Mineralogy and technological characterization of two kaolin deposits from the Borborema Pegmatite Province, northeastern Brazil.

This research presents the mineralogical and chemical characterization and beneficiation study of two kaolin deposits from the Borborema Pegmatite Province, Brazil. Seven samples were collected and treated in two different beneficiation routes involving magnetic separation and chemical bleaching. The fractions obtained were studied by X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, particle-size analyses, electron paramagnetic resonance and determination of optical properties. The samples are composed mainly of subhedral kaolinite in the form of booklets, as well as muscovite, quartz, microcline and illite impurities. The kaolinite structural formulae indicated significant replacement of Si4+ by Al3+ in tetrahedral sites and low replacement of Fe3+ by Al3+ in the octahedral sites. The first 30 min of chemical bleaching improved significantly the optical properties of kaolin, indicating that the process is more efficient than magnetic separation. [ABSTRACT FROM AUTHOR]