Union process “Q” and “QL” attritors achieve Ultra-Fine,
Uniform Dispersions Quickly and Consistently
© 2012, Union Process, Inc.
History
From a revolutionary idea proposed and developed by Dr.
andrew szegvari in 1945, attritor technology grew to become
the basis for Union process, inc., an independent family-owned
american company founded in akron, ohio. today, attritors are
considered to be the most efficient grinding/dispersing systems
and are used in hundreds of industries and research
laboratories worldwide.
How Attritors Work
the attritor is often referred to generically as an “internally
agitated high energy media mill.” the operation of an attritor is
simple and effective. the material to be ground is placed in a
stationary tank with the grinding media. the materials and
media are then agitated by a shaft with arms, rotating at high
speed. this causes the media to exert both shearing and
impact forces on the material. the final result of this remarkably
efficient process is extremely fine material, measured in
microns or fractions of microns, distributed on a very narrow
curve.
The Circulation Attritor
the circulation grinding attritor (“Q” machine) is a
combination of an attritor and a large holding tank which is
generally about ten times the size of the attritor. the attritor is
filled with media and contains grids which restrain the media
while the slurry is allowed to pass through.
the unique principle of the “Q” attritor is the high circulating
(pumping) rate. the entire contents of the holding tank are
passed through the attritor at least once every 7-1/2 minutes,
or about 8 times per hour.
this high pumping rate results in a faster grind and a
narrower particle size distribution. this phenomenon is explained
by the principle of preferential grinding (see Figure 1). the fast
pumping stream through the agitated media bed makes the
“Q” machine grinding chamber act as a dynamic sieve or filter,
allowing the fine particles to pass and move quickly through,
while the coarser particles follow a more tortuous path through
the media bed.
with the circulation process, unlike a continuous machine
with the slurry making a single pass, the material makes many
passes through the grinding chamber until the desired particle
size is obtained.
grinding media used in circulation attritors range in size
from 3/32" to 1/4" in diameter. Chrome, steel, steatite, and
zirconium oxide are commonly used media.
Figure 1:
Passage Of A Small & Large Particle Through
A Layer Of Agitated Media
retaining grids
Circulation
grinding
attritor
premix
holding tank
The Union Process Advantage
From years of experience in designing and building thousands
of attritors for use all over the world, Union process has
developed the “know-how” to custom-design units for specific
requirements, whether for production or laboratory use,
employing either a dry or wet grinding process. Union process
maintains a well-equipped laboratory and pilot plant where
actual production conditions can be simulated to assure that the
attritor we build for you will satisfy your requirements. skilled
technical service representatives are available for consultation.
they can arrange visits to customer and prospective customer
facilities to answer questions and provide solutions.
Advantages of Using a Circulation Attritor
n
Faster grinding with narrower particle size distribution
n
Uninterrupted, large-scale production
n
excellent temperature control
n
simple and safe to operate
n
Low maintenance and power consumption
Common Applications for Attritors
n
paints, toners, inks
n
Ceramics
n
agricultural flowables
n
Food products
n
Chocolate, confectionery
n
paper coatings, calcium carbonate, clay
n
Chemicals
n
Ferrites
n
metal oxides
n
minerals, ores, coal
n
sulphur dispersions
retaining grids
1 3,4