Contribution of Multivariate Analysis to the Correlation of Some Properties of Kaolin with Its Mineralogical and Chemical Composition

Abstract

According to multivariate analysis, the following were established (a) kaolinite crystallinity index (KCI) values determined by XRD are highly correlated to one another and seemingly influenced by kaolin impurities; (b) kaolin minerals are concentrated mainly in the fractions <4 μm; (c) the kaolin surface area as determined by the BET (nitrogen adsorption) method is more markedly affected by kaolin impurities than by kaolin minerals themselves; (d) BET surfaces increase when kaolinite crystallinity decreases; (e) brightness is inversely correlated with kaolin impurities; (f) the more ordered the kaolinite and the greater the proportion in the <4 μm fraction of the kaolin, the greater the brightness; and (g) KCI values are particle size-distribution dependent for sedimentary-residual kaolins. The correlations obtained were better when kaolins were selected according to their origin because the kaolin minerals and their impurities, particle size-distribution and texture were more alike. The industrial properties of kaolin can not be predicted from other basic properties such as mineralogy, KCI, etc., because they are intricately related to one another.