| 摘要 |
PURPOSE:To control the concn. of blown-out P effectively by first stopping top blown refining then sustaining the refining of the bottom blowing alone throughout a prescribed time in the end period of a blowing stage by combination use of top blowing and bottom blowing for molten steel, thereby changing the concn. of the iron oxide in the slag arbitrarily. CONSTITUTION:Gaseous O2 is blown into molten steel 3 through the plural tuyeres 2 in the bottom of a converter 1, and gaseous O2 is blown through a top blowing lance 4 toward the slag 5 on the surface of the steel 3, whereby the molten steel is refined. In the stage when the blowing stage arrives at the end period, first the top blown refining 4 is stopped, after which the refining 2 by bottom blowing until the blowing out is sustained independently throughout a time within a few minutes. More specifically, the refining time of the bottom blowing alone after the stopping of the top blowing at the end period of the refining is controlled within a few minutes, whereby the yield of blown out P and Fe, etc. are controlled according to kinds of steels so as to yield an overall advantage. |
