Chemical Technology May 2015

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Chemical Technology • May 2015
Veolia Water Technologies South Africa has
assumed the day-to-day chemical supply
and services of the on-site water treatment
for Evander Gold Mining in Mpumalanga.
After a recent review report, four months
into the three-year agreement, Veolia has
already improved substantially on past
practices and increased efficiency while
reducing overall water treatment costs for
the mine.
Veolia embarked on this total water
management agreement in November
last year following a full site survey on Pan
African Resources, Evander Gold Mining
MET Plant as well as 7 and 8 shaft. This
survey revealed that large parts of the
water circuits were not being treated by
any chemicals due to faulty dosing stations
while other parts of the circuits were facing
dangerous chemical spillages where dosing
station pumps had broken. As a result, high-
ly corrosive water and scale were flowing
through the above and below ground water
circuits, decreasing the mine’s cooling and
ventilation efficiency while damaging its
equipment.
“We opted for a full operation and
maintenance agreement with Evander
Gold Mine, where we will manage the en-
tire water treatment system. As part of the
agreement, a Veolia specialist will remain
on-site for the duration of the contract,
providing 24/7 technical direction, support
and consultancy,” says Carl van Heerden,
Hydrex Industrial Manager, Veolia Water
Technologies South Africa.
As part of this agreement, Veolia sup-
plied 12 new treatment solutions, including:
new chemical dosing stations; flocculants,
coagulants, anti-scalant and micro-biocide
chemical treatment; a semi-automated du-
plex flocculant plant; and coagulant plants
to address the water treatment problems.
Veolia also supplied its range of Hydrex™
chemicals at a variable fee after a weekly
stock-take –meaning the mine will ultimate-
ly only pay for chemicals it has used.
Since the revised treatment plan was
implemented, Junior Sales Consultant
Pieter Jacobs, together with van Heerden,
have managed and monitored the mine’s
water treatment progress through weekly
water analyses and reports. Results recently
detailed in the four-month review of the
programme show that the new treatment
regime is not only out-performing com-
pared to specification; it is also saving the
mine money through a much more efficient
operation.
Due to the bad state of the circuit’s
settlers at shaft 8, Veolia commenced
treatment using gel blocks and added a
Hydrex™ 3936 coagulant. This dual treat-
ment programme saw immediate positive
results: the turbidity and Total Suspended
Solids (TSS) levels were reduced by 45 %
on settler 1 and 37 % on settler 2. Further-
more, the duplex flocculant and coagulant
plants have resulted in a further turbidity
reduction of 27 % on settler 1 and 48 % on
settler 2 allowing for proper dosing control
while optimising the treatment programme.
In addition, all old non-functional dosing
stations at the fridge plant were replaced
with new dosing stations, drastically improv-
ing iron and Total Dissolved Solids (TDS)
concentrations.
At shaft 7, Veolia installed a new co-
agulant dosing station that employs a
custom-designed chemical treatment
programme consisting of Hydrex™ 6611
and Hydrex™ 3936. This new treatment
programme has resulted in a reduction of
turbidity levels of 32 % and overall settler
efficiency improvement from 90 % to 98 %.
Two new dosing stations were also
installed along with the condenser, main
compressor cooling tower and spray pond.
These stations utilised Hydrex™ 2204 and
Hydrex™ 7761 chemicals, which again im-
proved the overall iron and TDS concentra-
tions as well as a visible reduction of algae.
“The improvement of the water quality on
the settlers benefits the entire water circuit.
Overall TDS and iron concentrations are
down, the circuits require fewer chemicals
each month and the equipment gets closer
to spec – ultimately running more efficiently
and lowering overall maintenance costs,”
comments van Heerden. “We also worked
around the clock, 7 days-a-week to install
new equipment in just 30 days – half the ex-
pected time – and installation was relatively
seamless considering we were adding and
removing equipment so far below ground.”
Owing to the early success of this agree-
ment, Veolia is currently in negotiations
with Evander Gold Mining to expand its
outsourced agreements locally as well as
within Pan African Resources’ other mines
throughout southern Africa.
For more information contact:
Carl van Heerden, Hydrex Industrial man-
ager, on tel: +27 11 974 8161, or email
FOCUS ON WATER TREATMENT
Veolia stays on-site to reduce costs for Evander Gold Mine
Veolia installed spill-proof and accurate chemical dosing stations around the mine.
Veolia designed and installed 12 new treatment stations situated above ground and
1,8 km below ground that increased the mine's overall efficiency.