Background/Requirement
Bentonite is a naturally occurring aluminum silicate clay
which can take up several times is own weight of water to
form a highly thixotropic colloidal suspension or gel. The
gel structure is derived from hydrogen bonds which develop
between the clay particles (or platelets.) These bonds readily
break down with shear, reforming again if the shear force
is removed. One of the principal applications for bentonite
is in drilling muds, however it is widely used as a suspending
and stabilizing agent, and as an adsorbent or clarifying agent
in many industries, some examples of which are givenin the
table:
| Industry |
Use |
| Agrochemical |
Anticaking agent
for granular fertilizer, ingredient of pesticides, suspending
agent |
| Civil Engineering |
Foundations,
asphalt emulsions, grout |
| Cosmetic |
Antiperspirants,
deodorants, lipstick, creams and lotions |
| Food/Animal
Food |
Binder, carrier
and stabilizer in pet food. Clarifier for juice, wine
and edible oil |
| Household |
Detergent bulking
agent, polishes |
| Miscellaneous |
Paper coatings,
paper de-inking, inks and paints |
| Oil |
Drilling mud |
| Pharmaceutical |
Stabilizing,
thickening and suspending agent in creams and ointments |
Despite the diversity of end uses, and the various processing
methods and equipment used, there are a number of common processing
requirements which must be satisfied in order to obtain maximized
“functionality”.
| • |
Mixing equipment must be capable of rapidly incorporating
and dispersing the powder into the base liquid. |
| • |
The bentonite particles must be reduced to their finest constituent
parts to expose the maximum surface area to the surrounding
liquid and activate the gelling effect. |
The following problems can be encountered when using conventional
agitators:
| • |
Conventional agitators do not produce sufficient
shear to reduce particle size and activate the gelling effect. |
| • |
On addition to the water, the particles tend to agglomerate.
The washing action of conventional mixers cannot break these
down effectively. |
| • |
Long mixing cycles are required to obtain uniform dispersion
and to complete hydration. |
| • |
With in-tank mixing, once viscosity increase has started,
agitation of the solution becomes increasingly difficult reducing
the mixer’s ability to provide shear to reduce particle size
and maximize gelling effect. |
Quadro's Approach
The above problems can be overcome using a Quadro Ytron
Jet Mixer and Z Emulsifier. Bentonite Clay is made up
of organic platelets, which under shear break apart
to create multiple platelets, hence creating the viscosity
increase. The Jet Mixer with a bypass assembly will
introduce the Bentonite Clay powder into solution dust
free and the axial flow pattern of the Jet Mixer will
blend to a uniform concentration within minutes. When
the Bentonite Clay has been introduced and blended,
we recommend a single pass of the solution through the
high shear, fine radial tolerance Z Emulsifier to achieve
the maximum viscosity building properties of the Bentonite
Clay.
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