| 摘要 |
PROBLEM TO BE SOLVED: To reduce the generating quantity of dephosphorized slag containing fluorine as slag formation promoter of CaO, in the dephosphorized slag generated with dephosphorizing treatment, when molten iron is dephosphorized to the range of low concentration of 0.030 mass% or less phosphorus content by using CaO-series dephosphorize-refining agent. SOLUTION: When the dephosphorizing treatment is applied to the molten iron held in a reaction vessel by supplying oxygen source as the dephosphorizing agent and at least CaO-containing material as the dephosphorize-refining agent, in the front-half part of the dephosphorizing treatment, the molten iron is dephosphorized by using only CaO-containing material as the dephosphorize-refining agent and the dephosphorized slag generated with the dephosphorizing treatment is discharged from the reaction vessel as the slag containing no fluorine and recovered. In the rear-half part of the dephosphorizing treatment thereafter, the molten iron is dephosphorized by using the CaO-containing material as the dephosphorize-refining agent and CaF<SB>2</SB>-containing material as the slag formation promoter of CaO, and the dephosphorized slag generated with this dephosphorizing treatment is discharged from the reaction vessel as the slag containing the fluorine and recovered. COPYRIGHT: (C)2011,JPO&INPIT
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