BentoniteYour Logo Here

Uses and SourcesUses and Sources

Overview

Made up mainly of montmorillinite, (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O

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)

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)

Properties & Applications

Cohesion– Binder and pelletizer– Ironworks: ore pellets for feeding into furnaces, and

as a binder in casting sandmolds

(MiningLife 2005)

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)

Properties & Applications

Inertness– Won’t kill you to eat it!– Filler in pharmaceuticals, animal feed, and

cosmetics– Purifier and clarifier in beer, wine, and honey

(WSGS 2007)

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)

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)

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

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)

Simplified Bentonite Mill Flow-Chart

(WMA Minelife, 2007)

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)

Worldwide Distribution

(Mindat 2007)

End Use Statistics (USGS 2005)

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.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.)