Effects of Structure on the Thermodynamic and Transport Properties of Na2O-CaO-SiO2-FeO-Fe2O3 Melts

Iron oxide slags play a critical role in both ferrous and non-ferrous metallurgical processes. The relative abundance of FeO and Fe2O3 will determine the slag oxidation potential and influence transport properties, which makes an accurate prediction of their proportions crucial to process operations. The nature of the iron oxide structures in the liquid slag has been a long standing issue, which is in part related to the variety of structural species that can be formulated to accommodate the observed property changes. In this study, spectroscopic data is used to clarify the dual structural behaviour of both ferric and ferrous iron oxide. The identified oxide structures are shown to have characteristic effects on the thermodynamic properties and viscosity of Na2O-CaO-SiO2-FeO-Fe2O3 melts. These insights into the structural behaviour of iron oxide and its composition dependence can also improve the mathematical modelling of these properties.