FEATURE
staff. “We have just as many people getting
long service awards for 20 plus years as for
five years,” says Harding.
“We don’t hire our equipment because
one of our market segments is the plant
hire business and we would be competing
with our own clients.” ELB does not
manufacture its own equipment but over
the past century has cemented ties with
best-of-breed OEMs and distributes on
their behalf. “The world’s best from a single
supplier,” Harding describes.
The culture of conservatism when
choosing equipment is rapidly changing.
Previously an entire multi-operation group
standardised on a single brand but the
realisation that different sites are suited to
different equipment, has effected a change.
Customers realise that where a supplier
is assured of their business they tend to
become complacent and lack urgency
regarding after-sales service. It costs a quarry
a great deal of money every hour their plant
is down. That is the dilemma facing mining
operations that have purchased cheaper
Chinese plant: when it breaks down it can
be out of operation for months awaiting a
technician from China.
Screening efficiently
Hiring versus buying
Hiring rather than buying equipment is
often more practical at the beginning of
a quarry’s lifecycle and at the end when
remaining life of mine doesn’t warrant it.
In the middle phase, plant and equipment
suppliers will advise companies on the
merits of buying their own equipment as
opposed to hiring contractors to do the
job. The advantage of using a contractor
is that if tonnage targets are not met or
there are problems with the equipment, it
is the contractor’s issue not the quarry’s.
But it comes at a rand per tonne cost. If
a quarry has engineers and technicians
on site, as the bigger ones do, plant and
equipment can be run much cheaper,
salesmen argue.
It depends on the operation as there
are situations where the quality of the
contractor or the remaining length of
mining suggest outsourcing may be
superior, or even the only way to run
operations.
Local manufacturer Metal’lum is
constructing a large warehouse to ensure
easy availability of parts for its range
of screens and crushers – parts that are
standard to almost any machine. New
plant sales are relatively rare but parts
for screens, crushers and feeders are an
everyday event, so manufacturers are
increasing their stocks of spares to meet
this demand.
“Plant and equipment can last 20
years and more but regularly require
maintenance and spares, which the
technicians on site can undertake,” adds
Bajkay.
Screening is similarly critical to the overall
aggregates production process. Without
proper screening efficiency, the final
product can be contaminated and out of
the grading curve, therefore impacting
production rates. Undersize material will
go back to the crusher in a closed circuit,
which increases costs and can result in
lost sales.
In simple terms, screening efficiency is
how precise a screen is when separating
a feed material of different sized particles
into size groups. Material that is smaller
than the given aperture is designated
under-size and anything larger over-size.
The screen angle, material depth and
other factors influence the material that
passes the aperture. For example, a screen
at an 18-degree angle with an aperture of
8mm can produce 95% cut-size of 6mm,
which implies a screening efficiency of
95%. As a general rule, no screen is 100%
efficient and 95% is as close to perfect as
can be expected.
Hyundai is distributed by HPE.
26_QUARRY SA| JULY/AUGUST 2019
www.quarryonline.co.za