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Flexible Liner Solutions For Mineral Beneficiation Plant Mills
Circuit design has changed within
mineral beneficiation plants, which means that
traditional large banks of medium diameter mills
have been replaced by single stage AG and SAG mills.
Added to this, mills are becoming much larger
necessitating a spectrum of mill lining solutions
capable of meeting the varying needs within the
market.
Acting managing director at Multotec Rubber, Spike
Taylor, tells Mining Weekly that these changes
within the minerals processing sector prompted the
company to broaden its market offering to include
its traditional rubber mill liners for the small to
medium size ball mills; composite liners which
utilise rubber, together with either quenched or
tempered plate inserts, for the medium diameter ball
and sag mills and steel mill liners for the large
diameter mills.
Multotec Rubber is acknowledged as
South Africa’s leading manufacturer of rubber wear
products for the mineral processing and materials
handling industries, manufacturing and supplying
mill and scrubber linings as well as rubber
screening panels.
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Catering for all ends of the market, in
2007 Multotec Rubber formed a licence agreement with
USA-based ME Elecmetal to market the company’s range of
steel mill liners throughout Africa. “These mill liners are
particularly well suited to the large diameter (in excess of
5.5 metres) SAG and AG mills installed in a lot of the
modern plants,” Taylor explains.
“Our rubber mill liners are mostly used in mills with
diameters up to 4 metres and composite liners are used in
mills with diameters from 4 up to 5.5 metres, application
dependent, of course,” Taylor says. He points out that
rubber mill liners traditionally have the advantage of being
easier to handle and provide substantial noise reductions
which is a big plus factor in today’s operating environment.
“Our sales and technical department assists customers in
deciding when to move from rubber to composite, or to steel
liners,” Taylor says. “Contributing factors to this decision
would be the top size of the feed, the top size of grinding
media, the diameter of the mill and the percentage critical
speed of the mill. This results in there being ranges of
mill diameters where either rubber or composite liners are
appropriate, or conversely, where steel liners would be a
better choice.”
Taylor explains that one of the determining factors in
selecting rubber or composite liners or steel only liners is
the amount of energy involved in the grinding media falling
onto the charge and onto the mill lining.
“Composite liners have the advantage that they make use of
the best of both materials,” Taylor says. “The steel on the
leading face overcomes the cutting action and the high
energy of medium diameter mills whereas the rubber liner
provides energy or shock absorption and allows the steel to
last longer. Another advantage the composite liners have
over steel only liners is that they are made in sizes which
are still easy to handle. However, one must acknowledge that
steel mill liners are more robust and the alloy can be
chosen to suit the application, depending on the impact
involved.”
Taylor emphasised that the association between Multotec
Rubber and USA-based ME Elecmetal suits the current trend in
the market to fit larger steel liners. “Traditionally, the
practice in Africa has been to use lifting equipment to rig
the liners into place which limits the size of the liners
and therefore increases the quantity of the mill liners and
the mill relining time. With an increasing focus on
productivity, mines actually need to minimise the downtime
on the mills.
“The trend in industry is to move towards larger liners
using a mill liner handler. After the feed chute is removed,
the mill liner handler is pulled into position and secured
to the floor,” Taylor says. A shuttle carriage then moves
the worn liners out and moves the new liners into the mill.
An operator sits at the end of the mill liner handler and
uses a multi axis grapple to move the liners into position
so the installers can bolt these safely into position.
“With small components the safety aspects are critical and
this is definitely a far safer option,” Taylor adds. Mill
liner handlers are becoming more common in Africa due to the
proven capability of the accurate component casting which
ensures optimum fitment of large liner sections.
“In addition to its steel liner range, ME Elecmetal has also
re-entered the grinding media market and Multotec Rubber is
establishing the market potential for this product range in
Africa,” Taylor says. “We also supply ME Elecmetal alloy
concave liners for use in gyratory crushers to Metso and
other crusher OEMs for the gold, platinum and base metal
mining sectors.
“Multotec Rubber continuously invests in its rubber
manufacturing facility and we pride ourselves in our
skilled, competent people, and in the technology and design
capabilities we have,” Taylor says.
“We hold extensive intellectual property for our product
technology, which allows for a wider range of solutions for
our customers, ultimately resulting in an improved bottom
line,” Taylor concludes.
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