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Encyclopedia > Bentonite
Bentonite - USGS

Bentonite is an absorbent aluminium phyllosilicate generally impure clay consisting mostly of montmorillonite. There are a few types of bentonites and their names depend on the dominant elements, such as K, Na, Ca, and Al. As noted in several places in the geologic literature, there are some nomenclatorial problems with the classification of bentonite clays. Bentonite usually forms from weathering of volcanic ash, most often in the presence of water. However, the term bentonite, as well as a similar clay called tonstein, have been used for clay beds of uncertain origin. For industrial purposes, two main classes of bentonite exist: sodium and calcium bentonite. In stratigraphy and tephrochronology, completely devitrified (weathered volcanic glass) ash-fall beds are commonly referred to as K-bentonites when the dominant clay species is illite. Other common clay species, and sometimes dominant, are montmorillinite and kaolinite. Kaolinite dominated clays are commonly referred to as tonsteins and are typically associated with coal. Bentonite - USGS File links The following pages link to this file: Bentonite Categories: USGS images ... Bentonite - USGS File links The following pages link to this file: Bentonite Categories: USGS images ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... Aluminum redirects here. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... For other uses, see Clay (disambiguation). ... A sample of montmorillonite Montmorillonite is a very soft phyllosilicate mineral that typically forms in microscopic crystals, forming a clay. ... Ash plume from Mt Cleveland, a stratovolcano Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash consists of very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... Stratigraphy, a branch of geology, studies rock layers and layering (stratification). ... Tephrochronology is a geochronolgical technique that utilises discreet layers of tephra—volcanic ash from a single eruption— to create a chronological framework in which palaeoenvironmental or archaeological records can be placed. ... Structure of Illite mica - USGS. Illite is a non-expanding, clay-sized, micaceous mineral. ... Kaolin redirects here. ... Coal Example chemical structure of coal Coal (pronounced ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ...

Contents

Sodium bentonite

Sodium bentonite expands when wet, possibly absorbing several times its dry mass in water. Because of its excellent colloidal properties (see Odom ref below) it is often used in drilling mud for oil and gas wells and for geotechnical and environmental investigations. This article or section does not cite its references or sources. ...


The property of swelling also makes sodium bentonite useful as a sealant, especially for the sealing of subsurface disposal systems for spent nuclear fuel [1] [2] and for quarantining metal pollutants of groundwater. Similar uses include making slurry walls, waterproofing of below-grade walls and forming other impermeable barriers: e.g., to seal off the annulus of a water well, to plug old wells, or as a liner in the base of landfills to prevent migration of leachate. Slurrywall excavator A slurry wall is a type of wall used to build tunnels, open cuts and foundations in areas of soft earth close to open water or with a high ground water table. ... Look up well in Wiktionary, the free dictionary. ... Landfill can also refer to Land reclamation. ...


Sodium bentonite can also be "sandwiched" between synthetic materials to create geo-synthetic liners for the aforementioned purposes. This technique allows for more convenient transport and installation and it greatly reduces the volume of sodium bentonite required.


Various surface modifications to sodium bentonite improve some rheological or sealing performance in geoenviromental applications, for example the addidtion of polymers (Theng, B.K.G. 1979. Formation and Properties of Clay Polymer Complexes. Developments in Soil Science 9. Elsevier, Amsterdam, 362pp.)


Calcium bentonite

Calcium bentonite is a useful absorbant of ions in solution (Lagaly G., 1995. Surface and interlayer reactions: bentonites as absorbents. P 137-144. In Churchman, G.J., Fitzpatrick, R.W., Eggleton R.A. Clays Controlling the Environment. Proceedings of the 10th International Clay Conference, Adelaide, Australia. CSIRO Publishing, Melbourne) as well as fats and oils, being a main active ingredient of Fuller's Earth, probably one mankind's the first industrial cleaning agents (R.H.S, Robertson, 1986. Fuler's Earrth. A History of calcium montmorillonite. Volturna, Press, U.K.). Calcium bentonite may be converted to sodium bentonite (termed sodium beneficiation or sodium activation) to exhibit many of sodium bentonite's properties by a process known as "ion exchange" (patented in 1935 by Germans U Hofmann and K Endell). Commonly this means adding 5-10% of a soluble sodium salt such as sodium carbonate to wet bentonite, mixing well, and allowing time for the ion exchange to take place and water to remove the exchanged calcium.[citation needed] Some properties, such as viscosity and fluid loss of suspensions, of sodium beneficiated calcium bentonite (or sodium activated bentonite) may not be fully equivalent to natural sodium bentonite. (Reference:Odom, I.E. (1984) Smectite clay minerals: properties and uses. Philisophical Transactions Royal Society, London, A., 311, 391-409.) For example, residual calcium carbonates (formed if exchanged cations are insufficiently removed) may result in inferior performance of the bentonite in geosynthetic liners (Guyonnet, D., Gaucher, E., Gaboriau, H., Pons C.-H., Clinard, C., Norotte, V. Didier, G. 2005. Geosynthetic clay liner interactions with leachate: correlation between permeability, microstructure and surface chemistry. Journal of Geotechnical Engineering, Vol. 131, page740-749.).


