The deadly collapse of a Vale 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.