Slag foaming in electric furnace steelmaking

In order to understand the effect of slag composition on foaming in an EAF, slag foaming was quantitatively studied for CaO-SiO₂-FeO slags at temperatures ranging from 1,250 to 1,400°C. It was found that slag foaming could be characterized by a foaming index (Σ) which is equal to the retention or traveling time of the gas in the slag. The effects of P₂O₅, S, MgO and CaF₂ on foaming was studied. As expected, slag foaming increased with increasing viscosity and decreasing surface tension. Suspended second phase solid particles such as CaO, 2CaO-SiO₂ and MgO stabilized the foam and were more important than viscosity and surface tension. Anticipated foaming in the EAF was estimated using experimentally obtained parameter Σ for various operating conditions and slag compositions.