Magnesia aggregate for refractory article and method for manufacturing

Abstract

A magnesia aggregate for a refractory article, which comprises: a core portion comprising magnesia; a covering layer excellent in slag penetration resistance, which comprises a refractory material excellent in slag penetration resistance and covers the surface of said core portion; and an intermediate layer excellent in slag penetration resistance, formed between said core portion and said covering layer through combination thereof. Said magnesia aggregate is manufactured by: forming, on the surface of a core portion which comprises magnesia and has a particle size of from 40 .mu.m to 10 mm, a covering layer which comprises a powdery refractory material excellent in slag penetration resistance and has a covering thickness of from 20 .mu.m to 2.0 mm, to prepare a green aggregate; and firing said green aggregate at a temperature of from 1,700.degree. to 2,200.degree. C. for a period of time of 4 to 10 hours, to form an intermediate layer excellent in slag penetration resistance between said core portion and said covering layer through combination thereof, thereby manufacturing a magnesia aggregate comprising said core portion, said covering layer and said intermediate layer.