The red mud is a well known insoluble residue generated in the Bayer process to benefit bauxite ores. This residue is composed of ceramic related compounds such as iron oxide, sodium aluminum silicates, carbonates, calcium aluminates and titanium dioxide. The incorporation of industrial residues in clay ceramics has been extensively investigated, not only as an environmentally correct solution but also as an economic way to save raw materials. Therefore, the present work evaluated the properties of clay ceramics incorporated with up to 40 wt% of red mud. Clay bodies with different percentages of red mud were press-molded and fired at 750, 950 and 1050°C. The evaluated technological properties were linear shrinkage, water absorption and mechanical strength. Sensible changes in such properties were found with red mud addition. In particular, the ceramic fired at 1050°C displayed favorable water absorption with red mud incorporation.

Red mud is a specific term applied for a residue generated during the processing of aluminum ores, mainly bauxite in the Bayer process, to produce alumina (Al2O3). In several countries where bauxite is mined and processed, distinct red muds are generated in ever growing amounts and becoming an environmental problem. This problem is also affecting the large bauxite processing plants in Brazil and a possible solution for the red mud is its addition to clay ceramics. Before an industrial scale addition is implanted, the specific red mud needs to be characterized for compatible behavior with the ceramic clay matrix. Therefore, the objective of the present work was to characterize a red mud generated in Brazil for an eventual addition to clay ceramic. This was conducted through the determination of density, chemical and mineralogical composition as well as size distribution and microscopic observation of particles. The results indicated that the specific red mud investigated is compatible with clays and has a potential for addition in common red ceramics.