There has been another tailings dam failure at an iron ore mine in Brazil.
Following the Fundão mine tailings dam failure at Samarco (jointly owned by BHP and Vale) on 5 November 2015, a similar incident occurred this week at the Córrego de Feijão mine owned by Vale.
In this latest incident there has been a large loss of life. The failure occurred at lunchtime on Friday when many of the employees were in the company restaurant which was in the path of the debris flow.
The mining company Vale has released a new list with the names of 287 employees who have not yet contacted the company in Brumadinho (MG). In the last list, released late yesterday, there were 252 names. The search for possible survivors was resumed this afternoon after about 10 hours of suspension.
According to the Fire Department, so far 37 deaths have been registered and 192 survivors have been rescued from the rupture of the B1 ore tailings dam at the Córrego do Feijão mine complex. …
https://guaiba.com.br/2019/01/27/vale-divulga-lista-com-287-funcionarios-que-ainda-nao-fizeram-contato/
From the Vale website, some info about the failed structure,
Until 2015, the Dam I of the Córrego do Feijão mine, located in Brumadinho (MG, Brazil), received the disposal of tailings from the production of the above-mentioned mine. Since then, it was inactive (with no further disposal of tailings), without a lake, and there was not any other kind of operational activity in place at the dam. Currently, the decommissioning project of the dam was under development.
The dam was built in 1976 by Ferteco Mineração (acquired by Vale on April 27th, 2001), using the upstream method. The dam was 86 meters high with crest length of 720 meters. The disposed tailings occupied an area of 249.5 thousand m2 and the disposed volume was 11.7 million m3.
The Dam I had Stability Condition Statements issued by TUV SUD do Brasil, an international company specialized in Geotechnics. The Stability Condition Statements were issued on 6/13/18 and 9/26/18, related to the Periodic Safety Review of Dams and Regular Dam Safety Inspection processes, respectively, as determined by the DNPM Decree 70.389/2017. The dam had a Safety Factor in accordance with the world’s best practices and above the reference of the Brazilian Standard. Both of the abovementioned stability declarations attest to the physical and hydraulic safety of the dam. …
http://saladeimprensa.vale.com/en/Paginas/Articles.aspx?r=Vale_updates_information_on_the_dam_breach_in_Brumadinho&s=Mining&rID=1114&sID=6
And finally here is a before/after comparison of the site of the tragedy from approximately the same perspective.
Being an iron ore mine, the tailings/ processing waste stored in the dump will be mostly sand and perhaps clay that has been separated from the iron minerals. The waste is produced when the mined rock is processed (this mainly involves crushing and washing) to improve the iron content of the ore. It usually does not contain heavy metal or chemical residues.
So I suppose that’s one small mercy to be thankful for amid the tragedy.
moonkoon 