--Another description of the production and processing technology of large-scale kaolin base in Maoming, China
Cai Jian
(Suzhou Sinoma Nonmetallic Mining Industry Design and Research Institute, Suzhou, Jiangsu 215004)
Abstract This paper describes the history of kaolin industry development in China. Taking the kaolin production in Maoming as an example, it focuses on the current development and status of kaolin in China, including resources, production and processing, technical characteristics, and product applications. Comparing the world's kaolin industrial technology, the development direction of China's kaolin processing technology and development and utilization is analyzed.
Keywords Kaolin; exploitation and utilization; technological development.
Author's Introduction:Cai Jian, Prof. Senior Engineer, Vice President of Suzhou Sinoma Nonmetallic Mining Industry Design and Research Institute. Tel: 13806219775. E-mail: fkycj@163.com.
I. Introduction
Kaolin is a very important and widely used non-metallic mineral, which is widely used in paper, ceramics, plastics, rubber, chemicals, electronics, electronics, and other industries, due to its various process properties such as plasticity, adhesion, dispersibility, refractoriness, insulating properties, and chemical stability, Plastics, rubber, chemical, electronics, paint, paint, refractory materials, military, medicine, cosmetics, pesticides and dozens of other industries.
In the mid-1980s, Chinese geologists, with the cooperation of scientific research, production and other related departments, successively discovered large kaolin deposits in Longyan, Fujian Province and Maoming, Guangdong Province, which provided resources for the development of China's paper, plastics, building materials and other industries. Kaolin in Maoming has been recognized as an important production base for high-grade kaolin for paper making in China at present, and it also promotes the overall development of kaolin industry.
China's paper industry in the "Eighth Five-Year Plan", "Ninth Five-Year Plan" period of rapid development, has introduced a number of scraper coating machine, knife speed increased to 600 m/min, 800 m/min, and even 1,200 m/min; corresponding to the Accordingly, kaolin puts forward higher quality requirements, including fineness, whiteness, viscosity, abrasion value and so on. Through the kaolin industry and the application of industry researchers *** with the efforts, technology research, China's kaolin technology has been developed comprehensively, including purification, ultrafine, modification and other certain technologies have reached the world level.
Two, the current situation of kaolin industry
(A) Kaolin reserves
China has now proved the geological reserves of kaolin 14.32 × 108t, of which 4.18 × 108t in Guangdong, 1.59 × 108t in Fujian, 1.0 × 108t in Guangxi, 1.09 × 108t in Jiangxi, 0.80 × 108t in Hunan, Jiangsu, 0.54 × 108t in Jiangsu. 0.54×108t; another coal kaolin 16.7×108t, mainly distributed in Inner Mongolia, Shanxi, Shandong, Anhui, Liaoning, Shaanxi and other provinces and regions. Maoming kaolin resources are mainly distributed in the Shangpangdang, Xiachi, Shange, Flying Mouse Ridge area, about 40-60km2 range, proven reserves of 2.8×108t, the prospect of reserves of about 8×108t. Deposit type is sedimentary weathering type, the ore body is endowed with the Pliocene Tiger Ridge Formation and the Miocene Huangniu Ling Formation in the rock layer. The natural types of ore are gravelly kaolin, gravelly sandy kaolin, sandy kaolin, etc. The industrial type is mainly sandy kaolin.
(II) Kaolin Producing Enterprises
Currently, there are more than 100 kaolin enterprises above the county level in China, and there are more than 700 township enterprises. The production capacity of raw ore is more than 300×104t, and the processing capacity is more than 70×104t. The ones with a production scale of more than 10×104t include China Kaolin Corporation, Maoming Kaolin Science and Technology Co. Ltd., Fujian Longyan Kaolin Corporation, Yankuang Beihai Kaolin Corporation, and Maoming Petrochemical and Mining Corporation. The total production of kaolin in Maoming area is about 38×104t/a, and its papermaking scraper grade kaolin production accounts for 80% of the national total production.
