Development of mica industry in China

(Beijing Anpu New Material Development Company, Beijing 102308)

Mica has many excellent properties and is an indispensable and irreplaceable important material in electrical industry. Over the past decades, China's flaky mica, mica paper, mica powder, mica reinforced plastics, pearlescent mica pigments, refractory mica tapes and other products have developed rapidly and achieved gratifying results.

In order to supplement the shortage of natural mica resources and provide high-quality mica, China has researched and developed synthetic mica and its products. With the continuous decrease of mica resources, the development and utilization of mica resources will shift to broken mica products in the future. Improving the utilization rate of mica resources, improving product quality and developing new mica products are the problems that mica industry should pay attention to in the future.

Mica; Broken mica; Synthetic mica; Comprehensive utilization; Current situation; Development.

About the author: Dai, male, senior engineer; Engaged in comprehensive utilization and deep processing of mica (synthetic mica) and research and development of ultrafine processing of mineral powder. Tel: 0 10-88 130582.

Mica has become an indispensable and irreplaceable important material in electrical industry because of its excellent dielectric properties, mechanical properties, heat resistance, corona resistance and stable chemical properties. The traditional method of mica processing and application technology is to directly use the natural crystal of mica as electrical insulation or electronic parts. With the continuous reduction of mica resources in nature and the deepening of people's understanding of mica's strategic position, the structure of mica products has changed greatly, and all countries in the world have turned their attention to the development and utilization of mica minerals such as broken mica. At the end of the 20th century, the application of sericite also developed greatly. In order to meet the different requirements of national economic development for mica products, China developed internal thermal mica synthesis and seed mica synthesis in the 1960s [1, 2].

First, the current situation of mica resources in China

The industrial raw material mica resources in China are insufficient. Muscovite is mainly distributed in Xinjiang, Sichuan, Inner Mongolia, Henan, Yunnan, Qinghai, Shaanxi, Hubei, Hunan, Guangdong, Guangxi, Fujian, Jiangsu, Heilongjiang, Jilin, Liaoning, Shanxi, Hebei and other provinces. There are few phlogopite resources in China, mainly distributed in Xinjiang, Inner Mongolia, Jilin, Heilongjiang, Henan, Guangdong and other provinces.

Table 1 mica import and export volume (t)

China has three state-owned mica raw material bases in Sichuan, Xinjiang and Inner Mongolia. At present, due to the decrease of mica resources and the increase of mining cost, the Inner Mongolia base no longer exists. The industrial structure of mines in Sichuan and Xinjiang has been adjusted, and a small number of people have stayed in mines and turned to small-scale mining. There are some enterprises in other provinces, but they still can't meet the demand of domestic mica processing industry.

Metamorphic gneiss in China is rich in muscovite resources. According to the data, the proven reserves of muscovite resources in Pingshan County and Lingshou County, Hebei Province, China are 2000× 104t, which is the largest fragment muscovite deposit in China. Moreover, mica minerals have good peelability, pure texture, no spots and bright colors, and enjoy a high reputation at home and abroad.

China is also rich in sericite, which is distributed in Sichuan, Fujian, Anhui, Inner Mongolia, Zhejiang and other provinces. According to the general survey, the reserves of soft sericite in Anhui alone are 10× 104t, and the reserves of hard sericite are100x104t.

In order to make up for the shortage of raw materials in domestic mica processing industry, tens of thousands of tons of mica and broken mica are imported every year for flake mica processing and mica paper and mica powder production.

Second, the current situation of mica processing industry in China

(A) China mica processing and product application structure

The structure of mica processing and product application in China is shown in figure 1.

Figure 1 Structure diagram of mica processing and product application in China.

In order to make up for the shortage of mica resources in China and meet the needs of some special purposes, China began to develop and synthesize mica in the early 1960s, and in the mid-1960s, it successfully synthesized mica by internal heating method and seed method. Although there are many kinds of synthetic mica, the synthetic mica that can be made into large sheets and industrially produced at present is fluorophlogopite. The molecular formula is [kmg3 (aesi3o 10) f2].

Synthetic mica has the same uses as natural mica, but many properties of synthetic mica are better than natural mica. For example, it has high temperature resistance up to 1 100℃, high electrical insulation, acid and alkali corrosion resistance, extremely low high temperature vacuum outgassing and high light transmittance, so it also has some special uses.

(2) flaky mica

Flake mica includes muscovite, phlogopite and synthetic fluorophlogopite. Flake mica is made from industrial raw material mica by stripping. The effective area is generally required to be above 4cm2.

