• slag emulsification;
  • steel flow velocity;
  • CAS-OB;
  • droplet distribution;
  • interfacial area;
  • CFD model

Computational fluid dynamics (CFD) simulations have been carried out to study interfacial velocity and its effect on slag emulsification at the steel–slag interface. The multiphase volume of fluid (VOF) method was used to track the interface between slag and steel and a user defined function (UDF) was applied to calculate the interfacial velocity and to track separate droplets. Slag entrainment based on composition adjustment by sealed argon bubbling-oxygen blowing (CAS-OB) process was simulated using different inlet velocities of steel. The main objective of the present work was to study how steel flow velocity effects droplet distributions. Continuous Rosin–Rammler–Sperling (RRS) distribution function was fitted to computational results in order to provide a quantitative description of the droplet size distribution. The generation rates of the interfacial area between slag and steel were estimated based on obtained RRS-distributions. The Sauter diameter was found to vary between 4 and 6 mm and the generation rate of the interfacial area between 0.2 and 0.6 m2 s−1. The results agree well with previous studies presented in the literature.