Thermodynamic Analysis of Phase Diagrams Based on the Concept of the Bjerrum–guggenheim Osmotic Coefficient

Abstract

The aim of this study is to theoretically confirm or refute the high degree of lead and zinc volatilisation from the Shalkiya deposit (polymetallic refractory ores) by means of analysing the phase diagrams and the behaviour of the osmotic coefficient according to the Bjerrum-Guggenheim equation along the liquidus line for binary systems based on calcium. From the plots depicting the dependence of the Bjerrum-Guggenheim osmotic coefficient on activity, one can infer the structure of the melt (positive <1 or negative >1). That is, if the values of the Bjerrum-Guggenheim osmotic coefficient in a binary system indicate a positive character of interaction between the components, it implies interaction between like atoms in the melt, whereas negative values indicate interaction between unlike atoms, suggesting the formation of complex, high-temperature compounds, which would be undesirable in our case. The question related to the formation of complex high-temperature chemical compounds with impurity elements such as zinc and lead in the Fe-Si-Al-Ca-Mg-Zn-Pb system remains unresolved.