Bentonite is a non-metallic mineral mainly composed of montmorillonite. The montmorillonite structure is a 2: 1 crystal structure composed of two layers of silicon oxynitride intercalated with an aluminum octahedron. Due to the formation of montmorillonite unit cells Of the layered structure of some cations, such as Cu, Mg, Na, K, etc., and these cations and montmorillonite unit cell role is very unstable, easy to be exchanged by other cations, it has good ion exchange. Abroad has been applied in more than 100 sectors in 24 fields of industrial and agricultural production, with more than 300 products, so people call it "universal earth."
Bentonite is also called bentonite, bentonite or bentonite. The development of the use of bentonite in China has a long history, originally just as a detergent. (Renshou area in Sichuan hundreds of years ago there are open-pit mines, locals call bentonite soil). Really widely used but only a hundred years history. The earliest discovery in the United States was that in the paleo-formations of Wyoming, there was a yellowish-green clay that was expanded into a paste when added to water. Later, clay was commonly referred to as bentonite. In fact, the main mineral composition of bentonite is montmorillonite, content of 85-90%, some properties of bentonite are also determined by the montmorillonite. Montmorillonite can be various colors such as yellow-green, yellow-white, gray, white and so on. Can become a dense block, but also for the loose earth, rubbed with a finger when there is a sense of slippery, bulky small volume of water swelling several times to 20-30 times, was suspended in water, water was little paste . The nature of montmorillonite is related to its chemical composition and internal structure.
(1) Hydrogen bentonite
When the interlayer cations is Na +, it is called sodium bentonite; when the interlayer cations is Ca2 +, it is called calcium bentonite; when interlayer cations are H +, it is called hydrogen bentonite (activated clay, natural bleaching earth - acid clay); interlayer cations are organic cations When called organic bentonite.
(2) Activated clay
Activated clay is clay (mainly bentonite) as raw material, the inorganic acidification, and then water rinse, drying made of adsorbent, the appearance of white powder, odorless, tasteless, non-toxic, strong adsorption, can be adsorbed Colored matter, organic matter. Easy to absorb moisture in the air, placed too long will reduce the adsorption performance. However, the heating to 300 degrees Celsius began to lose water of crystallization, the structure changes, affecting the fading effect. Activated clay is not soluble in water, organic solvents and various oils, almost completely soluble in hot caustic soda and hydrochloric acid, the relative density of 2.3 to 2.5, swelling in water and oil minimal.
(3) natural bleaching earth
Naturally produced bleaching properties of the white clay itself is based on montmorillonite, albite, quartz as the main component of white, white-gray clay, is a kind of bentonite. Mainly glassy volcanic rocks after the decomposition of the product, it does not swell after swelling, the pH of the suspension is weakly acidic and alkaline bentonite phase; the bleaching performance than the active clay poor. Colors are generally pale yellow, green white, gray, 檄 brown, brown, milk white, pink, blue and so on. Pure white rarely. The density of 2.7-2.9g / cm. Visual density is often low due to porosity. Chemical composition and ordinary clay, the main chemical composition is aluminum oxide, silicon dioxide, water and a small amount of iron, magnesium, calcium and so on. No plasticity, high adsorption. Due to the large amount of hydrous silicic acid, the litmus is acidic. Water is easy to crack, water content is very big. The general fineness of the more fine decolorization.
In the exploration stage of quality evaluation, the need to determine the bleaching performance, acidity, filtration performance, oil absorption and other projects.
(4) organic bentonite
Organic bentonite is an inorganic mineral / organic ammonium complex, bentonite as raw material, the use of bentonite montmorillonite lamellar structure and its ability to swell in water or organic solvent dispersed into colloidal grade clay properties, by ion exchange Technology insert organic covering agent made. Organic bentonite in various organic solvents, oils, liquid resins can form a gel, with good thickening, thixotropy, suspension stability, high temperature stability, lubricity, film forming, water resistance and chemical stability , In the coating industry has important application value. In the paint ink, aviation, metallurgy, chemical fiber, petroleum and other industries also have a wide range of applications.
(5) bentonite mine
Bentonite is a multi-purpose mineral whose quality and application depends mainly on its montmorillonite content and attribute types and its crystalline chemistry. Therefore, its development and utilization must be mine-specific, depending on the role. Such as the production of activated clay, calcium-based sodium transfer, for drilling oil drilling grouting, instead of starch for spinning, printing and dyeing slurry, building materials used inside and outside the wall paint, preparation of organic bentonite bentonite synthesis 4A zeolite, production White carbon black and so on.
(6) Calcium-based and sodium-based difference
Bentonite intercalation cation species determines the type of bentonite, intercalated cations Na + is called sodium bentonite; interlayer cations when Ca + is called calcium bentonite sodium montmorillonite (or sodium bentonite) than the nature of calcium good . However, the distribution of calcareous soils in the world is much wider than that of sodium soils. Therefore, in addition to strengthening the search for sodium-bearing soils, it is necessary to modify the calcareous soils so that they become sodium-bearing soils.
These information are supplied by Keyway Industrial Limited.