| 摘要 |
PURPOSE:To minimize the total production amt. of slag and to improve overall balance in divided type refining for molten iron by subjecting the slag produced in the converter refining in post stages to component control, reusing the same in prerefining and performing prescribed dephosphorization and desulfurization. CONSTITUTION:After molten iron 1 is subjected to a desiliconizing treatment, it is transferred to dephosphorizing and desulfurizing treatment 9 of a fore stage. In this stage, the combined slag 13 made by adding iron oxide to the steel making slag 11 obtd. in converter refining 12 of a post stage and controlling the components to 0.5-3.0 T.Ca%/T.Fe% is reused. Further, if necessary, lime 5 and steel making slag 6 are used in combination. In this fore stage, the molten iron components are prerefined to a 0.10-0.01% Si, 0.04-0.01% P and 0.005- 0.020 S range. Thence, a dephosphorizing agent or a dephosphorizing agent plus a desiliconizing agent are added to the molten iron by converter refining 12 in the post stage whereby it is removed of C, P, S and the volume of the slag 11 is controlled to 15-30kg/t-steel. |
