Mines aim to turn pollution into profit
Acid mine drainage is a ticking bomb requiring a concerted response UK firm hopes to treat and sell water before it leaks
September 30, 2009
By INGI SALGADO
Gold mines are racing against the clock to prevent a looming decant of highly polluted water from underground voids caused by more than a century of mining.
Their method: collaboration. No single firm has the resources to deal with the magnitude of problems resulting from acid mine drainage (AMD).
Their ambition: to secure an offtake agreement with Rand Water. They hope to convince the utility by year end that vast quantities of water from unused mines can be treated to potable standards by removing the heavy metals and sulphates released when exposed ore comes into contact with water and oxygen in a process known as AMD. In this way, the project could be propelled towards a measure of self-sustainability.
A sustainable solution is critical, because - in the words of Mariette Liefferink, the chief executive of the non-governmental organisation Federation for a Sustainable Environment - the issue will continue not for decades but for centuries.
"In 120 years of gold mining, 120 gold mines have extracted 43 500 tons of gold and 73 000 tons of uranium, but they have left South Africa with a legacy of 410km178 of tailings dams and 6 billion tons of iron pyrite. There will always be AMD seepage," Liefferink says.
According to a paper on mine water pollution commissioned by the Department of Environmental Affairs last year, AMD threatens the country's scarce water resources, human health and food security in mining areas. There are no easy solutions, but AMD does present "an opportunity to provide usable water through appropriate treatment technologies", the paper says.
Time trials
After 1996, when the first predictions were m ade concerning decant from the western Witwatersrand basin, some gold producers tinkered with technologies to deal with the problem but did not explore them to commercialisation. And so when decant started in 2002, neither the mines nor the government were prepared to deal with the scale of the problem.
At the time, the industry responded by pumping water into the Robertson Lake in Randfontein. Today, that body of water contains uranium levels of 16 milligrams per litre, compared with regulatory limits of 0.07 milligrams per litre of drinking water and 0.01 milligrams per litre of water used for irrigation. The lake is the source of the Tweelopiespruit, which ultimately flows into the Limpopo River catchment.
These days, mines are partially treating the water after channelling it into a lined dam. Discharged into the Tweelopiespruit, it is contaminating boreholes downstream. Apart from the safety and environmental hazards, there are concerns for the structural integrity of the Johannesburg city centre and the N14 as AMD depletes underground dolomite.
The western basin is decanting at a daily rate of 15 megalitres. At the mines' treatment works, the water is neutralised by adding lime. The heavy metals form a complex solid. The water is pH neutral but elevated sulphate levels remain. In the meantime, the Department of Water and Environmental Affairs has issued a directive limiting sulphate levels of the mines' discharged water, effective at the end of October.
"To get sulphate levels below 600 parts per million, you need more technology," says Jaco Schoeman, the head of Western Utilities Corporation (WUC), a wholly-owned subsidiary of London-listed Watermark Global, commissioned by gold mining firms to develop a plan to treat AMD in the western, central and eastern basins.
The group's short-term plan is to pump water in the western basin via a pipeline to the central basin, which is itself predicted to decant at a rate of 60 megalitres a day when it floods in about two years' time. The eastern basin is forecast to decant at 80 megalitres a day in about two years, seeping out the ground at the Nigel taxi rank.
Over the medium term, WUC plans to treat some of the water to industrial quality for use by the gold mines. For every ton of ore mined, they require about a ton of water.
Second, WUC hopes to convert up to 100 megalitres a day to drinking water for sale to Rand Water, using a five-step alkali barium calcium process developed by the CSIR. This involves free acid neutralisation, heavy metal precipitation, removal of magnesium and sulphates, filtration and disinfection.
"We've run two pilot plants for eight months," says Schoeman. The results suggest that, provided the process is performed daily, water is produced to standards set by the SA National Accreditation System and the SA Bureau of Standards.
WUC is not the only company offering technological solutions for the gold mines' AMD headache, but it is the only project to have secured offshore funding. The mining industry has donated infrastructure to WUC and entered into a memorandum of understanding, while the Development Bank of Southern Africa has granted a R10 million non-recourse loan for a bankable feasibility study.
This gives WUC a time advantage in dealing with what Schoeman labels an imminent environmental disaster spreading outwards from Gauteng.
He says the project depends on securing a positive record of decision for its environmental impact assessment, a positive decision on an integrated water use licence, and an offtake agreement with Rand Water.
The water utility won't comment, but Schoeman says there are three outstanding issues: the utility's satisfaction with quality standards, agreeing on a price and formal state approval.
"On assumption we get approvals this year, we hope to start construction in the first quarter of 2010. We see a 12-month construction period and a three-month ramp-up to the second quarter of 2011. It's a tight schedule. We can't afford delay."
Urgent understanding
Internal briefing documents seen by Business Report suggest that high-ranking officials in the Department of Water and Environmental Affairs understand the urgency of the problem, and have considered spearheading WUC's projects on a political level with the government agencies that need to give the project the go-ahead.
However, they are believed to be fearful of being held responsible should WUC fail technologically and economically. There are also concerns that an overseas entity - Watermark Global - should benefit instead of local communities.
In a written response, the department says it does not have any special relationship with WUC. Asked whether it would prioritise the authorisation of WUC's application because of the urgency of the problem, it said: "These priorities are important to the department as long as the applicant fulfils the requirements of the regulator (government)."
Any agreement between Rand Water and WUC would amount to a business transaction between two entities and the department's mandate was to regulate and support initiatives from any party bringing solutions to the problem, it said.
Regulatory issues aside, WUC's bankable feasibility study and the securing of finance will ultimately determine whether it is going to walk its talk. The company needs to secure the bulk of R2 billion required to proceed with the mop-up. The mines have contributed about a quarter of the amount via existing infrastructure. The rest must be raised via debt and equity. Schoeman envisages this will be in the ratio of 75:25.
Markus Reichardt, an independent mining sustainability consultant and former corporate environmental manager at AngloGold, advises caution based on past efforts in dealing with AMD. "It's been tried quite a few times in the past. It's not as if the big firms haven't thrown money at this. That doesn't mean WUC can't be the first, but they're treading over the wreckage of previous projects."
Scheming success
A more successful scheme has been the Emalahleni water reclamation project in Witbank, initiated by Anglo American and BHP Billiton in 2007 to set up a central facility for treating water from underground collieries to potable standards. The water is sold to the municipality, and the products of the sludge are used in bricks.
"It's a triple-win solution in the sense that no polluted water goes into the water resource, communities have access to water and the department doesn't have to monitor or enforce procedures because there's proper management of water resources," says Mikisi Lesufi, the Chamber of Mines executive for environmental health.
"That kind of model is what WUC is trying to follow," he says. The big difference is that Emalahleni is not a self-sustaining project. "There are not a lot of mines able to give the kind of money that Emalahleni has. Companies need to put in capital expenditure on a continual basis. They need to have an exit strategy when the mines close," Lesufi says.
Koos Pretorius, a director at the Federation for a Sustainable Environment, estimates the Emalahleni treatment plant cost R350m to build and runs at a loss of R7 per cubic metre, or about R150 000 a day.
"Every 20 years the plant has to be rebuilt but they can't do the recapitalisation," he says, alleging that one of the mining houses behind Emalahleni "wouldn't even investigate a reclamation plant" at a proposed new joint venture colliery near Belfast.
Another possible shortcoming is the principle that consumers end up paying for a problem caused by mining firms. Lesufi, however, says consumers will buy from Rand Water in any case.
"It's simply an opportunity for Rand Water to augment its water supply. Gauteng is a major centre, mining water is an opportunity. It's not as if we are fleecing the consumer. We should be clear Rand Water will not buy water at an exorbitant price. It's up to WUC to optimise its treatment technology to meet Rand Water's very strict specifications," he says.
Lesufi concedes that the WUC model "may well have problems, but it still presents the best opportunity on the table to deal with the problem".
Barbara Schreiner, who is a practice director in charge of water strategy at Pegasys, and former deputy director-general in the old Department of Water Affairs and Forestry, says the WUC model is an "innovative approach, one of the things we need to look at more and more". Assuming the numbers are in order, Schreiner describes it as a "perfectly good response".
Authority action
Either way, all parties agree that to avert a crisis, the authorities need to act fast.
Otherwise, water shortages could take hold by about 2013 in Gauteng, Schreiner cautions. "Basically, we're on a pathway to water shortages unless we cut back significantly on water usage. Part of the challenge is a lot of industries are using poor quality water and have to use more water to dilute it. So requirements increase if quality declines," she says.
In Mpumalanga, AMD from coal mining - both historically and as a result of new mining applications - threatens the Vaal River basin, which supplies water to Gauteng.
"The upper Vaal River catchment is relatively unaffected by mining, but if all applications for mining permits in this catchment are granted, it is likely the Vaal River will suffer a similar fate to rivers in the Witbank area, creating serious water supply problems for the industrial heartland of the country," says a paper co-authored by Pretorius and Wits University geology professor Terence McCarthy.
Anthony Turton, a former CSIR scientist who resigned last year after spilling the beans about an imminent water crisis, says South Africa is starting to trade off current energy needs with future food security.
"I've called for a national debate on energy security, food security and water security. At the moment they are managed as separate issues. Energy is at the top of the hierarchy of importance but people don't realise that by securing energy needs in the short term, in effect they are writing off our agricultural food security," says Turton, now a professor at the University of Free State's Centre for Environmental Management.
Turton hopes National Planning Minister Trevor Manuel will co-ordinate the issue.
Lesufi supports the call for a dialogue on energy, water and agriculture. "It's a simple issue of land access and the competing interests of tourism, farming and mining. Each economic sector has to put its case on a cost-benefit analysis. If the impact of mining is so bad, that it does not carry South Africa to sustainability, then... that land use must not be supplied."
To read more stories on this topic follow the following links:
Downstream industries hit
Small firms, big headaches
Arguing over responsibility
Acid Mine Drainage: source and science
Acid mine water is a ticking bomb
Study looking into coal mining and water quality:
Coal mining on the Highveld and its implications for future water
quality in the Vaal River system - click here to download full document
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