PASTE SUPPLEMENT 2019
Thickening thought leadership
FLSmidth is a leading across the board equipment
supplier to the paste and filtered tailings industry,
including expertise in thickener solutions. Recently it
supplied paste and leach feed thickener solutions to
miners in Peru and Australia
Optimising paste thickening in Peru
eruvian mining company Volcan
Compañía Minera recently installed
FLSmidth paste thickeners and doubled
its capacity in six months. To find the optimal
solution for Volcan Compañía Minera’s
processing plant, engineers from Cerro de Pasco
travelled to FLSmidth’s R&D centre and test
facilities in Salt Lake City, USA. There, FLSmidth
offers leading test expertise in precious metals,
base metals, and industrial metals. The facilities
include crushing, grinding (including ultra-fine
grinding capabilities), gravity separation,
hydrometallurgy (ambient and autoclave
technology), column leaching and flotation.
Flotation equipment includes mechanical test
cells from 50 grams to 15,000 grams capacity.
The laboratory also offers in-plant consultation
services and plant auditing.
As a result of the project, in the thin air of
Cerro de Pasco, high in the Peruvian Andes
Mountains, Volcan Compañía Minera’s
processing plant more than doubled throughput
in six months. The plant now exceeds its
original design capacity of 2,500 t/d– and can
process as much as 3,000 t. However, half a
year earlier, the oxide plant was
underperforming as it only managed a
throughput of between 900 and 1,200 t of gold
and silver-bearing oxide ore per day. Juan
Manuel del Aguila, project engineer at Volcan,
and his colleague Luis Loaiza collaborated with
FLSmidth’s team in Peru to find a solution to
improve the process of recovering silver via
cyanide. Volcan’s team of engineers travelled to
Salt Lake City, Utah to perform further tests at
FLSmidth’s facilities.
“The initial tests in Salt Lake City resulted in
a large filtering area, but we also carried out
parallel tests to explore other options. It turned
P
out that we could meet the objectives with the
EIMCO ® Deep Cone ® Paste Thickeners. We
returned with these results and carried out
onsite tests at Cerro de Pasco,” says del Aguila.
“Our engineers installed a pilot thickener plant
at the site and after twenty days of testing, we
found that it would increase the tonnage at the
plant. This allowed Volcan to meet their capacity
needs. A solution that required less time and
less capital than applying additional filters,”
says Walter Gamero, Senior Process Engineer at
FLSmidth, Peru.
Volcan awarded FLSmidth an EPC contract to
supply two Deep Cone Paste Thickeners,
including the required tanks, piping, pumps
valves instrumentation, control boards, cables,
motors and control system. Only a week after
operation, the Volcan oxide plant exceeded its
original design capacity of 2,500 t/d. “We are
not limited to just supplying the equipment with
a mechanical guarantee but can also apply
business models providing guarantees on the
performance of the equipment in terms of
volumes and availability.” says Gamero. Through
extensive cooperation between Volcan and
FLSmidth, the process was fast-tracked, speeding
up the successful outcome.
Debottlenecking gold thickening in
Australia
A leach feed thickener was creating a bottleneck
in a gold mine in Western Australia. The
installed thickener was an existing ‘off-the-
shelf’ product, neither supplied nor installed by
FLSmidth. As the onsite maintenance contractor,
the client asked FLSmidth’s team of specialists
to assess the performance and offer a solution
to improve productivity and overall
performance. As a result, FLSmidth’s engineers
identified several improvements to the
thickener’s control set-
up. “The customer
realised their feed
system was undersized
and hampered by air
entrainment. The
density-reliant dilution
FLSmidth paste
thickeners at Volcan
Compañía Minera in
Peru
system meant that the feed stream was not
being diluted, resulting in high flocculant
consumption, poor overflow quality and lower
than desired underflow density,” explains Dane
Smith, Dewatering Product Manager at FLSmidth.
Following test work, a process review and
structural analysis of the bridge and thickener
tank, the FLSmidth team recommended a
combination of the E-DUC ® feed dilution
technology and the E-Volute™ feedwell. The E-
DUC system uses feed stream momentum to
induce large volumes of feed dilution prior to
the feedwell, thus optimising flocculation due to
improved mixing profiles and residence times.
The E-Volute feedwell is characterised by
excellent feed stream energy dissipation,
optimal mixing energy and shear profiles.
Subsequently, it promotes even feed
distribution into the thickener with minimal
floccule breakage, therefore improving the
overall sedimentation performance.
Specialists at the FLSmidth Supercentre in
Perth completed the project from onsite test
work and inspection, to process and mechanical
design, fabrication of all components,
installation, and finally, commissioning. “No
other original equipment manufacturer (OEM)
has the ability to provide such a breadth and
depth of service.”
“Having control of the project meant we could
keep to the required tight delivery schedule,
while remaining on top of quality and planning
onsite. This ability helped to shave three full
shifts off the installation, allowing the site to
return to full production far earlier than they
had thought possible,” says Smith.
Initial data analysis shows a reduction in
flocculant dose of approximately 34% and an
increase in underflow density by approximately
2 wt % during the first two months. As the plant
continues to optimise the new system under
FLSmidth’s recommended control setup,
flocculant savings are maintained and
underflow densities have increased up to 8%
age points from 48 wt % to 56 wt % (6% on
average), limited only by the rake drive torque.
In addition to the achieved flocculant savings,
the increase in leach feed density reduced total
volumes reporting to the CIL, the minerals
recovery process, by around 16.5%. This
decreases cyanide and lime requirements while
significantly increasing available leach
residence time, promoting gold recovery. The
results are such that the 34 m leach feed
thickener with FLSmidth technology is
producing higher densities than the 44 m
tailings thickener with non-FLSmidth OEM
technology. IM
APRIL 2019 Supplement | International Mining P1