Mica is a general term for layered aluminosilicate minerals containing K, Al, Mg, Fe, Li and other metal elements. According to the compositional characteristics, the mica group minerals are divided into three subgroups, namely, muscovite subfamily, phlogopite subfamily (including phlogopite and biotite), and lepidolite subfamily (including lepidolite and iron-lepidolite). Among them, muscovite minerals can be formed under different geological conditions and are widely distributed in a variety of geological bodies. They are the most widely distributed minerals in the mica family and are also the most widely used in industrial applications.
Muscovite minerals have excellent chemical stability, are difficult to dissolve in acid and alkali solutions, and have excellent electrical insulation, resistance to various radiation, water and moisture resistance, and specific optical properties. It is widely used in cutting-edge technology fields such as electrical appliances, electronics, aviation, aerospace, and high-end coatings and paints. At present, muscovite minerals mainly include muscovite, sericite, illite, microcrystalline muscovite, etc., all of which are important industrial minerals.
(1) Flake Muscovite
Generally refers to muscovite with an effective area greater than 4cm2, which is also the most industrially valuable type of mica. It is mainly used in the electronics and electrical industries, especially as an insulating support element.
On the one hand, flake muscovite is used to produce mica capacitors, which is one of its main uses in the electronics and electrical industries. Mica capacitors have good electrical properties, heat resistance, stability and high capacity accuracy. Taking advantage of its high insulation resistance, high stability and large capacitance changes, it is widely used in aircraft and missiles.
On the other hand, the use of flake muscovite's peeling performance is better than other mica characteristics to make large flake mica paper, which is also another main use of flake muscovite.
In addition, flake muscovite is used for dust-proof and moisture-proof enclosed motor and engine armature insulation, commutator commutator insulation, motor and engine coil insulation, insulating gaskets and terminal boards. It can also be used in various equipment (such as radios, televisions, hearing aids, etc.) in some parts of the support sheet and spacer sheet and heating appliances.
(2) Fragmented Muscovite
Fragmented muscovite refers to the muscovite produced in flake muscovite scraps and pegmatite that does not meet the requirements of industrial raw materials and metamorphic rocks.
Mica powder is obtained by dry or wet pulverization of crushed mica, and different particle sizes have different uses. For example: 8～12 mesh mica powder is used to make roofing materials such as linoleum, cable coating, etc.; 40～60 mesh mica powder is used for electrode coating; 60～120 mesh mica powder is used to produce mica insulating ceramics; 100 mesh Or finer mica powder is used as a paint admixture, rubber and plastics and other insulating materials as a reinforcing filler.
Mica paper is made from crushed mica through pulping, forming, pressing and other processes. It is mainly used as an insulator for motors and electrical appliances. It is especially suitable for manufacturing insulating gaskets in large generators, wire rods in motors, and Insulating materials for coils and processing multi-glue glass powder mica tapes, soft mica plates, etc.; and because of its good insulation, high temperature resistance and long service life, the thin and thick laminates made of mica can be used for Home appliances such as electric soldering iron and electric iron. In addition, it can also be used as high temperature insulation material for air conditioners, automobiles, and armored vehicles.
●Powder Mica Tape
The powder mica tape is a ribbon-shaped soft mica material made by baking mica paper adhesive (epoxy resin, etc.) and reinforcing material (glass cloth, etc.). It has excellent electrical and mechanical properties and is suitable for large and medium-sized high-voltage motor coils. It is insulated with various types of coils.
Powder mica board, mica ceramics, insulating and anti-static pressure board, etc. are all produced with crushed mica as the main or important raw material. The powder mica board is made by baking and pressing powder mica paper and adhesive. It is flexible and plastic. It also has special commutator powder mica board, liner powder mica board, powder mica foil and powder mica board for electric heating equipment. Etc.; Mica ceramic is a composite material with mica powder and glass powder as the main raw materials, and has the excellent properties of mica, ceramics and plastics. It is also a new type of electrical insulation material; used for insulating anti-static pressure board In the synthetic diamond firing process, the repeated use rate is high and it can completely replace the traditional asbestos board.
Sericite refers to very small scale-like (generally <0.01mm) muscovite, which has excellent physical and chemical properties and can be widely used in coatings, rubber, plastics, cosmetics, ceramics and other fields. For example, the layered structure of sericite can keep the paint film from fading for a long time after the dye particles enter the lattice layer of sericite; sericite's unique flake structure can effectively improve the damping performance of rubber; in the paper industry , Adding sericite powder can increase the color brightness of the paper, improve the ability of the paper to reflect ultraviolet rays and corrosion resistance, and the paper that is stored for a long time is not easy to yellow. In the production of welding electrodes, sericite powder can be used as the coating of the welding electrodes. It prevents the cracking of the coating, acts as a solder stopper, and also imparts good lubricity and viscosity to the electrode coating.
In recent years, research on sericite is mainly used as a filler in plastic insulation materials. The development and utilization of sericite resources can make up for the shortage of flake muscovite resources and promote the development of insulating materials. It has the function of reinforcement and modification, and has good heat resistance and insulation, so it can improve the heat resistance and electrical insulation of the product, and reduce the shrinkage and warpage.
Illite was first discovered by scholar Grim in Illinois, USA in 1937. It is named after its place of origin. It is a mineral with a layered structure that contains structural water and a large amount of adsorbed water.
Microcrystalline muscovite was first discovered in China by Sichuan Xinju Mining in 1997. It is a rare high-quality muscovite resource. The microcrystalline muscovite is mostly in the form of flakes, slabs, and scales, with a certain diameter-to-thickness ratio. The mica flakes have good toughness and elasticity, high sliding ability, tensile and compressive strength, and are resistant to acid and alkali and corrosion , The coefficient of thermal expansion is small, the heat resistance is good, and it can shield ultraviolet and infrared radiation. When used as a filler in rubber and plastics, because of its special microstructure and good physical properties, it can improve the mechanical properties of polymer materials while reducing material costs. Because of its low dielectric loss, arc resistance, corona resistance, and high insulation strength, it can be used as a functional filler to improve the electrical properties of the material.
Muscovite has excellent properties and has a wide range of applications in industry. With the development of industry, relevant enterprises have higher and higher requirements for the quality of muscovite powder, and the continuous demand has caused a shortage of muscovite. Research on the development and utilization of muscovite needs to be improved.