2014 Volume 100 Issue 3 Pages 331-339
Hot metal desiliconization is carried out by the addition of iron oxide at the tilting runner in the blast furnace casthouse for better hot metal dephosphorization and subsequent BOF operation. The authors proposed the application of a swirling flow to the hot metal at the tilting runner, aiming at effective silicon removal by mixing of the desiliconizing agent and hot metal, since hot metal desiliconization is determined by mass transfer of FexO in the slag in the low FexO concentration range. 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 proper flow condition was characterized by a swirl number. 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. The desiliconization experiment with addition of iron ore showed that silicon removal was enhanced by application of the swirling flow of hot metal, especially with slag of low FexO content. An analysis was performed for the desiliconization reaction after the addition of iron ore and showed that the mass transfer of Si was increased by almost two times when the swirling flow was applied, which reflects good mixing of the desiliconizing agent and hot metal.