REPROCESSING AND RETREATMENT
The Pyrite Leach Project is part of
Goldcorp’s $420 million
investment to improve the
processing facilities at its
Peñasquito operation
investment to improve the processing facilities at
its Peñasquito operation. It is expected to
recover some 35% of the gold and 42% of the
silver currently reporting to the tailings and add
production of over 1 Moz of gold and 45 Moz of
silver over the current life of mine.
The PLP plant processes the existing plant
tails, feeding a sequential flotation and leach
circuit with precious metals recovered through a
Merrill Crowe process, producing doré as the
final product. Tails from the new plant will report
to the existing tailings storage facility.
As the plant ramps up to achieve design
recovery, there will be ongoing optimisation of
the circuit chemistry and regrind performance,
according to Goldcorp.
The miner highlighted that the PLP was
delivered with over 9.5 million site-hours, zero
lost time incidents and an industry-leading all
injury frequency rate of 0.09. It was constructed
by a 100% Mexican workforce, commissioned
two quarters ahead of schedule and came in 9%
under the $420 million budget, Goldcorp said.
The carbon pre-flotation circuit (CPP), which is
integral to the performance of the PLP and
existing plant, was commissioned in the June
quarter as planned and
the circuit has treated
more than 6 Mt of high-
carbon ore. Up until
recently, it was
exceeding initial
performance
expectations.
The completion of the
CPP de-risks not only
stockpiled material, it
also enhances flexibility
to sequence ores and
has the capability to
process the complex
organic carbon ore types
remaining in the
reserves, according to
Goldcorp.
The CPP circuit
currently consists of
three stages of flotation
to remove organic
carbon from the cyclone
overflow prior to the
existing lead flotation
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12 International Mining | MAY 2019
mineral content considered for decades to be too
low for further beneficiation to be performed in a
cost-effective manner have accumulated
throughout industry, but EIRICH believes its
mixers offer a process to economically recover
these.
The company said: “Today – in a time when
raw materials are scarce and high-quality ore is
increasingly rare – beneficiation of the dumped
gangue materials often makes commercial sense,
particularly as they often represent an ecological
risk.
“Ores and other useful minerals occur in
nature almost entirely in a contaminated form.
For use as a raw material, the gangue needs to
be separated.
“Since the start of the 20th century, the
flotation method has been the primary way to
extract the raw materials.”
This sees the substances to be separated
initially ground down to a size small enough for
the individual components to exist as physically
separate grains. The mixture is then suspended
in an aqueous solution and aerated with a
turbulent gas flow. Under the addition of
auxiliary materials, it is then possible to bind
mineral granules to gas bubbles, which then rise
to the surface where they can be skimmed off as
froth.
“The other particles (referred to as the
flotation tails) remain in the turbid slurry or form
a sediment at the bottom of the flotation cell and
are then pumped for disposal into so-called
tailing mounds,” EIRICH said. “The rock that
accumulates during mining and the rock that is
co-extracted in the process, which is separated
out during beneficiation, forms these mounds.”
In the past, beneficiation of dumped fine
tailings, which often represent a risk for the
environment, was often not cost-effective, with
even mechanical dewatering seen as too complex
and expensive.
The company said: “Now, though, high-
performance mixing technology makes possible
cost-effective beneficiation of flotation tailings
that still contain a significant level of usable
minerals – and this even with varying moisture
contents.
“In order to extract the minerals, the gangue
materials usually need to be mixed with one or
more other materials and granulated. Suitable
mixing and granulation technology is required for
this.”
EIRICH said its mixers have proven themselves
in many applications, in a wide range of
industries for all kinds of mixing and granulating
tasks, particularly for applications demanding a
high-quality mix.
“The unique working principle of this mixer
normally enables very advantageous process
control,” it said. “Thanks to the EIRICH