Time:2022-02-12
Brightness and whiteness are important criteria for evaluating the quality of kaolin, especially for paper coating grade kaolin, its brightness/whiteness directly affects the optical properties of paper. It can be found from the Chinese kaolin product standard that the standard specifies whiteness but not brightness. This is because the brightness (Brightness) commonly used in foreign paper and clay industries is often translated as whiteness in China. Therefore, the accurate use of terminology, to distinguish concepts, to promote the international standardization of measurement.
The machines for kaolin grinding kaolin powder include kaolin micro powder grinding (usually using Raymond mill) and kaolin ultra-fine grinding (there are two types of ultra-fine vertical mill and ultra-fine ring roller mill). Kaolin micro-grinding uses a Raymond mill to produce mostly 80-mesh to 400-mesh powders, while kaolin ultra-fine grinding produces 325-mesh-3000-mesh kaolin fine powders.
So what is the necessary relationship between the kaolin mill and the whiteness and brightness of the kaolin? The machine for grinding kaolin powder just grinds the calcined kaolin into powder.
As for the whiteness and brightness of kaolin, people in the industry explained that whiteness is one of the main parameters of kaolin’s technological performance, and kaolin with high purity is white. The whiteness of kaolin is divided into natural whiteness and whiteness after calcination. For ceramic raw materials, the whiteness after calcination is more important, and the higher the calcination whiteness, the better the quality. The ceramic technology stipulates that drying at 105°C is the grading standard for natural whiteness, and calcining at 1300°C is the grading standard for calcining whiteness. Whiteness can be measured with a whiteness meter. A whiteness meter is a device that measures the reflectance of light with wavelengths of 3800-7000. In the whiteness meter, compare the reflectance of the sample to be tested with the standard sample (such as BaSO4, MgO, etc.), that is, the whiteness value (for example, the whiteness 90 means equivalent to 90% of the reflectance of the standard sample). Brightness is a process property similar to whiteness, which is equivalent to whiteness under 4570 ? wavelength light irradiation. The color of kaolin is mainly related to the metal oxides or organic matter it contains. Generally, it contains Fe2O3, which is rose red and brownish yellow; contains Fe2+, which is pale blue and pale green; contains MnO2, which is pale brown; contains organic matter, which is pale yellow, gray, blue, and black. The presence of these impurities reduces the natural whiteness of kaolin, and iron and titanium minerals also affect the calcined whiteness, causing stains or scarring in porcelain.
Shanghai joyal mining machine is a crusher mill manufacturer. The kaolin powder mill produced by joyal mining machine has a unique crushing cavity structure and advanced grading device to realize ultra-fine powder processing.