Differences Between Active Kaolin and Calcined Kaolin
Production Process
Calcined Kaolin: It is produced by heating natural kaolin to 400°C–1000°C in a kiln for dehydroxylation and crystal transformation. This process removes bound water, organic impurities and volatile components from raw ore, forming a relatively stable metakaolin structure.
Active Kaolin: It is usually prepared by further modifying calcined kaolin through acid leaching, surface grafting or chemical activation treatment. This process creates a large number of active hydroxyl groups and adsorption sites on the basis of calcined kaolin, significantly enhancing its chemical reactivity.
Core Properties
| Item | Calcined Kaolin | Active Kaolin |
|------|-----------------|---------------|
| Whiteness | Usually 85%–95%, with high purity and uniform color | Slightly lower than calcined kaolin, generally 80%–90% |
| Chemical Activity | Medium, with stable structure and low surface reactivity | Extremely high, with strong adsorption and ion exchange capacity |
| Oil Absorption | Medium, suitable for general filling scenarios | High, with excellent adsorption performance for pigments and impurities |
| Purity | Low impurity content, stable physical and chemical properties | Contains a large number of active sites, with strong chemical responsiveness |
Main Applications
Calcined Kaolin: Widely used as a functional filler in papermaking coating, high-grade paint, rubber products and electronic insulating materials. It can significantly improve the opacity, wear resistance and electrical insulation of products, and is the most mainstream high-grade kaolin product in the industrial field.
Active Kaolin: Mainly used in petrochemical catalyst carriers, sewage treatment heavy metal adsorbents, food industry impurity removal and pharmaceutical excipient scenarios. Its strong adsorption performance can efficiently remove trace impurities in oil, water and chemical systems, and it is a high-value functional kaolin product.