Kaolin is the pure form of clay (hydrated aluminum silicate). There are three distinct materials of it: kaolinite, nacrite, and dickite, all of which have a similar formula. It is found in earthy masses with a dull luster. Its structure consists of a two-layer sheet composed of one tetrahedral layer of silica (with associated hydroxyl ions) and one octahedral layer of aluminum. Aluminum ions are aligned with oxygen and hydroxyl ions of the tetrahedral layer on one side and hydroxyl ions on the other side. The bond between adjacent sheets is very weak, with hydrogen bonds existing between the hydroxyl ions of one sheet and the oxygen ions of the adjacent sheet. At high temperatures, they lose water and become refractory.
It is commonly found as a product of the chemical weathering of feldspars, transported by sedimentary processes, separated from other sedimentary materials, and deposited as pure beds. Kaolinite is mined from these beds, reaching various uses without the need for refining. It is also obtained as a product of the alteration of silicates by underground hot waters in sulfide vein surroundings and also in hot springs and geysers.
It is used in pharmaceutics and in the making of refractory bricks, porcelain, and ceramics as a whitener. It is used to make porcelain vessels and in chemical porcelain for valves, pipes, and tube lamps, fittings, as linings for kilns, electrical insulators, as a pigment and filler in paints, as a roughage in plastics, as an abrasive, in ceramic glazes, as an absorbent in oil purification. Kaolin is used as a neutral colloidal pigment in paints. This powder is hydrophobic but has good compatibility in oils and many organic solvents.
Application of kaolin powder in paper production
Application of kaolin powder in glass production
The use of kaolin powder in the production of latex gloves
Application of kaolin powder in pharmaceuticals