Caracterização dos quartzitos da Formação Taboões, presentes na área da mina da ERG mineração, São Joaquim de Bicas, MG, para usos industriais

Abstract

The quartzite of Taboões Formation is a potential supplier of raw materials of silica (industrial sands), and must be well characterized to define mineral processing routes aimed at its best use. Two lithotypes were classified in the weathered quartzites from this Formation present in the ERG Mineração mine in São Joaquim de Bicas MG: clayey quartzite and quartzite, being the main difference between them the relative amount of clay minerals. The quartzite lithotypes were characterized using chemical and particle size analysis, optical and scanning electron microscopies, and X-rays diffraction. It was established that the quartzite in natura does not meet specifications for industrial sands, mainly due to the contents of Fe2O3 and Al2O3, resulting from the presence of hematite, goethite, muscovite and kaolinite, irregularly distributed by the size fractions. Quartz has absolute massic predominance over the other minerals, but is unsuitable for use as a proppant, due to its low degree of roundness. Four types of contamination in quartzite were classified: iron minerals encrusted in quartz; films of clay and iron minerals; iron minerals released among quartzite; and rock particles unrelated to quartzite. To reduce contamination in quartzite, it was established that comminution would be innocuous and even deleterious because it would distribute the contaminations to all size fractions. Preliminary mineral processing tests were performed using a route of attrition/scrubbing with the dispersants sodium silicate, sodium hydroxide and citric acid in aqueous solution, followed by high intensity magnetic separation process. Results were technically feasible to reduce Fe2O3 and Al2O3, thus stimulating more detailed studies of this route.