Non-metallic inclusion (NMI) deposition in a slide-gate submerged entry nozzle (SEN)

Clogging of the submerged entry nozzle (SEN) is a common and persistent issue in the continuous casting process for steel alloys. The dominant clogging mechanism has been attributed to the deposition and accumulation of non-metallic inclusions (NMI) in the steel melt. Prior studies of NMI deposition assume that every collision between an inclusion and the nozzle wall results in adhesion, which is unrealistic. In this study, a macroscopic transport model for fluid and NMI motion is combined with a microscale model for NMI adhesion and applied to a slide-gate nozzle. Eight NMI sticking probabilities (S) and three slide-gate linear opening positions are explored. Simulation results indicated that the more closed the slide-gate, the greater the total deposition of NMI. When the slide-gate was partially open, the particle area number density was highest above, within and just below the slide-gate. But when the slide-gate was fully opened the deposition was concentrated in the upper tundish nozzle. Deposition behaviour fell into two regimes based on S. When S ≤ 0.05, the particle deposition was low and increased rapidly with sticking probability. When S ≥ 0.05, the particle deposition was high but changed very little with sticking probability. Changes to sticking probability did not significantly affect the deposition locations or relative distribution of particles within the nozzle.