Effect of ladle geometry on top slag and flow field during bottom argon blowing in ladle

Bottom argon blowing in a ladle promotes the circulation of molten steel through bubble plume flow. It can homogenize temperature and composition and promote the flotation of inclusions. However, it also causes the redistribution of the top slag and the formation of a slag eye. An excessively large slag eye may lead to the reoxidation of the molten steel and slag entrainment. Therefore, the slag phase distribution and slag eye area are important indicators for evaluating the rationality of argon blowing conditions and ladle structure. Previous studies mainly focused on gas flow rate, nozzle position, and slag layer thickness, while the effects of ladle geometric factors, such as the ladle aspect ratio and the ladle side wall angle, have rarely been considered. A three-dimensional numerical model of ladle bottom argon blowing was established by coupling the VOF model, the standard k-ε turbulence model, and the DPM bubble model. Water model experiments were conducted to validate the slag eye morphology. Under the condition of a constant molten steel volume, the effects of the ladle aspect ratio (h/d_l)and the ladle side wall angle on the flow field characteristics, slag phase distribution, and slag eye area in the ladle were systematically investigated. The results show that, as the aspect ratio of the molten steel increases from 0.9 to 1.2, the average speed in the ladle increases from 0.049 6 m/s to 0.070 1 m/s, and the average turbulent kinetic energy increases from 0.006 31 m²/s² to 0.010 20 m²/s². At the same time, the flow speed near the slag-metal interface gradually increases, and the slag eye area increases by 18.1% overall. When the aspect ratio is 1.1, the slag surface speed is relatively low, and the slag eye area is only 0.5% larger than that at an aspect ratio of 1.0, indicating a more balanced overall performance. As the ladle side wall angle increases from 90° to 100°, the average speed in the ladle generally decreases, while the average turbulent kinetic energy generally increases, and the slag eye area increases to 1.24 times that under the 90° condition. Among these cases, when the side wall angle is 94°, the average molten steel speed remains relatively high, the slag surface speed is low, and the slag eye area is only 3.5% larger than that under the 90° condition, showing relatively favorable overall characteristics. These results can provide a theoretical reference for the optimization of bottom argon blowing practice and ladle structure design under different ladle structural conditions.