PURPOSE: To form tuyeres at the shortest interval without causing troubles of falling off of tuyere bricks and pressure cracks when tuyeres at the bottom of bottom-blown converters, etc., are constructed, by giving a specific relationship between expanding amounts between tuyeres and expansion absorbing amounts between tuyere bricks.

CONSTITUTION: In a converter LD provided with bottom tuyeres 4, such as a top-blown converter, bottom-blown converter etc., the bottom tuyeres 4 are installed within a small area with a trunnion shaft 3 as the center. Ware bricks 2 fitted between tuyere bricks 1 fitted centering around the tuyere 4 are made larger in size than ware bricks 2' fitted to other parts of the furnace bottom, and the ware bricks 2 are fitted in such a way that a relationship, B=0.4AW 0.8A is satisfied between an expanding amount A expressed by a formula (I) which shows conditions between tuyeres at the time of high temperature and an expansion absorbing amount B between tuyere bricks 1. In this way, tuyeres can be installed at the shortest interval without having troubles, such as pressure cracks caused by expansion stresses of ware bricks 2 between tuyere bricks, joints 5 and 6, and tuyere bricks, and falling off of bricks due to shrinkages of the bricks and joints.