Kaolin - White Clay for Ceramics and Composites

Kaolin (CAS 1332-58-7): Overview

1. Mineralogy Basics

The main mineral of kaolin is kaolinite, whose layered structure determines its plasticity and formability. The purity of kaolin is determined by the absence of impurities (iron oxides that color the clay).

2. Properties

Chemical composition: Al₂Si₂O₅(OH)₄ (predominantly)

Appearance: White powder of various fractions

Density: ~2.6 g/cm³

Thermal transformations: Upon firing, converts to metakaolin, then to more stable phases

Solubility: Insoluble in water, but capable of retaining moisture

3. Applications

Building materials: Cement mortars, where kaolin improves plasticity.

Polymer composites: Mineral filler that increases mechanical resistance.

Cosmetic innovations: Microsponges are being developed for absorbing sebum and impurities.

Paper, paints, and ceramics: Traditional uses as a filler, coating pigment, and ceramic body component.

Pharmaceuticals: Used as an excipient and adsorbent in medicinal formulations.

4. Safety and Occupational Health

Dust: Constant inhalation of dust may lead to forms of pneumoconiosis; respiratory protection is required.

Quality control: Batch homogeneity and the absence of large inclusions affecting the final product are important.

5. Conclusion

Kaolin (CAS 1332-58-7) is valued for its chemical inertness and high whiteness. Its use covers traditional (ceramics, paper) and advanced (nanocomposites, cosmetic preparations) applications. Deep processing and firing provide additional functional application possibilities.