Environment

AngloGold Ashanti has planted around half a million trees over the last decade for research on using phyto (plant) technologies to prevent and repair environmental impacts from the company’s tailings storage facilities (TSFs) in South Africa.

Most TSFs emit dust and seepage containing salts and metals which can contaminate the surrounding environment. Thus the “Ecological Engineering and Phytoremediation Research Programme” was initiated in 1995 by AngloGold Ashanti (then Anglo American Gold Division) and the School of Animal, Plant and Environmental Sciences (APES) of the University of the Witwatersrand, Johannesburg (Wits University). Around 80 species of plants have been assessed to date in tailings experiments, and almost 60 species of trees are being assessed in woodlands trials on seepage from TSFs. It is expected that approximately 200 plant species will eventually be used out of the almost 600 species found to grow naturally on the reef outcrops, polluted soils and tailings.

Since 2000, research has focused on the effectiveness of different types of vegetation in groundwater and soil remediation. This builds on the earlier research by Wits University and AngloGold Ashanti which has shown that native plants and micro-organisms grow naturally in hostile mine environments, and how they can be propagated and grown to potentially rehabilitate TSFs and polluted soils. In 2006, Wits University and AngloGold Ashanti’s Environmental Management Department received an award for their scientific research from the National Research Foundation and the Department of Trade and Industry of South Africa.

New technologies ready for implementation

Some of the “phytotechnologies” identified during the research will start being implemented on three TSFs and selected sites at AngloGold Ashanti’s West Wits and Vaal River operations between 2009 and 2012 at an estimated cost of R4,000 to R40,000 per hectare. The aim is to use natural processes to convert mine waste to natural resources, and thereby achieve sustainable rehabilitation of entire mines. This involves preventing pollution through the strategic planting of different types of native woodland for evaporative and hydraulic control on and around TSFs, and fostering of the wetlands and riverside woodlands that cleanse water; the decontamination of soil and water through the planting and harvesting of plants that are able to concentrate pollutants in their leaves; and the use of plants to develop 'soil’ directly in tailings. The fostering of an enabling environment through education, public-private partnerships and community-business development is important if the project is to be successful.

Inoculated shrubs growing well on TSFs

This approach to the rehabilitation of TSFs relies on the use of acid-, salt- and metal-tolerant plants that do not take up contaminants into their stems and leaves, but can instead stabilise pollutants within the root zone. Vegetation trials have been assessed on tailings facilities for a decade, and successful types include a pseudo-savanna grassland with thorn trees, shrubland and open woodland. The plants were propagated from tolerant individuals growing on polluted soils as well as from individuals growing in non-polluted soils, then inoculated with micro-organisms to help them to grow in the tailings, and treated with slow-release nutrients and compost. The result is self-sustaining vegetation without reliance on liming, fertilising and irrigation. In 2008, the results of the 7 to 10-year old field trials on top of TSFs at Welkom (owned by Harmony since 2003) showed that over 90% of inoculated tolerant shrubs and trees have grown well and are producing viable seed for the next generation, whereas less than 50% of non-tolerant plants survived, and less than 20% of uninoculated plants survived.

Local communities getting involved

People from local communities (Kanana, Wedela, Doornfontein and Blyvooruitzicht) are trained by the Wits University team and practitioners EMPR Services, so that they can plant and care for the indigenous vegetation being used for pollution control measures on the company’s properties. Most of the company’s trees have been planted by local entrepreneurial company J. Mngomezulu CC. This enterprise currently provides employment for around seven months of the year to 54 people who were previously unemployed. Four community-based (township) nurseries have been developed since 2003, and have the materials and equipment to produce ‘designer’ plants to capture the phytoremediation market. Three more nurseries are being developed. An independent PhD survey of 65 community nurseries across South Africa included two of these fostered nurseries in an in-depth assessment, and found that they were the only ones to have started to achieve financial viability.

Using plant by-products a possibility in the future?

Many South Africans depend on plant products for poverty alleviation, and some of the plants found to grow on the company’s TSFs are known to have useful properties. The final phase of the research (taking place between 2009 and 2012) will look at how phytoremediation plants might be able to produce materials for secondary industries, and thus help local communities. Such materials might include precious woods, fibres, chemicals, essential oils, dyes, gums and recoverable minerals and metals.