A geopolimerização como técnica para a aplicação do residuo de bauxita

Abstract

Finding sustainable applications for the bauxite residue is one of the leading challenges in the aluminium industry. For this purpose, the geopolymerization could become an interesting alternative, because this technique could make use of some of the typical characteristics of the bauxite residue, such as its alkalinity and expressive silicates and aluminates contents, resulting in solid materials with similar properties to usual traditional ceramics. In this work, the properties, processing and possible applications of such materials were analyzed. Besides the apparent porosity and the mechanical resistance tests, the obtained samples were also submitted to a leaching test, aiming to a preliminary evaluation of the potential environmental risks of application that a supposed product would represent, and which procedures could favour its passivation. As the main results, it was possible to verify that firing at 800 °C allowed some compositions to reach compression resistance values up to 30 MPa, and a leaching resistance closer to a common pressed clay brick, which makes the building materials a potential area of application for the bauxite residue geopolymers, based on the enormous consumption capacity of this area and its increasing demand for more sustainable products.