Effective mine dewatering: Water management in mineral extraction Also: Neptuno Pumps
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THE INTERNATIONAL MAGAZINE FOR PUMP USERS Number 579 July/August 2012
Effective mine
dewatering:
Water management
in mineral extraction
Also:
• Oil & gas
• Construction
• Water & wastewater
in liaison with
www.worldpumps.com
36 Feature
WORLD PUMPS July/August 2012
Mining
Water management
for copper mining
Effective water management is critical in any mining operation, so
finding innovative mine dewatering and fluid transfer applications
is essential for today’s mineral extraction processes. Petar Ostojic
discusses how custom engineered barge pump systems help
accomplish this task in two copper mining companies.
C
entrifugal pumps are widely used no civil works, the barge can be easily support to a custom engineered free
in the global mining industry, handled and installed, it is always at floating barge. Vertical turbine pumps
from mine dewatering to hydro- the correct submergence, no priming are widely used in the mining industry
metallurgy extraction processes, and is required, and the design needs the because of their technical and practical
are considered the heart of any mining minimum of space. advantages, making them perfect for the
operation. Several of the most respected use in a barge pump system.
engineering, procurement, and construc- However, as simple as it may sound,
tion management (EPCM) companies are there are still some considerations that The design’s modular multistage
developing a record number of projects have discouraged clients over the years construction offers higher efficiencies on
for the world’s biggest mining companies in selecting this as a viable alternative for high head and high flow applications,
that are currently operating in Chile, Peru their projects. First, it is difficult to find a and allows the pump to be custom-
and the rest of Latin America. Most of complete single-vendor pumping station ized for many applications. No priming
these projects are mainly based on the supply that includes pump, motor and is required because the impellers are
extensive use of centrifugal pumps. barge; second, most manufacturers use submerged in the liquid, and the first
vertical cantilever sump pumps providing stage impeller can be lowered to provide
The current boom in the price of metals low heads (usually up to 60 m) and low the desired NPSH margin.
is pushing EPCM companies and their efficiencies of around 60-70% - usually
providers to deliver fast engineering solu- a booster pumping station is required The barge system was designed as a
tions without compromising project’s next to the pump to reach higher total modular concept using 3D CAD/CAE and
costs and operational safety. This scenario dynamic heads. finite element analysis (FEA) modelling
has allowed pump manufacturers to work (Figure 2), ensuring that the pump set
closely with engineering firms developing All-in-one package and pontoon are balanced for optimal
innovative solutions in order to accom- stability. It is custom manufactured on
plish these objectives. Neptuno Pumps, an engineered indus- high-density polyethylene (HDPE) with
trial pump manufacturer based in non-collapsible, foam filled flotation
Pumps on barges Iquique-Chile, wanted to develop a chambers, which eliminates the chance
complete pre-packaged modular barge of catastrophic failure from chamber leak
Barge pump systems (Figure 1) repre- pump system, which could provide and maintaining the system always at
sent a great alternative for today’s larger heads, avoiding the use of inter- proper submergence.
mining projects, delivering efficient, fast mediate booster stations and dimin-
and cost-effective solutions for current ishing the total number of pumps used Using high-pressure vertical turbine
mining requirements. Such a system is on a single project. pumps, with total dynamic heads up to
really simple in its design, consisting of 350 m (1,148 ft), and high efficiencies
a centrifugal pump, usually in vertical The design comprises a centralized indi- up to 85%, eliminates the need for an
disposition, attached to a free-floating vidual high-head and highly efficient immediate booster station, reducing the
barge. Among the main advantages are vertical turbine pump (VTP) attached amount of equipment used in the mining
that a free-floating barge design requires through a metallic reinforced base plate operation.
www.worldpumps.com 0262 1762/12 © 2012 Elsevier Ltd. All rights reserved
38 Feature
WORLD PUMPS July/August 2012
Figure 1. Schematic of a Neptuno barge pump system. A free-floating barge Figure 2. Finite element analysis (FEA) of an entire barge pumps system. This ensures
design requires no civil works, it can be easily handled and installed, is always that the pump set and pontoon are balanced for optimum stability.
at the correct submergence, needs no priming and takes up little space.