Pascalite is a commercial name for the calcium bentonite clay.


Uses for both types

Much of bentonite's usefulness in the drilling and geotechnical engineering industry comes from its unique rheological properties. Relatively small quantities of bentonite suspended in water form a viscous, shear thinning material. Most often, bentonite suspensions are also thixotropic, although rare cases of rheopectic behavior have also been reported. At high enough concentrations (~60 grams of bentonite per litre of suspension), bentonite suspensions begin to take on the characteristics of a gel (a fluid with a minimum yield strength required to make it move). For these reasons it is a common component of drilling mud used to curtail drilling fluid invasion by its propensity for aiding in the formation of mud cake. Bostons Big Dig presented geotechnical challenges in an urban environment. ... Rheology is the study of the deformation and flow of matter under the influence of an applied stress. ... Thixotropy is the property of some non-newtonian pseudoplastic fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear, the lower its viscosity. ... Rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear, the higher its viscosity. ... BIC pen cap, about 1 gram. ... The litre or liter (see spelling differences) is a unit of volume. ... In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. ... This article or section does not cite its references or sources. ... Drilling fluid invasion is a process that occurs in a well being drilled with higher wellbore pressure than formation pressure. ...


Bentonite can be used in cement, adhesives, ceramic bodies, and cat litter. Bentonite is also used as a binding agent in the manufacture of taconite pellets as used in the steelmaking industry. Fuller's earth, an ancient dry cleaning substance, is finely ground bentonite, typically used for purifying transformer oil. Bentonite, in small percentages, is used as an ingredient in commercially designed clay bodies and ceramic glazes. Bentonite clay is also used in pyrotechnics to make end plugs and rocket nozzles, and can also be used as a therapeutic face pack for the treatment of acne/oily skin. For other uses, see Cement (disambiguation). ... For the band, see Adhesive (band). ... This article is about ceramic materials. ... A packet of clumping cat litter & a litter box Cat litter is one of any of a number of materials used in litter boxes to absorb moisture from cat feces and urine, which reduces foul odors such as ammonia and renders them more tolerable within human dwellings. ... Taconite is an iron-bearing, high-silica, flint-like rock. ... Fullers earth is any nonplastic clay or claylike material that can be used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases. ... Pyrotechnics is a field of study often thought synonymous with the manufacture of fireworks, but more accurately it has a wider scope that includes items for military and industrial uses. ... This article is about vehicles powered by rocket engines. ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ...


The ionic surface of bentonite has a useful property in making a sticky coating on sand grains. When a small proportion of finely ground bentonite clay is added to hard sand and wetted, the clay binds the sand particles into a moldable aggregate known as green sand used for making molds in sand casting. Some river deltas naturally deposit just such a blend of such clay silt and sand, creating a natural source of excellent molding sand that was critical to ancient metalworking technology. Modern chemical processes to modify the ionic surface of bentonite greatly intensify this stickiness, resulting in remarkably dough-like yet strong casting sand mixes that stand up to molten metal temperatures. Description Green Sand is an aggregate of sand, bentonite clay, and water. ... Casting is the process of production of objects by pouring molten material into a cavity called a mould which is the negative of the object, and allowing it to cool and solidify. ...


The same effluvial deposition of bentonite clay onto beaches accounts for the variety of plasticity of sand from place to place for building sand castles. Beach sand consisting of only silica and shell grains does not mold well compared to grains coated with bentonite clay. This is why some beaches are so much better for building sand castles than others. An elaborate sand sculpture. ...


The self-stickiness of bentonite allows high-pressure ramming or pressing of the clay in molds to produce hard, refractory shapes, such as model rocket nozzles. Indeed, to test whether a particular brand of cat litter is bentonite, simply ram a sample with a hammer into a sturdy tube with a close-fitting rod; bentonite will form a very hard, consolidated plug that is not easily crumbled. A model rocket launching Model rocketry is a hobby similar to building model airplanes, where rocket-shaped models are flown vertically and recovered by a variety of means (see Recovery below). ...


