Resources giant Anglo American’s coal subsidiary, Anglo Coal, is regulating its water releases into the Olifants river catchment area, in the Mpumalanga province, following a directive set by the Department of Water Affairs and Forestry (Dwaf).
Anglo Coal’s ‘Report to Society 2007’ states that the Dwaf’s decision is based on the health of the Olifants river, as well as wetland status and water quality, which are monitored throughout the year.
In June this year, Water Affairs and Forestry Minister Lindiwe Hendricks said at the signing of a memorandum of agreement for the Olifants River Water Resources Development Project that mining houses had a respons-ibility to ensure that they did not pollute water resources.
Anglo Coal operates in the Witbank area from its Goedehoop, Greenside, Kleinkopje and Landau mines. The allowed discharge volumes allocated to Anglo Coal were 177 t sulphate, or 224 347 m3 of water over the set discharge period.
Creamer Media’s Research Channel Africa reports that Anglo Coal recognises water as a critical resource that requires responsible management in both its use and in its impact on water resources.
The company states that no natural water sources are significantly affected by the use of water at its operations and, as far as possible, Anglo Coal uses recycled or reused water for its processes.
About 47% of water use at the company comprises recycled or reused water and the operational eMalahleni water reclamation plant treats polluted mine water to potable quality and supplies this treated water to surrounding mines and the local municipality. This reduces the mine’s need to abstract water from the local municipal system and to discharge untreated mine water into the environ- ment.
Mine water in the upper Olifants river catchment is, at times, discharged into local streams, resulting in local acidification and regional salination of surface water resources.
The natural groundwater resources are also impacted on by dewatering around mining oper- ations, as well as by the migration of polluted subsurface plumes from mine workings.
In 1998, the South African coal industry initiated a research initiative, called Coaltech 2020, with the vision to promote collaboration between the industry, researchers and the State.
At the same time, the Olifants River Forum formulated the Cleanwater 2020 project, and the successful implementation of the project initiative offers the opportunity to convert a pollution threat into an augmentation of the water resources, as well as reducing the need to import fresh water to the Olifants river catchment from neighbouring catchments.
The pollution of surface water in the river can be prevented by collecting and treating mine water to a quality where it can be reused without restriction, and limestone and lime treatment is the most cost-effective technology for the neutralisation of the water.
As such, the partial sulphate removal of acidic, or sulphate-rich, water to sulphate levels of less than 1 500 mg/ℓ, means that the water can be used for several potential applications.
However, different levels of treatment are required to make excess mine water suitable for these applications, such as irrigation, use in coal processing plants, general industrial use, portable use and cooling water in power stations.
Each of these applications requires an acceptable sulphate concentration of treated water. For instance, mine water which is partially treated for removal of free acidity, metals, magnesium and sulphate to less than 2 000 mg/ℓ can be used for irrigation.
Treated mine water to a sulphate level in the range of 50 mg/ℓ to 500 mg/ℓ can be used for stock watering, urban and industrial use, as well as for power stations.
Kruger Park river manager Thomas Gyedu-Ababio believes that, at the moment, all the mines have zero effluent discharges and, as such, are not discharging into the river. He adds that the water quality has dramatically improved in recent months.
Meanwhile, the South African Institute of Mining and Metallurgy predicts that water usage in the upper Olifants river catchment will increase to an estimated 1 385-million litres a day by 2020, while the additional water demand by 2020, which will be 438-million litres a day, will still have to be supplied by importing water from neighbouring catchments.