(C) kaolin production process
Currently China's kaolin production process is more typical: the raw ore through the removal of sand, roughing, concentrating, to get concentrating concentrate; and then horizontal spiral centrifuges for concentrates grading and selection, chemical bleaching or high-gradient iron removal; the processed products with a butterfly separator for the pre-dehydration, and then dewatering filter press; and finally by the drying tower drying, the finished product packaging measurement. Finished products are packed and measured. Ltd. as a representative of the Maoming High Ridge Technology Co., Ltd. as follows.
Maoming kaolin is a highly ordered pseudo-hexagonal flaky crystalline, fine particle size, high whiteness, low viscosity substances, has been recognized as an important raw material for the current domestic high-grade paper kaolin. Kaolin ore is crushed and dispersed under the high-pressure impact of water gun, and the slurry is pumped into the spiral classifier to remove sand, and then sorted by hydrocyclone. The number of beneficiation segments depends on the nature of the original ore, generally 2 to 4 segments. After sorting, the rough concentrate is classified into paint grade and filler grade products by decanter centrifugal classifier. Paint-grade products, after bleaching, magnetic separation, filter press, drying, packaging and then leave the factory; filler-grade products, after filter press, packaging and then leave the factory. The beneficiation process flow is shown in Figure 1.
Figure 1 Process flow diagram
The quality of kaolin products in Maoming area is shown in Table 1.
Table 1 Product quality
1. Spiral classifier to remove the sand
The quartz and feldspar in the raw kaolin ore in Maoming is coarse in size, generally larger than 325 mesh; while the kaolin is fine in size and is mainly enriched in the -2μm. The kaolin particle size is fine, mainly enriched in -2μm. In addition, from the analysis of the particle size of the raw ore can be seen: +40μm content is high, accounting for 80.01%; fine-grained content of the next level, -2μm accounted for 12.97%; and the wide range of medium-grained content, but the content is very small, 40 ~ 2μm accounted for 7.02%. Therefore, with the help of large capacity grading equipment (spiral classifier) for roughing, throw off a large number of coarse tail, while the final particle size with hydrocyclone gatekeeper. At present, the domestic general kaolin plant are only used hydrocyclone classification, so that the handling capacity is small, and because of the need to be equipped with high-pressure slurry pumps and power consumption. The use of spiral classifier sand removal, breakthrough in the existing kaolin production process mode, China's kaolin beneficiation roughing scale from the annual output of a single machine (1 to 2) × 104t, increased to a single machine 20 × 104t.
2. Horizontal screw centrifugal grading
Selective process adopts a horizontal screw centrifugal grading technology, so that the product fineness reaches -2 μm 90% or more, grading efficiency of 80%. The classification efficiency is 80% or more. Especially, it is equipped with frequency conversion speed control, which can adjust the process parameters (such as separation factor) according to different materials and keep the stability of product quality, making the kaolin grading technology reach the world level at that time.
At present, most of the domestic kaolin plant using hydrocyclone selection and classification, in the case of automatic control has not yet been realized, by the flow, pressure changes, the product quality is difficult to stabilize at -2μm 90% or more, grading efficiency is not high, and annual production capacity of 10,000 tons of the size of the plant, the workshop configuration occupies an area too large.
3. Widely promoted bleaching - iron removal technology
According to the iron, titanium physical phase analysis, the state of iron in kaolin for the two kinds of mineral iron and lattice iron, a considerable portion of mineral iron, especially the surface iron leaching pollution; so the use of chemical bleaching is the most economical, effective, and is widely used. The use of reducing bleach (such as sodium sulfite) to reduce Fe3 + into soluble Fe2 +, and then removed by washing operations. Individual kaolin processing plants use a combination of magnetic separation and chemical bleaching process to further improve the whiteness of the product and reduce the consumption of chemicals. Through magnetic separation, Fe2O3 can be reduced from 0.66% to 0.5%, and whiteness can be increased from 70% to 88%.
4. Filtering process
Domestic general kaolin enterprises originally used low-pressure filtration. Through technological research, the factory in Maoming area adopts high-pressure slurry feeding, and the pressure reaches 2~2.5MPa; it improves the productivity, ensures that the moisture of the product is lower than 35%, saves energy consumption, and also improves the working environment.
5. Adopting new drying process
The products are easy to be transported and the working environment is also improved.
