The Atlanta Journal-Constitution
Deadly mining failures tied to cheap waste storage
The deadly collapse of a Vale SA tailings dam in Brazil is serving as a wake-up call for an industry that regularly cuts costs by storing mining waste in the cheapest possible way.
The slurry of ground rock and effluents left over after companies extract marketable minerals from the ground has been stored for decades in massive ponds held back by embankments or dams. Their safety, though, depends very much on the design of the ponds, and on the cost of building them.
The Vale SA dam that collapsed in Brazil last week, and a previous dam that failed there three years earlier, were both built on the go using the “upstream” method, typically the cheapest by far.
“There are a lot of calculations people can use for the cost of a failure,” said Dirk van Zyl, a professor of mining engineering at the University of British Columbia. “You not only have the real cash cost to the company, but you also open the whole discussion of what a human life is worth?”
This week, the mining sector is coming face-to-face with the math.
On top of the 99 dead and the 259 missing, Vale, the world’s largest iron ore producer, could face damages as high as $7 billion for the current disaster, according to Bloomberg Intelligence. That’s more than twice the $3.3 billion liability at the Samarco joint venture following the failure of another upstream dam in Brazil in 2015. Although it’s not yet clear what caused last week’s dam failure, Vale said it will decommission 10 “upstream” dams in the next three years.
In the case of Samarco, Brazil’s worst environmental disaster, the miner allegedly ignored warnings of potential risk and altered the dam’s structure improperly as it sought to keep production levels high.
At least one legislator, Joao Vitor Xavier, in Brazil’s mineral-rich Minas Gerais state, has previously tried to pass legislation banning upstream dams. In July, his measure was defeated without mining companies bothering to join the debate, he said.
Some countries have already moved to abandon the upstream pond method. For instance, in Chile, where mining is a pillar of the economy, no large tailings dams have ever collapsed. In 1970, upstream ponds were banned by that country, which has suffered some of the strongest earthquakes ever registered.