Open-pit mine dewatering
advance and mining conditions change is extracted from the acid leach with a
Compañía Minera Doña Inés de Colla- in the open-pit. solvent which flows to the leach pad
huasi is thought to be the world´s fourth- where it is collected and directed to
largest copper mine and it counts as one Over time, this arrangement allowed a flow into the leach ponds. Pumps then
of the biggest open-pit mine operations reduction in equipment through the use transfer it to the SX plant and the copper
on the planet. It is located at 4,400 m of high-head pumps, reduced haulage is subsequently electrolytically refined.
above sea level in the Andean plateau of costs because of having dry ore and
northern Chile's Tarapacá Region. waste, improved in-pit transport and The solutions used in this process are
operating conditions, plus reduced wear chemically aggressive because of their
Mine dewatering at Collahuasi was and tear of machinery. Also, the stability acid nature, and they require the use of
achieved by pumping continuously from of mine walls was improved during and special materials with superior corrosion
a series of dewatering wells around the after excavation. resistance, such as high alloy stainless
mine and installing low-head pumps steels, for all of the pump’s wet parts.
in special sumps on the mine floor to Copper hydrometallurgy
remove surface water. However, one main The other important aspect is that gener-
characteristic of this mine site was the Compañía Minera Lomas Bayas is located ally it is not possible to control the level
existence of huge lagoons in the bottom in the Atacama Desert, 120 km east of of the liquid in the pond, so vertical
of the mine pit, collecting enormous Antofagasta in northern Chile. This open turbine pumps represent the best choice
volumes of water which needed to be pit copper mine is one of the world’s because of their design flexibility.
pumped back to the surface. This needed lowest-grade copper operations with
several pump stations located at strategic average grades of 0.27% soluble copper. In these stations, the length of the
positions and depths. pumps is designed such that the impel-
Copper hydrometallurgy processes, such lers are submersed at all times, even
In 2010, a mine dewatering programme as solvent extraction/electrowinning (SX/ when the fluid level reaches its minimum.
was devised to reduce the impact of EW), can efficiently and economically Sometimes, when this length is too high,
groundwater on the mine. The project process lower-grade ores with lower water equipment’s cost can increase consider-
incorporated 10 75 kW (100 hp) and 112 consumption. This technique consists ably because of the high costs of mate-
kW (150 hp) barge pump systems (Figure basically in using an aqueous solvent to rials used for the pumps.
3), engineered as a modular, light-weight dissolve or leach minerals for ores.
design, with a total dynamic head of All the above considerations, plus the
150-250 m (492-820 ft), that could be In the SX/EW process, the ore is leached extensive use of ponds in the process,
easily transported as the exploration with sulphuric acid, and then the copper make the barge pump system the ideal
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Feature 39
WORLD PUMPS July/August 2012
Custom engineered
barge pumping
systems
Neptuno Pumps offers custom
engineered barge pumping systems
for the most diverse mining applica-
tions, including the following:
• Water supply
• Mine dewatering
• Tailings – post processed solutions
Figure 4. A Neptuno barge pump system designed for SX/EW’s pregnant leach solution (PLS) transfer. The vertical • Solvent extraction/electrowinning
turbine pumps must handle highly corrosive solutions, while providing high total dynamic heads up to 200 m. (SX/EW)
Operating parameters:
• Head up to 300 m (1000 feet)
• Capacities up to 3000 m3/h
(13,200 gpm)
• Power through 750 kW (1000 hp)
• Frequency 50/60 Hz
• Bowls sizes from 20.32 cm (8 inch)
to 50.8 cm (20 inch).
Figure 3. Collahuasi’s open-pit mine Neptuno barge pump dewatering system seen here operating at 4,400 m above
sea level.
Contact
solution for this application. Neptuno HDPE has also a superior chemical Contact: Petar Ostojic
Pumps engineered a barge pump system resistance to acid solutions, making the Mechanical Engineer, M.Sc.
(Figure 4) that included, depending on material ideal for the construction of Project Manager
Neptuno Pumps
precise fluid characteristics, fully cast the floating barges. This system required Av. Circunvalación 64B, Iquique-Chile
duplex 2205, super duplex 2507 or 254 minimum civil works and it was engi- Tel: + 56 57 424685
SMO vertical turbine pumps capable of neered to stay at the proper depth, Fax: +56 57 425504
Twitter: @NeptunoPumps
handling these highly corrosive solutions, requiring no priming. This allowed the use Email: projects@neptunopumps.com
while providing high total dynamic heads of much shorter vertical turbine pumps, Web: www.neptunopumps.com
up to 200 m (656 ft). futher reducing the project’s cost.
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