Sigma Lithium’s waste piles offer no ‘imminent risk’, says Brazil’s mining regulator

Sigma Lithium’s waste piles at a Brazilian mine offer no “imminent risk” and the country’s mining regulator saw no need to shut them down during a visit last month, the agency told Reuters in a statement on Monday evening.

The ANM’s technical staff visited the mine on January 20, about a month and a half after the piles were shut down by labor inspectors who warned of a “grave and imminent risk” to workers and the local community.

The shutdown sent Sigma’s shares tumbling some 30% after Reuters reported on the inspectors’ decision on January 15.

While ANM’s assessment does not overturn the order from Brazil’s Labor Ministry, it is a boost for the Toronto-listed miner, as it could be presented as evidence in a lawsuit filed against Brazil’s government in early January, in which Sigma seeks to overturn the closure of its waste piles.

The firm announced on Monday that it was resuming mining activities at its flagship Grota do Cirilo mine in the state of Minas Gerais, and previously said that the shutdown of the piles did not compromise its schedule for resuming production there.

In documents filed to the Labor Ministry, the firm previously said that losing access to the piles would cause “significant operational and economic impacts, in addition to jeopardizing the continuity of mining activity.”

Sigma declined to comment on the matter due to “ongoing administrative proceedings … in different jurisdictions.”

Brazil’s largest lithium mine

Sigma’s operation at Grota do Cirilo, its only productive asset, is Brazil’s largest lithium mine, with annual capacity of 270,000 metric tons of lithium concentrate. It had been inactive since October.

During the visit, ANM’s technical staff made a visual on-site assessment of the piles, and analyzed documentation presented by the miner, the agency said.

“ANM technicians did not identify any geotechnical anomalies indicative of an imminent risk of global destabilization of the piles,” it said in a statement.

While the agency found some issues during the visit, it added that it saw no reason for the “adoption of precautionary measures such as closure” of the piles “at the moment.”

ANM has notified Sigma that its piles lack a superficial water drainage system, but added that the issue is not “associated with imminent risk” but is a regulatory failure by the firm.

The agency also dismissed what labor inspectors said was a “partial rupture” at one of the waste piles near a school. According to ANM, the issue was a “localized erosion process” on a pile that indicated “local instability” but offered no immediate risk to the local population.

(By Fabio Teixeira; Editing by Andrea Ricci)