Currently in the Maoming area of the manufacturers of spray and flash drying two ways are used, each with its own characteristics. Flash drying, especially after the improvement of the strong drying, adaptability in the production process, in different concentrations, materials, the amount of feed can be dried, and domestic processing and manufacturing of the equipment quality is guaranteed.
Three, kaolin application and market
(A) paper industry
China's kaolin consumption structure and foreign countries have a big difference in the amount of kaolin used for ceramics and refractories accounted for 70% to 80%, accounting for 10% of the papermaking, rubber accounted for 3%, and other industries accounted for 7%; in the developed countries of the world accounted for 60% of the amount of papermaking, refractory accounted for 8%, rubber accounted for 5%, ceramics accounted for 10%, and other accounts for 5% of the amount of paper, refractory accounted for 5%, rubber accounted for 5%, and other accounted for 10%. In the developed countries of the world, 60% of the paper, 8% of the refractories, 5% of the rubber, 10% of the ceramics, other 17%.
Since the 1990s, China's kaolin consumption from the traditional ceramic industry to the paper industry, which is due to China's paper industry in the "Eighth Five-Year Plan" period of rapid development, the successive introduction of more than a dozen scraper production line. "Ninth Five-Year Plan" period and Suzhou Zixing Paper Mill, Guangzhou People's Paper Mill, Weifang Hengxin Paper Group, Suzhou Asia-Pacific Paper Products Co. China's annual per capita consumption of paper is only 38 kg, far below the world's annual per capita consumption. At the same time, China's coated paper with high-quality coating grade kaolin has long been in short supply, every year from the United States, the United Kingdom and other countries to import. With the development of China's paper industry, the demand for high-quality coating grade kaolin is increasing.
According to statistics, China's coated paper, white paper and other paper using kaolin total more than 1,000 × 104t, the need for papermaking grade kaolin 100 × 104t; the current annual production capacity of domestic papermaking kaolin is about 50 × 104t, there is still a part of the imported kaolin; it is expected that in the next few years there will be an 8% rate of development.
(B) electric porcelain industry
China's main electric porcelain factory has more than 30, the production of various types of high-voltage insulators, various types of pipe sets, various types of lightning arrester, machine and electrical porcelain parts. With China's hydropower, nuclear power development, electric porcelain industry using kaolin about 15 × 104t.
(C) building and sanitary ceramics industry
With the rapid development of China's urban construction industry and the improvement of people's living standards, the decoration industry is becoming more and more prosperous, the current production of 18.4 × 108m2 glazed tiles, wall and floor tiles and tens of millions of pieces of sanitary wares, these products require about kaolin per year. The production of these products requires about 250×104t of kaolin per year, especially the glaze of high-grade ceramics has a great demand for kaolin and high quality requirements. Longyan kaolin company's products have been used in the glaze industry, and achieved satisfactory results.
According to the information of Light Ceramics Company, China is the main producer, user and exporter of daily-use ceramics, which needs more than 10×104t of selected kaolin annually.
(D) architectural coatings
China's paint industry is developing rapidly, the output reached 500×104t in 2006, of which architectural coatings output in 2006 was 150×104t, an increase of 20% compared with 2005; with kaolin 5% to 10%, a year of about 12×104t of kaolin. ultrafine flaked earth is especially suitable for latex paint, ICI, Lipang The famous paint brands such as manufacturers try Maoming Kaolin Corporation's products, have asked for supply, the supply falls short of demand.
(E) plastics industry
China's plastics industry since 1958, the first set of polyvinyl chloride device was put into operation has gone through 50 years of history. China's synthetic resins from scratch, from small to large, in 1990 the output reached 237 × 104t, "Eighth Five-Year Plan", "Ninth Five-Year Plan" two Five-Year Plan and 15 sets of new ethylene projects were put into operation, plastic synthetic resin production reached 500 × 104t. But according to the per capita calculation, the annual consumption quantity is very low, compared with the developed countries there is still a big gap, the plastics industry will maintain a certain speed of development. 2006, the plastic products have reached 2800×104t. kaolin in the plastics industry as a functional filler occupies an important position, it is fine particles, into the flake, tubular, able to improve the strength of the plastic products, hardness, whiteness, electrical insulation, etc.; it also has the ability to increase the diffuse light transmittance of the plastic film, and to increase the light transmission of the plastic film. It also has the function of improving the transmission rate of scattered light in plastic film and blocking infrared rays, which makes it widely used in agricultural film. Especially as a volume filler, it greatly reduces the cost of products.
