BentoniteUses and SourcesYour Logo Here

OverviewMade up mainly of montmorillinite, (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2nH2OFormed from the weathering of volcanic ash bedsNamed for Fort Benton, WY, where it was first described as part of a Cretaceous tuff sequenceGrades vary, but it is generally impure, with inclusions of other smectite minerals, as well as quartz, feldspar, calcite, and gypsumExhibits a number of unique properties(IMA-NA 2007)

Properties & ApplicationsThixotropyCan be semi-solid at rest, but will be liquid when agitatedUsed as a thickening and suspension agent in paints, dyes, and varnishes

(KSGS 2002)

Properties & ApplicationsCohesionBinder and pelletizerIronworks: ore pellets for feeding into furnaces, andas a binder in casting sandmolds

(MiningLife 2005)

Properties & ApplicationsAbsorption / AdsorptionCan absorb several times it dry weight in waterPet litter, impermeable clay liners, wastewater treatment, detergent purification, paper pulp purification, de-inking(IMA-NA 2007)

Properties & ApplicationsInertnessWont kill you to eat it!Filler in pharmaceuticals, animal feed, and cosmeticsPurifier and clarifier in beer, wine, and honey(WSGS 2007)

Properties & ApplicationsViscosity and PlasticityDrilling: vertical and horizontalLubricates the bit, seals the walls of the borehole, removes drill cuttingsAdditive in Portland cement, mortars, and specialized plasters(WSGS 2007)

Bentonite as a Value-Added CommodityBentonite is not often taken straight from the ground to market.Much purification is often undergone to specialize the productSieving (for granular bentonite)Milling (fine and superfine powdered bentonite)Removal of associated gangue mineralsTreated with acids (bleaching earths)Treated with organics (organoclays)(IMA-NA 2007)

Bentonite Producers & RefinersAMCOL International (miner, refiner, large producer of bentonite products)Aqua Technologies (organoclay water treatment)Black Hills Bentonite LLC (miner and 1st-stage refiner)BPM Minerals LLC (producer)CETCO (special-purpose bentonite products)Montana Bentonite LLC (producer and refiner)and MANY others

Production MethodsDrilling & SamplingSoil Profiling (to aid in speedy recovery after reclamation)Topsoil & Overburden removal (usual with scrapers)Quarrying with loader & truckOnly economic to mine bentonite with no more than 50 feet of overburden

(WMA-Minelife 2007)

Simplified Bentonite Mill Flow-Chart(WMA Minelife, 2007)

World Reserves and Production StatisticsReserves of all clays used by man are extremely large, and are thought to be inexhaustible on human timescalesAs a result, no concrete measurements of world reserves have been performedIt is still a very lucrative sector. US production in 2005 amounted to 42 million tons worth $1.7 billion(Numbers are in thousands of metric tons)(USGS 2007)

Worldwide Distribution(Mindat 2007)

End Use Statistics(USGS 2005)

Works CitedIndustrial Minerals Association of North America, www.ima-na.org, (Accessed March 23, 2007).Kansas State Geological Survey, http://vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Notes/bentonite.html, (Accessed March 27, 2007).Mindat, http://www.mindat.org/min-9141.html, (Accessed March 27, 2007). MiningLife Media, http://www.mininglife.com/commodities/Bentonite.asp, (Accessed March 25, 2007).WMA-Minelife, http://www.wma-minelife.com/bent/bentmine/bentmine.htm, (Accessed March 27, 2007).Wyoming State Geological Survey, http://www.wsgs.uwyo.edu/minerals/bentonite.aspx, (Accessed March 27, 2007).USGS, http://minerals.usgs.gov/minerals/pubs/commodity/clays/, (Accessed March 27, 2007).USGS, 2005, Bentonite statistics, in Kelly, T.D., and Matos, G.R.,comps., Historical statistics for mineral and material commodities in the United States: U.S. Geological Survey Data Series 140, available online at http://pubs.usgs.gov/ds/2005/140/ . (Accessed March 27, 2007.)