Uses of Kaolin

Kaolin is a natural layered silicate dominated by kaolinite group minerals, the main component of which is hydrous aluminium silicate (Al₂O₃-2SiO₂-2H₂O), which is calcined to remove hydroxyl groups and form inorganic materials with high activity and whiteness. Calcined kaolin is the sintering of kaolin to a certain temperature and time in the calciner to make its physicochemical properties to produce certain changes to meet certain requirements.

Calcined kaolin main application areas and characteristics

1. Used in coating and paint industry

Calcined kaolin can replace 30%-60% of titanium dioxide, significantly reducing the cost of raw materials. Kaolin has excellent properties such as high chemical stability, high hiding power, high whiteness, good dispersion and suspensibility, which makes it occupy a large market share in the paint and coating industry. Meanwhile, the specific surface area of calcined kaolin will be increased accordingly, and the absorption capacity of ink will be increased. In addition, calcined kaolin is more resistant to brushing than uncalcined one, and it is more effective to be applied in exterior paint. It can be said that calcined kaolin makes kaolin with more good performance, making paints and coatings become the largest consumer market of calcined kaolin in China, especially high-grade coatings. At present, high whiteness quality calcined kaolin is used in large quantities in high-grade paints.

2. Used in plastics and rubber industry

In engineering plastics (e.g. PVC cable), calcined kaolin is filled up to 20%-40%, and as a reinforcing agent, it can improve the tensile strength, heat resistance and electrical insulation of the products. For example, modified kaolin is used in EPDM cable accessories to enhance aging resistance and flexibility;

3. Used in paper industry

As a functional filler, calcined kaolin can increase the pore volume and thickness of paper coating, improve opacity, gloss and printability. In coated paper production, its ink adsorption reduces printing spots, and with high-speed squeegee coating process, it can reduce the amount of titanium dioxide by 20%-30%, and at the same time, improve the mechanical strength of paper and writing smoothness.

4. Ceramics and refractory industry

Clay is an essential raw material in ceramic products, used in ceramic glaze and body. Kaolin usage rate averages 25% of pottery, 60% of porcelain, 20-30% of ceramic sanitary ware, and 20% of wall tiles.