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IQS Newsroom Articles on Mixers
About Mixers and Mixing Equipment Including: Agitators,
Batch Mixers, Blenders, Drum Mixers, Emulsifiers, Food Mixers, High Shear Mixers, Homogenizers, Mixers, Mixing Blades, Paddle Mixers
& Static
Mixers.
Mixers aid in industrial processes involving the mixture of multiple wet, slurry or dry bulk substances. Manufacturing processes across the industry use mixers of various configurations to combine, homogenize, de-lump, disperse and emulsify liquid-to-liquid mixtures, liquid-to-solid slurries and dry friable solids. Although the food processing industry has some of the most common applications for mixers, many other industries require high performance mixers and blenders to mix powder bulk chemicals, cosmetic slurries, liquid dyes, paints and many other substances. Mixers range widely in size and capacity, according to specific application, and equipment is engineered to deal with specific viscosities, agglomerations and even semi-solids, eliminating mixing problems such as clumping, fisheyes and uneven dispersal. Mixer manufacturers often cater to one or all of three process industries for which mixing is key: bio-pharmaceutical, food and beverage processing and cosmetics manufacturing. Petrochemical industries commonly use blenders and emulsifiers as well, as do most adhesive, converting, paint and dye industries.
Because mixing applications can vary so widely, mixers are configured into several broad category types which specialize in processing different levels of viscosity as well as different volumes. Mixers which process one large volume at a time are
batch mixers, while mixers which continually put out finished mixed substances are continuous mixers; both batch and continuous mixers may be equipped with inlet nozzles and built-in heating elements for streamlined, precisely controlled ingredient addition and in-process heating for temperature-specific ingredients such as gelatin and other colloids. Mixers are typically equipped with horizontal rotary axes attached to radiating paddles, with the exception of emulsifiers, homogenizers and portable drum mixers which use high-speed vertical axis blades in liquid-liquid or slurry applications. Horizontal mixing blades may be configured as
paddles or ribbons and are often equipped with additional small propellers along the interior mixer wall.
The most common mixer types are listed below, including static mixers, agitators, ribbon blenders, emulsifiers, homogenizers, drum mixers, paddle mixers and roller bar mixers.
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Agitators - A common example is
the central agitating blade in a top-loading washing machine. It remains stationary on its center axis,
agitating water and clothes with its paddle as it turns. Agitators in food and industrial product processing
may have similar configurations, or they may be removable agitating rods which are placed into a substance
only long enough to properly agitate it. Agitators are used mainly in liquids, as agitation is not as effective
with thick, highly viscous materials.
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Ribbon Blenders - While blenders
and mixers are basically synonymous, this type of blender is used in specific dry mixing of free-flowing
powder bulk solids. Usually housed in a semi-cylinder, ribbon blenders have long, ribbon-like paddles
which circle around a central axis, shearing through friable materials as the axis turns. Grains,
pharmaceutical powders, powdered food ingredients such as flour and many other solids are de-lumped or
combined in this blender.
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Paddle Mixers - These mixers
have the same configuration as ribbon blenders, but with paddle-shaped blades protruding from the axis
instead of shearing ribbons. Paddle mixers are also used to mix dry friable materials, but they may
also be used in wet-dry mixing, slurry mixing and other high viscosity liquid mixing applications.
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Static
Mixers - Also known as inline mixers, these smart
pieces of equipment have no moving parts. Carefully
designed ribbon-like obstructions are placed inside
a cylinder through which liquids flow. As the liquid
flows through, the obstructions inside cut the flow
of the liquid, forcing it to mix and blend together.
Inline mixers may be attached to flow tubes to enhance
a liquid's homogeneity without requiring a separate
mixer, additional energy or service to moving parts.
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Emulsifiers -
These may be inline, like static mixers, or they may be
a separate machine; both types are used in the blending
of immiscible liquids such as oil and water or cream and
milk. In inline and centrifugal emulsifiers, pressure
is applied to the liquid-liquid mixture as it is forced
through very small filters which break up larger molecules
into smaller molecules which do not separate. In the case
of milk and cream, cream is composed of large fat molecules
which separate from milk due to the huge difference in
molecule size; emulsification breaks cream molecules down
so they are similar in size to milk molecules. Emulsification
is sometimes achieved by adding emulsifying agents, by
centrifugal force or by fast shearing.
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Homogenizers -
Can be synonymous with certain types of emulsifiers.
Homogenizers combine heterogeneous liquid-liquid mixtures
by subjecting the mixture to extreme force and pressure,
resulting in a breakdown and complete blending of the
material. Most homogenizers have vertical axis shearing
blades which blend within a closed container at very
high speeds.
