Effective desiliconization method with swirling flow of hot metal at blast furnace casthouse

Hot metal desiliconization is carried out by adding iron oxide at a tilting runner in a blast furnace casthouse to improve BOF operation. Aiming at effective silicon removal by enhancing mixing of desiliconizing agent and hot metal, desiliconization experiments at an actual blast furnace casthouse was performed with the tilting runner that was specially designed to generate swirling flow of hot metal. 1. Amount of silicon removed from the hot metal through the entire desiliconization operation was larger under the swirling flow condition of hot metal compared with conventional non-swirling one. 2. Hot metal samples taken at the exit of the tilting runner showed that change in silicon content of hot metal in the tilting runner was larger with swirling condition. 3. Hot metal samples were also taken from the torpedo car, and desiliconization behavior in a transient basin part of the torpedo car was evaluated. Calculated silicon content in the basin part was lower with swirling condition. 4. A reaction analysis was made assuming that present system is a semi-batch reactor. Reaction rate constant of desiliconization through the swirling part of the tilting runner and the basin part of the torpedo car was 2.2 times higher with swirling condition. This result qualitatively agrees with the results of previous 5 ton hot metal experiments and reflects enhanced mixing of desiliconizing agent and hot metal by swirling flow in an industrial-scale operation.