Water everywhere - mining

Mining and Water

we need both!

How mining affects water and the water table. Firstly, let us establish that water is an important resource while also acknowledging that mining (gold, Platinum or Coal) creates jobs in their thousands. Conserving water and creating jobs is a balance that South Africa must face as water becomes scarce.

Let us quickly do facts: water can be obtained from rivers, lakes, dams and underground deposits. We know Vaal Dam, Fish River and the Lesotho Highlands. Ground water is where the problem is. The depth of the ground water is the water table (simplified!). The lower the water table, the more costly it is to get to the water (wells and so on). And worse: the water may no longer be available as the deposits have been exhausted.

Here are aspects to consider: gold mines alone use large volumes of water as a multi-purpose agent, from cooling of the mine to water-powered machinery. A mine shaft (and mine tunnels) will typically go through the water table and that means water will flood the mine unless it is pumped out.

So not only does a mine need a lot of water, it also ‘produces’ a lot of water.

However, All of this has a detrimental effect on the water and the water table even if the mines

recycle the water. This is because the large volumes of water produced from mine drainage, mine cooling, aqueous extraction and other mining processes increases the potential for chemicals to contaminate surface and ground water.

In terms of surface water, materials left over by the mining process can easily seep down to the ground water, leading to increased acidity and heavy metal contamination rendering water undrinkable.

Then when it comes to the water table, the literal digging and pumping that occurs in mining can extend below to the water table resulting in so much water inflow into the mine that the water table is lowered.

As water is getting more and more scarce thanks to climate change, we need to realise that this resource can be exhausted. It is not enough to just have water if the water is too polluted to use for consumption. If this is combined with scarcity of water (due to heavy usage of water to begin with), we have another ‘Houston, we have a problem’ situation.

Ground water must be ‘treated’ before it can be used for consumption, removing heavy metal pollution sulphur and other chemicals. It means that water pumped out of a mine cannot be consumed or discarded without treatment.

Can we achieve the balance between water consumption and jobs?

Of course, now that we have summed up the effects of mining (mind you, the list is not exhaustible) on the water table, there are few practices that are put forward in mining in order to mitigate some of the negative effects. The general term now is ‘green mining’. There are solutions for protecting the ground water. Extraction of heavy-metals and neutralising acid mine water is possible, but at a cost. The common solutions are usage of lime, caustic soda, limestone etc. But it is all chemical and it takes equipment and space to do.

The new techniques may also encompass bacteria and plants. This is new! It is now possible to ‘clean’ water via natural processes, but there is still a long way to go. Green mining needs to be further defined and environmental studies are required before we can achieve the balance between water and jobs in order to conserve an important, already scarce resource: water

Masiziba Hadebe