| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a top-blowing method in which reaction efficiency of refining agent is high. SOLUTION: In a refining process for top-blowing the refining agent onto molten steel surface in a vacuum vessel of a vacuum degassing apparatus, a vertical distance H between the lower end of a lance for top-blowing and the molten steel surface in the vacuum vessel is 0.5-3.1 m, a vacuum degree P in the vacuum vessel is 13.3-13300 Pa, a refining agent supplying rate V is 0.1-4 kg/(mass ton of the molten steel×min) and a carrier gas flow rate Q blown onto the molten steel surface in the vacuum vessel together with the refining agent is 0.3-5 m3 (standard state)/min and the H, P and V satisfies the following (1) inequality 7.5×10-8×P+0.09×H<=V<=2.2×10-4×P+0.9×H.</p> |
