Critical Evaluation and Thermodynamic Optimization of the Na2O-FeO-Fe2O3-SiO2 System

Abstract

A complete literature review, critical evaluation, and thermodynamic optimization of phase diagrams and thermodynamic properties of the Na2O-FeO-Fe2O3-SiO2 system were performed at 1 atm total pressure. A set of optimized model parameters obtained for all phases present in this system reproduces available and reliable thermodynamic properties and phase equilibria within experimental error limits from 298 K (25 °C) to above liquidus temperatures for all compositions and oxygen partial pressures from metallic Fe saturation to 1 atm. The liquid phase was modeled based on the Modified Quasichemical Model considering the possible formation of NaFeO2 associate in the liquid state. The NaFeO2 metaoxide solid solutions containing the excess SiO2 were described within the framework of Compound Energy Formalism. Based on the thermodynamic models and model parameters, unexplored thermodynamic properties and phase diagrams of the Na2O-FeO-Fe2O3-SiO2 system were predicted.