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°+O^2-=O^-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.