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H A R S C O M E TA L S & MINERALS

FEATURE


GOLD MINING’S

DIRTY SECRET

Harsco Metals & Minerals managing director Koos-Jan van Brouwershaven talks to South Africa Magazine about the problem of acid mine drainage and the solutions his firm has developed to cure it. By Ian Armitage 2

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Harsco Metals & Minerals FEATURE

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n the surface Tudor Shaft is a typical South African shantytown. However, when it rains, the streets pool with orange water, which smells awful – and you wouldn’t want to drink it or even stand in it. Experts say the water contains radioactive minerals and that it has killed all aquatic life in a nearby river. What’s happening at Tudor Shaft, which takes its name, and its troubles, from an abandoned gold mine, is just a fraction of the toxic legacy of South Africa’s mining industry. Mining accounts for 17 percent of everything South Africa produces, and the country is the world’s fourth biggest exporter; it’s not all good. There is a dark side – Acid mine drainage (amd). Amd is not new. But campaigners are seemingly fighting harder than ever before to stop it. The effects of mining are now the focus of parliamentary debate and media stories. Harsco Metals & Minerals has a readymade solution - Mineral CSA, a finely ground calcium silicate feedstock, which provides a solution for correcting acidic conditions and managing toxic metals associated with amd. Mineral CSA has been used on operating and abandoned mine sites since the early 90s and is a highly refined, repurposed calcium silicate aggregate, says Harsco Metals & Minerals South Africa (Pty) Limited managing director Koos-Jan van Brouwershaven. “Acid mine drainage is the flow, or seepage, of polluted water from old mining areas,” he explains. “Depending on the area, the water may contain toxic heavy metals and radioactive particles. These are dangerous for people’s health, as well as plants and animals. “Acid mine drainage is toxic water, and if it flows into rivers, it obviously contaminates rivers and underground waters, which become not a healthy source of drinking for humans, animals, plants - all living organisms. Because the necessary steps

were not taken from day one, South Africans are now reaping what you would call the misfortune of the benefit that we had from the legacy of mining in this country.” Acid mine drainage in several areas has reached a crisis point. This is because some mining companies allow acid mine water to flow into streams, dams and sources of groundwater. On the West Rand, toxic water has destroyed life in the WonderfonteinSpruit, Tweelopiespruit, and the Robinson Lake near Randfontein. Even some borehole water is polluted. The water has even polluted soil, so people cannot grow vegetables. “There is no quick fix,” says van Brouwershaven. “And amd is not a new issue.” Indeed it is not. It is an issue, which cynics say is one that has been conveniently silenced by the mining houses and South African government for decades.

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Fixing the problem is also costly. “In recent years, environmental organisations have brought amd to the fore and brought it into the public eye – it is now receiving international attention,” says van Brouwershaven. In a report presented to the Cabinet in February, a group of experts found that millions of litres of rapidly rising acid mine water under Johannesburg would start flooding the lower levels of the Gold Reef City tourist mine early next year. Shortly thereafter, the acid mine drainage would pass through an “environmentally critical” level -- with potentially devastating consequences -before starting to flow out on the surface. The report was titled “Mine Water Management in the Witwatersrand Gold Fields with Special Emphasis on Acid Mine Drainage”. It warned that if the water were allowed to continue to rise, it would start “decanting in low-lying areas in the vicinity of the ERPM Mine in Boksburg and possibly elsewhere across the Witwatersrand”. “Remediation of amd includes treatment systems designed to neutralise acidity and precipitate metal ions to improve water quality,” says van Brouwershaven. “The treatment is dependent on the types and amounts of metals in the water. Lime materials are often used, particularly in passive treatment systems. “Mineral CSA is an alternative to limestone,” he adds. “It provides a very effective and efficient means to correct the acidity. Unlike limestone, it is less vulnerable to armouring from metal hydroxide precipitates. This results in a product whose reagent characteristics are very suitable for use in a number of sustainable passive amd treatment systems.” Mineral CSA can be used in amd remediation and prevention, van Brouwershaven says. Harsco Metals & Minerals is the world’s largest provider of contract services to the metallurgical industry. It operates in 30 countries and hundreds of steel processing sites worldwide. “Traditionally we’ve taken care of the non-core work in the Metallurgical Industry, which can be seen as cleanup services – ladle wrecking, slag pot carrying, dig and haul,

We try to find alternatives to dumping. We use slag as a concrete aggregate, asphalt aggregate

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Harsco Metals & Minerals FEATURE

metal recovery and producing aggregates -- all services being part of our zero waste management,” van Brouwershaven explains. Recycling is an important part of the Harsco business model, he adds. “We try to find alternatives to dumping. We use slag as a concrete aggregate, asphalt aggregate. It’s also used back in the steel plant to reduce internal process costs. Harsco Metals & Minerals is interested working outside of the field of metals too and would be offering more to mines, such as non-core activities for them like crushing, screening, jigging, washing and amd remediation. “The work done in mining is very similar to our industries,” van Brouwershaven concludes. “There are different techniques but there’s a lot of overlap. Harsco Metals & Minerals is currently engaging with Wits University to do research with our Slag materials for usage as AMD solution.” END


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HARSCO METALS SA FEATURE  

SA Mag - Issue 15 - HARSCO METALS SA FEATURE

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