Slag Interface Instability

During the slag refining process for production of high-silicon alloys, a highly-convoluted interface between the slag and alloy phases is desired in order to maximize the transfer of impurities into the slag phase. The problem is considered as a purely mechanical system, working on the assumption that the breakup of the slag{alloy interface is due to a mechanical instability. Such instabilities have been seen in other systems, most notably in the oscillation of two-phase systems with high viscosity ratios. Informal experiments on such a system were carried out during the Study Group. In the first instance, the breakup of the fluid interface can be considered through a linear stability analysis of the type performed by Hooper & Boyd (1983), though their results did not extend to the high viscosity ratio case which is of relevance to this problem. Numerical and asymptotic analysis was therefore carried out to illuminate this limit, and the results were compared to the informal experiment and the slag{alloy system. Recommendations for further work are also given.