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Ironing out a problem?

Ironing out a problem? researchers from McGill University in Montreal, Canada, have found a new technique to treat water in acid lakes that form when mining operations are terminated. After the closure of mines, the water that fills up the pits becomes highly acidic. The traditional method of neutralising the water involves the addition of lime. But lime has not proved to be efficient because it creates a toxic sludge, packed with heavy metals. The Canadian scientists have now hit upon a novel method that would not only neutralise the water but also extract heavy metals such as small iron-based particles called ferrites ( New Scientist , Vol 151, No 2042).

Since ferrites are highly magnetic compounds, they can be easily separated from water and could find some commercial applications too. For instance, they could be used in the magnetic coating of recording tapes. Ferrites are more complex in nature than the other compounds found in the usual neutralised sludge and because their structure allows them to incorporate other metals such as zinc and aluminium, the water left behind is virtually free of metals.

The researchers, led by Zhenghe Xu, are not the first to hit upon the idea of using ferrites to clean up water in abandoned mines. There have been attempts to do so in the past but the earlier process of achieving the same was not very practical. It required the water to be heated to more than 60

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