Estudo da influência da adição do resíduo de alumina ativada em matriz cerâmica

Abstract

From the perspective of environmental preservation, several studies focusing on the use of solid waste have been developed, especially in the manufacture of ceramic products. One of the industrial rejects that can be reused is the saturated activated alumina. The γ-Al2O3 (activated alumina) is one of the allotropic phases of alumina, a ceramic obtained mainly from the beneficiation of bauxite by the Bayer aluminum production process. In the production process of ceramic materials, alumina can participate in the formation of a silico-aluminous glass phase associated with alkaline melting elements, and this can be found predominantly at the end of the firing, as mullite (3Al2O3.2SiO2). The objective of this research is to study the effects of adding activated alumina residue from a post-catalytic industrial process to a ceramic mixture. The standard mass for porcelain tiles was donated by a ceramic company located in Bahia, as well as the activated alumina residue, by a polyethylene industry in the same state. The materials were dried in an oven at 110ºC for 24 hours, for subsequent chemical analysis (XRay Fluorescence). The samples with and without residue were made with percentages by weight of 0, 2, 4, 6, 8 and 10% of residue in relation to the standard mass, in a 60x20 mm uniaxial matrix, approximately 5mm thick, with a compacting pressure of approximately 400Kgf/cm². Subsequently, they were sintered at intermediate firing steps of 200, 400, 700, 900, and 1200°C for 2 h and 57 min and cooled to ambient (24°C). Next, the samples were characterized by means of physical tests for linear firing shrinkage, apparent porosity, water absorption, apparent specific mass, bending tensile strength, and scanning electron microscopy. From the results obtained, it was concluded that the alumina waste, within the percentage of incorporation in the standard mass studied, did not change abruptly the properties of the samples developed when compared to specimens without waste, and that up to a concentration of 2%, it is possible to obtain a product with adequate percentages of water absorption and bending strength tension for the manufacture of porcelain tiles, according to NBR ISO 13006, besides contributing to environmental sustainability by using this waste.