Hazardous bauxite residue, blast furnace slag, and foundry sand application as the main components for environmentally friendly red ceramics production

Abstract

In the presented research were used residues of aluminum and iron production. Bauxite residue, which is also called bauxite tailings or red mud, and blast furnace slag are the key wastes of metallurgical industry. There was also used foundry sand, which is a residue of casting process. These three components were used together to develop ceramic construction material. The main idea was to use industrial wastes only, no traditional natural materials. The waste glass and wood ash were added to the compositions in order to decrease melting point of the samples. In the research 24 compositions were sintered at 800-1225°C and their properties were studied. Their mechanical characteristics were analyzed using flexural strength test, measuring water absorption, density, and linear shrinkage. Physicochemical properties were studied by XRF, XRD, AAS, SEM, EDS, LAMMA, mapping, DTA, and TGA. The main reason for high results of flexural strength (19.78 MPa) of the samples was identified as a development of new amorphous formations. As a result of research, some compositions were suggested for specific construction materials production. Compositions containing red mud (40-100%), blast furnace slag (0-50%), foundry sand (0-50%), waste glass (0-20%), and wood ash (0-20%), according to Brazilian Norms and regulations for construction materials, may substitute traditional ceramic materials, which involve enormous exploration of natural resources.