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The environmental impact of bauxite mining

Saturday, Jul 03, 2010

Aluminium is an incredibly useful metal, being lightweight, malleable, and non-corrosive.  Its uses range from parts for aeroplanes to packaging for soft drinks.  Aluminium does not exist in the familiar metallic state in nature although it is abundant.  What is turned into pure aluminium by refineries is bauxite.  Bauxite is basically a mixture of aluminium oxides in mixed in with other materials such as silicon and iron oxides as the main impurities in various combinations.

Bauxite is one of the most valuable mineral reserves a country can have, given the modern day demand for aluminium.   The countries with especially plentiful supplies include Australia, Vietnam, Guinea and Brazil; although it is common is most tropical and subtropical areas.

Bauxite is usually mined by open cast or strip mining.  Rather than tunnelling into the earth these methods involves extracting minerals from an open pit.  All the earth covering the minerals is removed by heavy machinery.  As you might expect this as an immediate and starkly visual impact on the environment.

The exact effects of bauxite mining are quite specific to the site.  It nearly always involves some habitat destruction, soil erosion, loss of biodiversity, or water pollution.  These effects can be reasonably short term, and followed by regrowth, or severe and permanent.

Since some of the countries with the most bauxite are also those countries with the greatest biodiversity in tropical forests there can be a substantial trade off between immediate economic gain and good sustainable practices.  Unsurprisingly most countries opt for the immediate economic gain of extracting the bauxite as quickly as possible.

Habitat destruction, especially of rainforests, may be the most obvious impact of bauxite mining but it is not the only one.  It is not even necessarily the greatest as most bauxite mining is not done in rainforests.

Open cast mining involves the removal of the top layer of soil in order to get at the ores underneath.  The resultant soil erosion means that it may be very difficult for vegetation, whether natural or crops, to re-establish itself.  This is especially the case if the removed soil is not replaced soon after the mining operation is finished.  Some mining companies have a better record of minimising soil erosion than others.

The deforestation and soil erosion can lead to problems associated with flooding, including wastewater being swept into the drinking supply.  Associated aluminium refineries, which produce the end product, can render the drinking water supply hazardous.  In some cases, usually in colder regions such as Hungary, the mining may be deep enough to interfere with the water table.   

Just how destructive bauxite mining will be depends a great deal on the location and how responsible the company concerned is.  In the worst cases it can wreck the environment and the lives of local people.  In the best cases the land can recover fairly well afterwards.

This of course doesn’t take into full account the environmental cost of refining the ore to turn it into aluminium, which can be equally, if not more, devastating.  Bringing the whole thing on to a personal level, these are some very good reasons to recycle.  Or, preferably, not buy aluminium cans in the first place.

(By Judith Willson)

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