AMD – Is dilution the solution to pollution?

AMD – Is dilution the solution to pollution?

Are there uniquely South African solutions to curb and perhaps even turn Johannesburg’s Acid Mine Drainage crisis around? MARCEL TROUT and ANZET DU PLESSIS investigate to see what they can uncover.

The public panic that has evolved surrounding Acid Mine Drainage (AMD) has many health, environment and economic experts grappling for answers. By no means a simplistic issue, AMD affects not only shaft-mining activity, but also businesses and communities in the CBD, and on the East and West Rand.

Acid Mine Drainage, also known as acid rock drainage, is highly acidic waste water, explained by mining experts as: “resulting from the oxidation of sulphide minerals in mines or bodies, such as pyrite, that are exposed in a mine or are present in dust in underground shafts … AMD dissolves rock material and may contain a range of toxic materials.” It can also contaminate underground and surface water, as it becomes saline when neutralised through its reactions with rock and other resources.

The AMD crisis in Johannesburg has a long history, that requires a quick geography lesson. Johannesburg, built on a series of springs, first attracted settlers because of the masses of water that rose to the surface.

The Witwatersrand has three basins – Eastern (Boksburg area), Western (Krugersdorp area) and Central (Johannesburg CBD and Witwatersrand). The area became famous for gold as early as 1886. When drilling for gold, however, miners had to pump out all of the spring water, which continually fills up again. Johannesburg’s problem at the moment, however, is that untreated AMD has filled the natural water table, and now AMD (instead of fresh spring water) is threatening to rise to ground level.

This would have drastic implications for the city, and Dr Anthony Turton has become something of the face of the AMD issue. A public speaker on many water-related issues, his campaign is to impress the seriousness of the issue upon the country: “Let us not forget, the water we are dealing with here is toxic waste – let’s call it what it is” (Carte Blanche).

While AMD has been a serious problem for 50 years, the media coverage as of late has sparked public and corporate panic. In fact, Dr Anthony Turton himself was suspended from the CSIR in 2008 for a paper the council feared could lead to public violence. Several banking headquarters in the CBD have brought in experts to assess the water levels, but experts are divided on how much time we have. The council of Geoscience claims that AMD is rising at a rate of between 0,4 and 0,6 metres a day, with Mining Weekly reporting that AMD could reach critical environmental levels by June 2012. The AMD in mine shafts also hampers mining activity, and presents a threat to the seismic stability of Johannesburg.

Solutions to the AMD crisis in South Africa are plentiful, but costs and accountability have tied both the public and private sector up in a political, legislative nightmare. A report was presented to an Inter Ministerial Committee (created by the Department of Water Affairs in December 2010. It suggested a two-year emergency plan that would not solve, but neutralise the AMD in the three basin. In February finance minister Pravin Gordhan announced a R225 million budget in accordance with the suggestions in the report.

Essentially, AMD will be pumped out of the basins and treated in various refurbished and repurposed plants.

While Dr Turton has commended the government for recognising and acting on the geo-hydrologists’ report, which he praised for having moved “away from the one size fits all” approach, the solution for all three basins is much the same. The AMD will be extracted from the ground, harmful salts removed (through a process called liming, which reduces the pH) and the diluted AMD/water will then be released into the Vaal dam, from where it is reprocessed into drinking water.

A very real reality exists that the precipitation (essentially concentrated salts and minerals from the AMD) will end up on mine dumps and, during the region’s high rainfall periods, seep back into the water system, creating the same problem over again. The Western Utilities Corporation (WUC) – a collaboration between the Department of Mineral Resources (DMR) and mining houses in the Witwatersrand – are to a great extent responsible for this process. Pumps have already been purchased by Central Rand Gold, and recent tests in Germany have confirmed that the pumps are capable of doing the job.

But the question of accountability is a pertinent one. While government has now committed the budget to neutralising AMD, many are of the opinion that government (and tax payers) are not responsible for this problem at all. Experts in the industry warn that the government’s response to the AMD will set a precedent in the mining industry in terms of who deals with the economic legacy of mining processes. That being said, the AMD issue is such an historically complicated one that in many cases it is impossible to pinpoint the responsible party, especially in mines that now stand empty, the owners having long since disappeared.

Environmental groups have slammed mines for not taking responsibility and for claiming poverty, but the issues extend far beyond environmental responsibility and accountability. These are serious issues, but the financial implications for the country’s economy could very well take priority over social justice.

An expert who spoke to SHEQ explains that paying for AMD treatment plants could essentially bankrupt mines: “Mines salvage roughly R112 worth of gold from a ton of sand, with the process and running costs coming close to R100 per ton. Add AMD treatment to that, and mines no longer make much of a profit.” Taking into consideration the labour value that mines add the economy, forcing mines to process AMD could be a dangerous route to follow.

The AMD issue therefore has mines and government stuck between a rock and a hard place – treatment of the AMD is essentially a “band-aid fix”, and other solutions are costly. While the government shouldn’t have to pay for it, many of the mines cannot. And between this accountability and financial debate, the underground water equilibrium of Johannesburg is trying to naturally balance out – rising up to the surface. The call for action is beyond urgent, and several private companies have taken an entrepreneurial approach to the problem.

Besides WUC’s approach, other solutions have come to the fore. In fact, South Africa has the potential to become the leading experts on AMD management, due to the gravity of the situation here. Amidst the proposed solutions, the most popular is Reverse Osmosis (RO), employed by the Aveng group, Veolia and Proxa. The problem with RO is the same as with the liming proposed by the government – the result is H20 and a concentrate of salts that cannot be repurposed.

Earth Metallurgical Solutions (EMS), however, has found a way to repurpose all elements of AMD, thereby breaking this cycle. What developer Richard Doyle likens to a “soup factory in reverse” is essentially a process that breaks AMD down in usable by-products. “The water is the easy part,” he says, explaining that the salts extracted from AMD can be used to make fertiliser and explosives.

Essentially, the EMS process would add value to AMD, creating products that can then be sold to turn the treatment process into a near cost-neutral process. EMS has run successful pilot tests and, with the help of the Clean Technology Fund and other investors, now aims to set up a demonstration plant.

Make no mistake, the AMD crisis is a complex one. The financial implications to both the tax payer and the labour force are massive. Environmentally it is unpredictable, as the natural equilibrium of Johannesburg’s underground water has been upset by the introduction of 30 m3/s from the Lesotho Highlands Water Project, as well as mines consistently extracting water from mine shafts over the past century – essentially turning Johannesburg’s water table into Swiss cheese.

However, a real opportunity exists here for the country to be at the forefront of the AMD treatment field – a global problem. While the government treatment plan is only a short-term fix, local companies’ solutions have, in true free-market style, begun to see this as an opportunity rather than as “South Africa’s own Chernobyl”.

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SHEQ Management

SHEQ MANAGEMENT is the definitive source for reliable, accurate and pertinent information to guarantee environmental health and safety in the workplace.
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