| 摘要 |
PURPOSE:To inexpensively obtain a molten iron pretreating material for dephosphorization, desiliconization, etc. by desulfurizing the blast furnace slag contg. CaO, SiO2, Al2O3, P2O5, at specific ratios thereby keeping its S amount at a value which does not exceed the specific ratio of the S amount of the molten iron to be treated. CONSTITUTION:The blast furnace slag contg. 25-50% CaO, 20-45% SiO2, 10- 20% Al2O3 and <=1% P2O5 is desulfurized. For example, it is desulfurized under oxygen vapor pressure kept at around 10<-4>-10<-5>, whereby its S content is reduced from about 0.8-1.7% to about 0.01-0.9%. This S amount should not exceed 10 times the S amount of the molten iron to be treated. Molten iron is desiliconized by using the thus treated blast furnace slag at about 10-20kg per ton of the molten metal. Thence, the molten metal is dephosphorized by using about 4.2kg the blast furnace slag based on, for example, about 100kg the molten iron. The treated molten iron is desulfurized by a conventional method, and this completes the pretreatment. |
