Aplicação de resíduos da mineração de bauxita na síntese de geopolímeros

Abstract

The process of extraction and beneficiation of bauxite deposits in the bauxite province of Paragominas/Rondon do Pará can generate large amounts of waste, mainly in two stages of the process: mining and processing. In the mining stage of the deposits, the “residue” comes from the removal of a thick layer of clay material (known as Belterra Clay). On the other hand, the “residue” from the beneficiation process is generated after the crushing, grinding and washing stages, which give rise to a large amount of clay material dispersed in a large amount of water. For the present study, it selected Belterra clay from the bauxite deposits of Rondon do Pará, a sample of Bauxite Washing Clay from the Hydro company and a sample of kaolin benefited from Imerys Company. The samples and geopolymers were characterized by X-ray Diffraction (XRD), X-ray Fluorescence (FRX), Gravimetric Thermal Analysis (TG), Differential Exploratory Calorimeter (DSC), Optical Emission Spectrometry with Coupled Plasma (ICP-OES) and Laser Particle Analyzer (APL). Geopolymers were synthesized from Belterra clay, microsilica and NaOH according to the Box-Benkhen design. Synthesis of geopolymers from Belterra clay and beneficiated kaolin was also carried out (a comparative study) using KOH and microsilica. Finally, geopolymers were synthesized from Bauxite washing clay with NaOH and microsilica according to the Doehlert design. In the study with only Belterra clay, the highest resistance result was 47.78MPa and the lowest result was 7.05MPa. In the comparative study between Belterra Clay and beneficiated kaolin, the best results of compressive strength were obtained with the beneficiated kaolin. The compressive strength results of the geopolymers synthesized from the Washing Clay ranged from 8.99 to 41.89MPa. These results demonstrate the positive potential of both samples for the synthesis of geopolymers that can be used as possible “Eco-friendly” substitutes for traditional materials, mainly ceramics and cement.