Examination of ball clays derived from a new seam in northern Thailand

Domestic ceramic industrial demand requires intensive searches for a new source of ball clay with acceptable quality. Analysis of clay samples derived from a new seam in Payao province, northern Thailand was performed using a series of techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), laser diffraction, thermogravimetric analysis (TGA) and L^*a^*b^* color space method. Geological study of this clay seam showed the division into 5 sub-layers, from top to bottom, and was coded as K_R, K_C K_A, K_B and K_Q respectively. The main minerals found in these clays were illite, quartz, kaolinite and rutile with a trace of clinochlore. K_Q was quartzitic with a relatively low clay mineral content. K_R was reddish due to the high content of iron bearing mineral. This clay was least refractory so it was not attractive for high firing white ware industry. In K_B layer, large particles of plant relicts were generally observed so it showed abnormal distribution of the particle size and a substantial thermal weight loss. K_A and K_C showed the greatest potential for utilisation in whiteware industry. These clay samples were off-white after firing at 1150 °C.