PURPOSE: To increase the service number of the porous plug for injecting gas into molten steel, while eliminating its damages caused by thermal spalling, by making the area of its gas-ejecting surface smaller than a specified value.
CONSTITUTION: A porous plug to be attached to a ladle for molten steel, a refining ladle, a tandish, etc. for injecting oxygen or other gas into the molten steel is formed by fixing a plurality of porous bricks in a refractory sleeve 1. The gas-ejecting surface 1a of the porous brick 1 is formed into a small surface having a diameter below 70mm, and several pieces of said porous bricks are used to maintain a certain amount of permeating gas. If the gas-ejecting surface of the porous bricks is other than the round one, one side of the gas-ejecting surface 3a, 5a is controlled below 70mm. Accordingly, the porous bricks are protected from damages in a short time by thermal spalling, and its sevice number can be remarkably increased.
KAWAMURA TOSHIO
SANO SHIYOU
ODA HIDENORI
