Splashing behavior of metal droplets in basic oxygen furnace steelmaking process

Splashing behavior of metal droplets is one of the main phenomena in basic oxygen furnace steelmaking process. The size distribution of metal droplets and the residence time of the metal droplets in the slag have important effects on the kinetics of the metal–slag reactions. The particle size distribution law, characteristic diameter, splashing velocity and splashing angle of metal droplets were investigated, and an improved prediction model of trajectory and residence time for metal droplets was established based on the combination of expanded droplets theory, decarburization mechanism model and ballistic motion principle. Meanwhile, the trajectory and residence time of metal droplets under different working conditions were analyzed based on this model. The results illustrate that the metal droplets with larger particle size are produced at low lance distance, while the metal droplets with smaller particle size are produced at high lance distance. There is a significant linear relationship between the three diameters (maximum droplet diameter, distribution characteristic diameter, reaction characteristic diameter) and the blowing number. The residence time of decarbonized metal droplets in slag is about 0.2–73 s. Meanwhile, the initial carbon content and diameter of the metal droplets and the FeO content of slag are the main factors affecting the motion state of the metal droplets in the slag, while the splashing velocity, splashing angle and the height of the foam slag have little influence. This model can be used to predict the trajectory and residence time of decarburized metal droplets in a variety of complex multiphase slag conditions, overcoming the limitation that the known model is only applicable to a few specific conditions.