679,273. Refractory compositions. CANADIAN REFRACTORIES, Ltd. Feb. 2, 1950, No. 2740/50. Drawings to Specification. Class 22 Refractory grains containing at least 80 per cent by weight of magnesia, silica and alumina, and in which the ratio of magnesia to silica, when present, and alumina is at least 1.5 times the silica plus 0.5 times the alumina are mixed with non-refractory material containing at least 75 per cent by weight of silica, magnesia and alumina of which 35-82 per cent is silica, 0 to 40 per cent is magnesia and 0 to 50 is alumina the complete mixture having a ratio of magnesia to silica and alumina of at least 1.34 times the silica plus 0.4 times the alumina, and heating the mixture above the incipient fusion point of the non-refractory material whereby liquid is formed and coats the refractory grains, and by reaction eliminates the non-refractory materials and bonds the grains. The refractory grains should not have more than 5 per cent of lime and should have at least 10 per cent excess of free magnesia over that required to form the orthosilicate and aluminate i.e. spinel. The refractory grains may be periclase whilst the non-refractory may be at least one of granite, syenite, diorite, olivine, serpentine, talc and enstatite. Temporary binders, e.g. ligrin liquor may be present, and also clay brick grog. Naturally securing materials when used may contain titania and iron oxide as impurities.
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