Hydrated kaolin, also known as hydrous kaolin or water-washed kaolin, is a type of kaolin clay that has been processed to remove impurities and excess water content. It is characterized by its fine particle size, high brightness, and excellent rheological properties, making it suitable for various industrial applications.
The process of manufacturing hydrated kaolin typically involves the following steps:
- Mining: The raw kaolin clay is mined from natural deposits using methods like open-pit mining or underground mining.
- Beneficiation: The mined kaolin clay undergoes beneficiation processes to remove impurities such as sand, quartz, iron oxides, and organic matter. These impurities can affect the quality and properties of the final product.
- Washing: The beneficiated kaolin clay is washed with water to remove soluble salts and other water-soluble impurities. This washing process helps to further purify the kaolin and reduce its mineral content.
- Classification: The washed kaolin clay is then classified or fractionated based on particle size using methods such as sedimentation, centrifugation, or hydrocycloning. This step helps to control the particle size distribution and improve the consistency of the final product.
- Drying: The classified kaolin clay is dried to remove excess moisture and achieve the desired moisture content for further processing. Drying can be done using methods such as spray drying, rotary drying, or flash drying.
- Milling: The dried kaolin clay is milled or pulverized to achieve the desired particle size distribution and fineness. This step helps to enhance the performance and applicability of the kaolin in various applications.
- Packaging: The processed hydrated kaolin is then packaged in bags, bulk containers, or other suitable packaging formats for distribution and sale to customers.
Uses of hydrated kaolin:
- Paper Industry: Hydrated kaolin is widely used as a filler and coating pigment in the paper industry to improve the opacity, brightness, printability, and ink receptivity of paper products.
- Ceramics Industry: It is used as a raw material in the production of ceramics, porcelain, and refractory materials due to its high alumina content, fine particle size, and white color.
- Paints and Coatings: Hydrated kaolin is used as an extender and functional pigment in paints, coatings, and adhesives to improve rheological properties, opacity, and durability.
- Plastics and Rubber Industry: It is used as a filler and reinforcing agent in plastics, rubber, and polymer composites to enhance mechanical properties, dimensional stability, and surface finish.
- Cosmetics and Pharmaceuticals: Hydrated kaolin is used in cosmetic formulations such as skincare products, powders, and creams for its absorbent, bulking, and texturizing properties. In pharmaceuticals, it is used as an excipient in tablet formulations.
- Agrochemicals: It is used as a carrier or inert ingredient in agrochemical formulations such as pesticides, herbicides, and fertilizers to improve dispersion, adhesion, and efficacy.
Overall, hydrated kaolin is a versatile industrial mineral with a wide range of applications across various industries due to its unique properties and performance benefits.