| 摘要 |
PROBLEM TO BE SOLVED: To improve the yield of auxiliary material added into molten steel in a degassing vessel. SOLUTION: In the plane observing the degassing vessel 1 from the upper part, the arcs having the same distance as the radius R of the degassing vessel with both ends A of the contacting parts between the degassing vessel 1 and a vacuum evacuating duct 2 as the center points are drawn, and the crossing points C of the center axial line B of the vacuum evacuating duct 2 with the arcs, are obtd. Then, the auxiliary material is charged from an auxiliary material charging hole 3a disposed in a roof part in the other void zone except the hatched zone surrounding with the lines connecting the crossing points C and both ends A of the contacting parts of the vacuum evacuating ducts 2, respectively and the arc D cut off with the inner surface of the iron shell of the degassing vessel 1. The auxiliary material charged from an auxiliary material charging hole 3b disposed at the hatched zone, is accompanied with the exhaust gas sucked with the vacuum evacuating duct, and on the contrary, the auxiliary material charged from the auxiliary material hole 3a disposed at the void zone is not accompanied with the exhaust gas, but this material can be added into the molten steel at the good yield.
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