(F) other industries
China has more than 200 rubber factories, the annual need for kaolin about 5 × 104t as filler. In addition, in the enamel, petroleum catalysts, molecular sieve, electronic components, plastics, paints, coatings, chemical fibers, refractories and pesticides and other industries, each year, a certain amount of kaolin, the amount of gradually increasing; some departments need to use kaolin superfine modified powder. In short, the domestic market demand for kaolin is getting bigger and bigger.
Four, kaolin development direction
(A) the perfection of the calcined kaolin process
With the rapid development of the national economy, especially in the paper industry, the national power grid renovation, communications construction and the development of the construction industry, the demand for calcined kaolin is growing and more demanding. Domestic paper, plastics, paint and other industries on the demand for calcined kaolin is about 20 × 104t, of which the demand for high-quality calcined kaolin is 10 × 104t. Due to the lack of domestic production of high-quality soil, every year, but also from the United Kingdom, the United States and other countries to import high-quality soil.
At present, although the domestic calcined kaolin products have reached the requirements of customers, the unit product investment is large, the process is complicated, the quality control is difficult, and the energy consumption is high. Suzhou Sinoma Non-metallic Mining Industry Design and Research Institute has been working with the producer *** with the new production line is being built, the production line will aim at the world's advanced level, the production of higher quality kaolin products.
(B) kaolin surface modification technology
China's plastic synthetic resin production of 500 × 104t. Although China's plastics industry has achieved remarkable development, but per capita, the annual consumption of a very low number of less than 5 kg, compared with developed countries there is still a big gap. In recent years has been in the ultra-fine, modified two aspects of a lot of research work, and achieved certain results, so that the share of mineral fillers in plastic products accounted for more than 10%, some plastic products (such as packing tape) can reach more than 50%.
Maoming and other places kaolin whiteness, fineness has reached a certain requirement, in order to occupy a greater share of plastic products, and further open the market of the plastics industry, the surface treatment is the most critical issue.
Ultra-fine modified kaolin used in rubber products have obvious reinforcing properties, that is, higher tear strength, corrosion resistance, tensile strength, can reduce the content of raw rubber, in order to achieve the purpose of reducing costs. General products by reinforcing, tear resistance can be increased by more than double, the number of times of flexure increased by 5 to 6 times. Therefore, the application of modified kaolin in rubber products is more popular, used to replace a large number of carbon black and silica. Japan accounted for 50%, China's current dosage (25 ~ 30) × 104t.
Paint filler commonly known as the body pigment, kaolin filled with the role of the skeleton, with chemical stability, corrosion resistance, water resistance and other characteristics. Through filling, improve the mechanical properties of paint film, and play a durable, anti-corrosion, heat insulation, digestion. At the same time, due to the cheap price, reduce the cost of finished products, such as partially replacing titanium dioxide, for highway marking paint, building exterior latex paint, etc., the use of about 10%.
Surface modification of kaolin, generally using mechanical modification, chemical modification or mechanical-chemical modification, such as kaolin dry powder in the continuous modification machine with surface modifiers mixed at high speed. To achieve a better modification effect, there are many influencing factors; the key lies in the preparation of raw materials, process equipment and surface modification chemicals, of which the surface modification chemicals are the most critical technology. The surface modification agent used for kaolin surface modification is silane coupling agent.
According to the production practice of a kaolin plant in China, the surface treatment of modified products after the new output value of 1000-1500 yuan / t, profit of 300-500 yuan / t. The economic benefits are significant, and the market prospect is broad.
(C) kaolin synthesis 4?Molecular sieve
Zeolite (also known as molecular sieve) is a tetrahedral skeleton of silica-aluminate, due to its large number of pore size uniform microporous and exchangeable cations, and thus has a special adsorption, separation and ion exchange characteristics. For detergents, what is needed is a 4?zeolite with strong ion exchange capacity.
