MINERAL SEPARATION
Parting brings profits
With mining companies enjoying a brief period of
commodity price stability over the past few years,
the emphasis on operational excellence has
increased. Dan Gleeson looks at what the mineral
separation sector has to offer on this front
ffective mineral separation can be the
difference between an operation making a
profit or recording a loss.
It is becoming apparent that the miners
gaining the most financial gain from these ore
and waste separation techniques are the ones
employing them earlier in the process.
As a result, technologies have evolved to fill
the void between the mine and the mill, with
several of them showing that they can bolster a
mine’s bottom line through, either, early waste
rejection, a higher-grade product feed or being
able to move ‘waste’ into the ore pile.
E
Pre-concentration
Gekko Systems may have started out designing
and manufacturing its now well-established
InLine Pressure Jigs (IPJs) for continuous gravity
separation, but it has evolved into a company
with several energy-efficient mineral processing
solutions.
Its portfolio includes modular ore concentration
plants (Python), intensive leaching technology
(InLine Leach Reactor), density (InLine Spinner)
and magnetic separation (Mag Screen)
equipment. Gekko’s newest innovative
technologies, meanwhile, include the Carbon
Scout and OnLine Gold Analyzer.
Mineral pre-concentration – ore treatment
that goes on prior to the processing plants – has
become the Ballarat, Victoria-based company’s
forte and Greg Rasmussen, Vice President, Sales
and Operations – North America, told IM that
14 International Mining | MAY 2019
both greenfield and brownfield mining projects
are seeing the benefits Gekko’s technology can
provide.
“There has been a lot of interest in pre-
concentration and for different reasons; some
are related to reducing the size of the
downstream plant, while others are looking at
improving the downstream process,” he said.
“For instance, one project we’re working on at
the moment is looking at pre-concentration to
reduce the amount of clay in their feed as it
affects the downstream process.”
Applying technology such as Gekko’s IPJ in a
flowsheet can potentially move a project from
uneconomic to economic status, he claimed.
“The IPJ for pre-concentration definitely
provides the biggest impact on a plant,” he
said. “You can have the potential to reduce your
feed by 50%, lowering both the project capex
and opex.”
One project where this equipment had a
telling impact was SSR Mining’s Pirquitas silver-
zinc-tin mine in Argentina.
Here, the ore contained 5% to 20%
sulphides, 199 g/t Ag, 0.82% Zn (sphalerite)
and 0.22% Sn (cassiterite).
Gekko previously engaged in the test work,
design, manufacturing and commissioning of
the pre-concentration plant at Pirquitas, with
testing of the ore at coarse feeds of between 2-
12 mm returning probable recoveries of up to a
total of 95% silver into 50% of the mass fed to
the IPJs.
In test work in its extensive Spartan
manufacturing and research facility near
Johannesburg, Multotec has succeeded in
separating elements of lithium using spiral
technology
The eventual Pirquitas plant was designed
and built to include a preparation screen to
bypass the fines – that are naturally higher in
grade – and re-pulping of the coarse feed, which
is then pumped to three parallel trains of two-
stage IPJ roughing-scavenging.
This IPJ circuit was designed for operation at
214 t/h and featured three parallel 100 t/h
IPJ2400s, Gekko said.
“The target 50% yield to concentrate passes
over a dewatering screen and the solids are
returned back to the mill feed conveyor,”
Gekko’s Technical Director, Sandy Gray, said in a
white paper.
“The IPJ tails are transferred to a dewatering
screen and solid rejects are stockpiled off the
end of a transfer conveyor. All dewatered
underflow products are processed via
hydrocyclones to recover dirty water for use
back into the IPJ circuit and return entrained
fines to the fines bypass line,” he said.
With the Pirquitas sulphide orebody
undergoing processing, the results from
operations to date have shown plant
performance is matching the original laboratory
test work data, according to Gray.
“The objective of the pre-concentration step
is to both reject gangue and achieve grades