Brazil to decommission all upstream tailings dams by 2021

Vale's S11D mine at Carajás.

The Brazilian Government has elected to impose a ban on all upstream tailings dams in the coming years.

The decision comes in light of Vale’s tailings dam disaster at the Feijao iron ore mine on January 25 that killed at least 169 people in Brazil’s mining state of Minas Gerais.

It was Vale’s second such disaster in just over three years, following on from a tailings dam breach at the Samarco joint venture project with BHP in the same region in November 2015. The Samarco incident killed 19 people and caused major environmental damage.

Brazil’s National Mining Agency ANM (Agencia Nacional de Minería) announced yesterday that it would ban upstream tailings dams and decommission all existing tailings dams by August 2021.

Upstream tailings dams begin construction with a dyke that continually expands upwards with the construction of raising lifts built in a trapezoidal pattern to accomodate waste as the tailings level rises.

These lifts are constructed on a bed of spigots (or a tailings beach) at the pond’s perimeter, a construction technique that can introduce liquefaction to the sand or soil used to construct the lifts.

This is in contrast to downstream dams, which build on the dam wall successively away (downstream) from the tailings pond, and centreline dams, where dykes are built vertically on top of each other.

Bloomberg reported today that the vast majority of the 80 miners listed with upstream dams in the Brazilian Government’s announcement belonged to smaller producers, including producers of materials that aren’t iron ore.

Vale — the world’s largest iron ore mining company — has seen its stock price fall dramatically since the disaster last month from $US14.86 the day before the disaster (January 24) to a recent low of $US11.17 on February 7, though it has recovered slightly as of Friday to $US12.33.

In contrast, Australian producers such as Rio Tinto, Fortescue and BHP have all seen large rises in their stock price.

From January 24 to yesterday, Rio Tinto’s stock price has increased from $79.60 to $92.60, BHP’s from $32.62 to $37 and Fortescue’s from $4.76 to $6.37.

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