DEVELOPMENT OF REFRACTORY SPINEL-BONDED MAGNESIA BRICKS FROM EGYPTIAN MAGNESITE

摘要

The development of highly refractory and corrosion resistant spinel-bonded magnesia bricks from appropriate mixtures of Egyptian magnesite and either presynthesised magnesium aluminate spinel (MA) or bauxite material was carried out, where MA spinel and periclase (MgO) represent the major constituting phases. Such bricks have higher spalling and slagging properties with better resistance to hot load deformation. Optimal brick characteristics were reached when the MA spinel was between 15 - 20 percent in the batch compositions. SEM examinations proved that part of the formed MA spine is incorporated into the composition of the solid solution with periclase mineral, leading to its sintering and grain growth. The other part goes into the intergranular spaces between periclase grains forming a layer to protect them against corrosion. These bricks could be used advantageously as a substitute for the currently used magnesia-chrome bricks (MK), in the lining of the upper transition and sintering zones of the rotary cement kiln as well as steel-making furnaces roofs.