Effect of SiO₂ and Al₂O₃ on the Thermophysical Properties and the Foaming Index of Electric Arc Furnace Slag from the Production of Construction Steel

Abstract

Viscosity, density, and surface tension of an industrial electric arc furnace (EAF) slag from production of construction steel with varying SiO2 and Al2O3 contents are investigated using a rotating viscometer and the maximum bubble pressure method. In addition, influence of thermophysical properties on foaming index is discussed. To predict the behavior of the solid phase in the slag at different temperatures, thermodynamic calculations are performed using FactSage 8.1 software. The experiments demonstratethat SiO2 and Al2O3 act as network formers in the studied slag systems, resulting in increased viscosity values in the liquid‐dominant region and decreased density of the slag. The presence of alumina and silica altered the behavior of the slag in the liquid‐dominant region, shifting the breaking point of the slags. Furthermore, the addition of silica decreases the surface tension of the slag, confirming its role as a surfactant. However, the addition of Al2O3 increases the surface tension due to the high surface tension of pure alumina. Consequently, the foaming index of the slag can increase by ≈40%, primarily due to the polymerization of the slag.