Slag foaming practice in the steelmaking process

Slag engineering (i.e. conditioning and foaming practices) is becoming an essential issue in many companies due to the increasing need felt by the end-users to cut costs and produce high quality steel. Slag foaming has been mainly used in electric arc furnaces (EAF) in order to protect the refractory materials from the high energy intensity (radiation) generated by electrodes, decrease the noise level, improve productivity and the energy efficiency of this equipment. Nevertheless, the correct control and optimization of the foam generation are still limited and some of the main factors (basicity, viscosity, surface tension, presence of suspended solid particles, FeO content and injection rate of carbon particles and oxygen, and others) that affect this complex phenomenon are discussed in this review. Considering the data presented in the literature, there are various conditions and opportunities to be exploited, and a standard procedure for the experimental evaluation of the foam formation is still required. Thermodynamic calculations can be an alternative tool to help understand the phase transformations related to slag foaming at high temperatures.