| 摘要 |
PROBLEM TO BE SOLVED: To provide a means for reducing the scattering of a powdery auxiliary raw material with an exhaust gas stream and improving the adding yield, at the time of supplying the powdery auxiliary raw material of a slag-making agent, an iron oxide source, etc., into a converter on the molten iron surface from a top-blown lance, etc., in a pressurizing type top-bottom blown converter operation. SOLUTION: This powdery auxiliary raw material having <=45% weight ratio in 150-500μm grain diameter, is supplied by being entrained with a carrier gas from an oxygen top-blown lance and/or a powder supplying exclusive lance. Further, as the above powdery auxiliary raw material, a powdery material containing >=60% weight ratio in <=150μm grain diameter, 1-20% weight ratio in >=500μm grain diameter and <=45% weight ratio in 150-500μm grain diameter, is used. Further, the whole of a basic slag-making agent is supplied from a nozzle for jetting gaseous oxygen by being entrained with the oxygen and the whole of an iron oxide source and a manganese source are supplied from another nozzle by being entrained with the non- oxidizing gas. Furthermore, the max. flowing speed U of the carrier gas to reach the molten metal surface is made to 40-200 m/s.
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