Thermodynamic model for ternary silicate systems

Abstract

A thermodynamic model has been developed for the representation of ternary liquid silicate systems SiO2-AO-BO, where A and B are metals such as Ca, Fe, Mn, etc. It is based on a structural model which assumes that each metallic oxide produces the depolymerization reaction O°+O2- = 2O- with a characteristic free energy change. The model can calculate the properties of ternary systems solely from data of the binary sub-systems. No ternary terms are required. The model is used to calculate the activities of the components in complex silicates such as SiO2-FeO-CaO where the behavior of Fe2+ is very different from that of Ca2+ in the silicate structure. This model has been also used to calculate the activities in the systems SiO2-MgO-FeO, SiO2-MgO-CaO, SiO2-MgO-MnO, SiO2-Na-O-MgO and SiO2-Na2O-CaO. Good agreement is obtained between calculated and experimental results.