Saturday 26 January 2019

Hundreds feared dead after collapse of mine tailings dam in Minas Gerais State, Brazil.

Ten people have now been confirmed dead and over 200 more are missing, following the collapse of a tailings dam at a Vale mining operated iron mine in Minas Gerais State, Brazil, on Friday 25 January 2019. The incident happened close to the Alegria Mine site where a similar tailings dam collapse in November 2015, resulting in 19 deaths and a major environmental catastrophe which is still causing problems today. The dam that collapsed this week is only about a fifth of the size of that dam, and is not thought likely to cause environmental problems on the same scale, but it is feared that the number of deaths will be much greater, as the dam was uphill of an encampment used by workers at the mine.

The remains of a mine camp in Minas Gerais State, Brazil, where it is feared over 200 people died when the camp was hit by a wave of slurry following the collapse of a tailings dam on 25 January 2019. Leo Drumond/Nitro/AP.

Tailings ponds are used to store sediment-laden waters from mines; such waters typically contain a high proportion of fine silt and clay particles, which take time to settle out of the water. The resulting water may be fairly clean, or may contain other pollutants (typically acids, either generated by the local geology or used in the mining process), and need further treatment. In some instances acid is added to such pools in order to dissolve the product, which is then released from the resultant chemical slurry by further treatment, however this is not a typical procedure at iron ore mines.

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