Effect of White Mud Addition on Desulfurization Rate of Molten Steel

Fluorspar (CaF2) is commonly used to control the fluidity of slag in ladle-refining of steel. However, because it is desirable to reduce CaF2 consumption due to its environmental impacts, the industrial waste material such as white mud (WM) was investigated as a potential substitute for fluorspar. Steel samples were melted in a high-frequency induction furnace, followed by additions of ladle slag and the fluxing agent WM at a high temperature. The desulfurization experiments were carried out by reducing CaF2 content in the ladle slag and increasing the WM addition. Experimental results demonstrated that ladle slag with added WM showed an overall mass transfer coefficient of sulfur equivalent to or higher than that of conventional CaF2-containing ladle slag. Furthermore, the melting rate of mixed slag increased with the amount of WM added, which positively affected the initial desulfurization rate. Additionally, the capacity of the slag to accommodate sulfides was equivalent to that of CaF2-containing slag. Consequently, the use of WM yielded slag performance comparable to that of traditional ladle slag with 10 pct CaF2, indicating that WM shows promise as a partial replacement for fluorspar.