Variation In Textural Properties Of Aplitic Kaolin From Kinta Valley

Textural properties are among one of the fundamental characteristics especially important to be understood before suitable application(s) of a kaolin can be determined as they have direct influence on the other properties such as plasticity, brightness, firing and rheological behavior. This paper presents an investigation on the textural properties of aplitic kaolin from Kinta Valley. Two degritted kaolin samples from different location of Kinta Valley were measured for their particle size distribution by laser diffraction method. The samples were then classified into different size fractions followed by examination of their morphological property by various techniques which X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FESEM). Generally, the kaolin can be classified into two different types based on the fine fraction content which may be consists of; i) delaminated platy kaolinite, or ii) tubular shaped halloysite. These fine fractions however constitute only to minor amount or not more than 12 % of the clays, as both clay consist predominantly of coarse book like kaolinite stacks. The degree of crystallinity of kaolinite samples shows a positive correlation to its particle size during examination by XRD, but FTIR spectrum shows a high degree of crystallinity for all kaolinite samples regardless of their particle size. Slight presence of halloysite is sufficient to give an adverse effect on the clay crystallinity index measured from XRD pattern. Sorting of the clay into different size and morphological fraction creates a product with less variation in properties between individual particles, and with more potential for tailoring or engineering of their properties.