Evaluation of Swat kaolin deposits of Pakistan for industrial uses

The Swat kaolin deposits are characterized and evaluated for their potential as industrial raw materials. Their particle size, colour measurement, viscosity, plastic limits, liquid limits, drying, firing shrinkage, water absorption, oil absorption, pH, water soluble matter, moisture and bulk density are tested for <63, <10, <5 and <2 μm size fractions. Due to low plasticity index and high Fe2O3, TiO2 and CaO contents, the “water-washed” <63-μm fraction of kaolin is unsuitable for ceramic use. The yellowness of this fraction, 1.3-9.8%, can be reduced by 20.4-61.3%, by chemical bleaching. The <2-μm fraction can be used for high-solids formulation for publication-grade paper and medium-finish lower cost enamels. The <5-μm fraction is useable in paper filling. The <10-μm fraction is suitable for the ceramics, paint, plastic and rubber-filler industries.