Systematic characterization of bentonitic clay and its industrial significance

Abstract

Systematic study for characterization of bentonitic clay revealed the occurrences of multi-mineral phases therein. Bentonite has the assemblage of smectite group of minerals processed for specialized industrial applications. The minerals of bentonite do not possess with definite theoretical compositional formula, because of ample scope of their common exchangeable cation viz. Ca++, Mg++, Na++ and P+ present in their lattice making the characterization complicated. The ancillary minerals associated with bentonitic ores are characterized as un-altered remnant of parent rock of bentonitic clay. Characterization of different pocket of bentonitic clay leads to a difference in mineralogical assemblage depending on the degree of transformation of parent rock. The characteristic of interlayer mineral composition of bentonite is the phenomenon of incomplete transformation of parent rock to bentonite. The interlayer mineral are mainly characterized as Montmorillonite -illite, Montmorillonite -+chlorite, Montmorillonite-illite-chlorite. The characterization of these interlayer mineral phases is difficult by means of simple microscopic studies merely due to its sub-microscopic grain size occurrences, but the textural features are determined from microscopic study. The instrumental technique of X-Ray Diffraction is found to be useful with applications of some physical and chemical treatment on the samples for the detailed characterization of bentonite. The quantitative distribution of bentonite minerals and associated hydroxides impurities are accurately determined with the help of Differential Thermal Analyser. This paper deals with the systematic approach for the evaluation of bentonitic clay in order to assess their quality and scope of their processing. This paper also emphasizes that even though the characterization of bentonite is complicated, but can be carried out by combining different instrumental techniques.