• Bentonite Synonyms:

bentonite clay, taylorite, southern bentonite, fuller's earth, wyoming sodium bentonite, sodium montmorillonite, calcium montmorillonite, saponite, montmorillonite (Na), montmorillonite (Ca),  hectorite, hormite clay bentonite magma,  tixoton, volclay, volclay bentonite BC, wilkinite, CAS# 1302-78-9

• Bentonite Designations:

Chemical Formula: Al2O34SiO2H2O

Chemical Name: Naturally occurring hydrated aluminum silicate

• Bentonite Description:

a) A rock composed essentially of a crystalline clay-like mineral formed by devitrification and the accompanying chemical alteration of a glassy igneous material, usually a tuff or volcanic ash.

b) Smectite refers to a family of non-metallic clays primarily composed of hydrated sodium calcium aluminum silicate. Common names for smectite include montmorillonite or sodium montmorillonite ("sodium bentonite" or "Wyoming bentonite") and swelling bentonite ("Western bentonite").

c) There are three types of bentonite:

1) Natural Calcium Bentonite or Calcium Montmorillonite

2) Natural Sodium Bentonite or Sodium Montmorillonite

3) Sodium Activated Bentonites or Sodium Activated Montmorillonites

d) Bentonite minerals occur as lenses or seams containing up to 50% moisture. They are rocklike in nature and usually extracted by opencast mining (quarrying).

e) Natural sodium bentonite as the name suggests occurs with sodium as the predominant exchange cation. The name originates from its discovery near Fort Benton, USA. Sodium bentonites are characterized by high swelling, high liquid limit and high thermal durability.

f) The vast majority of the montmorillonites occurring in abundance world wide are of the calcium type and referred to as calcium bentonites. The name montmorillonite originates from a discovery made at Montmorillon in France. Calcium bentonites are often characterized by much lower swelling and liquid limit values compared to natural sodium bentonite.

g) Sodium activated bentonites are produced by the substitution of calcium ions by sodium ions. This transformation can be achieved by the addition of a soluble sodium salt to calcium bentonite.

• Typical Bentonite Chemical Properties (wt. %):

a) Commercial Grade: SiO2= 61.3 and Al2O3= 19.8

b) Food Grade: Si02 = 58-61, Ca0= 2.0-2.5, Al203=21-22, Mg0= 3-4, Na20= 3.7-4.2, As= 5 ppm max., and Pb= 40 ppm max.

• Bentonite Physical Properties Available:

Numerous particle size options are available in the lower micron area from a mean particle size of 2.5 to 4.0 microns.

• Bentonite Physical Constants:

• Fact Sheet on Bentonite:

Visit this useful website

• Bentonite Typical Applications:

a) Used as a foundry sand, paints, fuller's earth, drilling mud, bleaching clay, filtering agents, water impedance, inks, additive to ceramic materials, and iron ore pelletizing

b) Pharmaceuticals, beverage, food, cosmetics, and personal care products (Suspending agent, gellant and binder)

c) Bentonite possesses thixotropic properties and deposits a thin water proofing film on the walls of the bore holes & thus renders permeable formations impermeable.

d) Both natural & synthetic Bentonite are used in preparation of drilling muds. It is mainly used as circulation mud in rotary system of drilling for oil. The main purpose of Bentonite is to lubricate & cool the rotary cutting bits, carry away rock cutting fragments & to act as a seal against the escape of gas from the bore hole & to improve & prevent the hole from blowing out. Another function of such Bentonite based fluids is to condition the wall of the drill hole to prevent caving.

• Bentonite Industry Economic Outlook:

World demand for bentonite and fuller's earth is forecast to rise by an average of 2.2%py from 20Mt in 2007 to 22.4Mt in 2012. Growth will be led by the foundry sand sector (5%py), filtering and decolourising of edible oils, industrial oils, solvents and chemicals (5%py) and iron ore pelletising (3%py). The highest rates of growth will be found in Asia, notably China, and in South America where demand will be driven by the requirements of the iron ore pelletising and foundry sands markets. The main regional markets for bentonite are North America (7.5Mt), Asia (5.6Mt) and Europe (5Mt), although there are significant variations in the pattern of consumption within each of these regions. Source: Roskill

• Bentonite Packaging:

Jars, pails, drums, multiply paper bags, bulk bags and fiberboard containers

• Bentonite TSCA (SARA Title III) Status:

Listed. Bentonites are aluminate silicate and can contain crystalline silica. The content varies widely from less than 1% to about 24%. For further information please call the E.P.A. at +1.202.554.1404 or visit this NIOSH link to the left.

• Bentonite CAS Number:

CAS# 1302-78-9