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Overview
MIKRONS® Multi-shaft
disperser can be employed
to work on high concentration
and high viscosity products
which give rise to finer
and faster dispersions eliminating
conventional milling.
Multi-shaft mixers have
a center mounted low speed
blade sweeping the mixing
vessel wall and an additional
high speed shaft. The high
speed blade typically provides
high shear to disperse ingredients.
The low speed blade feeds
the high speed blade by
blending and folding the
mass in the vessel and improves
product uniformity by scraping
the walls.
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| Design
Highlights: |
| A
high speed disperser alone
has a limited zone of influence
in viscous products, so the
low speed blade is necessary
to achieve a homogeneous mixture.
When equipped with scrapers,
the low speed blade also aids
in heat transfer to an external
jacket. Multi-shaft mixers
are sometimes used with low
viscosity products when scraping
the vessel wall is beneficial.
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Option 1: Triple Shaft
mixer is essentially the same
as the Dual Shaft design with
the addition of another offset
high speed shaft located on
the opposite side of the low
speed shaft. The second high
speed shaft provides additional
shear and can reduce process
time. A Rotor Stator can also
be used as the third shaft.
The Rotor Stator provides
mechanical and high hydraulic
shear that is useful in disintegration
of solids into liquids or
emulsification. |
| Option
2: A typical combination
includes a low-speed butterfly
impeller, an efficient auger
blade, and a high-speed high
shear impeller-disc.
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| Three
stages of Mixing |
| 1.
Mixer: a slow speed open
impeller with three risers
starts the batch moving and
continually forces it into
the thinner high speed blades.
Risers usually have scrapers
to clean the tank walls.
2. Dispersion -
a high-speed disc with sharp
teeth breaks up agglomerates
when they hit the disc or
each other in the intense
zone of attrition.
3. Homogenizing
- a high-speed rotor-stator
further separates the batch
into smaller droplets of
mutually incompatible material
and forces them into a mixture.
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