The catastrophic collapse of a dam at a mine in Brazil has exposed a darker side of an industry that the world depends on. At nearly 800 sites across the country and thousands more around the world, dams contain huge loads of mining waste.
One British scientist, Dr Stephen Edwards of UCL, has warned that “we are sitting on a time bomb”. He told BBC News that further disasters were inevitable.
Over the last few days in the heart of Brazil’s mining belt, I’ve been investigating two very different sites where the risks of massive damage seem plausible. One is a vast lake of sludge perched high above a nervous community; the other is an abandoned gold mine at risk of leaking poisons.
Why are there dumps of mining waste?
The answer begins with the world’s growing demand for metals such as steel which is used to make everything from buildings to ships to cars. The key ingredient of steel is iron ore which is extracted from the ground in huge mines – Brazil is one of the world’s largest producers.
The ore is broken up, and because only a small fraction of the rock is actually iron, the vast majority is unwanted, a by-product that’s thrown away.
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