| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To perform desulfurization at drastically high efficiency in comparison with the conventional method, when molten steel is desulfurized after heating up molten steel with the combustion of aluminum, in an RH vacuum-degassing apparatus. <P>SOLUTION: After tapping off the molten steel into a ladle from a decarburize-refining furnace for applying a decarburize-refining under atmospheric pressure, this ladle is carried to the RH vacuum-degassing apparatus 1, and the aluminum is added to the molten steel 3 sucked into a vacuum vessel for the RH vacuum-degassing apparatus and successively, oxygen gas is supplied toward the molten steel surface under reducing pressure to heat up the molten steel by firing the aluminum in the molten steel. After completing the supply of the oxygen gas for heating the molten steel, the molten steel is circularly flown for 2 min or more while securing the aluminum concentration melted in the molten steel to≥0.005 mass%, and thereafter, a slag-solidifying agent is charged into the molten steel in the vacuum vessel and successively, the molten steel is desulfurized by injection-adding a CaO-based desulfurizing agent together with carriage gas through a top-blowing lance 13 toward the molten steel surface in the vacuum vessel. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
