Brazil set to ban upstream tailings dams after collapse kills hundreds

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BRASILIA (Reuters) – Brazil’s mining agency titans ban upstream tailings dams employed for storing mining waste, a director within the National Mining Agency (ANM) said on Thursday, after a great dam burst a few weeks ago, likely killing at a minimum 300 people.

Eduardo Le?o, a director at ANM, said the business aims to issue an ordinance on Friday requiring that such dams be used down or became other types of dams.

A tailings dam with a Vale SA iron ore mine through the southeastern state of Minas Gerais burst on Jan. 25, releasing a torrent of sludge that buried buildings and the ones. At least 150 citizens were killed and 182 are missing and presumed dead after the disaster during the town of Brumadinho.

Brazil has 88 upstream tailings dams, in line with Le?o. It was not immediately clear what sort of deadline the dam operators would face to have down or convert the dams.

The reason for the disaster remains unknown. Situations regulatory official told Reuters yesterday morning that evidence suggested the dam burst resulting from liquefaction, a process where solid materials like sand lose strength and stiffness and behave like a liquid.

Vale’s dam in Brumadinho was built with all the cheapest and least stable particular tailings dam design, known as an “upstream construction.” Upstream dams are waterlogged and for that reason susceptible to cracks that can cause bursts.

A third-party audit of this dam conducted just last year found cracks in drainage channels and recommended improvements in monitoring, depending on the audit report reviewed by Reuters earlier this week.