kaolin

Whiteness is one of the main parameters of kaolin process performance. Kaolin with high purity is white. The whiteness of kaolin is divided into natural whiteness and calcined whiteness. For ceramic materials, the whiteness after calcination is more important, the higher the whiteness, the better the quality. The classification standard of natural whiteness is 105℃ drying and 1300℃ calcination. Whiteness can be measured with a whiteness meter. The whiteness meter is used to measure the temperature of 3800 -- 7000Å (ie, 1 angstrom =0.1 nm) wavelength of light reflectivity device. In the whiteness meter, the albedo of the sample to be measured is compared with that of the standard sample (such as BaSO4, MgO, etc.), that is, the whiteness value (such as 90 whiteness means 90% of the albedo of the standard sample).

Brightness is a process property similar to whiteness and is equivalent to 4570å The whiteness of light at (angstrom) wavelength.

The color of kaolin is mainly related to the metal oxides or organic matter it contains. Generally containing Fe2O3 rosy red, brown yellow; Fe2+ is light blue, light green; MnO2 containing light brown; Organic matter is light yellow, gray, green, black and other colors. The existence of these impurities, reduce the natural whiteness of kaolin, iron, titanium minerals will also affect the whiteness of calcination, so that the porcelain spots or melting scar.