Method of manufacture of a refractory surcalcinée magnesia, magnesium oxide obtained by the process or a similar process, and refractory products manufactured from the magnesia

摘要

Dead-burnt high purity refractory magnesia is produced from synthetic magnesia which contains a sufficient quantity of sodium oxide, potassium oxide or lithium oxide or a compound which will yield such an oxide under the conditions of dead-burning to increase the modulus of rupture at 1260 DEG C., of a refractory brick made from the magnesia to in excess of 1000 lb/square inch and by at least 100% over that of a similarly formulated refractory brick made from magnesia only containing alkali metal oxide in amounts in which these compounds normally occur in high purity magnesia. The lime/silica ratio in the refractory should be between 1.5: 1 and 2.7: 1 with a total of about 1.5-2.0% before dead-burning. The Na2O content is generally less than 1% before dead-burning. The magnesia material can additionally contain at least one of the oxides Cr2O3MnO and TiO2 to increase the densification but Fe2O3 content is preferably less than 2%. Synthetic magnesia is defined as that prepared from sea water and similar brines.