| 摘要 |
PROBLEM TO BE SOLVED: To provide an operational method, that is, a lowered level operation in a blast furnace can be performed under stable condition, by developing the operational method, in which on the way of the lowered level operation, blow-by of gas in the furnace and the furnace-cooling are not developed and the furnace-top gas temperature can be restrained to≤400°C. SOLUTION: In the method for the lowered level operation in the blast furnace, this operation is performed while continuing the raw material charge into the blast furnace until the charged material level in the furnace comes to a prescribed height at the lower part from a stock line and the lowered level operation is performed by stopping the raw material charge in the lower part than the above height while adjusting the raw material charging quantity so that the level-lowering speed during continuing the raw material charge becomes in a prescribed range. Then, the lowered level operation is performed till the lower level by a prescribed distance from the last target, by adjusting the blasting quantity so that a value of the ratio (ΔP/W<SB>S</SB>) of a pressure loss quantity (ΔP) of hot blast blown from a tuyere and the pressure (W<SB>S</SB>) in the tuyere level, becomes a prescribed value or lower, and the water-spray is stopped and also, the last adjusted charge of the raw material is performed so as to return back the raw material charge to the last target level. COPYRIGHT: (C)2008,JPO&INPIT
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