Developed countries have basically limited the production of phosphorus-containing detergents, China also issued in 1993, "detergent with 4 ? Zeolite" standard in 1993, and on January 1, 1999 began to enforce the ban on the production, sale and use of phosphorus-containing detergents in the circum-Taihu Lake Basin. It is predicted that in 2010 China's demand for 4 ? molecular sieve demand will exceed 30×104t.
Synthesis of 4 ? zeolite has kaolin method, activated white clay method and chemical synthesis method, the synthesis of 4 ? zeolite with kaolin is the most economical and reasonable. Because of kaolin and 4? zeolite silicon and aluminum ratio of the two are the same, as long as the kaolin to add Na2O components, and make it happen crystal transformation can be generated 4? The process is as follows: calcination→crystallization→washing→drying and packaging.
Product quality implementation of QB1768-93, indicators, such as Table 2.
Table 2 QB1768-93 indicators
(D) nano clay materials
Nanomaterials due to the spatial size of molecules, atoms into the world, so it can achieve many peculiar properties, such as the ability to shield ultraviolet light, electromagnetic waves. Such as the ability to shield ultraviolet rays, electromagnetic waves, used in the military, communications, computers and other industries; with nano-clay added to the refrigerator, water dispenser, with antibacterial, disinfection; especially ceramics, add nano-clay, so that the strength of 50 times, used to make engine parts. Add nano mineral material plastic, with high strength, good heat resistance, low density; especially wear-resistant enhancement, is 27 times of brass, steel 7 times; and has a flame retardant self-extinguishing. Nanoplastics are made into pipes, automobile mechanical parts, packaging materials for beer and meat products. At present, the turnover generated by nanotechnology has reached 50 billion U.S. dollars, becoming the representative technology of the 21st century.
Suzhou Zhongmai Nonmetallic Mining Industry Design and Research Institute of Al2O3-based nanomaterials have completed the small test, and achieved milestones, the strength from 200-300MPa to 1200-1300MPa.
(E) whitening, viscosity reduction technology advances
Nearly two decades, whitening, viscosity reduction technology has been one of the research topics of kaolin industry, and has made progress in the development and development of nanotechnology. One of the research topics, and has made great progress. At present, the whiteness reaches 88% and the viscosity concentration reaches 68%. The rapid development of the paper industry has put forward higher requirements for kaolin, especially the entry of American kaolin and Brazilian kaolin into the Chinese market, which has intensified the competition of technology. "Tenth Five-Year" period of scientific and technological research, kaolin products to reach 90% whiteness, viscosity concentration of 72% level.
(F) Application of low-temperature superconducting magnetic separation technology
Chinese kaolin resources compared with the United States, Brazil and other countries, there is a low whiteness, viscosity defects. Yankuang Group Beihai Kaolin Company has introduced the low temperature superconducting technology and equipment from Carpco and other companies in the U.S. The equipment has a magnetic induction strength of 5T, an installed capacity of 37 kW, and the Fe2O3 has been reduced from 0.9% to less than 0.5%.
(VII) Ultrafine Flotation Technology
The particle size of kaolin and embedded impurities is very fine, which can be separated by ultrafine flotation technology.
The Exploitation and Application of Kaolin and Technological Development of Kaolin Industry in China
Cai Jian
(Suzhou Zhongcai Design and Research Institute for Non-metallic Mineral Industry, Suzhou Jiangsu 215004, China)
Abstract: The article describes the history of the development of kaolin mining and processing industry. development of kaolin mining and processing industry in China.Taking the kaolin production in Maoming kaolin producing base in Guangdong province as an Taking the kaolin production in Maoming kaolin producing base in Guangdong province as an example, the article emphatically sets forth the development condition of kaolin industry in China, including kaolin resources, producing and The article emphatically sets forth the development condition of kaolin industry in China, including kaolin resources, producing and processing, technological characteristics and application of its products. The article makes a comparison between the kaolin production technologies in China and abroad and analyses the development trends of processing technology and exploitation and application of kaolin in China.
Key words: kaolin, exploitation and application, technological development.