With the decrease of flaky mica resources and the development of broken mica development and utilization technology, there are fewer and fewer fields for direct application of flaky mica. However, at present, no natural mineral material has all the excellent properties of mica, and flaky mica still has a wide range of uses.

In the electrical industry, mica is used as insulation material for generators and motors, insulation components for high-voltage electrical equipment, and heat-resistant insulation materials for various industrial and household appliances. The thermal stability of phlogopite is obviously better than that of muscovite, and it is more suitable for heat-resistant and heat-insulating materials.

In the electronics industry, mica can be made into brackets, capacitors, insulators and so on. All kinds of electronic components. Such as the production of electronic computers, electron microscopes, electronic oscilloscopes and other components.

In aerospace and other advanced scientific and technological fields, mica can be used to manufacture spark plugs and gaskets of aircraft engines, valves of oxygen cylinders for pilots, insulating parts in radar lines, large-capacity capacitor chips and electron tubes for satellites and missiles.

In addition, mica sheet can also be used to make diaphragm in oxygen respirator, protective lining of heat-resistant water level gauge, panel and capacitor of large gyro compass, and insulating gasket and terminal board of various household appliances, motors and generators.

After 1970s, mica sheets were gradually replaced by mica paper and products. The sales market of mica is shrinking day by day, and the world market is decreasing at a rate of 3% every year.

With the development of synthetic mica technology in China, the output of synthetic flake mica will increase, which will make up for the shortage of natural high-quality mica flakes in China.

(3) Broken mica

Broken mica refers to mica minerals (mainly muscovite and phlogopite) whose flake diameter or other indexes can't reach the industrial indexes of flake mica; Second, it refers to the leftover materials after the processing of flaky mica; The third refers to metamorphic gneiss muscovite and sericite, which are mainly used to make mica paper and mica powder.

Broken mica, like flaky mica, has many excellent physical and chemical properties, so it is widely used in industry.

The research on comprehensive utilization of broken mica in China began with 1958. Firstly, mica powder paper was studied, and dry grinding mica powder and recycled mica paper were developed in 1960s. In 1970s, large-scale recycled mica paper was developed, and synthetic mica paper was trial-produced. In the 1980s, wet ground mica powder and mica titanium pearlescent pigment were developed. According to the needs of insulating material industry, mica paper and synthetic mica paper for fire-resistant mica tape were trial-produced in 1990s, and mica functional fillers (such as insulation, reflection, sun protection, corrosion resistance, etc. ), mica glass-ceramics and mica ceramics have been developed successively.

(4) mica paper

Mica paper is made by crushing broken mica into fine scales through a special process and rolling on a mica paper machine. It is the raw material for making mica plates, mica foils, mica tapes and other electrically insulating mica products.

There are three kinds of mica paper: mica paper, phlogopite paper and synthetic mica paper (also called synthetic fluorophlogopite paper).

At present, mica paper has excellent properties of flake mica. The thickness of mica paper is uniform, the dielectric strength changes little, and the corona initial voltage is high and stable. Based on mica paper (or mica), electrical insulation mica products with different heat-resistant grades such as mica tape, soft mica board, plastic mica, commutator mica board, electric mica board, mica mat board, mica foil and mica tube are widely used in industrial fields such as large and medium-sized motors, special motors, electrical appliances, wires and cables.

Since mica paper was put into production in the early 1960s, with the joint efforts of scientific research institutes and production enterprises, technology and production have made great progress. By 2006, it will reach 15000 t/a, and the variety will also increase from single MPM 1 mica paper to MPM2, MPM3, MPP4 mica paper, 5 10 mixed mica paper, 51capacitor mica paper and synthetic mica paper.

Mica paper is mainly supplied to the domestic market, but also exported to some extent, mainly to the United States, Germany and other countries.

At present, China mica paper is mainly produced in Hubei Province (Tongcheng County), Hunan Province (Pingjiang County), Guangdong Province (Shenzhen City), Zhejiang Province (Hangzhou City) and Hebei Province (Baixiang County).

(5) mica powder

Mica powder is made of crushed mica, metamorphic gneiss mica and sericite through purification, crushing and classification. According to different production methods, it can be divided into dry grinding mica powder and wet grinding mica powder.

Mica powder has the advantages of high electrical insulation, heat resistance, acid and alkali corrosion resistance and small thermal expansion coefficient. No matter how broken it is, it is flaky, with good elasticity and toughness. Mica powder has good sliding performance, good coverage and high adhesion.

