| 摘要 |
<p>PURPOSE:To reduce the consumption unit of quicklime, to shorten refining time and to improve a scrap ratio by charging molten iron into a converter, then subjecting the molten iron to dephosphorizing by executing addition of a flux and oxygen blowing, then subjecting the molten iron to decarburization refining after discharging slag at the time of smelting a lowphosphorus steel by using the same converter. CONSTITUTION:The molten iron is subjected to dephosphorization refining by executing the flux addition and oxygen blowing as a first stage after charging of the molten iron at the time of producing the molten steel having a [C' concn. of >=0.1% and [P] concn. of <=0.015% by refining the molten iron. The slag formed in the first stage is then discharged by tilting the furnace as a second stage. In succession, the furnace is erected and the decarburization refining is executed as a third stage. In such a case, an MnO source is added to the slag in such a manner that the MnO concn. in the slag at the time of the decarburization defining of the third stage attains >=5 to <=15%. The slag is discharged to at least >=60% and nearest possible to 100% of the formed slag right after the end of the oxygen blowing in order to prevent phosphorizing.</p> |
