| 摘要 |
PURPOSE:To reduce N concn. in molten iron by charging ore containing element rising activity coefficient of N in the molten iron or element generating nitride by reacting with N, together with oxygen enrichment in blast in a blast furnace operation. CONSTITUTION:The oxygen enrichment in the blast is executed under the operation of fine powered coal blast in the blast furnace. Together with this, the ore containing one kind or more of elements, which increases the activity coefficient of N in the molten iron, such as Ni, B, or which generates the nitride by reacting with N in the molten iron, such as Ti, B, Nb, Ta, V, is charged by lump state from the furnace top in the blast furnace. Or, the powdery ore is blasted from tuyere in the blast furnace. In this way, as the N concn. in the molten iron in the blast furnace is stably reduced, burden of denitrogenization in steel making process can be reduced. Further, a hitting ratio of N at the time of producing dead low N steel is improved.
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