Calculation for density of molten slags using optical basicity

Abstract

A model for density calculation of multicomponent slags was developed in the present work. This model is an extension of a previous model proposed by the present author. Density values of molten slags were calculated from molar volume values, which were calculated from molar volume of pure component and mixing molar volume. Mixing molar volume is correlated to differences between reciprocals of optical basicities of network forming oxides and those of network modifying oxides. Charge compensation for AIO₄ ⁵⁻ was taken into consideration explicitly. An increase in molar volume due to Al coordination shift from sixfold to fourfold was modelled by defining molar volume of a hypothetical state of alumina in fourfold coordination in the present work. Density values of M₂O–SiO₂ (M = Na, K), CaO–Na₂O–SiO₂, MgO–Na₂O–SiO₂, Al₂O₃–CaO–SiO₂, Al₂O₃–Na₂O–SiO₂ and Al₂O₃–CaO–MgO–SiO₂ system were calculated by employing the present model. Comparisons between calculated and experimental values in literature were also made. The calculated values are in good agreement with experimental data with a mean deviation within 2%. The present work also showed that the addition of network modifying oxide with high optical basicity values would lead to a remarkable negative deviation of molar volume from ideal mixing, which could be interpreted by considering larger Si–O shortening caused by metal cations with lower electronegativity. In addition, the positive deviation for metal oxide and alumina join was also well explained in terms of molar volume increase due to Al coordination change in the present work.