Role of Magnesia as an Additive on Sintering and Micro-Structural Characteristics of Indian Bauxite

Raw Indian Bauxite from Saurashtra region, Gujarat is selected for experimental studies to produce refractory material after sintering with addition of chemical grade magnesia powder of variable fractions (4wt%, 8wt%, 12wt %) as sintering aid for 4hours after mixing in rubber lined pot. Powder X-Ray diffraction study confirmed the formation of spinel (magnesio- aluminate phase) along with corundum as major crystalline phase. Physical properties like bulk density, apparent porosity is measured for the prepared samples. The maximum bulk density (3.57gm/cc) is obtained with 4wt% MgO containing batch with 0.53% of apparent porosity fired at 1500oC. Maximum shrinkage (29.59%) is attained at 1550oC with no additive batch. The elongated corundum crystals and rectangular spinel phase is observed in the thermally etched polished surface of the magnesia containing bauxite batch.