Grinding and modification of ultrafine mica powder
With the development of industry, downstream application companies have increasingly higher requirements for the quality of mica powder. Currently, muscovite powder with a D90 of about 45 μm is mainly used in papermaking, latex paint, rubber and other industries, while high-end coatings, pearlescent mica and other products are The particle size of mica powder has put forward higher requirements, and the preparation of micro-nano-level ultra-fine mica powder is urgent.
During the grinding process, muscovite can still be tightly combined along the fresh surface after interlayer cleavage. It is one of the more difficult minerals to grind. Currently, micro-nano-level muscovite ultrafine powder is difficult to prepare using conventional grinding equipment. Many domestic mica manufacturers will mine high-quality muscovite and simply coarsely grind it for export. Others will be made into muscovite products with D90 particle size of about 45μm or even coarser, resulting in a waste of resources and reducing product competitiveness.
Mica ultrafine grinding preparation
At present, the ultra-fine grinding process of mica is divided into two grinding methods: dry method and wet method. Among them: the main equipment for dry ultra-fine grinding include high-speed mechanical impact mill, airflow mill, cyclone or cyclone flow autogenous grinding machine, etc. and the corresponding dry airflow classifier; the production equipment for wet grinding sericite powder includes sand mill, grinding machine, etc. Flaking machines and colloid mills are the main ones, while wet fine classification uses hydrocyclone classification technology.
The high-speed planetary roller mill can effectively perform dry and wet grinding of mica. The median diameter of the particles after grinding can reach 10 μm or less; the mica material stays in the grinding for a very short time, generally 5-10s. ; By adjusting the roller structure, mica powder with the required diameter-thickness ratio can be obtained. Under wet grinding conditions, mica powder can obtain a diameter-thickness ratio in the range of 20-60.
The stirring mill adopts special grinding media, which has good application effect in ultra-fine peeling of mica powder without damaging the surface of mica, and can make the diameter-thickness ratio of mica powder >60.
Mica powder surface coating or modification
The surface coating or modification of mica powder can prepare pearlescent mica and colored mica pigments to improve their corresponding properties in materials such as rubber and coatings. There are also many related studies.
Mica is surface-coated to prepare pearlescent mica and colored mica pigments. Currently, the liquid phase deposition method is mainly used. Common methods include alkali addition, thermal hydrolysis, buffering, etc. Commonly used coating agent titanium sources in industry are titanium tetrachloride and titanyl sulfate.
Application of mica powder
Mica powder can be used in fields such as electrical insulation materials, functional coating fillers, rubber fillers, plastic fillers, cosmetics and welding materials.