MINING CHEMICALS
Balancing the formula
Dan Gleeson delves into a sector focused on providing more
environmentally friendly chemicals that retain, if not increase,
their effectiveness in the process plant
hether it is for dewatering, mineral/
metal recovery, optimisation of mineral
processing, or long-term protection of
key equipment, the use of mining chemicals is
vital to the success of today’s operations.
As mining companies take on the challenge of
processing even more complex ores, using the
right chemicals – with the right dosages – will
continue to be critical into the future.
Yet, as manufacturers of reagents, frothers and
processing aids are being asked to develop more
effective products, they are also battling with
requirements to lower the impact on the
workforces that interact with these chemicals and
the environment in which they work.
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Reduced exposure
Bernard Oosterndorp, Technical Manager at
South Africa-based reagent producer Axis House,
has seen the company’s clients demand exactly
this – products that reduce handling or mixing on
site.
“We have seen a gradual move away from
xanthates to liquid sulphide collectors for this
very reason,” he told IM.
While xanthates have been used in sulphide
flotation since 1924 and are the most widely used
sulphide collector in the flotation space, they
pose some major risks, according to fellow
reagent producer Clariant.
They present health risks to workers, come
with disposal challenges for mining companies,
may require additional infrastructure for
handling, and are classified as a fire and
explosion hazard by many regulators, according
to the company.
Business Queensland, an arm of the
Queensland Government, classifies xanthates as
liable to spontaneous combustion in the
Australian Dangerous Goods (ADG) Code, adding
36 International Mining | MAY 2020
that they pose a number of hazards due to their
nature, the vast quantities used in industry and
the climate conditions at most Queensland mines
using them.
For these reasons, it is hardly surprising there
has been a gradual market move away from
xanthates.
In the lead flotation process, Eammon Guitard,
Global Marketing Manager, Mineral Processing,
at Solvay Mining Solutions, says the company
has seen more and more polymetallic (Cu/Pb/Zn)
mines requesting selective collectors to replace
xanthates in the flotation process.
“Today over 40% of the industry has switched
to alternative products,” he said, adding that
Solvay’s AEROPHINE ® is one of the leading
technologies in these applications.
Going to trial
Clariant says its own push to replace xanthates
worldwide is driven by three major factors.
One is the simplification of flotation circuits
through avoiding the use of multiple collectors
where possible.
Two is the elimination of the need for
operational mine employees to handle large
amounts of xanthate powder or pellets.
Three is the problems associated with
discarding contaminated packaging.
“The goal to replace xanthates that have been
in use for nearly 100 years is an ongoing challenge
for the Clariant Mining Solutions team,” it said.
The company has been making significant
progress with this “ongoing challenge” since it
launched its HOSTAFLOT ® line of xanthate
replacement technologies, part of its EcoTain®
range of products, in 2015.
The company told IM: “Clariant’s goal is to
help mining operations increase their production
efficiencies, lower production costs and improve
Solvay says its AEROPHINE xanthate
replacement chemical technology enables base
metal miners to maximise their net smelter
returns for concentrate through the effective
extraction of precious metals that can be sold
as by-products
sustainability with their HOSTAFLOT line of
xanthate replacements.”
Clariant’s application development teams have
been working with customers to create and test
several chemistries from the HOSTAFLOT series
to replace xanthates in their respective regions,
moving the products towards commercial
applications, it said.
In a previously reported initial plant trial of
HOSTAFLOT chemistry at a large copper/gold
mine in Brazil, collector consumption was
reduced by 40% and frother consumption by
25%, according to Clariant. The company noted
the mine continues to experience both lower
collector consumption and frother consumption
since the trial.
At another large copper/gold mine in Brazil,
Clariant said the HOSTAFLOT xanthate
replacement technology was able to replace not
only the xanthate but also the supplemental
collector, resulting in an overall reduction in
collector consumption of 33%. Frother
consumption has also been reduced by 50% at
this mine.
“In both copper mines, metallurgical targets
for copper recovery continue to be achieved, with
operational acceptance in the plants,” Clariant
said. “Additional mines in Brazil have shown
interest in the HOSTAFLOT xanthate replacement
chemistries, and laboratory qualification is
ongoing in gold flotation plants.”
In Chile, some of the largest copper mines
have moved from xanthate to HOSTAFLOT
xanthate replacement technology, according to
Clariant.
Plant results have indicated a 1% improvement
in copper recovery over sodium isopropyl
xanthate, with the HOSTAFLOT collector
indicating a better response at a lower pH than
xanthates, which results in less lime
consumption and lower reagent costs for the
operator, Clariant explained.
“Currently there are gold flotation plants in
Chile undergoing lab trial qualifications to
evaluate whether the HOSTAFLOT xanthate
replacement product can replace their xanthate
collector,” the company added.
In Australia, a plant trial is ongoing at a large
copper/gold mine where the miner is evaluating
one of the HOSTAFLOT xanthate replacement
chemistries to replace sodium ethyl xanthate in
its flotation process. There are also several
laboratory trials ongoing with a large lead-zinc-
silver-copper producer to replace sodium ethyl
xanthate in its zinc flotation circuit.