Vale warns of risk of another tailings dam collapse

Reuters has reported that Brazilian iron ore miner Vale SA has warned that another tailings dam is at risk of rupturing at its Gongo Soco mine, about 65 km from where its Brumadinho dam collapsed on 25 January, killing more than 230 people.

According to a document published on Thursday, prosecutors for the Brazilian state of Minas Gerais said Vale is predicting the dam in the city of Barao de Cocais may collapse next week if the current rate of movement in the embankment of the mine pit close to the dam is maintained.

About 500 people are seen to be at risk from a collapse of the dam and have been evacuated from their homes since February under orders from the mining regulator.

The warning underlines ongoing concern about the stability of dams in Brazil’s mining heartland of Minas Gerais in the aftermath of the Brumadinho accident, which itself came less than four years after another deadly dam collapse at a joint venture between Vale and BHP Group killed 19 people.

The Brumadinho incident was the 11th serious tailings dam failure in the last decade and such catastrophic events are becoming more frequent, according to researchers at World Mine Tailings Failures (WMTF). Indeed, the number of incidents is going to rise further, according to the organisation, which tracks all recorded tailings storage facility (TSF) failures.

“Without major changes to law and regulation, and to industry practices, and without new technology that substantially reduces risk and increases loss control, our current prediction is for 19 very serious failures between 2018 and 2027.”

The volumes of mine waste greatly exceed the total volumes of materials handled by civil engineering throughout the world. A “very serious” failure is defined by how much waste material is released, how far it travels and how many fatalities result.

Top image: Damage from the Brumadhni dam collapse. Source: Guilherme Venaglia - Wikipedia (https://commons.wikimedia.org/w/index.php?curid=76197045)