Densities and viscosities of slags modeling and experimental investigations

Sammanfattning: The present dissertation describes part of the efforts directed towards the development of computational tools to support process modeling. This work is also a further development of the Thermoslag? software developed in the Division of Materials Process Science, KTH.The essential parts of the thesis area) development of a semi-empirical model for the estimation of the molar volumes/densities of multicomponent slags with a view to incorporate the same in the model for viscosities andb) further development of the viscosity model for application towards fluorid- containing slags, as for example, mould flux slags.The model for the estimation of molar volume is based on a correlation between the relative integral molar volume of a slag system and the relative integral molar enthalpies of mixing of the same system. The integral molar enthalpies of the relevant systems could be evaluated from the Gibbs energy data available in the Thermoslag? software. The binary parameters were evaluated from experimental measurements of the molar volumes. Satisfactory correlations were obtained in the case of the binary silicate and aluminate systems. The model was extended to ternary and multi component systems by computing the molar volumes using the binary parameters. The model predictions showed agreements with the molar volume data available in literature. The model was used to estimate the molar volumes of industrial slags as well as to trace the trends in molar volume due to compositional variations. The advantage of the present approach is that it would enable prediction of molar volumes of slags that are compatible with the thermodynamic data available.With a view to extend the existing model for viscosities to F--containing slags, the viscosities of mould flux slags for continues casting in steel production have been investigated in the present work. The measurements were carried out utilizing the rotating cylinder method. Seven mould fluxes used in the Swedish steel industry and the impact of Al2O3 pick up by mould flux slags on viscosities were included in the study. The results showed that even relatively small additions of Al2O3 are related with a significant increase in viscosity