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Taking water purification to the next level

Taking water purification to the next level
An employee makes adjustments to the reverse osmosis filters at the Emalahleni water reclamation plant. An employee makes adjustments to the reverse osmosis filters at the Emalahleni water reclamation plant.

As a global leader in water purification technology, our thermal coal business in South Africa is employing its water treatment and reclamation technology to minimise any future risk of acid mine drainage, a challenge inherent in the coal mining industry.

Stepping up purification efforts
Up until now, our coal operations have managed to contain their excess water by reducing, re-using and separating clean and dirty water streams to reduce their footprint.

“With an increasing volume of coal mining activity at our existing mines and a number of greenfield projects in the pipeline, together with the fact that water-treatment technology is now commercially viable, we plan to take our work on water purification to the next level,” says Peter Günther, regional manager for hydrology.

“Our Emalahleni water reclamation plant (EWRP) was preceded by 10 years of research and development, and what we have learned from this is guiding us into the future,” he says.

Through the application of science and planning, Anglo American’s integrated water modelling system enables the business to determine the amount of excess water at each of its mines and when appropriate steps for dealing with it in an environmentally responsible manner are required.

“Two mobile treatment plants have already been installed at New Vaal colliery and a further four will be installed at other operations in 2011,” he says.

At New Vaal, excess water is purified to potable quality and released into the Vaal River as a short term solution. Negotiations are under way for its transfer to water utility Rand Water during the construction of a pipeline to the Lethabo power station, which will use the entire treated volume of water for the generation of electricity.

Finding regional solutions
The EWRP, which has been described as a ‘world class initiative’ and an ‘exemplary model for development’, will soon enter its second phase, doubling its current capacity to 50 million litres a day (Ml/day). It is expected to be a zero-waste facility as it will produce no brine, and its gypsum by-product will be converted into commercially viable products. (See case study on page 59.)

“We are moving beyond seeking solutions purely for our own mines. What we are after is a holistic way of dealing with the water problems of the entire region,” says Peter.

The additional water the plant will purify is expected to come from nine mines within a 30 kilometre radius, and will see three competing mining houses collaborate to provide a lasting solution to a regional problem.

Water will be desalinated to potable quality and will be released into a local river; supply discussions are, however, under way with the Emalahleni local municipality, which already draws 20% of its daily requirements, or 18Ml/day, from the facility.

“Projections show that the municipality will need a further 60Ml/day by 2030 to cater for the growing water needs of the community,” says Peter. The second phase of the plant has also been designed to manage water from thermal coal mines that have reached the end of their lives.

Making the most change
Thermal Coal believes that the most effective way of making change is to work with our competitors. It led the way in establishing a Joint Investigation Agreement, which includes the power utility, Eskom, and all major mining houses in the Highveld coalfields.

These partners are jointly undertaking water-related investigations and projects, pooling their resources of capital and expertise and benefiting from the accompanying economies of scale. Their work is aligned with South Africa’s Department of Water and Environmental Affairs and the Department of Mineral Resources’ mine closure and rehabilitation strategy, which views an integrated approach to closure and rehabilitation as the way forward.

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