Kaolin is derived their name from Cao Territory (高岭土, ie land Cao Linh, the white clay in Cao Linh), a hilly area in Jingdezhen, Jiangsu, China. The white clay quarry here are exploited to produce raw materials of Chinese porcelain. Called kaolin was the French Jesuit introduced into Europe in the 18th century and they are transcribed Vietnamese back then it became kaolin.
Physicochemical properties
Kaolin 2 layer structured 1: 1 (similar dickit, nacrit, halloysit) ... with the general formula Al2Si2O5 (OH) 4.nH2O (n = 0, 2), composed of SiO2, Al2O3, H2O , in addition to a small amount of impurity Fe, Ti, K and Mg. Kaolin is white, gray and white, specific forms are narrow or block light soil types, set small scales, the crystal unit linked hexagonal form of small plates, thin, 12 micron diameter between 0.2 , specific weight of about 2.1 to 2.6 g / cm3, hardness from 1 to 2.5, capable of cation exchange about 2-15 meq / 100g and highly dependent on the size of the county, but the reaction to replace cation occurs with great speed []. When soaked, it has flexibility, but no elastic phenomenon. This is nature's earliest known kaolin, people use it in the form of thick lake to shaping and sintering furnaces to create pottery. The melting temperature of kaolin: 1.750-1.787oC. When heated, kaolin endothermic effects, pic at 510-600 ° C related to dehydration, crystalline and amorphous phenomenon of minerals. Two exothermic peaks from 960 to 1,000 and 1,200 ° C involves chemical processes of the product mulit kaolin amorphous, with peaks of 1,200 ° C is the crystallization of amorphous silicon oxide to form cristobalite
Application
Kaolin is widely used in many industrial fields such as industrial ceramics, paper, paint, rubber, fiberglass, plastics, building materials, refractories, catalyst for oil refining industry ... Thanks to the special ability to absorb not only the fats, proteins which are capable of absorbing all kinds of viruses and bacteria, so, kaolinin be applied both in the medical field, pharmaceutical , cosmetic...[]. - Industrial production of paper: paper industry, kaolin is used as filler for paper creates smoother surface, increasing the tightness, reduced optical lenses and increases the ink seep to the extent possible. Type ordinary paper containing 20% ​​kaolin, which contains up to 40% type. Typically, one ton of paper requires 250-300 kg kaolin. Quality kaolin paper used is determined by the brightness, dispersion and uniform level of the grain group. - Industrial production of ceramics: manufacturing porcelain, ceramic and porcelain, ceramic art, laboratory instruments, insulators, sanitary ware, etc. Each material used is kaolin; adhesive material is fire clay plastic, white color. Quality kaolin requires very high and right to control the coloring oxide (Fe2O3 and TiO2). Fe2O3 content should not exceed 0.4 to 1.5%; 0.4 to 1.4% TiO2 not exceed; Not more than 0.8% CaO and SO3 not more than 0.4%. - Production of refractories: in manufacturing refractory materials, people use kaolin to produce refractory bricks, tiles acid half and the other refractory map. In the black metallurgy, refractory bricks made of kaolin mainly used for lining of the blast furnace, iron furnaces, hot blast furnace. The other industries need refractory bricks with less volume, mainly for lining furnaces, boilers in color metallurgy and chemical industry, in refineries, in glass and ceramic industry, at home cement plants and lime kilns. - Manufacture of glass fiber: another area also uses kaolin annual increase that is used as raw material in production of glass fibers. The components of both silica and kaolin containing alumina, in the composition of the glass fibers. Kaolin is used in conjunction with a small amount of iron and titanium. The increase demand for kaolin in this field because the limited use of asbestos material in, what kind of substances harmful to health. Field filler: kaolin are widely used as a filler in paper, plastics, rubber, spices, ... Kaolin work densified, elasticity, insulation, durability of rubber, increased stiffness and reduced product cost of plastics such as PE, PP, PVC ... In manufacturing artificial leather (leatherette), kaolin works to increase durability, elasticity. - In the production of soap: kaolin curing effects when produced, absorb grease when using. Soap manufacturing sector requires highly kaolin particles 0.053 mm sieve under greater than 90%; not sandy, no sediment before 8 o'clock, Fe2O3 content of ≤ 2-3% TiO2 ≤ 1%; base exchange of ≤ 0.8 to 2% and ≤ carbonate 15-20%. - In manufacturing pesticides: use kaolin has a large diffuser, good grip strength, chemically inert, low iron compound, 22 mm grain size from 40 to 75%. In synthetic zeolites: Kaolin is the main raw material for synthetic zeolites substance is applied in many industries such as adsorption, as a catalyst ... - In other sectors, kaolin is used as raw materials for cement production White concrete, coated materials in construction and materials to produce aluminum, alum ...