METHOD FOR REDUCING REMAINING IRON AT THE TIME OF BLOWING DOWN IN BLAST FURNACE

摘要

PURPOSE:To easily reduce remaining iron quantity in basin part at furnace bottom at a low cost by increasing molted iron discharging quantity per unit of time accompanying to lowering of charged material level and dissipation of a part of fusing zone before stopping hot blast at the time of blowing down in a blast furnace. CONSTITUTION:Charge of the charging material is stopped in the blast furnace 1 and also supplying quantity of the hot blast blowing from tuyeres 4 at the lower part is decreased and stopped at the prescribed charged material level. At the time of the above blowing down in the blast furnace, before stopping the hot blast, gas flow resistance in the furnace is rapidly reduced and furnace core 3 is descended accompanying to dissipation of a part of the fusing zone 2 by lowering the charging material level, and the molten iron 8 level in the basin part 7 is ascended. This partial dissipation of fusing zone 2 can be detected with a pressure gage 11. In this stage, by forcedly executing the discharge of molten iron, the discharging quantity of molten iron per unit time is increased. Then, before starting blowing down, increasing coke ratio or by substituting the iron source with slow cooling slag in the blast furnace or by forming the fusing zone 2 to cap shape, etc., it is desirable to reduce the produced quantity of molten iron. By this method, the remaining iron quantity in the basin part 7 can be reduced.