Influence of Physicochemical Properties and Chemical Composition of Slags on the Slag Foaming Index

The use of foaming slag in an electric arc furnace provides a reduction in the consumption of electric energy, electrodes, and refractories in the furnace. The objective of this study is to determine the foaming index of different slags of the CaO-FeO-SiO2-MgO system, and to relate this index with the composition and viscosity of the slag and the volume of CO generated. The Factsage 8.0 software was used to simulate the determination of the viscosity of the liquid slag and the phases present in the slag at the temperature of 1650 °C. The height reached and the time of the foaming were measured by experiments carried out in an induction furnace with a MgO crucible. The generated volume of CO and the carbon consumption was calculated by mass balance through the variation of FeO between the initial and final percentages of FeO in the slag. The experimental results indicate that the best foaming conditions were achieved with slags containing 8% FeO and 22% MgO, 12% precipitated phases, ternary basicity between 1.2 and 1.4, and viscosity of 0.499 poise. The results showed that the most important parameter for obtaining a higher slag foaming index is the viscosity value.