| 摘要 |
PURPOSE: A method for operating a blast furnace is provided to increase recovery ratio of sintered ore by reinforcing reduction degradation index in qualities of the sintered ore used as a principal raw material in the blast furnace operation. CONSTITUTION: In a method for operating a blast furnace in which hot metal is manufactured by charging sintered ore into the blast furnace as a principal raw material, the method comprises the process of charging into the blast furnace sintered ore in which small grain sintered ore having a reduction degradation index of 27 to 34 and a grain size of 3 to 5 mm is mixed to a maximum mixed amount for radically increasing air-permeability resistance in the relation of the mixed amount of the small grain sintered ore with the air-permeability resistance index, wherein an average grain size of the sintered ore mixed with the small grain sintered ore having a grain size of 3 to 5 mm is from 18 to 20 mm, and a mixing ratio of the small grain sintered ore having a grain size of 3 to 5 mm is 6 wt.% or less.
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