| 摘要 |
PURPOSE:To make thorough use of the effective components of low-phosphorus high- manganese slag obtd. at the time of subjecting a molten iron which is dephosphorized by a preliminary treatment to less slag refining by adding Mn ore thereto and to reduce the amt. of the ferromanganese, quicklime, etc., to be used by using the above- mentioned slag as slag for converter blowing of the molten iron. CONSTITUTION:Steel making refining is executed by subjecting the molten iron tapped from a blast furnace to the preliminary dephosphorization treatment to produce the low-phosphorus molten iron, charging the low-phosphorus molten iron into a converter, and executing less slag oxygen blowing and throwing manganese ore thereto during the operation to form the low-phosphorus high-manganese slag. Only the slag is made to remain in the converter after the end of refining of the molten iron to the molten steel and the molten steel is tapped. The similar less slag blowing is repeated several times in succession and thereafter, the increased low-phosphorus high Mn slag is taken out of the converter. The slag contains Fe, Ca, etc., at a high ratio in addition to the low-phosphorus high-manganese contents and since the slag is coated on the inside wall of the converter, the molten iron from the blast furnace is subjected to direct oxygen blowing without preliminary refining and the molten steel is produced without using alloy iron such as Fe-Mn and quicklime, etc.
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