IE830678L - Manufacturing refractory magnesia-chromium products. - Google Patents

Abstract

1. Method of manufacturing magnesia-chromium refractory products by preparing a mixture of a caustically burned magnesia having a grain size of less than 0.2 mm, preferably at most 0.12 mm, and of fine grained chromium ore having a FeO content of 20 to 28 % by weight , in a ratio producing in the mixture a Cr2 O3 content of 10 to 30 % by weight, preferably 15 to 25 % by weight, and a Cr2 O3 /Al2 O3 weight ratio of more than 2.5 preferably more than 3, shaping the mixture into briquettes or shaped bodies and sintering the same at temperatures of at least 2 0008C, preferably at least 2 1008C, but without melting down, and further treating the resultant magnesia-chromium sinter material to obtain burned bricks by burning at temperatures of about 1 8008C or above as well as unburned bricks or refractory masses, characterized in that the caustic magnesia having a weight content of more than 97 % MgO, at most 0.2 % SiO2 , at most 0.7 % Fe2 O3 + Al2 , preferably at most 0.3 % Fe2 03 + Al2 O3 , at most 2 % CaO, and at most 0.06 % B2 O3 and the chromium ore having a grain size up to 1.5 mm and a weight content of at most 1.5 % SiO2 , preferably at most 1.0 % SiO2 , and at most 0.2 % CaO are used in such a ratio producing in the mixture a weight content of at most 1.1 % CaO and at most 0.7 % SiO2 , the sum of the weight content of CaO + SiO2 , however, not exceeding 1.3 %. [EP0091704A1]