Effective Desiliconization Method with Strong Mixing of Agent in Swirling Flow of Hot Metal

Abstract

Control of the silicon content in hot metal is one important strategy for better hot metal dephosphorization and subsequent BOF operation. For this purpose, hot metal desiliconization is carried out by the addition of iron oxide at the tilting runner in the blast furnace casthouse. Since hot metal desiliconization is determined by mass transfer of FexO in the slag as well as mass transfer of silicon in the metal in the low FexO concentration range, attention should be focused on mixing of the desiliconizing agent and hot metal at the tilting runner. The authors therefore applied a swirling flow to the hot metal, aiming at effective silicon removal. A basic investigation of the swirling flow was carried out in a water model experiment. The swirling flow was generated in a funnel-shaped container with various flow rates, outlet diameters, etc. The experiment showed that mass transfer of a tracer in model slag was enhanced under the swirling flow condition. A 5-ton hot metal experiment was carried out with a specially designed vessel to generate a swirling flow of hot metal. A desiliconization experiment with addition of iron ore showed that silicon removal was enhanced by the swirling flow of hot metal, especially with slag of low FexO content.