ORE SORTING
the presence of an effective ore sorting
system can lead to higher metal
production using the same plant inputs.
Beal said: “If they can feed all of the
ore they would have sent to an expanded
plant to a bulk ore sorter, they can
deliver a substantial amount of metal out
of that in a much reduced amount of
tonnage.
“You have effectively bumped that
metal production back up without having
to spend that capital (associated with a
plant expansion), expand the tailings
pond and start using twice as much
water and electricity, as well.”
More than profit
As Beal indicates and du Preez confirms,
the reasons for employing ore sorting at mine
sites are multifaceted and depend on the
commodity, operation and environment in
question.
waste,” Ilpo Auranen, Chairman of IMA
“In general, I believe reducing water, energy
Engineering, a firm that specialises in testing and
and reagent consumption, is one of the major
installing ore sorting systems, says. “At a typical
ones,” du Preez said in answer to a question
open-pit mine, the mining cost (factoring in ore
about the main reasons mining companies employ
and waste) is $10/t of ore. With ore sorting it is
ore sorting.
less than $1/t, which means that the cutoff rate for
“In turn, this reduces the environmental impact
the whole operation can be reduced significantly.”
of processing ore, and consequently leads to
This is why it should be factored into the mine
significantly less time spent on environmental
expansion debate with plant and fleet upgrades as
permitting.”
As explained earlier,
with water scarcity
concerns rising,
obtaining permission to
either expand wet
tailings ponds or
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complex. This has seen
ore sorting being
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included alongside the
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either brownfield
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assets.
The footprint dynamic
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is also on the list of
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reasons.
“Removing waste from
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ore prior to final
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processing reduces the
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size, cost and often
complexity of the
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downstream processes,”
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du Preez said.
Auranen said existing
waste stockpiles can be
reprocessed and
IMA Engineering’s Ilpo Auranen says ore
sorting sensors work best just after primary
crushing as that is where the ore and waste can
still be effectively separated
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58 International Mining | MARCH 2020
recovered too, freeing up land for other activities
that may strengthen a company’s social licence to
operate.
And, in some instances, ore sorting can lead to
a change in mining method from selective mining
to bulk mining, according to Auranen.
“When we talk about automation and
robotisation of mining machinery, this bulk mining
makes it all much simpler,” he said. “You wouldn’t
need to separate ore and waste in the mining
process – the ore sorters would effectively do that.”
When it comes to greenfield projects,
employing ore sorting can lead to mining
companies being able to more accurately size
their processing plant from the off.
Beal explains: “The larger value proposition
(both in terms of straight economics but also for
reductions in electricity/water consumption and
reductions in tailings generation) is the
application of this technology to projects where a
processing plant has not yet been built, and being
able to build a significantly smaller plant while
maintaining planned product output.”
It's hard to find examples of this, such is the
dearth of greenfield projects moving forward, but
NextOre has aligned itself with one in Australia.
The Magnetite Mines-owned Razorback Iron
project, in South Australia, is the asset in
question, with a recent report from the two
companies demonstrating that the natural
heterogeneity of the Razorback and Iron Peak
resources would potentially allow for significant
upgrading from ore sorting.
“For example, at a 50% rejection level
(corresponding to a cutoff grade of approximately
16% Fe at Iron Peak and 14% Fe at Razorback), the
grade of the accepted material would be increased
by a factor of about 1.4,” Magnetite Mines said.
Were this to be implemented as part of the
project’s development – by increasing mining
rates, and pre-concentrating the plant feed – the
throughput of a given plant capacity could be
increased by some 40%, the company said. This
would translate to significant savings in capital
and operating costs per tonne of concentrate
product.
Due diligence
Not all sensor-based ore sorters will be able to
produce results such as these.
du Preez explained: “People are gradually
becoming more aware of the potential value that
sensor-based sorting can add to their business. It
needs to be evaluated as a potential key
processing step in the flowsheet development of
the project.”
NextOre’s Beal is upfront about this fact,
explaining that his company’s MR technology,
originally developed by CSIRO, is currently
configured for around three dozen minerals at this
stage – copper, iron ore and gold among them.