8 ~ 12 mesh mica powder is mostly used for roofing materials such as linoleum and cable cladding and similar purposes. Mica powder of 40 ~ 60 mesh is used for covered electrode coating. 60 ~ 120 mesh mica powder is the basic raw material for producing mica ceramics. /kloc-mica powder with 0/00 mesh or less is used as a mixture of paint, filler, covering agent and lubricant for rubber, filler for plastics and coatings, etc. Mica powder of 200 mesh or less can be used as the base material of mica pearlescent pigment.

Mica powder is also used as a material for drilling closed wells in oil wells, as a model coating for metal casting, as a polishing agent for aluminum products, as a filler for degreasing agent in electroplating bath coating, as an additive for antifreeze and sunscreen paint, and as an admixture for sealing paint ash. Dry mica powder can be used as suspending agent for fire extinguishers in fire fighting equipment.

Since the dry-grinding mica powder was put into production in 1960s, there have been dozens of production enterprises with annual production capacity exceeding 20× 104t (there are dozens of enterprises with annual production capacity exceeding 10× 104t in Lingshou County, Hebei Province alone). At present, the national actual annual output is above100000 tons, of which Lingshou County accounts for about 75% of the national total output. The main raw material is metamorphic gneiss mica.

Wet grinding mica powder is made of mica as raw material and water as medium. Compared with dry-milled mica powder, it has better performance, pure texture, smooth surface, large diameter-thickness ratio and strong adhesion. Widely used in mica pearlescent pigment substrate, mica reinforced plastics, paint and coating industries.

(6) Mica ceramics

Mica ceramics can be divided into natural mica ceramics and synthetic mica ceramics. Natural mica ceramics are also called mica glass, and synthetic mica ceramics are also called ceramic plastics.

Mica ceramics are made by mixing mica powder (natural mica powder or synthetic mica powder) with special glass powder, mineralizer and flux in a certain proportion, and then pressing, roasting, molding (hot pressing or injection), annealing and other processes. It is a composite material that combines the advantages of mica, ceramics and plastics.

Mica ceramics is an excellent insulating material with good arc resistance. It does not carbonize and burst under strong arc, and can be used for a long time below 350℃. Its thermal expansion coefficient can be adjusted according to needs, and it can be combined with some metals for sealing and coating.

The surface of mica ceramics can be plated with copper, silver, gold and other metals, which can maintain a firm bond within a certain temperature range.

The most outstanding advantage of mica ceramics is that it can be turned, milled, planed, ground and drilled with ordinary machine tools and tools to meet the precise requirements of geometric dimensions of parts.

Mica ceramics do not shrink, deform, resist corrosion, radiation and moisture after molding, and are not affected by ultraviolet rays and ozone.

Mica ceramics are mainly used as insulating parts and arc extinguishing parts in electrical equipment and precision instruments. Used in post and telecommunications, radio, aerospace, shipping, aviation and national defense industries.

(7) mica reinforced plastics-mica reinforced polypropylene

The plastic made by adding mica flake as reinforcing filler to resin is called mica reinforced plastic, which is characterized by strengthening the strength of plastic in two dimensions.

The properties of mica reinforced plastics depend on the diameter of mica flake, the ratio of diameter to thickness, the mixing ratio of mica and matrix resin, the interfacial bonding strength, molding method and molding conditions. The aspect ratio and thickness of mica scales improve the tensile strength and bending strength of plastics. The elastic modulus of mica sheet is very high in a wide range from normal temperature to high temperature, which makes the plastic size stable, creep resistance and thermal change temperature high. The shape of mica scale strengthens the plastic in the plane direction, prevents the product from warping and blocks the penetration of liquid and gas. The electrical insulation of mica improves the electrical insulation of plastics. Mica scales can also enhance the chemical stability, radiation resistance and weather resistance of plastics. The tensile strength and bending strength of mica reinforced plastics are similar to those of FRP, and the deformation temperature is higher than that of FRP. Mica reinforced plastics are widely used in automobile parts, household appliances and special plastic films.

Many scientific research units and enterprises have carried out the research and development of mica reinforced plastics, and successfully developed household appliances such as automobile dashboard, bumper, headlight protection ring, motor fan, automobile parts and audio parts. At present, due to the high price and high surface energy of wet ground mica powder, there are still some technical problems in surface organic treatment such as coating and coupling, resulting in less actual consumption of mica powder.

