PURPOSE: To restrain molten iron tapping mixing gas, to extend molten iron tapping interval and to reduce the number of the molten iron tapping times, etc., by boring neiborhood of inner part of a molten iron tapping hole and mud material part in a furnace developing crack, etc., with the deterioration in the blast furnace larger than the ordinary method and pouring the mud material into the obtd. space part.

CONSTITUTION: In inner part of molten iron tapping opening 2 arranged at side wall in the blast furnace body 1, the molten iron tapping hole 3 shown with the dotted line is arranged, and the mud material 5 is packed into the inner part of molten iron tapping hole 3 and to position from neighborhood of tip part to the furnace bottom 6. This mud material 5 part is opened in about 80-300mm diameter by using oxygen, etc., to the neighbor position at the very limit where the molten iron is not spouted out to dig the space part 7, and the mud material is buried into the space part 7 with a mud gun, etc. By this method, the part, where ordinarily the mud material is deteriorated and crack is developed and the gas is spouted, is sealed with the mud material 5 and the spout of gas is prevented.