HEAP LEACH – SX-EW_proof 26/10/2016 10:00 Page 4
HEAP LEACH – SX/EW
driving the overall performance of the mine with
much greater success.
Looking at total gold recovery of the pad as a
function of time, heap-leach modelling may
impact the cutoff grades—either higher or
lower—for mining. This information is critical for
operators looking to optimise processes and
maximise the recovery of metals. Instead of
looking at the heap-leach pad operation in
isolation, it becomes part of the entire operation
of the gold mine that’s being evaluated.
Stacking the pads
HUESKER says heap leach pads are considered
the highest lined fills in the world. “The stability
of the ore lifts is critical in order to avoid
potential downhill heap failure. Stacking more
ore faster enables faster returns, however, high
loads and harsh chemical environments provide
limited pad liner interface stabilisation
options.”
The stabilisation of the pad liner/overliner
interface with chemically resistant geosynthetic
reinforcement materials provides opportunities
to stack ore lifts higher while maintaining the
stability and integrity of critical interfaces.
HUESKER offers engineered geogrid or geotextile
reinforcement solutions which are proven to have
high chemical resistance and long term stability.
The advantages are:
n Increased liner interface stability
n Faster stacking of more ore leading to greater
and quicker returns on investment
n Chemical resistant raw materials contributes
to pad liner longevity
n Increased heap leach pad site safety.
HUESKER’s geosynthetic engineering
experience and capabilities enable the design of
project specific solutions to enable the
decoupling of loads from the heap leach pad
barrier system. Geosynthetic reinforcement
solutions which reduce or eliminate ore load
transfer to the barrier system contribute to
critical barrier system longevity and improved
seismic interface stability. Advantages:
n Decoupling the barrier system from the ore
loads
n Enabling steeper slope construction
n Increasing ore stacking volumes
n Contributing to interface stability of barrier
systems.
In Arizona, North America's largest producer of
copper, and the world's largest producer of
copper cathode from the SX-EW, uses multiple
leach pads.
In support of stacking operations on one of
these leaching sites, between 2007 and 2014
Terra Nova Technologies (TNT) was responsible
for the design, supply and construction of a total
of five 72”x250’ and three 54”x250’ Super
Portable® conveyors. Each of these mobile
20 International Mining | NOVEMBER 2016
conveyors was supplied wi th an initial design
capacity of 2,600 t/h.
For the development of a new heap leach pad
as part of this mine’s Southwest Mine-for-Leach
project, TNT designed, supplied and erected 5 km
of overland conveyors and a Super Portable
stacking system (including an additional five
72”x250’ Super Portable® conveyors, horizontal
feed, horizontal and radial stacker) for the
Southwest Pad. Equipment in this mobile
stacking system has a capacity of 5,467 t/h.
Superior Industries TeleStacker® Conveyor is a
telescoping radial stacker conveyor that, Superior
says, “achieves speedy payback, which is
measured in more tonnes per move, larger leach
pad footprints and increased profitability.”
Engineered with an internal stinger conveyor
that maintains constant motion along a cell, the
TeleStacker Conveyor distributes material evenly
to achieve flat top piles, while also piling more
material per move. Its longer stinger conveyor
allows for greater flexibility and the popular FD
Series Axle assembly allows a quick transition
from radial to linear modes.
Irrigating the heaps
Netafim, known worldwide for its driplines,
filters, valves, air valves, sprinklers, flushing
packages and flow meters, recently introduced a
cost-saving way to increase leaching
performance while helping mines reduce labour
and downtime. This comes in the form of a radio
or cell-based monitoring and control package
designed to increase operational efficiency from
a single location so mines have real-time
information regarding flow, temperature and
pressure. This complete package of software,
hardware and support equipment remotely
monitors any number of elements deemed
important by the mine and provides real-time
information on which to act. The scalable system
can also manage automated flushing of piping
networks which until now has been a timeconsuming and labour-intensive manual
operation that required personnel to walk from
area to area to open and close ball valves.
Whether used in a cloud-based application or
managed locally at a site, the technology ‘turns on
the mine’ in a way that lets operators know realtime what is occurring across the site and helps to
remove the need for personnel to walk the site in
search of problems that may not be there.
Mike Stoll, Netafim Industrial Division Director
Of Sales & Marketing, explains that “in addition
to the newest control package, Netafim has a 50+
year history of manufacturing low-volume drip
and driplines for applications as varied as
landscape irrigation, agriculture, greenhouse and
nursery as well as wastewater treatment and mining.
“In mining Netafim offers the broadest range
of flow rates that start at 1.0 litres/h and go up to
8 litres/h (0.26-2.0 g/h), and uses the latest
evolution in emitter technology that does not rely
on a long flow path to reduce the pressure and
manage the flow rate. This is critical because the
shorter the flow path in an emitter, the less likely
it is to become clogged. Simply put, the faster
you can reduce the pressure along the length of
the dripper from the point of entry to the exit, the
more suspended particles will be and as such,
the less likely that clogging will occur. In
addition, Netafim’s ability to mount the dripper to
the inside wall of the dripline allows the emitter
to capture its flow from the centre of the tubing
where the flow is fastest and cleanest. That
means the emitter is not capturing its flow from
the wall of the dripline where debris collects.”
Ore-Max was a pioneer in the application of
drip irrigation to gold and copper mines in the
late 1980s. The company says that “previously
mines had used sprinklers which had many
environmental and production limitations which
were solved by the application of mining solution
using drip systems.
“Today the use of drip on mines is standard on
90% of the gold, copper and uranium mines and
it is also used on nickel and extraction of
lithium.”
Ore-Max says its Max-Emitter™ is “designed
to reduce plugging because mining solution
always has contaminants in it. Hundreds of
screens filter the solution so that it is almost
impossible to plug the screens and the flow path
is the largest available on the market. Further,
two exit holes are standard but the emitter can
be ordered with four holes to reduce plugging. All
of this means that more emitters will be
operating more of the time so you can achieve
maximum ore extraction.”
The Max-Emitter has a full 330° flow path fully 90% of the emitter is flow path. This ensures
that much lower flow rates can be used without
plugging.
Senninger Irrigation’s position is that low
pressure, 1.03-1.38 bar spray nozzles like its
“mini-Wobbler® evenly apply solution over large
surface areas, much like a gentle rain,”
maximising solution/ore contact, while
minimising the potential for channelling or
clogging.
Senninger’s WinSIPP2 custom mining software
was developed to help leaching operations
achieve required application rates and uniformity.
It provides visual comparisons of various
combinations of applicators, flows, pressures,
and spacing options. “Analysing these
combinations in advance helps assure optimal
system design and operation,” the company
says.
WinSIPP2 software calculates the precipitation
rate of irrigation systems. It aids in the selection
of the best heap irrigation products by testing