Investigation on the control of multiphase flow behavior in a continuous casting tundish during ladle change

The transient multiphase flow behavior in a single-strand tundish during ladle change was studied using physical modeling. The water and silicon oil were employed to simulate the liquid steel and slag. The effect of the turbulence inhibitor on the slag entrainment and the steel exposure during ladle change were evaluated and discussed. The effect of the slag carry-over on the water-oil-air flow was also analyzed. For the original tundish, the top oil phase in the impact zone was continuously dragged into the tundish bath and opened during ladle change, forming an emulsification phenomenon. By decreasing the liquid velocities in the upper part of the impact zone, the turbulence inhibitor decreased considerably the amount of entrained slag and the steel exposure during ladle change, thereby eliminating the emulsification phenomenon. Furthermore, the use of the TI-2 effectively lowered the effect of the slag carry-over on the steel cleanliness by controlling the movement of slag droplets. The results from industrial trials indicated that the application of the TI-2 reduced considerably the number of linear inclusions caused by ladle change in hot-rolled strip coils.

New Process with Argon Injected into Ladle around the Tapping Hole for Controlling Slag Carry-over during Continuous Casting Ladle

A new process with argon injected into the ladle around the tapping hole for controlling slag carry-over in a teeming ladle was presented. Physical modeling was used to study the mechanism of controlling slag carry-over, and the feasibility of the new process was also investigated by industrial trials. The results show that vortex forms firstly, and then converts to drain sink. With argon injected into the ladle around the tapping hole, an argon ring was formed, and the rotating angular velocity of the melt close to the tapping hole reduced dramatically, and even vanished when the melt passed the argon ring. Therefore, the new controlling slag carry-over process can eliminate the slag carry-over caused by vortex. The velocity of the melt toward the tapping hole was reduced due to the bubble buoyancy as the melt passed the argon ring. So, the new process can decrease the critical height of slag carry-over caused by drain sink. The application feasibility of the new controlling slag carry-over process is verified by the plant trials. Compared to the traditional teeming ladle process, the new controlling slag carry-over process shows much better efficiency on decreasing the steel residual in the poured ladle.