Page 36 - Chemical Technology
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Chemical Technology •January 2013
34
FOCUS
on water treatment
The 2012 SASSDA
(Southern Africa
Stainless Steel Development Asso-
ciation) Project Award for Engineering
has been awarded to the Veolia Water
Solutions & Technologies South Africa
subcontractor, Metso ND Engineering,
for work completed on the Ammonium
Sulphate Plant at the Ambatovy Nickel
Cobalt Refinery in Madagascar.
Veolia commissioned Metso ND Engi-
neering to pre-manufacture three large
crystalliser structures, along with a se-
ries of ancillary tanks and equipment, in
modular form for shipment from Durban
to the mine’s processing site, Toamasina,
for final assembly. The project marks the
first time, in South Africa, that a crystal-
lisation plant of this size was constructed
off-site to enable reduced costs and
shorter construction periods.
The structures, 10 m x 10 m and 17
m high in size, are designed to withstand
280 km/h hurricane winds, as well as
mild earthquakes caused by nearby fault
lines. Metso ND Engineering used 316 L
stainless steel, and carefully co-ordinat-
ed the three shipments to coincide with
Veolia’s ground-up assembly approach.
Veolia has since successfully handed
over a completely functional ammonium
sulphate extraction plant to the Ambatovy
Mine, capable of drying up to 26 tons per
hour for sale as a fertiliser to agricultural
markets. Because the ammonium sul-
phate is found in a slurry solution
Veolia Water completes winning zero liquid discharge plant
The ammonium sulphate extraction plant will boost
Ambatovy’s profitability.
For more information
contact: Gunter Rencken
on tel: +27 11 663 3600;
or email:
;
or go to
.
(already stripped of nickel and cobalt by
the mine’s main refinement processes),
engineers agreed that crystallisation
would be the best extraction technol-
ogy: Crystallisation facilitates large
scale evaporation, effectively drying the
ammonium sulphate into a waterless and
manageable product.
Veolia designed the zero liquid discharge
(ZLD) recovery plant, manufactured system
components, and project-managed suppliers
from around the world, including Metso ND
Veolia has since successfully handed over a com-
pletely functional ammonium sulphate extraction
plant to the Ambatovy Mine.
Engineering, to deliver the plant to suit
the refinery start-up schedule.
The ammonium sulphate extraction
plant will boost Ambatovy’s profitability,
while utilising available resources to the
maximum. This flagship project will set the
trend in the African mining industry to make
the most of available mineral assets using
viable ZLD and extraction technology.
South Africa
is a water-stressed country.
Being semi-arid with limited annual rainfall
supply and a lack of perennial streams, the
future implications of population growth com-
bined with the uncertainty of climate change
are likely to have significant financial, human
and ecological impacts on already scarce wa-
ter resources. Much of South Africa’s water
supply originates from groundwater sources.
These occur widely and geographically and
almost two thirds of South Africa’s population
depend on it for their domestic water needs.
On a global scale, groundwater is an
essential freshwater resource for both
socio-economic and environmental systems,
and forms a critical buffer during periods of
drought. This makes the protection of ground-
water supplies (management, pollution con-
trol and remediation) essential, particularly
in developing countries where groundwater
management is neither strongly emphasized
The importance of groundwater management
in national water legislation, nor implemented
where it is needed.
Groundwater is water that exists in the
pore spaces and fractures in rock and
sediment beneath the Earth’s surface. It
is naturally replenished by surface water
from precipitation or snow, and then moves
through the soil into the groundwater system
where it recharges the water table. Ground-
water sources are generally extracted through
the construction and operation of extraction
wells or bore holes.
In areas where rural infrastructure is
minimal, rural communities will often rely
on more informal, traditionally developed
groundwater sources such as hand-dug wells,
springs and sand abstraction. Currently,
South Africa’s groundwater resources supply
approximately 15% of the total volume of wa-
ter consumed nationally. Of this, almost 64%
is used for agricultural irrigation purposes,
while exploitation for mining and domestic
consumption constitutes 8%.
Despite our reliance on groundwater, it has
remained a poorly understood and managed
resource, most likely due to its ‘hidden’ nature
and the lack of adequate knowledge and
physical data pertaining to aquifer characteris-
tics and behavior such as recharge, discharge,
base flow and aquifer dependent ecosys-
tems. Most groundwater quality and quantity
problems in South Africa are related to human
activities such as industry (eg, infiltration of
chemicals and toxins) and mining (eg, acidi-
fication and increased metal content), urban
development (eg, salinization, eutrophication,
microbial effects) and the intensification of
agricultural practices (e.g., sedimentation,
infiltration of agro-chemicals and salinization
through irrigation return flows).
Deteriorating standards in wastewater
treatment, agricultural drainage, land use
