscosity data. This paper describes a systemic evaluation procedure to determine the viscosity data to be used for model development. 1780 viscosity data from 10 to 65 wt pct SiO₂, 3.5 to 40 wt pct Al₂O₃, 2 to 60 wt pct CaO, and 2 to 38 wt pct MgO in the SiO₂-Al₂O₃-CaO-MgO system have been accepted for model evaluation after critical reviews. The existing 14 viscosity models in SiO₂-Al₂O₃-CaO-MgO system is also reviewed and evaluated. Based on the structure of alumina-silicate slag and evaluated viscosity data, a new viscosity model has been proposed for the system SiO₂-Al₂O₃-CaO-MgO. A new term “probability,” based on the basic oxide and electronegativity, is introduced to calculate the integral activation energy of slag. The model has been evaluated and compared with existing viscosity models in three different composition ranges in SiO₂-Al₂O₃-CaO-MgO system for different applications. The new model reports an outstanding agreement between predictions and experimental data. The industrial implications of the new model have also been discussed in ironmaking and steelmaking processes.