Characterization by granulometric range of kaolin residue in the pegmatitic-Borborema region of northeast Brazil, aiming at potential uses

Abstract This study aimed to characterize kaolin residues originating from the pegmatitic region of northeastern Brazil, an area that annually produces and disposes of thousands of tons of kaolin residue into the environment without any control. The research focused on the industrial potential of these residues through chemical composition analysis by X-ray fluorescence (XRF), mineralogical characterization by X-ray diffraction (XRD), and morphological characterization by scanning electron microscopy (SEM) across different granulometric fractions. The results, supported by the literature, revealed that both siri and sarrabulho residues exhibited chemical, mineralogical, and textural compositions dominated by silica (SiO2) and aluminum oxide (Al2O3), which varied according to particle size. The fine fractions (< 74 µm) showed higher Al2O3 contents (42%), corresponding to kaolinite and muscovite minerals, which confer favorable properties to produce ceramic coatings, cement, and paints. Conversely, the coarse fractions (> 150 µm) contained 83% SiO2, attributed to quartz mineral, contributes to improved mechanical strength and thermal stability in aggregates for the construction industry. Additionally, 8.10% potassium oxide (K2O) and 3.22% phosphorus pentoxide (P2O5) were identified, suggesting potential agricultural applications as soil conditioners. Based on the results, it is concluded that the Siri and Sarrabulho residues, according to literature, exhibit physicochemical and mineralogical characteristics that support their reuse in various industrial sectors, particularly in ceramics, civil construction, and agriculture. The valorization of these residues represents a strategic approach to mitigating environmental impacts and promotes the integration of these materials into production chains aligned with the principles of economic, environmental, and social sustainability.