| 摘要 |
PROBLEM TO BE SOLVED: To realize reduction in the cost of an auxiliary material such as lime, and the shortening of a treating time by reducing the dispersion of phosphorus distribution ratio at the final stage in the dephosphorizing treatment with a converter type refining furnace. SOLUTION: The components and the flow rate of exhaust gas from a converter type refining vessel are continuously measured and also, oxygen potential in slag is continuously calculated from the mass balance of oxygen source and the auxiliary material supplied into the furnace, and at least one or more conditions among an oxygen supplying condition, a bottom-blown stirring condition, a supplying amount or a supplying timing of the auxiliary material, are decided based on the calculated value. Further, the impregnation amount of the gas from the outside of the system at the exhaust gas measured position is restrained to <=80 vol.% of the generated gas amount in the furnace while regulating the oxygen supplying velocity per one ton of the treated molten iron to <=140 Nm3/hr and the oxygen supplying time for dephosphorizing is regulated to within 16 min.
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