| 摘要 |
<p>PURPOSE: To produce a low sulfur steel at a low cost by enabling the desulfurization of a molten steel to the extent of low-level sulfur content by the existing equipment without using specific blowing device. CONSTITUTION: This process consists of the following stages: a hot metal pretreating stage for preliminarily desulfurizing a hot metal to <=0.004wt.% sulfur content [S]; a converter refining stage for subjecting this pretreated hot metal to dephosphorization, decarburization, and temp.-rise in a converter; a stage of introducing Al component and CaO component at the time of tapping from the converter after the completion of refining; a degassing treating stage for degassing the molten metal after the introduction; and a bubbling stage for agitating the molten steel by an inert gas after the degassing treating stage. Further, in the stage of introduction, Al component and CaO component are introduced so that a composition of slag satisfies the composition formulae CaO/SiO2 >=2.0 and T.Fe+MnO<=15wt.%. Moreover, in the degassing treating stage, sulfur content [S] in the molten steel is reduced to <=0.002wt.% by adding a desulfurizing agent to a vacuum tank.</p> |
