The use of pure quality kaolin kaolin has high whiteness, soft, easily dispersed or suspended in water, good plasticity and a high sticky, excellent electrical insulating properties; having good acid-soluble, low cation exchange capacity, Good physical and chemical properties such as fire resistance.
Therefore, kaolin has become a necessary mineral raw material for dozens of industries such as paper, ceramics, rubber, chemicals, coatings, medicine and national defense.
Whiteness is one of the main parameters of kaolin's process performance, and the high purity kaolin is white. Kaolin whiteness is divided into natural whiteness and whiteness after calcination. For ceramic raw materials, the whiteness after calcination is more important, and the higher the whiteness of calcination, the better the quality. The ceramic process stipulates that drying 105 ° C is the grading standard of natural whiteness, and calcination 1300 ° C is the grading standard of calcination whiteness. The whiteness can be measured by a whiteness meter. A whiteness meter is a device that measures the reflectance of light at a wavelength of 3800-7000 Å; (ie, angstroms, 1 angstrom = 0.1 nm). In the whiteness meter, the reflectance of the sample to be tested is compared with the reflectance of the standard sample (such as BaSO 4 , MgO, etc.), that is, the whiteness value (for example, the whiteness of 90 means 90% of the reflectance of the standard sample).
Brightness is a process property similar to whiteness, which is equivalent to the whiteness of 4570 Ã… (angstrom) wavelength light.
The main color of kaolin and its metal oxide contained in or related to organic matter. Generally, Fe 2 O 3 is reddish brown and brownish yellow; Fe 2+ is light blue and light green; MnO 2 is light brown; and organic matter is light yellow, gray, blue and black. The presence of these impurities reduces the natural whiteness of the kaolin. The iron and titanium minerals also affect the whiteness of the calcination, causing stains or melting of the porcelain.
Particle size distribution refers to the proportion (in percent) of particles in natural kaolin that are within a given range of different particle sizes (represented by the mesh of millimeter or micrometer mesh). The particle size distribution characteristics of kaolin are of great significance to the ore selectivity and process application. The particle size has a great influence on its plasticity, mud viscosity, ion exchange capacity, forming property, drying performance and firing performance. Kaolin mines require technical processing and are easy to process to the required fineness of the process. It has become one of the criteria for evaluating ore quality. Each industrial sector has specific particle size and fineness requirements for kaolin for different uses. For example, in the United States, the content of kaolin used as a coating is less than 2 μm, and the content of papermaking filler is less than 2 μm, which is 78-80%.
The mud formed by the combination of kaolin and water can be deformed under the action of external force, and the plasticity can be maintained after the external force is removed. Plasticity is the basis of the molding process of kaolin in the ceramic body, and is also the main process technical index. The plasticity index and the plasticity index are usually used to indicate the plasticity. The plasticity index refers to the liquid limited water content of the kaolin clay minus the plastic limit moisture content, expressed as a percentage, that is, the W plasticity index = 100 (W liquid limit - W plastic limit). The plasticity index represents the forming property of kaolin clay. The load and deformation of the mud ball under pressure and crushing can be directly measured by a plasticizer. It is expressed in kg·cm. The higher the plasticity index, the better the forming property. The plasticity of kaolin can be divided into four levels.
Binding refers to the combination of kaolin and non-plastic materials to form plastic clay and have a certain drying strength. The binding ability is determined by adding standard quartz sand to the kaolin (the mass composition is 0.25-0.15, 70%, and 0.15-0.09mm, 30%). The highest sand content and the flexural strength after drying can be judged by the highest sand content and the flexural strength after drying. The more sand is mixed, the stronger the kaolin binding ability is. Generally, kaolin with strong plasticity is also strong.
The firing shrinkage refers to a series of physicochemical changes (dehydration, decomposition, mullite formation, melting of fusible impurities to form a glass phase filled in the space between the particles, etc.) during the calcination of the dried kaolinite. The performance that causes the product to shrink is also divided into two types: line shrinkage and body shrinkage. Like the drying shrinkage, the firing shrinkage is too large, which tends to cause cracking of the green body. In addition, when calcined, if a large amount of quartz is mixed in the billet, it will undergo crystal transformation (trigonal to hexagonal), causing its volume to expand and also causing back shrinkage.
