SLURRY ENGINEERING/PIPELINES
“The beauty of the SlurrySucker Maxi
is that we only need one small area to
begin the desilting work,” says Vine, “In
this case, we started in one corner of the
dam and created a cut by attacking the
sediment to create space for more water
to re-enter the working area.” He
highlights that the mine needed the dam
to remain on line during the dredging, so
water would continue to enter the pond
from the processing plant.
“The SlurrySucker only needs a 400
mm draught of water above the sediment
for the floating unit to operate,” he says.
“A dewatering pump takes the top layer
of water and feeds it down to the dredge-
head, where the slurry is agitated so it
can be pumped away.”
The dredging unit is pulled back and
forth across the dam, creating a new cut
on each journey by removing a lane of silt
at a time.
Australian technology is being used in
African mining and other industries to remove
heavily solid-laden slurries and sludges normally
considered impossible with conventional pumps.
Brain Industries’ Airloader is a portable,
compressed air powered unit. Unlike
conventional pumps, which rely on vacuum
displacement, the Airloader combines high
velocity suction airflow (25 m 3 /min) with a
powerful vacuum (-0.88 bar).
Brain Industries’ managing director Gillian
Summers said the pump acts like a vacuum
truck, sucking up material and then discharging
it. Ms Summers said it is the only one of its kind
in the world that can suck up the thickest and
most viscous (up to 80 mm in lump size)
materials across horizontal distances of more
than 100 m and at depths of more than 35 m
below the pump. It can discharge the material
over distances of more than 1 km horizontally
and heads of up to 60 m.
“Brain’s Airloader can convey any flowable
material containing solids,” Ms Summers said.
“Because there are no moving parts in contact
with the material, the pump can handle large
lump sizes, waxy, fibrous and abrasive
materials,” she explained.
Autoclave pump
David Donato an Inside Sales Engineer for ABEL
Pump Technology comments on his pumps used
in the autoclave cycle used to extract value from
sulphide ores. “An autoclave must be fed at
specific, constant and often times high pressures
and flow rates, requiring a very specialised type
of pump.
“Transferring the ore slurry through the
autoclave circuit is not a job that can be left to
just any pump. A positive displacement,
20 International Mining | DECEMBER 2018
Brain Industries’ Airloader
hydraulic piston-diaphragm (or piston-
membrane) pump is the best tool for the job.”
These slurries can usually have a high solids
concentration. “The exact operating conditions of
an autoclave will vary depending on the sulphide
ore however, during some autoclave circuits,
temperatures can reach more than 200°C and
pressures can rise to more than 55 bar. The
temperature and pressure of the slurry must be
considered when choosing materials for the
positive displacement piston diaphragm pump.
Many positive displacement pumps can easily
handle the high flow rate and pressure required
ABEL Hydraulic Quadruplex
Diaphragm Pump (HMQ)
by the autoclave process. However, few
pumps can also handle abrasive slurry like
the ABEL model HM piston-diaphragm
pump. As with temperature and pressure,
flow rates for autoclaves vary, usually from
22 m 3 /h to 75 m 3 /h, or more. The flow rate
and pressure fall well within normal
operating capabilities of some of the
larger positive displacement pumps.
“A triplex positive displacement,
hydraulic piston diaphragm pump like the
ABEL HMT model, is a three piston, single
acting pump. The pistons are 120°out of
phase from each other to maximise their
natural dampening effect. During each
stroke cycle of the crankshaft, each piston
acts on a volume of hydraulic fluid, driving
one of three diaphragms into a
hermetically sealed pumping chamber. The
decrease in volume of the pumping
chamber discharges slurry through the
discharge check valve.
A quadraplex pump, or more accurately,
a duplex double-acting pump like the ABEL
model HMQ is another high flow rate, high
pressure hydraulic piston diaphragm pump used
in autoclave feed. Unlike a triplex pump a
duplex-double acting pump uses only two
pistons to actuate four diaphragm housings. The
suction and discharge concept is the same as the
triplex piston when acting on a single volume of
hydraulic fluid. The difference with the duplex-
double acting pump is that one piston acts on
two diaphragm housings on the same side of the
pump. Whether the piston acts in the forward
stroke or aft stroke, hydraulic fluid is being acted
on in both diaphragm housings causing both a
suction and discharge action in the two
diaphragm housings. IM