(VIII) Pearlescent mica pigment

Pearlescent mica pigment is a pearlescent pigment coated with one or more layers of titanium dioxide or other metal oxides on high-quality wet-ground mica sheets. Because of its stable chemical properties, non-toxicity, high refractive index, high hiding power and high temperature resistance, it can give objects pearl-like luster and give people a profound three-dimensional sense. As a filler or coating, it can greatly enhance the luminosity of the matrix and produce pearlescent effect, so it is widely used in plastics, rubber, coatings, ceramics, papermaking, leather, printing, decoration, cosmetics and so on.

The pearlescent mica pigments widely used in industry are mostly single-layer structures, that is, only a colorless transparent or colored metal oxide film is covered on the mica surface. Single-coated pearlescent mica pigment was developed earlier and the technology was mature. With the wide application of pearlescent mica pigment, the application of pearlescent mica pigment with single coating structure is limited in some special occasions because of its poor covering performance and coloring performance. For this reason, many countries have developed various multi-layer structures aimed at improving the hiding performance and organic colored pearlescent mica pigments aimed at improving the coloring performance.

Compared with the single coating, the double-coated pearlescent mica pigment is not only coated with colorless transparent metal oxide film which produces pearlescent by interference, but also has metal oxide film which absorbs color. Moreover, the pearlescent luster is strong, the hiding power is high, and there is a certain coloring power.

Multi-coating pearlescent mica pigment is further developed on the basis of double-coating pearlescent mica pigment to improve covering performance, coloring performance and pearlescent effect. It consists of a colorless and transparent metal oxide film, a metal oxide film that absorbs natural colors and a nano-level metal particle layer. Its pearlescent effect, covering performance and coloring performance have been improved.

Organic color pearlescent mica pigment is a new type of pearlescent pigment formed by coating organic pigment or dye on mica surface. It mainly uses a series of advantages of organic pigments or dyes, such as wide color spectrum, bright color, good dispersibility and high color saturation, to improve the coloring performance of pearlescent mica pigments.

Pearlescent mica pigments are produced in Shantou, Guangzhou, Taixing, Danyang, Beijing, Ya 'an and other places, with an annual output of several thousand tons. Besides self-use, it is also exported to the United States, Japan, Germany and other countries. High-grade pearlescent mica raw materials need to be imported.

(9) Synthetic mica

The synthesis of fluorophlogopite by internal heating method is made by melting chemical raw materials at high temperature and cooling and crystallizing. The seed crystal method is produced by crucible descent method with crushed synthetic mica as raw material.

The internal heating method can reach more than ten tons, which can provide large pieces of mica for direct application and a large number of broken mica for making synthetic mica paper and synthetic mica powder. Large-area synthetic mica produced by seed method can be directly used to produce electron tube supports, capacitor chips, high-resistance insulation frameworks, high-pressure boiler water level gauges, microwaves and various ray window materials.

With the development of fire-resistant wire and cable industry, especially the fire-resistant wire and cable with Class A fire resistance requirements, it is best to use synthetic mica tape made of synthetic mica paper as fire-resistant insulation layer, which will promote the development of synthetic mica through internal heating.

(10) mica tape for fire-resistant wires and cables (fire-resistant mica tape)

In 1980s, with the development of cables, some developed countries abroad began to introduce mica into the cable industry as a fire-resistant insulating layer, which made the manufacture of fire-resistant cables more simple and reliable. Therefore, major cable factories and mica processing enterprises have invested in the development and research of fire-resistant cables and mica tapes for cables.

Fire-resistant mica tape is made of mica paper, adhesive and reinforcing material on special mica tape. The mica paper used includes phlogopite paper and synthetic mica paper to ensure that the fire-resistant wires and cables meet the fire-resistant requirements of Grade B (750 ~ 800℃) and Grade A (950 ~ 1000℃). Silicone resin is generally used as adhesive, and alkali-free glass cloth or polymer film is used as reinforcing material.

Many enterprises use glass cloth for reinforcement. Due to technical reasons, the mica tape produced by some enterprises has some problems in the wrapping process, such as mica paper falling off, mica paper sticking back, stretching and low strength, which affects its use. Therefore, the quality of glass cloth and mica paper should be improved, and the manufacturing process should be improved to improve the quality of fire-resistant mica tape.

Table 2 Import and export volume of mica products and mica paper

Polymer film reinforced mica tape has been developed abroad. It is reinforced by single-sided vinyl film, single-sided polyester film, one layer of glass cloth and one layer of polyester film, and glass fiber reinforced single-sided polyester film.

The wrapping process has been greatly improved, with high dielectric properties, and the outer protective layer can be omitted.

