Caulins amazônicos: possíveis materiais de referência (Amazon kaolin: possible reference materials)

Kaolin is a product originated by the weathering action of aluminum silicates, such as feldspars, which in the Amazon region is favored by warm and humid climate. Used in fabrication of refractory, cement, pharmaceuticals, catalysts, paper coating and filler and other several purposes. This study aims to characterization and comparison of kaolins for paper coating and in natura from different regions in Para ( Rio Capim, Jari and Vila do Conde) of sedimentary origin with kaolins used as reference materials (IPT28, IPT-32, IPT-42, KGa-1b e KGa-2). The characterizations were carried out by methods of chemical, physical and mineralogical analyses: Particle size distribution, X-Ray Diffraction, X-Ray Fluorescence, Scanning Electron Microscopy, Differential Thermal Analysis. The results showed as main mineral phase in all kaolin studied the kaolinite, with different degrees of “crystallinity”. The Amazon kaolins presented high and low degree of structural order as well as reference materials. With respect to the properties of chemical composition, both materials showed levels of SiO 2 + Al 2 O 3 above 90%, low levels of Na 2 O and TiO 2 , with average of 0.6% and 1.92%, respectively for the reference materials, and for amazon kaolins were 0.3% and 1.62% to TiO 2 . The particle size analysis showed variances of the D 50 from 0.7 to 9 µm to the amazon kaolins and from 1.7 to 6 µm to the reference materials. The sedimentary amazon kaolins, with low levels of impurities and found in large quantities, suggest a strong potential for use as reference kaolins