Thermodynamic Properties and Viscosities of CaO-SiO2-MgO-Al2O3 Slags

In this work, the effects of Al2O3, basicity, and MgO/Al2O3 ratio on the heat capacity, enthalpy change, and viscosity of CaO-SiO2-MgO-Al2O3 slags at 1773 K, 1823 K, and 1873 K (1500 °C, 1550 °C, and 1600 °C) were investigated. The heat capacity of the slag increased with increasing Al2O3, basicity, and MgO/Al2O3 ratio in the experimental temperature range. The enthalpy change increased with increasing Al2O3 content and MgO/Al2O3 ratio, and decreasing basicity. Under the fixed heat quantity of the slag, the addition of Al2O3 would result in a decrease of slag temperature and increase of slag viscosity. The effect of decreasing temperature on the viscosity was more significant than increasing Al2O3 content. Increases of slag basicity led to the increased slag temperature and the decreased viscosity which was due to the increased slag temperature. The viscosity change rate with different temperatures was more pronounced than that of different slag compositions. The change of the slag temperature at fixed heat quantity would be opposite due to different expressions of MgO/Al2O3 ratio. In addition, when the heat decrement of the slag was fixed, the slag temperature rose first with the increase of MgO/Al2O3 ratio and then decreased, while the viscosity decreased gradually. The viscosity fluctuation caused by different heat decrements reduced as well with increasing MgO/Al2O3 ratio.