Maintworld 2/2020

ASSET MANAGEMENT
THERE ARE MANY ELECTRICAL
5| SYSTEMS involved in the mining
industry from DC to HV. In many cases
dust is a major contributor to failure.
One of the key problems associated with
the build-up of dirt, dust and moisture
on the surface of components is tracking.
The ceramic insulator pictured here
failed because it was covered in dust
which was causing the tracking. Oncondition
cleaning using ultrasound to
identify the presence of the tracking is
used to eliminate failures by optimising
cleaning procedures.
The mining community in South Africa
are also leading the way in the adoption
of ultrasound as a safety screening
tool to protect electricians working in
substations. A small ultrasound kit is
located at the entrance to the substation
and there is a series of assessment
measurements to be performed in order
to provide approved safe access to the
building and proximity to the panels
inside. This approach is undoubtedly
saving lives by providing a higher level of
safety in the work environment than can
be provided by flameproof or arc-flash
clothing alone.
TIGHTNESS testing of the air intake
systems of the large diesel
6|
engines in haul trucks using ultrasound
has saved one mining company alone
over €14M in three years for an investment
of less than €28,000. Additional
operational savings have been seen by
minimising the time spent ensuring
that the drivers’ cab environments are
dust-free.
MINING MACHINERY is diverse
7| – sometimes simple like a conveyor,
other times more complex as in
the case of a reclaimer. The condition
monitoring requirements in the mining
world are, therefore, quite diverse
and frequently not simple.
Airborne ultrasound, sometimes
using a parabolic dish pointing out of
the window of a pickup is a very quick
and reliable means of inspecting the
condition of a conveyor – especially if it
is 12km long.
There is more than the usual amount
of slow-speed equipment in mining
which is often in critical operational
roles. Ultrasound is perfectly capable
of listening to bearings rotating at even
less than 1rpm and still providing valuable
diagnostic information.
Finally, there is the need to consider
the condition of machinery, which is
itself moving – like shovels or is moving
violently – like vibrating screens.
This critical bearing rotating at
24rpm was found to have failed during
an ultrasound inspection. The bearing
had recently been replaced, so it was
relatively new. Unfortunately, the
replacement bearing was not quite the
correct one and was undersized for
the load requirement. Very quickly,
the new bearing disintegrated.
OVER-LUBRICATION is quite
8| an established tradition in the
mining world – “grease that bearing
until I can see the grease coming out
of the sides”.
So, there you have it. One technology,
Ultrasound, used in either airborne
or contact mode to identify problems
in 8 major problem areas in mining.
Conservatively, in the last decade the
savings that customers have achieved
must be well beyond €23.5M. Time
for you to start?
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