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Drum
Mixers - This is a broad category of mixers which
may include portable drum mixers used for in-container
mixing. Other drum mixers have static containers in
which ingredients must be poured. Drum mixers are generally
used to blend mixtures of low to medium viscosities
such as cement or adhesive slurries; this particular
mixer is capable of mixing substances of very different
particle sizes, such as gravel and cement slurry or
ice cream and fruit.
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Roller Bar Mixers - Unlike other mixers with shearing,
homogenizing and blending capabilities, roller bar mixers
are used almost exclusively for kneading applications.
Multiple horizontally aligned stainless steel bars are
arranged around a center axis, lifting and kneading as
the axis turns. Large batches of bread dough are most
often processed in roller bar mixers and similarly configured
kneaders.
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Articles
http://pffc-online.com/ar/paper_mixing
http://www.adhesivesmag.com/CDA/Archives/
http://www.pcimag.com/CDA/Archives/
Mixer Types
- commonly mix substances with low viscosities
in low-shear applications. Agitators range in size from small agitators
used in laboratory applications to large industrial agitators with
10,000-gallon capacities.
- mix one load of material at a time and are refilled with one load after another.
- usually mix miscible substances possessing comparable viscosities.
Because substance properties remain similar, blending can usually be
accomplished with relative ease.
- are important parts of large production lines
that typically have paddle type agitators with a series of mixing stages
that progressively move and blend ingredients. Materials are constantly
fed in specified proportions into continuous mixers, then are mixed,
conveyed to the opposite end and discharged.
- are single-shaft mixers that break apart or dissolve
solid particles into liquid using a high-speed, rotating saw-tooth
blade.
The blade provides high shear forces that break apart the ingredients
of low viscosity products, such as paints.
- are low-cost plastic spouts containing plastic
mixing elements. Disposable mixers are as efficient as most metal mixers
but
are not appropriate for in-line use at high pressures.
- have
adjustable blades in a swing-blade design that maximize liquid movement
at all speeds.
- are
fast mixers that use horizontal rotating shafts with fixed arms and attached
paddle-shaped feet to impact the
solids and throw some of them onto the second shaft, while pushing
the rest toward one end of the device. The paddles on the other
shaft push the solids toward the opposite end and toward the other
shaft
and paddle set.
- provide high speed
rotation and centrifugal force through a perforated screen to achieve
emulsification. Emulsifiers are very
effective where a high shear is required, as they can provide
fast mechanical and hydraulic shear
- utilize
counter-current mixing, which places very high parallel forces upon
substances. During counter-current mixing,
the mixing pan and the mixing tools rapidly revolve in opposite
directions, resulting in substance uniformity.
- are continuous mixers that break down particle masses to efficiently
provide fine dispersions and stable emulsions.
-
are high-shear mixers that subject mixtures of varying viscosities to
intense mechanical and hydraulic forces, reducing mixing time and assuring
uniform blend.
- have three
or four augers and are used for quick mechanical mixing of particular
substances, especially in feed processing.
- are being used
more and more in large volume operations, as they can handle an extremely
large batch with much lower horsepower
and with predictable batch turnover. Dynamic in-line mixers
utilize a combination of pump pressure and high-speed rotating elements,
while
static in-line mixers have specially contoured stationary
mixing elements located in a tubular housing that serves as part of
the pipeline.
- are an integral
part of any laboratory or processing environment, as they can perform
a variety of functions, such as mixing,
emulsifying, homogenizing, disintegrating and dissolving.
Types of lab mixers include compact, dual-shaft, constant-torque and
high viscosity.
- create a uniform mixture from various combined substances.
- push materials around the mixer.
- ,
also known as static mixers, inline mixers and pipeline mixers, are
continuous mixers that operate inline and have no moving parts. Motionless
mixers allow for the blending of two or more fluids and disperse treatment
chemicals into fluid streams.
- are
used in processing a variety of liquids, powders and crystalline solids
in the pharmaceutical processing industry.
Common applications that utilize pharmaceutical mixers include
the mixing of medicine, such as cough syrups and the creation of tablet
coatings for pills.
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are efficient, high-speed dispersion mills that can quickly disperse,
emulsify, suspend, cook, aerate and deaerate masses of particles. Material
can be put in the production mill through radial slots where they are
hurled off the slot tips against the stator slots, which produces efficient
wetting-out of the solid phase and the quick achievement of stable suspensions,
dispersions and emulsions.
- properly
mix concentrations of water to produce working and make-up solutions
for applications that include coolants,
cleaners, strippers, degreasers, fertilizers and fungicides.