At present, the technology of film reinforced refractory mica tape in China has also developed rapidly, and many manufacturers have tried out various film reinforced refractory mica tapes.

Third, the development direction of mica industry

With the continuous decrease of mica resources, the development and utilization of mica resources will obviously shift to the development of broken mica products in the future. We should strengthen geological exploration, increase investment in science and technology, strengthen scientific management, improve the comprehensive utilization rate of mica resources, improve product quality and develop new mica products.

(A) improve the quality of mica paper, increase the variety of mica paper

1. Improving the quality of mica paper

At present, the insulation of large motors in China is mainly multi-mica powder tape, and MPM 1 mica paper is the main base material of multi-mica powder tape. The domestic multi-mica powder tape insulation generally has the problem of low mica content. The mica content in mica powder belt is generally 38% ~ 42%, and the highest is 44%. The main insulation is thicker than that of foreign countries (about 10%). In foreign countries, most of them are single-sided reinforced mica tapes with mica content between 48%-5 1%. High mica content can reduce the insulation thickness of motor and improve the reliability of motor.

Therefore, in order to develop F-class multi-mica powder tape with high mica content and produce high-quality mica paper, mica paper manufacturers must increase the thickness of mica paper. To improve the electrical strength of mica paper and stabilize the soaking time, it is necessary to find a good process control point between them: preparing materials, strictly controlling pulping process, purifying water quality and improving the dewatering function of paper machine, which is the guarantee for producing high-quality mica paper.

The mica tape with less glue is characterized by low glue content (about 6% ~ 10%), no volatile matter and mica content as high as 82%. Because of the vacuum impregnation process, the production efficiency is high, the insulation performance is high, and the bar is not hollow, but the requirements for production equipment, materials and management are very high.

Because the installation size of electric locomotive traction motor is limited by the railway gauge and the height of locomotive bogie, F-class and H-class heat-resistant mica tapes are used at home and abroad to achieve the purpose of small size, light weight and large capacity of traction motor and improve the output power of motor.

Marine motors generally work in the environment of high temperature, high humidity, oil pollution and impact vibration, which requires small volume, light weight, low repair rate and long service life. After more than ten years' development, China has formed a relatively perfect insulation system for marine F-class motors, and the power of large marine propulsion motors has reached more than 5000 kW, which meets the needs of various ship types.

One-sided reinforced mica tape is the main insulating material of traction motor and marine motor. MPM3 large mica paper is the main substrate of single-sided reinforced mica tape. Compared with foreign countries, there is still a gap between domestic mica tapes, mainly in powder dropping, low hardness and electrical properties. The production of single-sided reinforced mica tape requires mica paper with good permeability, high dielectric strength, no impurities, good tensile strength, large and thin mica scales, good uniformity and no broken ends. Therefore, mica paper manufacturers should actively cooperate with insulating material factories to improve the quality of mica tape to meet the demand of China motor manufacturing industry.

2. Develop phlogopite paper and synthetic mica paper steadily according to domestic resources and market demand.

Commutator mica board not only has special requirements such as elastic compression and plastic deformation, but also needs to withstand the test of short-term high-temperature welding. Silicone commutator mica plate made of mica paper is widely used. Practice has proved that the mica board of silicone commutator has the advantages of high temperature resistance, high mechanical strength and improved process level. If it can be popularized and applied, it will certainly promote the development of phlogopite paper.

In addition to non-diffusion combustion, fire-resistant wires and cables also need to ensure their working ability when they are on fire. With the rapid development of nuclear power plants and substations in China and the further implementation of the Fire Protection Law, the fire-resistant mica tape will be used as the protective layer of fire-resistant wires and cables. Fire-resistant cables have developed greatly in recent years, so the demand for phlogopite paper and synthetic fluorophlogopite paper will also increase greatly.

At present, the cost of synthetic mica in China is relatively high, so the price is relatively high, which affects its application. Therefore, selecting lower-priced industrial raw materials, improving technology and reducing power consumption are the fundamental measures to expand its application.

3. Continue to develop aramid fiber mixed mica paper.

Polyacrylamide fiber can improve the tensile strength, corona resistance, impregnation and cut-through resistance of mica. This kind of fiber reinforced blended mica paper can be used not only for less adhesive tape and imine film composite tape, but also for more adhesive tape. After aging at 2 10℃, the breakdown voltage (ratio) is much better than that of mica paper prepared by traditional methods, which completely overcomes the problem of powder dropping and can also improve the tensile strength of capacitor mica paper, which will be welcomed by users.

