Physical Simulation Study on Flow Field Characteristics of Molten Steel in 70t Ladle Bottom Argon Blowing Process

Abstract

In the LF refining process, argon blowing at the bottom of ladle can play an important role in unifying the composition and temperature of molten steel and removing inclusions. However, unreasonable bottom argon blowing process can also cause many problems. Slag entrapment and slag surface exposure may occur, affecting the steel quality. Since the working conditions of different enterprises are very different, corresponding optimization is required for specific parameters. There were some problems in 70t ladle of a steel plant, such as unclear control of bottom argon blowing system in different refining periods, unobvious floating removal effect of inclusions in ladle, high total oxygen content and large fluctuation, etc. In this study, a 1:3 physical model was established according to the similarity principle. Then, on this basis, the experimental schemes with different blowing hole positions and argon flow rates were designed for simulation experiments. By means of mixing time measurement, flow field display and oil film measurement, the optimal argon blowing position was double holes 6, 12 (2/3R), and the included angle between them was 135°. The optimal argon flow rate for wire feeding and soft blowing should be 7.6 L/min (corresponding to the actual production of 180 L/min) and 0.6 L/min (corresponding to the actual production of 15 L/min), respectively. According to this scheme, the industrial experiments showed that the contents of total oxygen and nitrogen in the whole process were reduced, the surface density of inclusions in billet was reduced by 11.81% on average, and calcium sulfide and various inclusions containing aluminum were reduced to varying degrees.