Rocks that are rich in kaolinite are known as Kaoling, kaolin, Kalaba or china clay. China Clay falls under Kaolinite group of clays. It has the usual compositions of Al2O3, 2SiO2, 2H2O, Hydrous Aluminium Silicate.
China Clay mining is a complicated process which can be split into three distinct sections opencast mining, refining and drying. China Clay occurs in the deposits of rock china clay, a mixture of up to 15 percent China Clay, and up to 10 per cent mica, and the remainder being quartz. The clay itself varies considerably from pit to pit. In some deposits, the clay is ideally suited for the filling and coating of paper, while in other deposits,other gradess China clay suits best. China clay has a low shrink-swell capacity and a low cation exchange capacity (1-15 meq/100g). It is a soft, earthy, usually white mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar.
China clay is available in the form of lumps and powder (Pure white colour, off white colour and calcined powder).
- Low shrink swell capacity at 1300C is about 12%
- Lowcation exchange capacity (1-15 meq/100g
- High luster, opacity, gloss
- High mechanical strength
- Dimensionally stable
- Improved electrical properties
- High extrusion properties
- Anti cracking