| 摘要 |
PROBLEM TO BE SOLVED: To execute an efficient dephosphorizing treatment by using a flux containing no F source, such as CaF2, in the dephosphorizing treatment executed as a pre-treatment of molten iron. SOLUTION: From such a viewpoint that the dephosphorization reaction efficiency in the case of executing the dephosphorizing treatment of the molten low Si iron without adding the F source is largely affected by the molten iron temps. before and after the dephosphorizing treatment, to the molten iron having <=0.1 wt.% Si concn., the flux mainly containing CaO and no F source is added and the molten iron temp. is controlled so as to satisfy the following relations (1)-(4) between the molten iron temp. A ( deg.C) at the time of starting the dephosphorizing treatment and the molten iron temp. B ( deg.C) at the time of completing the dephosphorizing treatment to execute the dephosphorizing treatment. (1) In the case of being A<1300, 1300<=B<1350, (2) in the case of being 1300<=A<1330, [2600-A]<=B<1330, (3) in the case of being 1330<=A<1350, 1270<=B<[2680-A] and (4) in the case of being A>=1350, 1270<=B<=1330.
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