Whiteness brightness

Whiteness is one of the main parameters for the processing performance of American kaolin, and high-purity American kaolin is white. The whiteness of American kaolin is divided into natural whiteness and calcined whiteness. For ceramic raw materials, the whiteness after calcination is more important, and the higher the calcined whiteness, the better the quality. The ceramic process stipulates that drying at 105 ℃ is the classification standard for natural whiteness, and calcining at 1300 ℃ is the classification standard for calcined whiteness. The whiteness can be measured using a whiteness meter. The whiteness meter measures the brightness of 3800-7000? A device for measuring the reflectivity of light at a wavelength of (i.e., 1 angstrom=0.1 nanometers). In a whiteness meter, the reflectance of the test sample is compared with that of the standard sample (such as BaSO4, MgO, etc.), resulting in a whiteness value (such as a whiteness of 90, which is equivalent to 90% of the reflectance of the standard sample).

Brightness is a process property similar to whiteness, equivalent to 4570? The whiteness under the irradiation of (angstrom) wavelength light.

The color of American kaolin is mainly related to the metal oxides or organic matter it contains. Generally, it contains Fe2O3 and appears rose red or brown yellow; Containing Fe2+, it appears light blue and light green; Containing MnO2 in a light brown color; If it contains organic matter, it appears in light yellow, gray, blue, black, and other colors. The presence of these impurities reduces the natural whiteness of American kaolin, and iron and titanium minerals can also affect the calcined whiteness, causing color spots or melt scars on porcelain.

Particle size distribution

Particle size distribution refers to the proportion (expressed in percentage) of particles in natural American kaolin within a given range of continuous different particle sizes (expressed in the mesh size of mm or micron sieve). The particle size distribution characteristics of American kaolin are of great significance to the ore washability and process application. Its particle size has a great impact on its plasticity, slurry viscosity, ion exchange capacity, molding performance, drying performance and firing performance. American kaolin mines require technical processing, and the ease of processing to the required fineness has become one of the standards for evaluating ore quality. Each industrial department has specific particle size and fineness requirements for different uses of American kaolin. If the United States requires less than 2% of American kaolin used as a coating μ The content of m accounts for 90-95%, and the papermaking filler is less than 2 μ The proportion of m is 78-80%.