Water, Sewage & Effluent Mar Vol 30 No 2 | Page 17

Water Sewage & Effluent March/April 2016

industry
debate
infrastructure

Shepherd says higher variability and more
intense rainfall is expected as a result of
climate change, meaning more uncertainty.
“Mines should consider a buffer with a
reticulation system that allows movement
of water within a closed circuit on the
mine site. A buffer dam would retain
excess water, while a ‘ring system’ could
pump water to anywhere on the site where
needed.” Mines can use open pits as water
buffer reservoirs, provided that the water
quality is suitable and approved by
the DWS.
Another strategy is to re-use municipal
sewage water from nearby towns. This is
part of a more efficient, hierarchical use
of water resources, directing it to uses
depending on its quality, rather than trying
to return it all to potable standard.
Shepherd says dust suppression
consumes substantial volumes of water.
The lower rainfall increases the presence
of dust which undermines worker health,
has a negative effect on the environment
and reduces the lifespan of machinery.
Environmentally conscious mines are
tackling this by using vegetation, chemical
dust suppressants and rock cladding.
Despite being the most commonly used
dust suppressant, water is limited in its
effectiveness. Using only water to control
dust is costly and offers limited dust
suppression. Water quickly evaporates and
dust is again released.

tech news

Closed circuits

Anton van der Merwe, director of
environmental management company
I-Cat, says that its polymer dust
suppressant RDC 20 improves surface
stabilisation and ensures much less water
is used. When sprayed onto a road surface,
it forms a durable cross-linked matrix that
binds fine soil particles with larger heavier
particles, which are less prone to become
airborne. RDC 20 is used on temporary
roads, to reduce dust cost-effectively. I-Cat
has received positive feedback, especially
its use on mine roads. “The overall ambient
dust at our largest operation in the
Northern Cape has improved by more than
40% when compared to the readings taken
prior to I-Cat managing the secondary
roads at the mine,” says van der Merwe.
Spillage and overfilling water bowsers is
also an issue. As much as 10 000ℓ/min of
water can be saved onsite using camera-based
E-Cam and radio frequency identification
(RFID) technology to help water bowser
operators in lining up 85 000ℓ water bowsers
at the filling points across sites.
According to a report by Kissell (2003),
several common and widely available
alternatives to traditional water sprays can
be used during crushing, screening and
conveying material. These include fogging
systems and foam, which significantly
reduce water consumption.
Most of SA’s large mines shared
resources have been well served by the
water infrastructure. The Vaal Dam has
played a major role in the growth of the
local industry. But, as Shepherd points out,
there has not been as much competition
for water from cities as there is now, but
population growth in the Vaal area has
changed this. Therefore, planning and
shared management of water resources
between mines and government is critical.
“Planning leads to win-win solutions
such as helping ensure potable water for
local communities while mines re-treat
municipal sewage for mine processing
purposes,” he says. If mines partner with
other industries, more can be achieved
to share infrastructure and implement
hierarchical water use.
“Droughts force roleplayers to prioritise
their thinking. Hopefully this refocus will
allow drought relief programmes to be
implemented as well as developing plans
to ensure water 7Wǒ6V7W&