Bentonite also has the interesting property of adsorbing relatively large amounts of protein molecules from aqueous solutions. It is therefore uniquely useful in the process of winemaking, where it is used to remove excessive amounts of protein from white wines. Were it not for this use of bentonite, many or most white wines would precipitate undesirable flocculent clouds or hazes upon exposure to warmer temperatures, as these proteins denature. It also has the incidental use of inducing more rapid clarification of both red and white wines. Adsorption is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or, more rarely, a liquid (adsorbent), forming a molecular or atomic film (the adsorbate). ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Winemakers often use carboys like these to ferment smaller quantities of wine Winemaking, or vinification, is the process of wine production, from the selection of grapes to the bottling of finished wine. ... This article is about the beverage. ... This article needs additional references or sources for verification. ...


Bentonite is used in medicine as a bulk laxative[3] and for pruritis[4] Laxatives (or purgatives) are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. ... Pruritis is a misspelling of the medical condition pruritus. ...


Also it is used in acne medication such as Clearasil lotion with benzoyl peroxide as an agent that absorbs excess sebum, clearing pores. This article or section contains information that has not been verified and thus might not be reliable. ... The sebaceous glands are glands found in the skin of mammals. ...


History and natural occurrence

Bentonite output in 2005. Click the image for the details.
Bentonite output in 2005. Click the image for the details.

In 2005, U.S. was the top producer of bentonite with almost one-third world share followed by China and Greece, reports the British Geological Survey. Image File history File links Size of this preview: 800 × 351 pixelsFull resolution (1425 × 625 pixels, file size: 59 KB, MIME type: image/png)This bubble map shows the global distribution of bentonite output in 2005 as a percentage of the the top producer (USA - 4,430,000 tonnes). ... Image File history File links Size of this preview: 800 × 351 pixelsFull resolution (1425 × 625 pixels, file size: 59 KB, MIME type: image/png)This bubble map shows the global distribution of bentonite output in 2005 as a percentage of the the top producer (USA - 4,430,000 tonnes). ... The British Geological Survey is a publicly-funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. ...


The absorbent clay was given the name bentonite by an American geologist sometime after its discovery in about 1890 — after the Benton Formation (a geological stratum, at one time Fort Benton) in Montana's Rock Creek area. Other modern discoveries include montmorillonite discovered in 1847 in Montmorillon in the Vienne prefecture of France, in Poitou-Charentes, South of the Loire Valley. For other uses, see strata (novel) and strata title. ... Fort Benton is a city located in Chouteau County, Montana. ... This article is about the U.S. State. ... A sample of montmorillonite Montmorillonite is a very soft phyllosilicate mineral that typically forms in microscopic crystals, forming a clay. ... Montmorillon is a commune of the Vienne département, in France. ... This article is about the French département. ... Categories: Stub | Regions of France ... For the wine region, see Loire Valley (wine). ...


Most high-grade natural sodium bentonite is produced from the western United States in an area between the Black Hills of South Dakota and the Big Horn Basin of Wyoming. Mixed sodium/calcium bentonite is mined in Greece, Australia, India, Russia and the Ukraine. In the United States, calcium bentonite is primarily mined in Mississippi and Alabama. Other major locations producing calcium bentonite include Germany, Greece, Turkey, and China.


It should be noted that in some countries like the UK, calcium bentonite is known as fuller's earth, a term which is also used to refer attapulgite, a mineralogically distinct clay mineral but exhibiting similar properties. Fullers earth is any nonplastic clay or claylike material that can be used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases. ... Palygorskite (also known as attapulgite) is a magnesium aluminum silicate from a type of clay soil common to the Southeastern United States. ...


References

Cosmetic use of Bentonite


A white clay of volcanic origin found primarily in the US. A thickener and emulsifier, in makeup, it also absorbs oil and reduces shine. It has a cooling feel since water evaporates quickly from clay.


  Results from FactBites:
 
Bentonite, green clay, volcanic clay, volcanic ash, Bowel Cleanse, MONTMORILLONITE (1348 words)
Bentonite is not a mineral but a commercial name for montmorillonite, the active mineral in many medicinal clays and which comes from weathered volcanic ash.
Bentonite is made of a great number of tiny platelets, with negative electrical charges on their flat surfaces and positive charges on their edges.
Bentonite Minerals are derived from an ancient seabed formation in Utah; according to geologists, the clay formed when a layer of volcanic ash fell into what was, long ago, a shallow inland sea.
  More results at FactBites »

 
 

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