(2) increase investment in science and technology to improve the production technology and equipment level of mica powder.

The production of mica powder abroad has a long history, and advanced complete sets of technologies and equipment such as grinding, grading, drying, testing and packaging have been developed, which can produce mica powder with various particle sizes and different uses.

The production of wet ground mica powder in China lags far behind the advanced level abroad in key equipment and detection means. Aiming at the problems existing in the production of high-grade wet-milled mica powder, we should focus on developing technologies and equipment suitable for the production of high-grade wet-milled mica.

(three) according to the different uses of mica products, rational development and utilization of resources.

Like other mineral resources, mica is non-renewable. There are limited resources of high-quality muscovite and phlogopite in pegmatite in China, but abundant resources of muscovite and sericite in metamorphic gneiss. Rational development and utilization of mica resources is of strategic significance to the sustainable development of mica industry in China in the 2nd1century.

The quality of mica raw materials directly affects the final quality of mica products. However, we often ignore how to choose different types of mica raw materials for mica products. Due to different geological conditions, the chemical composition and physical properties of mica are quite different. Choosing suitable mica raw materials according to the use of mica products can get twice the result with half the effort. According to the quality requirements of the application field, metamorphic gneiss mica is selected as raw material, which not only makes full use of metamorphic gneiss mica, but also saves some raw materials suitable for producing pearlescent wet-grinding mica powder and mica paper. Due to the low cost of raw materials for metamorphic gneiss mica, both supply and demand sides benefit.

China's heat-resistant mica board for household appliances accounts for 60% of the total output of mica paper in China every year. According to the requirements of home appliances for the physical properties of mica board, it is necessary to further test and analyze the chemical composition and physical properties of metamorphic gneiss mica to replace pegmatite mica. If this is feasible, the cost per ton of raw materials can be reduced by 50%, which will produce huge economic benefits; At the same time, it can also improve the protection of existing pegmatite mica resources to national economic construction, strongly support the development of electrical industry, optimize the utilization of superior minerals and comprehensive utilization of inferior minerals, and rationally utilize limited mica resources.

In 2000, the Science and Technology Education Committee of the former State Building Materials Bureau invited Russian mica experts to inspect the raw materials of metamorphic gneiss and some mica processing enterprises in Hebei Province, China, and brought back the metamorphic gneiss mica from Lingshou County, Hebei Province for experiments. It is reported that gneiss mica from Hebei Province, China can be used to process higher-grade mica powder.

(4) Study on reinforcing refractory mica tape with reinforcing film.

The refractory mica tape is reinforced with film. During the combustion test, the film has decomposed and volatilized at low temperature, and no carbon deposit will be formed. Mica decomposes and volatilizes before expansion, so it is not easy to damage the mica layer, so it can pass the fire resistance test.

The invention not only improves the quality of the refractory mica tape, but also reduces the cost and improves the manufacturability and reliability of the cable.

China has also studied and developed the film reinforced fire-resistant mica tape for many years, and it has been successful in many enterprises. In the future, we should increase the specifications and varieties, improve the quality and better meet the requirements of wire and cable technology.

At present, foreign countries have shifted the focus of mica resource utilization to non-electrical application materials. For example, nearly 60% of total mica consumption in the United States is used in the field of building materials. At present, there is little research and application of mica resources in China, especially in building materials, and the research work in this field should be strengthened in the future.

refer to

[1] Feng Xiaohua. Mica minerals will become a new bright spot of mineral materials in this century. Development and Application of Non-metallic Minerals .2005 (2)

[2] Fu Dong. Broken mica minerals in shijiazhuang, hebei province and their development countermeasures. Development and Application of Non-metallic Minerals.2005 (4)

Development Status of Mica Industry in China

Dai weisheng

(Beijing Anpu New Materials Company, Beijing 102308)

Abstract: Mica has many excellent properties and is an indispensable and irreplaceable important material in electrical industry. Over the past decades, mica products such as mica sheet, mica paper, mica powder, mica reinforced plastics, pearlescent mica and refractory mica tape have developed rapidly and achieved gratifying results.

In order to supplement the shortage of natural mica resources and supply high-quality mica, China has done a lot of work in the research and development of synthetic mica and its products. With the continuous decrease of natural mica resources, the development and utilization of mica resources in China will point to the production of waste mica products in the future. In the future, we should pay attention to improving the utilization rate of mica resources, improving product quality and developing new mica products.

Key words: mica, waste mica, synthetic mica, comprehensive utilization, present situation and development.