GB424741A - Improvements relating to the manufacture of refractory magnesia products - Google Patents

Abstract

A refractory magnesia product bonded predominantly by calcium ferrite is made by calcining a mixture providing magnesia, not over 3 per cent of silica, a component rateable as ferric oxide and containing not less than 50 per cent of ferric oxide, and lime in amount sufficient to convert the silica into dicalcium silicate and to provide lime free to combine with the component rateable as ferric oxide in amount which is not less than four tenths of the amount of such component. The component rateable as ferric oxide may contain oxides of chromium and aluminium, or may be non-siliceous iron ore, or mill scale. The lime may be added as limestone or dolomite. The proportion of lime should not exceed seven-tenths of the total ferric oxide component when the latter is all ferric oxide, or eighty-six hundredths when the latter is sixty per cent ferric oxide. The finished refractory product may contain from 7 to 20 per cent of calcium ferrite. Three analyses are given of clinkers made by this process, in which the silica amounts to from 1,2 to 2,2 per cent, the component rateable as ferric oxide (which in these three cases includes aluminia) from 4,7 to 9,7 per cent, and the lime from 5,5 to 10,4 per cent. Specification 394,115 is referred to.