Quasi-Chemical Viscosity Model for Fully Liquid Slag in the Al₂O₃-CaO-MgO-SiO₂ System—Part I: Revision of the Model

A model has been developed that enables the viscosities of the fully liquid slag in the multi-component Al₂O₃-CaO-FeO-Fe₂O₃-MgO-Na₂O-SiO₂ system to be predicted within experimental uncertainties over a wide range of compositions and temperatures. The Eyring equation is used to express viscosity as a function of temperature and composition. The model links the activation and pre-exponential energy terms in the viscosity expression to the slag internal structure through the concentrations of various Si_0.5O, \( {\text{Me}}^{n + }_{2/n} {\text{O}} \) , and \( {\text{Me}}^{n + }_{ 1/n} {\text{Si}}_{0. 2 5} {\text{O}} \) viscous flow structural units (SUs). The concentrations of these SUs are derived from a quasi-chemical thermodynamic model of the liquid slag using the thermodynamic computer package FactSage. The model describes a number of slag viscosity features including the charge compensation effect specific for the Al₂O₃-containing systems. The predictive capability of the model is enhanced by the physical aspects of the model parameters—the correlation with other physicochemical properties as well as experimental viscosity data is used to determine model parameters. The present series of two papers outlines (a) recent significant improvements introduced into the model formalism and (b) application of the model to the Al₂O₃-CaO-MgO-SiO₂ system, review of experimental viscosity data, and optimization of the corresponding model parameters for this system.