FIXED & BULK MATERIALS HANDLING – MAGNETIC SEPARATORS
A pulley magnet installed in a plastic waste
recycling plant has picked up spanners
Use the force
Magnetic separators are often installed in arduous conditions. How do they
work, and what are their maintenance requirements?
or extra-strong neodymium rare earth.
Examples of smaller magnetic
separators provided by Bunting
include drawer lter magnets, bullet
magnets, in-line magnets, liquid pipeline
separators, magnetic liquid lters, plate
magnets and tubes and grid magnets.
The liquid pipeline magnetic separator,
for example, extracts iron nes and other
magnetically-susceptible materials from
wet or viscous products conveyed in a
pipeline. Additionally, special welds are
available for corrosive applications, such
as fruit juices (www.is.gd/cilaje).
Larger magnetic separators provided
by Bunting include drum magnets,
permanent overband magnets, stainless
steel separators, pulley magnets,
rare earth roll separators, suspension
permanent magnets and wet drum
magnetic separators. The pulley magnet,
for example, replaces the head pulley of a
conveyor. The magnetic eld covers the
entire 360°-circumference of the pulley,
ensuring that conveyed material is fully
exposed to the magnetic extraction force
at all times. It is also commonly used as a
second-stage metal separator
(www.is.gd/micilu).
In contrast, electromagnetic
A drawer fi lter magnet installed in a plastic
waste recycling plant with ferrous
materials captured on
the tube magnets
Two eddy current separators installed in a
metals recycling plant to recover
non-ferrous metals
separators only attract particles when
powered. Then, “electromagnetic coils
generate strong and deep magnetic
elds to separate either larger or
weakly magnetic particles,” the Bunting
spokesperson says. Examples include
electro drum magnets, electromagnetic
lters, permanent overband magnets,
induced roll separators, magnetic disc
separators and suspension electro
magnets. Overband magnets, for
example, are suspended over conveyors
to separate tramp ferrous metal.
The nal type of separator uses
eddy current generated by a changing
magnetic eld. In this case, “permanent
magnets are used in a speciallycon
gured, high-speed, high-strength
magnetic rotor to repel and thus
separate non-ferrous metals,” the
spokesman says. This particular unit is
said to be used widely in the recycling
industry. Designs include both concentric
and eccentric rotor designs (www.is.gd/
cezobu).
Both permanent magnetic separators
and electromagnetic separators are
designed and manufactured to meet
each customers’ speci c separation
requirements, says supplier Eriez-
Europe, which has a manufacturing
facility in South Wales (www.is.gd/ediduk).
Among its range of products are
the CP (centre-pole) or TP (twin-pole)
20/120 SC2 HYD (permanent overband),
which are said to typically be used in
M agnetic separators are
By Adam O ord
used across a range
of industrial sectors.
For example, in waste
processing, they help
recover ferrous metals from other waste
materials such as plastics, demolition
waste and wood, by attracting them
through magnetism. In food processing,
they can remove ferrous and non-ferrous
metals introduced with the raw material
or following process equipment wear or
damage. Other industrial sectors where
this technology can be used include
aggregates and quarries, ceramics, glass,
mining, mineral processing and plastics.
SEPARATOR DESIGNS
There are an extensive range of di erent
magnetic separator designs, according
to equipment designer and manufacturer
Bunting. There are essentially three
types: permanent magnetic separators,
electromagnetic separators and eddy
current separators.
The rst sort use permanent magnets
to “attract, hold, de ect and separate
ferrous and weakly magnetic particles,”
a Bunting spokesperson explains. Those
magnets can be standard strength ferrite
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/cilaje)
/micilu)
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/ediduk)
/www.operationsengineer.org.uk