| 摘要 |
<p>PROBLEM TO BE SOLVED: To shorten desulfurizing treatment time without using a special equipment and to obtain high efficiency in a vacuum degassing apparatus by injecting desulfurizing agent blended with Ca and CaO at a specified ratio under reduced pressure onto the surface of molten steel and adsorbing to Ca the CaS produced in the combination with Si. SOLUTION: The molten steel after a converter treatment is tapped into a ladle to execute the vacuum desulfurizing treatment. At this time, the desulfurizing agent comprising Ca and CaO blended according to the formula 0.41>=Ca/ CaO>=0.02 (wt. ratio), is injected onto the molten steel surface under reduced pressure. The desulfurizing agent restraines vaporization of Ca even in the high temp. of the molten steel, and Ca is efficiently reacted with S in the molten steel and the produced CaS is adsorbed and also oxygen concn. is reduced and the CaS adsorption by CaO is promoted. The high speed desulfurization under reduced pressure can be executed with the synergistic effect of this suitable blending ratio of Ca and CaO, and S concn. in the molten steel is decreased to about 5 ppm in the short time of about 5 min. Further, the injection is preferably executed at about 0.1-1 kg/t.min injecting speed and <= about 8000 Nl/min flow rate.</p> |
