Particle size distribution refers to the proportion (expressed as percentage) of particles in natural kaolin in a given continuous range of different particle sizes (expressed as mesh mesh in millimeters or microns). The size and distribution of kaolin particles have great influence on its properties and applications. Such as viscosity, specific surface, fluidity, adhesion, covering force, brightness and the difficulty of processing and purification, sintering shrinkage, sintering hardness, chemical catalytic activity and so on are related to particle size and shape. Kaolin ore needs to be processed by technology, and whether it is easy to be processed to the required fineness has become one of the criteria to evaluate the quality of ore.
Kaolin powder body is a collection of statistical particles whose distribution varies with powder manufacturing process or natural formation process. Due to many influencing factors, particle size measurement and particle size distribution are very complicated. For example, an experiment shows that after calcination, the particle size of coal-measure kaolin changes, and the change range of fine particle composition is significantly higher than that of coarse particle composition. The particle size measurement methods of kaolin include laser method, sedimentation method, photon cross correlation spectroscopy method, sifting method, microscope method, ultrasonic particle size analysis method, X-ray small Angle diffraction method and so on.
Various industrial departments have specific requirements on the granularity and fineness of kaolin for different uses. For example, the content of kaolin less than 2μm used as coating in the United States accounts for 90-95%, and that of papermaking filler less than 2μm accounts for 78-80%. China requires that the content of kaolin less than 10μm for coatings be more than 70%, and that of papermaking fillers less than 2μm be more than 70%.
The content of less than 2μm of kaolin from our company can reach 85-86%. The particle size distribution diagram is obtained by using laser method as follows: