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COLLECTIVE RESPONSE TO A
120-YEAR OLD CONUNDRUM
by Marilyn Boyd
Mining [ June - September 2008]
In the well-known Brothers Grimm fairy tale, the miller’s
daughter has to find a way to spin straw into gold or face a
gruesome execution. Fortunately for her, a magical little man
appears and helps her achieve this seemingly impossible task.
Now, in a 21st century tale of technological magic and teamwork,
water severely contaminated by decades of gold mining in the
Witwatersrand’s Western Basin, is being turned back into clean
water again.
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South Africa is a water-scarce country,
receiving an average annual rainfall of 497 mm, compared with a
world average of 870 mm.
Water is essential for economic development and social
upliftment and its sustainable use is absolutely critical. In
addition
to the semi-arid nature of the country, with its erratic
rainfall patterns, other factors influence the supply of water
in South Africa: regions of high runoff, moving water away from
areas of maximum demand, limited and poor quality groundwater,
invader vegetation infesting catchments and a general
deterioration in water quality.
At the same time, the population of the country continues to
grow and become urbanised, economic development is extensive and
people are demanding higher levels of municipal services. The
already challenged water resources are being stretched to
accommodate the demands of agriculture, industry, recreation,
domestic users – and aquatic ecosystems.
Water and the law
The South African Constitution includes in its Bill of Rights,
the right to an environment that is not harmful to health or
wellbeing and the right to an environment that is protected for
the benefit of present and future generations.
These rights are to be ensured through measures that prevent
pollution and ecological degradation.
From the time South Africa’s rich ore deposits were first
discovered by George Harrison in 1886, mining exploration in
Johannesburg has burgeoned. The seam along the North-West of
Johannesburg proved particularly lucrative and was mined
unrestrainedly until the early 1990s.
Gold mining on the Witwatersrand for the past 120 years has been
the backbone of the region’s economic growth, producing as much
as 35% of the world’s gold.
But, by the time the South African Department of Water Affairs
and Forestry (DWAF) introduced environmental regulations – the
National Water Act (1956) and the Fanie Botha Accord (1970) –
the foundations of a challenging scenario had already been laid.
The National Water Act was promulgated to protect water and to
limit effluent discharge by the mining industry. Prior to this,
many mines were being abandoned without implementation of
adequate pollution control measures. The Fanie Botha Accord was
an agreement reached between the mining industry and government
to guide the provision of pollution control measures at
abandoned collieries and to outline the responsibility for costs
to institute these measures.
However, since the turn of the new century, underground voids
created by the mining of the Witwatersrand orebody –
specifically the Western Basin void – have filled with water and
started to discharge into the surrounding water courses at an
annual average rate of 15 megalitres a day.
Acid mine drainage
This water poses a severe environmental threat because it is
contaminated by acid mine drainage, a sulphuric acid solution
generated when exposed ore comes into contact with water and
air.This polluted water threatens not only water resources and
the fast-growing domestic and commercial populations that depend
upon them, but also one of the world’s most historically
important and environmentally-sensitive sites – the Sterkfontein
Caves. Unless the acid mine drainage is effectively addressed,
the potential exists for this contaminated water to enter and
irreversibly damage the caves, which form part of the 3.5
million year old Cradle of Humankind, and the nearby Krugersdorp
Nature Reserve.
Many of the mining houses active in the West Rand over the last
100 years have ceased operations, or no longer exist, placing
the onus for finding an effective and sustainable solution to
this significant environmental challenge on the few players who
continue to have active interests in the area.
These companies include MinTails (through its operating
subsidiary, Mogale Gold Mine), Harmony Gold Mining Company Ltd
(through its operating subsidiary, Randfontein Estates Ltd) and
Durban Roodepoort Deep (DRD), whose operations are dormant,
though technically active, at West Wits Gold Mine. Aside from a
moral imperative to address
the acid mine drainage problem, these three remaining players
are required to do so by the National Water Act, which
stipulates that ‘the polluter pays’. The Act provides for the
use of economic instruments to encourage waste dischargers to
discharge waste without causing harm to others or imposing a
cost upon society. In terms of this, the DWAF has issued a
directive that no mining house will be permitted to close any
further operations in the area until the affected water has been
satisfactorily rehabilitated.
WBEC
In response, the three gold mining operations have joined forces
to form a company called the Western Basin Environmental
Corporation (WBEC) – a Section 21 company that will execute a
sustainable solution to acid mine drainage on behalf of the
three mines. WBEC in turn signed a management agreement with
Western Utilities Corporation (WUC) to provide funding,
management, construction and operational capacity. Jaco
Schoeman, the chief executive officer of WUC says:‘The
environmental challenge is twofold: first, how to overcome the
contamination of potable water sources inadvertently caused by
decades of gold mining activity and secondly, how to satisfy the
ever increasing demand for greater volumes of potable and ‘grey’
or industrial quality water by industry and the surrounding
communities. ‘It is an irony that the gold mining industry,
which has made such a significant and positive, contribution to
South Africa’s economy in the past century, should be at the
centre of an issue that has such potentially detrimental
consequences for one of the regions in which it has been most
active.
‘As a scientist I can state that science is wonderfully equipped
to answer the question:
HOW? But it gets more complicated when you ask the question,
WHY? Why did we allow acid mine drainage to occur?
Why didn’t we act sooner? Why did we allow tailings storage
facilities to be created on top of dolomitic areas?
‘The only thing we learn from history is that we do not learn.
‘Those of us still involved in mining on the Reef accept that we
have a moral obligation to resolve the water problems and,
together we’ve innovated a solution that has the potential to
overcome the twin challenges of contamination and burgeoning
demand simultaneously,’ says Schoeman.
As an interim measure, the three companies have been removing
most of the contaminants by neutralising and clarifying the
water at existing water treatment plants at Mogale Gold Mine and
Harmony Gold Mine.
However, to fully address the problem, WBEC – the new Section 21
company – will directly address the process of environmental
water rehabilitation associated with acid mine drainage and
investigate and develop sustainable initiatives in close
consultation with the relevant government authorities.
WBEC’s imperatives are to:
rehabilitate the contaminated water that is already decanting
from the underground voids of the Western Basin minimise further
contamination of potable water sources preserve the Sterkfontein
Caves by mitigating the risk of exposure to acid mine drainage
reduce off-take of potable water sources by industrial users by
making industrial water
available in its place minimise the transmission of acid mine
drainage to sensitive downstream areas such as the Cradle of
Humankind, by reducing the water level in the underground voids.
WBEC has been granted the right to register as a water services
provider, which entitles it to remove the water associated with
its own mines, treat it to a specified quality and to on-sell it
to the industrial market. ‘It is important to stress,’ says
Schoeman, ‘that although none of the mining houses involved in
WBEC will profit financially from the treatment and selling of
acid mine drainage, all will ultimately benefit from its success
by being able to implement closure strategies for their mining
operations.’
To implement and manage this self management agreement with the
Western Utilities Corporation, which will construct a
state-of-the-art water treatment plant capable of processing 75
megalitres of acid mine drainage a day to industrial (grey
water) quality – equivalent to South African National
Accreditation System Class II quality water.
WUC is a wholly-owned subsidiary of Watermark Global plc, listed
on the United Kingdom’s Alternative Investment Market, and was
established to implement a commercially self-sustainable
solution on behalf of WBEC. Phase 1 of the plant is estimated to
cost Ł16-million to treat 75 Megalitres a day, while the cost of
the total project to treat up to 300 Megalitres a day is
expected to be around Ł240-million, which will include
collection and distribution infrastructure.
‘The plant will make use of a chemical precipitation treatment
process that has the capability to remove heavy metals and
sulphates from the contaminated water,’ says Schoeman.
‘It also uses a pyrometallurgical methodology, developed by
South Africa’s Council for Scientific and Industrial Research (CSIR),
to convert various by-products back into raw materials that can
be sold or reused to reduce processing costs.’ WBEC’s ultimate
goal is to create a zero effluent discharge plant that in effect
will mean the contaminated acid mine drainage water could be
purified up to potable water quality if required, but at
additional cost.
To demonstrate the viability of the technologies available,WUC
has commissioned three pilot plants at one of the old mine
shafts from which acid mine drainage is currently
being pumped, in Randfontein. Based on the performance of the
different technologies being tested, WBEC will ultimately settle
on one or two of them – or a compromise between technologies –
for its full-scale water treatment plant.
ATOMIN plant
The ATOMIN Plant, operational for WBEC since 5 April 2008, uses
the SAVMIN methodology (patented by Mintek and operated by
Atomaer RSA (Pty) Ltd) to treat four cubic metres of acid mine
drainage an hour to industrial quality standards. This novel
technology is based on the selective precipitation of insoluble
complexes at different stages during the process. Mintek says
the process has several major advantages compared with similar
technology applications. For instance, it can treat a broad
spectrum of polluted mine water – from gold, platinum, coal and
base metal mines – and easily treats and purifies the polluted
water to DWAF standards.
Waste products from this process can be disposed of either as
stable waste or may constitute a value-add by-product.
Gypslim plant
The Gypslim (Gypsum, Limestone and Magnesite) Plant, operational
since 5 March 2008, uses the CSIR-patented Gypslim process to
produce industrial quality water at a processing rate of one
cubic metre an hour. Until recently, gypsum was a waste product
that created an economical nightmare for industry. Gypslim
technology focuses on the recovery of valuable by-products from
the gypsum that is produced during the neutralisation of acid
mine water.
The CSIR and its industrial partner on this project, Key
Structure Holdings, have jointly developed the cost-effective
Gypslim process for the recovery of sulphur, lime/limestone and
magnesium carbonate from gypsum, which has significant
commercial value.
Sulphur required for the African and Australian economy is
currently imported from Canada and the Middle-East. With the
implementation of this process for the treatment of the
pollutants such as gypsum and sulphur dioxide, the CSIR and Key
Structure Holdings believe that they can reduce annual sulphur
imports by 40%. This will have both a major positive effect on
the environment, and save huge amounts of money from leaving the
country.
By-product recovery plant
The By-Product Recovery Plant (operational since 10 March 2008)
designed, engineered and operated by the CSIR, Key Structure
Holdings and Sulphidetech, processes and isolates by-products
produced by the SAVMIN and Gypslim water treatment processes.
EIA
‘Of course, development of the envisaged water treatment plant
will inevitably hinge on the findings of an Environmental Impact
Assessment,’ says Schoeman. ‘In advance of which, WUC
commissioned consultants Golder Associates, in February 2008, to
determine how the water, once treated, can be redistributed to
industrial users as far north as Rustenburg and as far south as
Vanderbijlpark – as well as identify the optimum location for
the eventual construction of the water treatment plant. Golder
Associates is a global group specialising in ground engineering
and environmental services. ‘However, the key to the success and
sustainability of this solution rests on the plant’s ability to
produce water of a suitable quality at a cost-effective price
for on-selling to high-volume industrial users, such as the
nearby platinum mines that have major expansion strategies and
that need more water than the local municipalities are able to
supply. ‘At present, platinum mining operations are drawing
large amounts of potable quality water for their operations,
because there is no other source. Anglo Platinum currently
requires about 50 megalitres of water a day for its operations
and the nearby Impala Platinum operations require similar
quantities.’
Another sustainable benefit of using rehabilitated water to meet
industrial demand is the positive impact it will have on
availability of potable water for the surrounding communities,
since pressure on potable resources will be reduced by
substituting with industrial quality water.
‘This is a bold and creative response to a serious environmental
challenge,’ says Schoeman, ‘and we are confident that not only
can WBEC/WUC provide a sustainable solution to the issue of
contaminated water in the Western Basin, but that the same
solution can be rolled out elsewhere, in South Africa and around
the world, to effectively overcome the damage inadvertently
caused by mining activity.
It is, in fact, already being considered as a viable option for
water sources in the Central and Eastern Basin and possibly as
far as the Far Western Basin, which will have the potential to
provide closure strategies for a large number of the mines
across the Witwatersrand Basin region.
Hartbeespoort Dam pipeline project
The WBEC initiative is likely to slot into a larger water
project in the region, currently in the feasibility
stage.Working in close cooperation with the DWAF, Anglo Platinum
is financing a pre-feasibility study in the provinces of Limpopo
and North West that could provide an innovative solution to
water challenges in the region.
This will be the first time that the mining industry has made
such a bold and united social commitment to reducing its potable
water usage from local municipalities by as much as 50%, freeing
up this water to meet the future needs of the local communities
in which it operates.
Still in the planning stage, the Hartbeespoort Dam pipeline
project is intended to meet the challenges of future domestic
water requirements in the Bojanala and Waterberg municipal
areas, at the same time offering a longterm solution to the
escalating water needs of the expanding platinum mines in the
area.
In essence, the proposed Hartbeespoort Dam pipeline project
could see the construction of a pipeline around 300 km long,
with a capacity of between 100 to 250 megalitres per day, from
the Hartbeespoort Dam through Rustenburg and on to Thabazimbi
and Lephalele. The actual required capacity is still being
determined and will be greatly influenced by the participation
of the power generation and petrochemical companies in this
project.
WUC’s Schoeman says this project presents an ideal fit for the
Western Basin water treatment initiative, providing a key source
of water.
‘A key principle of the proposed Hartbeespoort project is that
the water discharged into the pipeline must have been treated to
a purity level acceptable to the other parties involved in the
project.And this is where we’re focusing right now,’ he says. |
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