MINING PUMPS
diaphragm pumps in the process circuit to handle
the underflow from the thickener at this operation.
This stream had a solid content of 58-72% (by
weight), along with an abrasive material both
difficult to handle and pump, it said.
ABEL said: “Due to these properties, the
equipment used for transferring these materials
acquires a high level of wear, unexpected
downtime, unscheduled maintenance, etc. These
are costs that the mining industry cannot accept.”
Originally, two centrifugal pumps were installed
in an unconventional way to perform the required
task at the operation.
ABEL explained: “Centrifugal pumps are
designed for specific conditions which generally
never occur given that the operating flow and the
solid content of the materials being transferred
vary during operation due to pressure fluctuations
in other phases of the process.
“In such circumstances, this type of technology
sees its performance dramatically reduced, which
directly impacts the pumps’ output, causes
product recirculation and frequent downtime of
the related production line.”
The ABEL HM hydraulic diaphragm pumps now
installed use piston-diaphragm pump technology
and, therefore, can be operated for one year under
the described conditions without requiring any
preventive or corrective maintenance, according to
ABEL.
Among the benefits of ABEL HM pumps are:
n A performance range of up to 100 m³/h and 10
MPa;
n The ability to transfer media with a solid
content up to 75%;
n Extra-large suction valves for a high degree of
volumetric efficiency;
n Equipped with a pre-formed diaphragm to
improve pumping efficiency, durability and
availability of the equipment;
n Offer constant operating flow, independent
from the discharge pressure, which is mainly
influenced by fluctuations of solid contents; and
n The strokes per minute are low, ensuring low
mechanic wear.
Wear life and corrosion protection
Increased impeller, casing and back liner wear life
were just some of the reasons why Namawka
Diamonds chose to install a FLSmidth KREBS
millMAX™ pump at its Kao mine, in Lesotho.
FLSmidth’s engagement at Kao started when
the mine required a pump conversion in the field –
a difficult and time-consuming task, according to
the mining OEM.
“It is also a high-stakes operation as a cyclone
feed is critical to the overall process and ability to
generate returns. A wrong decision can mean a lot
of lost revenue,” FLSmidth said.
It was the potential for cost efficiency that
convinced the Kao diamond mine to implement
the KREBS millMAX Pump, according to FLSmidth.
After initial discussions, the first trial pump – a
millMAX 8×6 centrifugal seal – was installed in a
cyclone feed application.
Initial results after seven months showed the
millMAX was performing extremely well on the
wear side, FLSmidth said.
Brad Moralee, Head of Product Unit Pumps,
Cyclones and Valves at FLSmidth, said: “It’s high
pressure for us: you are typically given a window
of opportunity during a shutdown to complete the
change, after which the new pump must run as
expected when the plant is re-started.
“You need the combination of a great product
but, more importantly, great technical
understanding of the duty to be able to propose
the correct solution. We understand what is at
stake from the customer side.”
The change produced impressive results in
comparison with the previous solution from
another supplier, according to FLSmidth, with the
millMAX pump increasing the wear life by nine
times across the impeller, casing and back liner.
“This has seen Kao make significant cost saving
on direct replacement costs, reduced downtime
and saved labour expenditure,” the company said.
While Kao mine operators were impressed with
the benefits from the switch, a slight gland
leakage was causing concern, according to
FLSmidth. To resolve this, it suggested running a
one-month trial with the slurryMAX, which had
only just arrived on the South Africa market.
“The slurryMAX trial was based purely on its
sealing capabilities as Kao were confident of the
hydraulic performance of the pump and had no
concern about wear,” the company said.
Kao’s confidence also came from the fact the
slurryMAX design is based on the millMAX range,
whose wear ring technology has created an
efficient and long-lasting slurry pump, FLSmidth
said.
The main difference between the two is the
millMAX is an all-metal pump without an outer
casing and an inner wear liner (the casing itself is
made from the high chrome wear material), while
the slurryMAX is a split casing design that has a
replaceable inner liner. The purpose of this design
is that multiple material liner options are available
to fit in the same outer casing.
“The slurryMAX features an improved, more
efficient impeller and an optional water drain plug
for easier maintenance, allowing water that might
have settled at the bottom of the pump to be
drained quickly,” the company said.
Leigh Rieder, FLSmidth Sales Engineer,
concluded: “Kao is extremely happy with the
hydraulics and lack of excessive wear of our
pumps, which has meant that their cost of
ownership is low. We have recently received an
order from the customer for two more slurryMAX
pumps and they have expressed interest in our
slurryMAX 6×4 and slurryMAX 10×8 pumps.”
As well as producing general drainage pumps,
Tsurumi Manufacturing Co has put considerable
effort into designing pumps for applications for
difficult-to-handle materials, such as corrosive and
high temperature liquids and seawater.
In recent years, polluted water and runoff from
mines and quarries have been cited as social
problems in many countries to the point demand
for pumps that can handle such liquids has
increased year-on-year.
According to Tsurumi, more than 40% of the
runoff from mines is strongly acidic with a pH
value of less than 4.
To cater for this demand, Tsurumi recently
launched its LH-14/LH-W-14 series corrosionresistant
pumps that use 316 stainless steel. This
type of molybdenum-bearing steel enables the
pumps to handle corrosive acidic liquids and
chemical-rich fluids with low pH values, according
to the company.
The use of highly corrosion-resistant materials
goes beyond the pump casing, with all parts
exposed to low pH fluids – including the impeller,
motor frame, outer cover, strainer stand and flange
– thoroughly protected from corrosion, according
to the company.
“These pumps deliver the durability needed in
harsh fields where pumps made of aluminium,
stainless steel and cast iron suffer damage in a
matter of weeks, if not days,” it said.
Cylindrical and slim, the pumps can be installed
in a well casing for deep well dewatering,
according to the company. The centre flange
construction, meanwhile, assures a stable
installation even if fixed by the discharge pipe.
The pump incorporates seal pressure relief
ports that prevent pressure from being applied on
the shaft seal. Furthermore, to endure even
extended operation at low water levels, these
pumps feature a flow-through design that forcibly
cools down the motor, Tsurumi said.
The LH-14 series has a single impeller, with the
LH-W-14 series having dual impellers. They are
both available in a product line up that covers a
discharge bore diameter of 80-200 mm, motor
output of 11-110 kW, and heads of 51.8-184 m.
These pumps, as well as Tsurumi's general
drainage pumps, are equipped with an antiwicking
cable, motor protector, SiC dual inside
mechanical seals with silicon carbide faces, and
oil lifter.
The material used for the rubber parts, such as
the mechanical seal, oil seal, O-ring and packing,
uses fluorocarbon rubber to provide high
resistance to heat and chemical exposure,
meanwhile.
“With these features, Tsurumi pumps are
designed to provide high reliability and excellent
durability, enabling continuous operations for long
periods,” the company said.
IM
52 International Mining | JUNE 2020