Houses out of hazards

2013-06-02 14:00

A progressive way to treat acid mine drainage is cleaning up the water and producing houses, writes Xolani Mbanjwa.

An environmental catastrophe waiting to happen could instead become a massive opportunity.

Acid mine drainage – the toxic water seeping out of abandoned mines and into river systems – is being treated so successfully at a Mpumalanga plant that it is solving water and housing problems in the area in one fell swoop.

Environmentalists have hailed this new water-treatment system as the future in dealing with the crisis of acid mine drainage at abandoned mines.

The water-treatment plant in eMalahleni, Mpumalanga, which belongs to Anglo Coal, was the first to successfully treat acid mine drainage when it was commissioned in 2007.

But now the company has built 62 houses for workers using bricks made from gypsum, a waste product extracted during the treatment process.

It also pumps millions of litres of water a day directly into the eMalahleni Local Municipality’s reservoirs – more than 20% of the council’s daily water requirements. The rest of the water is recycled and used within the mine.

Gypsum, which looks like a grey powder-like substance, is the mineral that experts say can change the face of construction and improve the pace of housing delivery.

John Quinn, project manager at Anglo’s gypsum housing project, hopes government and the construction industry will see the benefits and “commercialise” the production of the mineral to build homes partly made of gypsum.

The gypsum is used in place of river sand, which means only half the river sand will be used every time a brick is manufactured.

But this can only be done if the water-treatment plants used to treat decanting acid mine drainage use the same process.

The gypsum bricks have been tested by the SA Bureau of Standards and were found to be as good as traditional bricks, which are mixed with concrete, river sand and water.

Acid mine drainage is a severe problem in Gauteng and Mpumalanga. The toxic water is laden with heavy salts and metals which, if allowed to seep into river systems, can poison crops and render valuable agricultural land useless for farming for decades.

By dealing with the crisis of acid mine drainage, particularly in Johannesburg, which is sitting on rising levels of toxic water, treatment plants can extract gypsum and sell it as an additive for cement or construct clay bricks for housing.

“There’s a big opportunity to turn a waste product into a resource. There’s also a large possible market for these bricks. The brick making companies don’t have to make any changes. All they have to do is have another production line that makes these gypsum bricks. They don’t need to have special equipment,” said Quinn.

“All they have to do is mix clay, brown-sludge gypsum and water, and bake it in an oven like normal clay bricks.”

Quinn said the plant had the potential to produce between 100?000 and 150?000 gypsum bricks per day, with 100 tons of gypsum produced. These bricks could build between 15 and 20 houses a day, he said.

The eMalahleni plant currently produces more than 200 tons of gypsum a day, enough for 7?000 houses a year.

Kate Mofo (45) and her mine worker husband, Isaiah

(56), were among the first to receive their three-bedroom house in KwaMthunzi Vilakazi village, west of eMalahleni.

Three years after moving into the only house they have ever owned, Kate is still as ecstatic as the day she walked in for the first time.

“I know very little about this brick, but what I know is the project has helped my husband, after many years living in a mining hostel, to own our house,” she said.

“The feeling of being in your own garden, under your own roof, after more than 20 years working at the mine, is a gift from God.”

She and other mine workers have continued the recycling, using materials including bricks and panels from the demolished mine hostels nearby to build their driveway.

“Without the mine, we wouldn’t be able to own a house of our own. I have not had any problems since we moved into this house, but instead we are getting a clinic down the road, which will be very useful for all of us,” said Kate.

Environmental activist Mariette Liefferink – known for her extensive work around acid mine drainage and advocating for its treatment in Johannesburg, where the toxic water threatens dams, rivers and buildings – welcomed the gypsum development.

“The reverse osmosis process used to treat the water at eMalahleni is regarded around the world as the best of its kind,” she said.

“This water treatment is the most prudent and sustainable way to treat the acid mine drainage properly, instead of neutralising the water.

“It is like killing two birds with one stone?.?.?.?using the by-product to manufacture bricks for housing.”

Houses out of hazards

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