| 摘要 |
PROBLEM TO BE SOLVED: To inhibit the wear of refractory brick in a side wall of a vacuum chamber compared to a conventional method without causing a problem of lowering a decarburization reaction speed, when smelting a molten steel by spraying oxygen gas toward the molten steel in the vacuum chamber from a top-blowing lance which penetrates through a top cover of the vacuum chamber in an RH vacuum degassing apparatus. SOLUTION: When smelting the molten steel 3 while spraying the oxygen gas toward the surface of the molten steel in the vacuum chamber 5 from the top-blowing lance 13, this refining method includes: adjusting the height H (m) of a lance, which is a distance between the surface of the molten steel in the vacuum chamber and the head of the top-blowing lance, a spreading angleθ(deg. ) of the oxygen gas sprayed from the top-blowing lance with respect to the center line of the top-blowing lance, and the distance R (m) between the center of the top-blowing lance and the surface of the refractory brick in the side wall of the vacuum chamber, on the surface of the molten steel in the vacuum chamber, into such a range as to satisfy a relation of the expression: H≤(R-0.2)/tanθ; and supplying the oxygen gas so that the dynamic pressure of the oxygen gas can be 2 kPa or lower on the surface of the molten steel. COPYRIGHT: (C)2008,JPO&INPIT
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