PURPOSE: To improve the resistance to spalling and erosion by forming the lower nozzle with a fired magnesia-carbon brick using a boron-modified phenolic resin excellent in oxidation resistance at high temps. as a binder.

CONSTITUTION: The magnesia and carbon as the brick material and an additive are mixed, and 0.5-10wt.% boron-modified phenolic resin contg. 10-50wt.% B is added along with a binder such as pitch, tar and phenolic resin. The admixture is kneaded, press-formed, then heated at 30-300°C to remove the volatile component to the extent that the firing is not disturbed and fired in a reducing atmosphere or in a nonoxidizing atmosphere such as a gaseous N2. current to obtain the lower nozzle. Although the boron-modified phenolic resin can be singly used as a binder, the resin should be jointly used with common novolac resin, resol-type phenolic resin, etc., from the standpoint of economy and formability.