Water, Sewage & Effluent November December 2018 | Page 33

“At Verder, our focus is ‘less is more’,”
says Macdougall. “This means less
water, less power, less space, less
pollution, less process chemicals,
and ultimately less risk.” Macdougall
explains that the three core elements
of peristaltic pumps are gentle, low
shear transfer, minimising chemical
usage by maintaining flocculent
size, and maximising process
recovery, since concentrations are
preserved. “All of this translates
to less maintenance and downtime
for mining processes,” he says.
“Verder’s range of peristaltic pump
solutions can pump high solid content
(up to 80%) and high SG slurries (up
to 2.0), with minimal abrasive wear,
while reducing water usage and
improving process efficiencies. And
for the miners, this translates into
greatly reduced water requirements,
power, and infrastructure savings,”
says Macdougall. u
Water Sewage & Effluent November/December 2018
Peristaltic pumps work by
alternating
compression
and relaxation of a hose or
tube, drawing fluid in and
propelling it away from
the pump. A rotating shoe
or roller passes along the
length of the hose or tube,
creating a seal between the
suction and discharge sides
of the pump. As the pump’s
rotor turns, this sealing point
moves along the tube or hose
displacing product into the
discharge line.
The hose or tube recovers
after the pressure has
been released, creating
a vacuum. This is the
priming mechanism, which
draws the product into the
suction side of the pump.
Combining these suction and
discharge principles results
in a powerful self-priming
positive displacement action,
the benefits of which are a
gentle pumping action at a
low velocity with no product
degradation.
innovations
Less is more
How does a
peristaltic
pump work?
“Verderflex peristaltic hose pumps
are the ideal solution for demanding
applications such as mining thickener
slurries and highly abrasive, high-
density, and shear-sensitive or
corrosive liquids,” says Macdougall.
These pumps have earned a
reputation as the mining industry’s
slurry pumping workhorse. They are
designed to pump slurry at a higher
SG at a steady flow rate, which
significantly reduces the amount
of water to product ratio, thereby
increasing the per tonnage of product
being transported.
www.waterafrica.co.za
Peristaltic pumps use less water. Hose pumps can circulate slurry SGs of 1.6 to 1.8 or up to 80%
solid content, whereas the traditional centrifugal pump loses efficiency when the slurry SG
reaches 1.3 or 30% solids.
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product to the beneficiation plant, but
because it still contains so much water,
the company loses out on the cost of
the water weight versus tonnage of
product transported.
Currently, few traditional centrifugal
pumps on the market are able to
transfer slurry at the high specific
gravities (SGs) required to save water,
and those that can will certainly
experience increased wear rates.
Slurries are often acidic and or
highly abrasive. Consequentially,
conventional slurry pumps use
impellers made from increasingly
expensive materials with service lives
that are sometimes measured in mere
days. However, adopting peristaltic
pump technology is a solution that will
improve the dewatering of the product
and subsequently water conservation,
and in the process contribute to higher
production capacity and a reduction in
maintenance and operating costs.
Bottom line, peristaltic pumps use
less water. Hose pumps can circulate
slurry SGs of 1.6 to 1.8 or up to 80%
solid content, whereas the traditional
centrifugal pump loses efficiency when
the slurry SG reaches 1.3 or 30% solids.
Given this limitation, slurry pumps have
significant process water demands:
for example, on a plant processing
75 tonnes of ore per hour, and at 65%
solids, every time a peristaltic hose
replaces a process slurry pump, it
could save up to 1 100 million litres of
water annually when compared with
the traditional slurry pump. The hose
pump requires less than 25% of the
process water of a slurry pump.
Every time a peristaltic hose
pump replaces a process
slurry pump, at a flow rate
of 75 tonnes per hour, it
could save 1 100 million
litres of water annually
when compared with the
traditional slurry pump.