| 摘要 |
PROBLEM TO BE SOLVED: To provide a top-blown refining method in a pressurizing type converter steelmaking method, with which the ranges independently controllable to atmospheric pressure and oxygen feeding speed are widened and the pressure at the inlet side of a nozzle can be kept to a suitable range and the blow- refining can be executed at an ideal jetting intensity. SOLUTION: A top-blown lance having independent two or more systems of oxygen gas piping and one or more nozzle holes communicating with an oxygen gas piping therein and >=2 ratio of the max. and the min. total cross sectional areas at a nozzle throat parts in the systems, is used. Then the oxygen feeding speed F (Nm3/hr) is changed by switching the system at least once so that the pressure Po at the inlet side of the nozzle becomes in the range of 3-21 (kgf/cm2) and Po/Pe(-) becomes >=2 according to the carbon concn. [C]. (wherein, Pe: atmospheric pressure in the furnace (kgf/cm2)).
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