Slag-metal equilibrium in the ferromanganese blast furnace

Abstract The work developed at SFPO is directly related to the production of ferromanganese blast furnaces. Ferromanganese blast furnace slags are complex systems whose major components are SiO 2 - Al 2 O 3 - CaO - MgO - MnO. For this five component system, available information is very limited. To represent its properties and get complete phase diagrams, SFPO makes use of a statistical thermodynamic model developed at IRSID by GAYE and Co. Another very interesting point to examine, is whether or not the metal and slags extracted from a furnace are in equilibrium or close to equilibrium. A model has then been developed to define slag metal equilibrium. Thermodynamic properties of the slag components are evaluated with the IRSID model. Thermodynamic properties of the metal phase components, Mn, Fe, Si, and C have been determined using two thermodynamic models: - The central atom model proposed by C.H.F. LUPIS and Co; - The model proposed more recently by W. DRESLER. While the first model necessitates critical simplifying assumptions, the second one can be used without inducing any particular questions. The results obtained in both cases, if not equivalent, show the same trends about the influence of various operating parameters and can be used to explain experimental observations. They lead to the conclusion that equilibrium is reached for Mn but not for Si.