Bentonite

1
Bentonite
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• Uses and Sources

2
Overview

• Made up mainly of montmorillinite,
  (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2nH2O
• Formed from the weathering of volcanic ash beds
• Named for Fort Benton, WY, where it was first
  described as part of a Cretaceous tuff sequence
• Grades vary, but it is generally impure, with
  inclusions of other smectite minerals, as well as
  quartz, feldspar, calcite, and gypsum
• Exhibits a number of unique properties

(IMA-NA 2007)
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Properties Applications

• Thixotropy
• Can be semi-solid at rest, but
• will be liquid when agitated
• Used as a thickening and suspension agent in
  paints, dyes, and varnishes

(KSGS 2002)
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Properties Applications

• Cohesion
• Binder and pelletizer
• Ironworks ore pellets for
• feeding into furnaces, and
• as a binder in casting sand
• molds

(MiningLife 2005)
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Properties Applications

• Absorption / Adsorption
• Can absorb several times it dry weight in water
• Pet litter, impermeable clay liners, wastewater
  treatment, detergent purification, paper pulp
  purification, de-inking

(IMA-NA 2007)
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Properties Applications

• Inertness
• Wont kill you to eat it!
• Filler in pharmaceuticals, animal feed, and
  cosmetics
• Purifier and clarifier in beer, wine, and honey

(WSGS 2007)
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Properties Applications

• Viscosity and Plasticity
• Drilling vertical and horizontal
• Lubricates the bit, seals the walls of the
  borehole, removes drill cuttings
• Additive in Portland cement,
  mortars, and specialized plasters

(WSGS 2007)
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Bentonite as a Value-Added Commodity

• Bentonite is not often taken straight from the
  ground to market.
• Much purification is often undergone to
  specialize the product
• Sieving (for granular bentonite)
• Milling (fine and superfine powdered bentonite)
• Removal of associated gangue minerals
• Treated with acids (bleaching earths)
• Treated with organics (organoclays)

(IMA-NA 2007)
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Bentonite Producers Refiners

• AMCOL 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

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Production Methods

• Drilling Sampling
• Soil Profiling (to aid in speedy recovery after
  reclamation)
• Topsoil Overburden removal (usual with
  scrapers)
• Quarrying with loader truck
• Only economic to mine bentonite with no more than
  50 feet of overburden

(WMA-Minelife 2007)
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Simplified Bentonite Mill Flow-Chart
(WMA Minelife, 2007)
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World Reserves and Production Statistics

• Reserves of all clays used by man are extremely
  large, and are thought to be inexhaustible on
  human timescales
• As a result, no concrete measurements of world
  reserves have been performed
• It 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)
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Worldwide Distribution
(Mindat 2007)
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End Use Statistics
(USGS 2005)
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Works Cited

• Industrial 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.as
  p, (Accessed March 25, 2007).
• WMA-Minelife, http//www.wma-minelife.com/bent/ben
  tmine/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/commo
  dity/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/2005/1
  40/ . (Accessed March 27, 2007.)