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Home >> Products >> Bentonite
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Bentonite
CAS number: 1302-78-9
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CHEMICAL
COMPOSITION |
| Silica |
SiO2 |
50.73 % |
| Alumina |
Al2O3 |
15.97 % |
| Titanium
Oxide |
TiO2 |
1.55 % |
| Iron
Oxide |
Fe2O3 |
17.07 % |
| Lime |
CaO |
0.83 % |
| Magnesia |
MgO |
1.79 % |
| Potash |
K2O |
0.30 % |
| Sodium |
Na2O |
3.19 % |
| Phosphorus |
P2O5 |
0.05 % |
| LOI |
|
8.46 % |
The
typical ranges shown above
have been derived from recent
analysis data from representative
samples of raw bentonite.
PHYSICAL
PROPERTIES |
| Mesh
(through B.S.S. 200
sieve) |
90% |
| Incombustibility |
Can
be used upto 10000C |
| Swelling capacity
|
33 ml. |
| Melting Point |
12000
C |
| Gel Time |
35 sec. |
| Liquid Limit |
600 |
| PH Value |
9 - 10 |
| Fluid Loss (22.5
gm/350 gm.) |
15 ml. |
| MBA (mg/gm of clay) |
411 |
| Moisture content |
11.5% |
NOTE: As
Bentonite is a natural mineral,
the properties and composition
of supplied material may
vary slightly from the above. |
USES:
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.
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.
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.
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.
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.
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.
Bentonite is used in medicine
as a bulk laxative and for
pruritis.
Also it is used in acne
medication such as Clearasil
lotion with benzoyl peroxide
as an agent that absorbs
excess sebum, clearing pores.
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