Interfacial area in top blown oxygen steelmaking

The overall rate of chemical reactions is critical in achieving an efficient steelmaking process. Generally, multiphase reactions occur during oxygen steelmaking. As pointed out by Levenspiel, for multi-phase reaction, the requirements are (i) the reactants must contact or meet each other, and (ii) both mass transfer and chemical reaction rate determine the overall rate of reaction. The phase contact area of reactants or reacting interface is called the interfacial area. Due to the importance of the contact area in the steelmaking process, this has been the subject of several investigations. Considering the major reactions in oxygen steelmaking, we will concentrate on the dissolution of oxygen into the metal from O2 gas or FeO, decarburization through dissolved oxygen, and oxidation of Fe, Si, Mn, and P. These seven reactions are the most important to the overall steelmaking kinetics. The aim of the present paper is to critically review what is known about interfacial area from plant data and physical modeling studies, addressing the connection between theory and practice, as well as identifying unresolved issues. The study will start with infonnation on the interfacial area in slag-metal-gas emulsions followed by an analysis of the importance ofthis interfacial area in the overall reaction rate.