Mechanical Technology may 2015

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Mechanical Technology — May 2015 23
⎪ Materials handling and minerals processing ⎪
Multotec’s intimate un-
derstanding of minerals
processing and handling
applications, coupled with
its flexibility in being able to offer its
customers fit-for-purpose solutions,
has resulted in a repeat order for two
overbelt magnets sold into a coal mining
application in the Witbank/Middelburg
coalfields. “This order follows the suc-
cessful commissioning two years ago
of two overbelt magnets at another coal
mine in the same group,” Willem Slab-
bert, process and applications manager
at Multotec, says.
“Multotec has a good standing within
the Witbank/Middelburg coalfields,
where our products are supported by
our local branches,” says Slabbert.
Commenting on the latest order, he ex-
plains that the application is to remove
tramp metal from run-of-mine
material in order to prevent it
from entering coal gasifiers.
“This is a critical ap-
plication as the coal
gasifiers have ver y
stringent tramp metal
removal specifications,”
Slabbert says. Tramp
iron traditionally removed
from coal carrying conveyors
includes sections of continuous
mine core breaker teeth, conveyor belt
idlers, belt joints, wire, roof bolts, metal
plates, slings, picks and pick cases, cable
hooks, expanded metal, tools, tin cans
and other such objects.
Multotec supplied the original over-
belt magnets in September 2012, with
the latest order representing the second
phase of an ongoing expansion project.
Stuart Cullum, process engineer, explains
that the width of the conveyor belts in
this coal mining application is 1.8 m,
with the overbelt magnets themselves
being 5.1 m wide and 2.45 m high.
They incorporate the latest technical
specifications of the client, including pul-
ley design, control and instrumentation.
The overbelt magnets are suspended
Overbelt magnets delivered to coal mine
Right: Multotec’s
Magnetics Division
assembly team
standing next to
a locally manu-
factured 33.7 t
Longi-Multotec
overbelt magnet.
Above: Longi-Multotec overbelt magnets are designed to remove tramp metal from
run-of-mine material in order to prevent it from entering coal gasifiers or mill
circuits. Left: Longi-Multotec overbelt magnets are engineered to effectively remove
even the most challenging tramp metal.
Following the successful completion of an order
placed in September 2012, Multotec has received
a repeat order for two 33.7 t overbelt magnets for
a second phase expansion project at a Witbank/
Middelburg coalfield.
over the conveyor on
gantries for easy removal
for maintenance purposes.
Features include an automatic belt-
driven self-cleaning system that dumps
the tramp iron into collection bins at the
side of the conveyor.
The latest two overbelt magnets were
transported to Mpumalanga on low bed
trucks, and weigh 28 t each without their
cooling oil. The latter is added once on
site using an oil tanker, with a final total
weight of 33.7 t for each overbelt mag-
net. As per client safety specifications,
the overbelt magnets have eight safety
chains rated and certified for a load of
16 t each. This is double the normal
requirement, with four chains rated at
8.0 t each being the norm.
Slabbert confirms that these are the
largest overbelt magnets available in
the Longi-Multotec range. “Through our
partnership with Longi, Multotec now
has access to a comprehensive range of
off-the-shelf air-cooled overbelt magnets
for underground tramp metal removal,
with the option of flame proofing.” Having
a standard range on hand means that
Multotec can meet customer require-
ments more quickly, and this reduces
lead times significantly.
Multotec is one of the largest suppliers
of overbelt magnets in Africa for a range
of commodities from coal to iron ore.
It has a dedicated team of expert engi-
neers that is able to assess a customer’s
specific application requirement, taking
into account factors such as conveyor
belt speed and size, burden depth, the
properties of the load on the belt and
the size of the tramp metal that must be
extracted. q