Abstract: The foaming behavior of slag significantly influences the submerged arc operation and energy efficiency of electric arc furnaces. The foaming characteristics of the CaO-SiO₂-FeO-Al₂O₃-MgO slag system under homogeneous melting conditions were systematically investigated. Based on thermodynamic calculations, the experimental composition ranges were determined as follows: w(FeO)=21%-30%,w(MgO)=3%-7%, and basicity 1.0-2.2. Through single-factor experiments and physical property analysis, the following conclusions were drawn: as the mass fraction of FeO increased from 21% to 25%, the foaming index rose significantly due to decreased viscosity. And a further increase to 30% slowed the growth trend, attributed to increased density and surface tension. Increasing basicity caused a non-monotonic change in the foaming index, with a minimum observed at 1.25 and a maximum at 1.7, resulting from the combined effects of decreased viscosity and increased surface tension and density. The mass fraction of MgO showed a negligible effect on the foaming index, owing to its limited ability to modify viscosity and surface tension. Additionally, high-temperature experiments involving solid-liquid mixtures (with similar liquid phase composition) revealed that the solid particle content affected foaming behavior in a parabolic trend.

Key words: electric arc furnace, CaO-SiO₂-FeO-Al₂O₃-MgO slag, foaming behavior, homogeneous melting, solid particles