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Bentonite encyclopedic knowledge

Bentonite (Bentonite) is an aqueous clay mineral montmorillonite based. The chemical composition of montmorillonite as: (Al2, Mg3) Si4O10 OH2 ยท nH2O, because of its special properties. Such as swelling, adhesion, adsorption, catalysis, thixotropy, suspension and cation exchange. It is widely used in various industrial fields.

Bentonite is non-metallic mineral montmorillonite as the main mineral composition, the structure of montmorillonite is 2:1 type crystal structure consists of two silicon oxygen tetrahedron sandwiching a layer of alumina in eight face bentonite composition, due to the layered structure of montmorillonite crystal formation in the presence of some cations, such as Cu, Mg, Na, K, and these cationic and montmorillonite lattice effect is very unstable, easily by other cation exchange, it has good ion exchange. Abroad has been in the industry and agriculture production more than 100 departments in 24 fields of application, there are more than 300 products, so people called the “universal soil”.

Bentonite is also called bentonite, bentonite and bentonite. History of China’s development of the use of bentonite is long, just as a detergent. (Sichuan Renshou area hundreds of years ago in open-pit mine, the locals of bentonite clay powder). Really is widely used but only a hundred years of history. USA was first discovered in the ancient stratigraphic Wyoming, green yellow clay, the water after the expansion into paste, then people will take all the properties of bentonite clay, collectively referred to as. In fact, the main mineral component of bentonite is montmorillonite, content of 85-90%, some properties of bentonite are also determined by the montmorillonite. Montmorillonite can be a variety of colors such as yellow green, Huang Bai, gray, white and so on. Can a dense block, but also loose earth sometimes, when you rub it with your fingers with smooth feel, small body after adding water volume swell several times to 20-30 times, is suspended in the water, when water is little mushy. The properties of montmorillonite and the chemical composition and its internal structure.


The bentonite interlayer cations depends on the type of bentonite type, interlayer cation is Na+ called sodium bentonite; interlayer cation is Ca2+ called calcium base bentonite; interlayer cation is H+ called hydrogen bentonite (activated clay, natural bleaching soil acid clay); interlayer cation organic cation organic bentonite.

Bentonite is a kind of clay, montmorillonite clay rock or rock, often containing a small amount of illite, kaolinite, halloysite, chlorite, quartz, feldspar, zeolite, calcite; usually white, pale yellow, due to changes in iron content is light gray, light green, pink, brown red, brick red, black etc.; with wax, earthy or oil sheen; bentonite some loose soil, there are dense and hard. The main chemical composition is three silica, two aluminum oxide and water, also contain iron, magnesium, calcium, sodium, potassium and other elements, Na2O and CaO content on properties of physical and chemical properties of bentonite and technology influence. Montmorillonite belongs to monoclinic system, usually it is earthy block, white, sometimes reddish, greenish, yellowish color. Luster dim. Hardness of 1 ~ 2, density of 2 ~ 3g/cm3. Type, content and layer charge of montmorillonite according to the size of the exchangeable cation, bentonite can be divided into Na bentonite (alkaline soil), calcium base bentonite (alkaline soil), natural bleaching earth (acidic soil or clay acid), in which calcium bentonite and sodium calcium base and calcium and magnesium based etc.. Bentonite has strong hygroscopic and expansion, water adsorption can be 8 to 15 times their size, the volume expansion of up to two to 30 times; can be dispersed into gelatinous and suspended in water medium, the medium solution with viscosity, degeneration and some lubrication; strong cation exchange capacity; for various gases, liquids, organic matter has certain adsorption capacity, the maximum adsorption capacity of up to 5 times its own weight; it with water, mud or sand blends with plasticity and cohesiveness; acid bleaching soil with surface activity (active white soil, natural bleaching soil acidity clay can adsorb colored ion).

Bentonite has strong moisture absorption, can absorb the equivalent volume 8 20 times of water and swells to 30 times; can be dispersed colloidal suspensions in water medium, and has a certain viscosity, thixotropy and lubrication, the admixture of bentonite and silt has plasticity and cohesiveness, strong cation exchange capacity and adsorption capacity.

The naked eye identification, high-quality bentonite was pure white, generally have gray or no yellow white, often due to water or containing impurities are pale green, pale green, rose red color. After drying is pure white, gray or pale yellow white. In section is not smooth hand after the break, but a jelly. There are oil sheen, hand touch with smooth feel. Can water swelling, good can become colloid. If long-term dry moisture loss, and can become loose. Bentonite has strong ion exchange capacity, so it can be adsorbed or absorbed a variety of colors. It can make the oil and oil mixed, more smooth. Suspension of fine powder of its water, dispersion (divergence) is very good, not easy to precipitate. The natural bentonite type, mainly by the relative content of montmorillonite cation species divided into calcium, sodium, hydrogen, Lithium Montmorillonite, such as the calcium montmorillonite based clay called calcium base bentonite. Most of bentonite ore in China in the production of calcium base bentonite, calcium base bentonite sodium bentonite is cheap, and easily, so we in the broiler and layer test, are calcium base bentonite. With the addition of bentonite feeding chickens, because good palatability, chicken to eat.

But only by the naked eye, sensory evaluation is not accurate. There is no uniform identification of bentonite in China National standard. The majority of mine to execute a machine on the “casting bentonite, a clay ministerial standard” (1997) and enterprise standards. The main absorption of blue, water, colloid medium, pass rate, wet strength, expansion coefficient, pH value, determination methods and standards here omitted.

The county more than bentonite plant has more than 20, and do the bentonite plant has more than 100, the vast majority of provinces (autonomous regions) are. Most of the county (city) building materials company or goods shopping malls have bentonite. Market town where the foundry factory usually with bentonite, less dosage can contact them, but must pay attention to quality.