Modeling inclusion approach to the steel/slag interface

The removal of non-metallic inclusions from a steel melt to the upper slag phase involves the movement of buoyant particles from a lower, less viscous phase (steel) to an upper, more viscous phase (slag). The film that forms ahead of the impinging inclusion must drain and rupture for particle capture by the slag. This deformation and drainage process has been modeled for a Newtonian fluid using no-slip boundary conditions at all surfaces and a pressure balance across the liquid–liquid interface for the given interfacial shape. Computer implementation of this model shows that particles of 5 μm in radius can be delayed up to two seconds by the resultant drag, with delays of a tenth of a second for 100 μm particles. Decreasing the interfacial tension between the lower and upper phases [corresponding to the presence of sulfur (of activity 0.7) at the steel–slag interface] can increase this time by 1 or 2%.