JPS57104605A - Method for blowing out of blast furnace - Google Patents

Abstract

PURPOSE:To permit discharging of approximately the entire amt. of residual molten iron by increasing the pressure in the furnace and seleting the position for piercing a horizontal hole for discharging at the region right under the furnace bottom in discharging the residual molten iron in the furnace. CONSTITUTION:When a blast furnace is to be blown out, first the supply of charging materials from the furnace top is stopped, after which the rate of blast is gradually decreased, thence an iron notch 5 is opened to allow molten iron and molten slag above its level to flow out. In parallel with the operation of reducing the blast, the cooling of a shell 2 is made weaker than before, and the shell is maintained at a high temp. After the notch 5 is closed, blasting is resumed through tuyeres to increase the pressure in the furnace slightly higher than the atmospheric pressure which is the pressure of the furnace outside. The position of the enroded surface of a furnace bottom 3a is forecast and operated from the temp. distribution in the furnace body height direction measured with the thermocouples buried in hearth side walls 3b or the like, and the bricks of the bottom 3a are pierced from the shell 2 side toward the position slightly lower (about 500mm.) than the above-described eroded surface in the furnace central part. When a discharge hole 6 inclining downward toward the outside of the furnace beyond the part right under the outside of the furnace beyond the part right under the conical part of the bottom 3a, is pierced hole 6 and the furnace inside are communicated by the high pressure in the furnace and the occurrence of joint breakage owing to loosening of the brick joint at the surface of the bottom 3a, and remaining molten slag is discharged.