Recently ceramics, rubber, plastics, leather, since the cement, refractories, chemicals and other industrial and agricultural equipment coalfield geological system no widely used. With the further improvement of high lacewing soil beneficiation process, the scope of application of kaolin will become increasingly widespread. Units can be based on actual conditions and based on high bauxite resources and market demand in coal-bearing strata. Kaolin is a kind of non-metallic mineral that is common in nature. In the past, it was generally used to produce ceramics, refractory materials, and a small amount of plastics, rubber and ruthenium fillers. With the development of various fields of the national economy, people pay more and more attention to high Deep processing of bauxite, because it can not only obtain new materials with special properties, but also improve economic benefits. One of the methods for deep processing of kaolin is to further heat the kaolin washed by scouring and toughening. , roasting, dehydration, making it into metakaolin, used as a filler in the plastic cable section to improve the insulation properties of the cable sheath. Commonly used filler rubber footwear mainly organic fillers and inorganic fillers, the former includes a regeneration and recovery of materials such as rubber, the latter comprising silica, calcium carbonate, titanium dioxide, magnesium carbonate, magnesium oxide, carbon black, and Zinc oxide powder, etc. Kaolin is a new type of rubber product filler developed in recent years.
Ceramics are made of clay as the main raw material and various natural minerals obtained by pulverizing, kneading, molding and calcining, as well as various products. A general term for pottery and porcelain. The traditional concept of ceramics refers to all artificial industrial products that use inorganic non-metallic minerals such as clay as raw materials. It includes various articles prepared by kneading, forming, and calcining a mixture of clay or clay. From the coarsest earthenware to the finest fine pottery and porcelain, it belongs to its range. The main raw material for it is the silicate minerals (such as clay, quartz, etc.) taken from nature, so it belongs to the category of “silicate industry†with industries such as glass, cement, enamel and refractory materials.
The production process of ceramic products refers to the whole process from the start of raw materials to the production of ceramic products. It is a process in which laborers use certain labor tools to directly or indirectly act on labor objects according to certain methods and steps, making them ceramic products with useful value. In some processes of the ceramic production process, such as the staleness of the ceramic blank, the natural drying process of the blank, and the like. It also needs the help of natural forces. The physical or chemical changes occur in the labor object. At this time, the production process is a combination of the labor process and the natural process.
It is because of the process of ceramic production and the specific properties of kaolin, which makes kaolin one of the raw materials for ceramic production.
China's porcelain making process is also becoming more and more excellent as the original single material of porcelain tires is made into porcelain (using porcelain stone as a raw material to make porcelain) to the later binary formula (using porcelain stone and kaolin to make porcelain). The use of kaolin as a raw material for porcelain has greatly promoted the improvement of the level of ceramic technology and the quality of products, and promoted the development of ceramics. The development and utilization of kaolin has laid a solid foundation for the rapid development of Jingdezhen's porcelain industry. Since the use of kaolin to prepare porcelain, Jingdezhen has produced porcelain that is white and flawless and more beautiful. The porcelain produced in Jingdezhen, Jiangxi is famous both at home and abroad. It has always been known as "white as jade, bright as mirror, thin as paper, and sound like a beggar".
China's kaolin resources are abundant. Suzhou soil in Jiangsu, Jiepai soil in Hunan, Xingzi soil in Jiangxi, Shangdian soil in Shaanxi, Datong soil in Shanxi, etc. are all kaolinites with kaolinite as the main mineral. The clay minerals belonging to kaolinite include dickite, pearl clay and halloysite (Hallysite, also known as Yongxu stone), which is the clay that is rich in this mineral in Yongxu County, Sichuan Province, China. Named) and so on. The composition of kaolin in each property is different.
Kaolin plays a role as a mainstay in the manufacture of ceramics, which makes China's ceramic technology flourish in the world has a very high status.
Through this course, I learned a lot about the knowledge of ceramic raw materials. Ceramics has a long history in China. The world-recognized ceramics were invented by China. This is the pride of every descendant of the Yellow Emperor. Learning ceramics is also the knowledge of every Chinese son and daughter. This point. Especially in such an era of cultural aggression, every Chinese has the responsibility to defend our national culture. The long history of 5,000 years needs us to pass on. The cultural treasures created by the predecessors need to be cherished and carried forward.
I am fortunate to be able to learn ceramic knowledge during college. I will cherish this experience. In the days to come, I will continue to work hard to learn Chinese culture, carry forward the spirit of the Chinese nation, and let the world know the greatness of the Chinese nation.
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