Calcined kaolin, also known as calcined clay, is a type of kaolin that has undergone specific physicochemical changes through calcination. This process involves sintering kaolin in a calcining furnace at a certain temperature for a defined duration, altering its properties to meet specific requirements.
Kaolin, an inorganic non-metallic mixture, undergoes complex changes during calcination. Initially, water molecules, including adsorbed and structural water, are removed at temperatures ranging from 100°C to 550°C. Beyond 550°C, the dehydration process slows down until around 800°C, when residual water is completely removed. At temperatures above 925°C, the dehydrated kaolin transforms into new phases such as aluminum spinel and mullite, which further modify its structure and properties.
Calcined kaolin boasts high whiteness, strong covering power, excellent light scattering performance, low oil absorption, good suspension, strong adhesion, and high viscosity of dispersions. These characteristics make it widely used in paints, coatings, papermaking, ceramics, plastics, rubber, and electrical cables. It can enhance product performance and significantly reduce production costs. For instance, in the paper industry, calcined kaolin can partially or fully replace titanium dioxide as a filler, lowering costs while maintaining good performance.
In summary, calcined kaolin, with its superior properties and versatile applications, plays a crucial role in various industries. Its unique characteristics and wide range of uses make it an indispensable material in modern manufacturing.
