Thermodynamic evaluation of viscosity behavior for CaO-SiO-AlO-MgO slag systems examined at the temperatures range from 1500 to 1700 °C.

This work showed an application of computational tools to understand systematically the behavior of viscosity on CSAM systems relevant to industrial uses. Consequently in this study, the viscosity experimental data obtained from the literature were compared with the thermodynamic calculated results via the software FactSage v.7.3 for melts in CaO-SiO-AlO-MgO slag system with the range of compositions slags cover 0-100 wt% CaO, 0-100 wt% SiO, 0-100 wt% AlO and 0-15 wt% MgO at temperature ranges of 1500-1700 °C. Using open-source software in Python, the results of viscosity, liquid, and solid fraction of the slag, as a function of composition and temperature, are represented by multiple color maps and by iso-viscosity contours. The results of the viscosity values indicated that the effect of all the oxides in the CSAM slag system follows the well-known behavior trend observed in the literature. Viscosities of the slag were found to increase with increasing SiO contents and decrease with increasing basicities (high CaO). The increase in AlO content increases the viscosity values. An increase of 0-15% MgO depolymerized the slag melt and decreases the viscosity. However, above 5% MgO content occur a decrease in the liquid zone (single phase) and a liquid fraction (two-phase region) of the slag. For a constant MgO concentration, the increase in temperature generates an expansion of low-viscosity zones associated with an increase in the liquid phase of the slag. From the comparison between the calculated and experimental viscosities data keeps up within 30% average relative deviation (Δ), the predictions are considered acceptable for viscosity in the CSAM slag system at high temperatures.