Kaolin, or China clay, is nearly white in color. It is distinguished from other industrial clays based on its fine particle size and pure coloring. Its ability to disperse in water makes it an ideal pigment.
The primary constituent in kaolin is the mineral kaolinite, a hydrous aluminum silicate formed by the decomposition of minerals such as feldspar.
The name kaolin derives from the Chinese and means high ridge. High ridge is a reference to the hill in south-eastern China where the clay was originally discovered and used. In the 7th and 8th centuries, the Chinese were the first to use kaolin to make porcelain. It was not until centuries later that other areas of the world could duplicate the process.
The white color of the mineral can either be naturally occurring or can result after processing which removes minerals and other color-bearing compounds. The small particle size of the mineral contributes to its white color by scattering light.
Although kaolin is found throughout the world, deposits with suitable whiteness, viscosity, and other favorable characteristics are rare. Ironically, the best deposits are not located in China. The United States has high-quality deposits in the Southeast. The mineral has been mined since colonial times in Georgia and South Carolina. Other valuable deposits are located in Brazil and the United Kingdom.
Uses of Kaolin
- Paper Industry:
It serves as a paper coating that improves appearance by contributing to brightness, smoothness, and gloss. It also improves printability. Additionally, it is used by the paper industry as a filler reducing cost and the use of tree-based resources.
- Porcelain and Tableware:
As a valuable component in China and other tableware. Its color, gloss, and hardness are ideal characteristics for such products.
- Other Uses:
Kaolin has a variety of other uses in products including paint, rubber, cable insulation, specialty films, and fertilizers. also, Kaolin is used in ceramics, medicine, as a food additive, toothpaste, a light diffusing material in white incandescent light bulbs, and cosmetics. Until the early 1990s, it was the active substance of anti-diarrhea medicine.
Kaolin in Egypt
Sinai Peninsula (Abu Zenima (southwestern part of central Sinai)
Kaolin layers are found in Abu Zenima area as alternative layers with thick layers of sandstone. Kaolin layers range in thickness from 1 to 4.5 meters. Where sandstone layers range from10 to 20 meters. Reserve estimated in Abu Zenima area is about 16.5 million tons. New deposits of kaolin have been discovered at El – teeh plateau, about 25 km to the east of Abu Zenima city. The reserve, which has been explored in this area is about 88 million tons. Kaolin in Abu Zenima area uneven aluminum oxide ratio from region to the region between 20 to 36%.
in the Kalabsha area southwest of Aswan city, Kaolin has been exploited in the regular refractories industry. Reserve estimated in this area is about 16.5 million tons of kaolin. Ranging alumina by 29% to 35%.
Abo Eldarag area (south of Suez – Zafarana).
Kaolin in lower quality of the Sinai Peninsula. Ranging alumina by 22% to28%.