Control of Swirl Motion of a Bottom Blown Bath using an Immersed Circular Disk

Abstract

Gas injection systems are extensively employed in the steelmaking industry for mixing molten metal baths and, hence, for removing impurities and nonmetallic inclusions such as C, P, S, and Al₂O₃. A bath subjected to bottom gas injection is sometimes accompanied by a swirl motion of the deep-water wave type when the aspect ratio of the bath, H_L/D, ranges from about 0.3 to about unity. Here, H_L is the bath depth and D is the bath diameter. Although the swirl motion has high mixing ability, it causes vessel oscillations in the vertical and horizontal directions. Accordingly, the conventional refining processes are usually operated in the absence of the swirl motions. In a previous water model study a method of suppressing the swirl motion was proposed. A circular disk was set in contact with the surface of a water bath. The size of the disk capable of suppressing the swirl motion was experimentally clarified. In this study a circular disk was immersed in the bath to investigate the possibility of suppressing the swirl motion more effectively.