Caracterização dos minerais micáceos presentes em minérios fosfáticos do Centro-Sudeste do Brasil

Abstract

Currently, challenges are being faced to reduce impurities in phosphorus ores concentration plants in various mines. In this work, minerals present in phosphate ores from the alkaline-carbonatite complexes of Araxá, Tapira and Catalão I, located in the Alto do Paranaíba Province, which occupies the northwestern Minas Gerais and southeastern Goiás regions, were focused. The goal was to characterize the micaceous minerals present in samples collected in the three mines, emphasizing the interstratified phyllosilicates. The knowledge of the physical and chemical characteristics of the phyllosilicates can contribute to improvement in the flotation processes in mineral processing. Scanning electron microscopy (SEM) techniques, EDS chemical microanalysis, X-ray fluorescence and X-ray diffractometry (XRD) were used, the latter as the main analytical method. All the samples presented interstratified phyllosilicates or mixed layer phyllosilicates and also vermiculite. The basis for the identification of the interstratified phyllosilicates was the study of Reynolds, 1980, comparing the observed samples diffractograms and the corresponding model diffractograms. In cases where it was possible to have definitive conclusions, these phyllosilicates showed regular stratification of the unit cell, always in the micavermiculite sequence. The SEM-EDS studies were consistent with the XRD identifications. In the EDS case, the K2O content was the best indicator of the degree of transformation between mica and vermiculite, since the lower this content, the greater the proportion of vermiculite in the minerals structure