PASTE & TAILINGS 2020
Positive displacement
Paul Moore spoke with Erik Vlot, Weir Minerals Global
Product Manager for GEHO ® pumps, about its range,
market position & trends in tailings pump demand
Q Have the high-profile dam failures had an
effect on tailings pump demand?
A I wouldn’t say that the tragic tailings disasters
have directly caused a major increase in
enquiries for positive displacement pumps.
Interest levels have been high for many years
and the vast majority of GEHO ® positive
displacement (PD) pumps we manufacture,
whether piston diaphragm or hydraulic, are for
mine paste and thickened tailings applications.
We are receiving a lot more questions around
filtered tailings. From a technical perspective,
filtered tailings are not always the right solution
and this sentiment is also shared by some
independent experts. Filtered tailings still
contain a percentage of water, therefore
liquefaction is still a risk, and the CAPEX and
OPEX is high as the material has to be conveyed
rather than pumped. Finally, if the filtered
tailings don’t end up providing the stability you
are looking for after stacking, then the added
cost may not be justifiable.
Q What are the main factors in pump selection
for thickened tailings? Can you give some more
detail on the piston diaphragm design?
A The challenges with paste are centred around
the control of slurry quality, which can be
difficult and how to manage the logistics at the
Tailings Storage Facility (TSF). Mines can’t just
dump their paste in one place, they need to
think about the flowing fields that allow it to dry
and compact, but if you get it right, it can be
much more cost effective than filtered tailings.
The GEHO ® PD pump configuration selected
varies depending on the customer requirements
for flows, pressures and densities. Our most
popular model for tailings applications is our
GEHO ® TZPM and ZPM high pressure, piston
diaphragm pumps. This range is crankshaft
driven, with a significant power range starting
from 50 kW up to 2,500 kW, and can handle
solids of up to 70-75%. Within this range, the
working principles are more or less the same,
you are scaling up on the size for the frames,
crankshafts, valves, diaphragms. The unique
preformed diaphragm separates the pumped
slurry from all the pump moving parts. This
pump handles abrasive and corrosive slurries,
dirty water and process mixtures at the lowest
possible total costs of ownership, thanks to its
low energy consumption and high reliability.
Q What about hydraulic piston pump demand?
Why and where are these used?
A Weir Minerals is noticing a trend towards
thicker paste which requires more hydraulically
driven pumps instead of piston diaphragm, as
the latter has limits up to a certain slurry
thickness. Piston diaphragm pumps often rely
on a centrifugal pump to feed material whilst
hydraulic pumps do not.
Hydraulic pumps which can handle solids of
up to 90% are required for paste backfill
projects where paste is used to fill underground
mining stopes to minimise surface disposal and
footprint. This trend is particularly prominent in
North America and Australia.
The crankshaft driven PD pump uses a
gearbox and motor, so these pumps are quite
efficient but with the mentioned limitation on
paste yield. The hydraulic driven piston pump
(GEHO ® DH series) has a full hydraulic power
pack to move the slurry cylinder up and down,
and therefore is less energy efficient that the
crankshaft driven PD pumps. However, when
combined with the GEHO ® VZ-system for
pulsation free operation, it has an increased
level of control, preventing damage, excessive
wear and noise. This pump type also ensures
uninterrupted, troublefree
operation, high
reliability and low
operational costs.
The GEHO ® DH
series has two models
of hydraulic driven
piston pumps – the
GEHO ® DHC, which
features cone valves
and is suitable for
pumping paste with a
maximum solids
diameter of 30mm,
and the GEHO ®
DHT, which uses a
transfer tube and
can work with
larger particles, up
to 100 mm. The
DHC is the most
commonly used in
tailings
applications whilst
the DHT is used for
coarse rockfill
material.
Q How do you see Weir in the wider OEM
market? How is demand split by mined
commodity?
A Weir Minerals is not the only pump supplier in
mining for tailings, but I think we are unique in
providing the widest range of pumps to suit our
customer’s tailings applications. We truly
support the customer every step of the way,
from operation through to servicing. We don’t
just focus on the pump, instead we take a
holistic approach and make improvements to
the overall paste pumping system. We support
customers locally though our global service
network, and our teams are highly trained in the
product performance and operation.
In regard to commodities, gold is big
currently in both tailings and dewatering, even
gold process feed, all driven by high gold prices.
Nickel is still important in China, where they are
investing heavily in their domestic mines. Iron
ore is still going strong too, while copper and
aluminium projects in regard to tailings have
seen less growth.
Q What about digitalisation potential with these
pumps?
A Our Synertrex ® IIoT platform can monitor our
pumps in real-time for peak reliability and
performance. This is the only way to understand
fundamentally what is happening in your
machines and systems, and achieve true
preventative maintenance where there is little or
no unscheduled downtime with the correct level
of spares and parts stored onsite. We already
have a significant number of tailings pumps out
in the market with Synertrex ® technology
installed. In the past we could dial into the
pumps and look at performance through the
Programmable Logic Controller (PLC), now we
have online monitoring and are working towards
having predictive algorithms. Common failures
include crankshaft pump valve seals wearing
out and seals on the hydraulic models being
affected by wear. Both parts are in direct contact
with the slurry or paste. This is where the
Synertrex ® monitoring system has the most
positive impact. IM
P2 International Mining | SEPTEMBER 2020 Supplement