Venturi proportional mixers use water passing over an orifice to create
suction
to draw the concentrate from the container and mix it with
water, while water-driven mixers use water to drive a piston, which
then pumps concentrate
into a mixing chamber where the concentrate is mixed with
water.
- create an extremely
diverse velocity field by using a counter-transport mechanism consisting
of an outside right-hand ribbon
and an inside left-hand ribbon, both connected to the same
horizontal shaft. Ribbon mixers provide fast blending and mixing in
the vertical
plane, as they can transport an entire mass of solids a short
distance in both directions of the axis of the shaft while lifting
a portion
of the solids a short distance in each direction; however,
they are slow when mixing end to end.
- contain
blades that spin around the axis of the drum, mixing the substances,
such as concrete. Drum mixer axes may
be either horizontal or inclined.
- includes high-speed mixers that utilize a rotor and stationary stator
to produce high
rotor tip speeds. The differential
speed between the rotor and the stator in these mixers imparts
extremely high shear and turbulent energy in the gap between the rotor
and stator.
- ,
also referred to as in-line mixers, are motionless mixers that operate
continuously. Static mixers remain quite efficient and generally require
very little maintenance.
- have either
top- or bottom-mounted mixers and are used to eliminate air pulled
into the material during mixing, which increases
product quality.
Mixer Terms
- The recombination of finely dispersed
particles into larger particles, typically caused by a disturbance of
surface forces resulting from a change in environment.
- Salt found in the cell wall of brown algae. Alginates
are used in food processing to stabilize certain mixtures (e.g. emulsions),
to seal in moisture and to thicken texture, among other things.
- The movement of fluid from the top to the bottom of
a tank.
- Mixing process
that involves the weighing and measuring of ingredients, the creation
of a mixture from separate ingredients, the removal of the mixture and
the cleaning of the mixer and mixing tools before the start of a new batch.
- Mineralized water consisting
of sodium chloride, metallic and/or organic contaminants. Brine solutions
are utilized in food processing procedures.
- Fine particles of a substance that remain between the
dissolution phase and the suspension phase. Colloids neither dissolve
into other substances, remain suspended within the other substances nor
settle out of the substances.
- Mixing process, involving the automatic creation
of a series of mixtures, in which the mixer contains a metering mechanism,
such as a pump, and measures, combines and mixes the ingredients. Because
smaller amounts are mixed continuously, cleaning of the mixer and mixing
tools usually remains fast and easy.
- The ratio of substance mass to substance volume, measured
in g/cm3 (grams per cubic cm).
- Small particles of a substance evenly distributed
throughout another substance. Dispersed particles are small, but remain
larger than colloids.
- A suspension in which one substance is suspended within
the other. They are unable to be blended or mixed but can be combined,
though not dissolved (e.g. oil and vinegar).
- Consisting of different components that may not
be distributed evenly throughout a mixture. The components, while mixed
together, still remain separate entities.
- Consisting of identical components distributed uniformly
throughout the mixture. The components no longer remain separate entities,
but have become one entity, as in a solution.
- The part of the agitator that imparts force to the material
being mixed. Examples of impellers are propellers, turbines, gates, anchors
and paddles.
- The use of motion to create and transmit power.
- A device consisting of two rings, one stationary
and one rotating with the agitator shaft, which is used to seal against
pressure where the shaft enters the vessel. Springs or tank pressure
forces the accurately machined faces of these rings together.
- A unit of measurement equivalent to one-millionth
of a meter.
- A substance containing two or more substances that may
not be distributed evenly throughout and do not bond together chemically.
Substances in mixtures, although combined, maintain separateness.
- A two-bladed impeller whose diameter is somewhat larger
than the radius of the tank.
- The average time a component remains in a continuous-process
mixing environment.
- The breakdown of immiscible particles in a mixture
that cannot be dissolved.
- A homogenous formation created by the dissolution of
a substance or substances into another substance.
- In a solution, the liquid, gaseous or solid substance
or substances that dissolve into a liquid or gaseous substance, called
a solvent. Solutes usually consist of smaller quantities than the substance
into which they are dissolved.
- The liquid or gaseous substance into which a liquid,
gaseous or solid substance, known as a solute, is dissolved.
- A heterogeneous mixture in which fine particles of
a solid neither dissolve into a liquid or gaseous substance nor settle
out, but remain within the substance supported by buoyancy. In suspension,
both substances remain separate entities.
- The resistance of a fluid, whether liquid or gas, to
flow easily. Fluids with high viscosity, such as molasses, flow slowly;
low viscosity fluids, such as water, flow easily.