| 摘要 |
PURPOSE: To reduce (T.Fe) in slag at the time of stopping blowing and the generation quantity of dust, in a top-bottom combined blowing converter. CONSTITUTION: A top-blowing lance in the top-bottom combined blowing converter-type refining furnace has concentrical polygonal or concentrical circular cross section arranged with two to ten shield plates at the part of the tip opening surface. The ratio B/h of the long side length B (mm) to the short side length (h) (mm) of the individual opening hole part 2 separated by the shield plates 3, is 10 to 225, and it taking R (mm) for the lance diameter, one line of the slit oxygen supplying pipe having 0.4-4 of (B×h)/R, and 1-6 circular nozzles 4 arranged at the inside of the concentrical polygonal series or the concentrical circle and connected with the oxygen supplying piping independent of the slit oxygen supplying pipe, are formed. The lance body and the tip part of the lance containing the lance center point (a) are fitted through the shield plate 3.
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