Dynamic Model of Slag Foaming in Oxygen Steelmaking Converters

Abstract

The foaming and emulsification of steelmaking slags can be analyzed in terms of an emulsion number which is defined as the ratio of the velocity of gas bubbles and that of metal droplets present in slag at any given stage of the blow. An improved procedure is suggested to evaluate the viscosity of gas–slag foam at high gas void fractions. The calculated velocity of gas bubbles in foaming slags is verified using the experimental results reported in literature. A critical comparison is also made with the other approaches available in the literature. It is shown that the emulsion number is directly related to foaming conditions. A dynamic model of slag foaming is developed on the basis of the bubble and droplet velocities, changing slag composition and temperature and the continuous reduction of iron oxide content of slag during the main blow period. Combined effects of lance nozzle design and blowing regime on slag foaming are discussed.