Process characteristics of kaolin

    Pure kaolin has high whiteness, soft texture, easy dispersion and suspension in water, good plasticity and high adhesion, excellent electrical insulation properties; good acid resistance, low cation exchange capacity, better Physicochemical properties such as fire resistance. Therefore, kaolin has become a necessary mineral raw material for dozens of industries such as paper making, ceramics, rubber, chemicals, coatings, medicine and national defense. It is reported that Japan also will be used in place of kaolin aspects of manufacturing steel cutting tools, lathes, drills and internal combustion engine housing applications. Especially in recent years, the rapid development of modern science and technology has made the application of kaolin more extensive. Some high-tech fields have begun to use kaolin as a new material, even high-temperature porcelain parts of atomic reactors, space shuttles and spacecraft, and kaolin. production.
At present, the global total kaolin production is about 40 million tons ( this data is a combination of simple country-to-country production, which does not count the trade volume of raw ore, including more double counting ) , of which refined soil is about 23.5 million tons. The paper industry is the largest consumer sector of refined kaolin, accounting for about 60% of total kaolin consumption. According to data provided by Temanex Consulting, Canada, the total global paper and board production in 2000 was approximately 319 million tons, and the total amount of kaolin used in paper coatings worldwide was approximately 13.6 million tons.

1 . Whiteness and brightness

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. Ceramic process specified drying 105 °C Calcination for grading standards for natural whiteness 1300 °C It is the grading standard for calcination whiteness. The whiteness can be measured by a whiteness meter. The white meter is measuring 3800 — 7000 Å A device for the reflectivity of wavelength light. 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, equivalent to whiteness at 4570 Å wavelength illumination.

    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.

2 . Particle size distribution

The particle size distribution refers to natural kaolin particles in given successive different grain size (in microns or mm sieve mesh indicates) the proportion of the range (expressed as percentages). 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. U.S. content of less than 2 μ m is used as a coating kaolin requirements accounted 90--95% papermaking filler accounts for less than 2 μ m 78--80%.

3 . plasticity

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 plasticity meter . It is expressed in kg · cm . The higher the plasticity index, the better the forming property.

For a mineral Beneficiation Plant, there are still some percentage which are not liberating the ore thoroughly, so it's necessary to separate them and send to Ball Mill for regrinding, both Spiral Classifier and hydro-cyclone are here to achieve the function of mineral classifying, spiral classifier is used to separate the ore and gangue with overflow method, the fine particles will overflow the spiral classifier meanwhile the gangue sets at the bottom of the spiral classifier, and will move upwards to the higher end, finally will be sent back to ball mill, and the hydro-cyclone is to separate the two parts by gravity difference.both of them are commonly used for mineral beneficiation plant, for example, gold ore processing plant, copper ore processing plant, zinc ore processing plant, lead ore processing plant, graphite processing plant, iron ore processing plant, and so on.

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