Minnesota Court of Appeals dismisses challenge to PolyMet air permit

Last month, the US Environmental Protection Agency (EPA) dealt another blow to PolyMet Mining’s plans to build an open pit copper-nickel mine in Minnesota, by recommending the US Army Corps of Engineers not re-issue a key water-related permit.

The agency said the $1 billion NorthMet project, the first large-scale project to be permitted within the Duluth Complex in northeastern Minnesota, risked increasing levels of mercury and other pollutants in the St. Louis River downstream from the proposed mine. 

Barring an appeal to the Minnesota Supreme Court, Tuesday’s ruling lays to rest multiple legal challenges that mining opponents have brought against the air permit since it was issued by the Minnesota Pollution Control Agency (MPCA) more than three years ago.

The agency reinstated the permit in December 2021 after fulfilling a Court of Appeals order to further explain its reasoning.

“This ruling is one more step toward delivering on our promise to build a modern, responsible mining operation that will feed a supply chain that is growing ever more hungry for the clean-energy minerals we will produce,” said Polymet CEO Jon Cherry in a media statement.

According to PolyMet Mining, the project comprises 290 million tonnes of proven and probable reserves grading 0.288% copper and 0.083% nickel and marketable reserves of palladium, cobalt, platinum and gold.

NorthMet is not the only project to face headwinds as it tries moving forward in Minnesota. Chilean miner Antofagasta (LON: ANTO) had to deal with several concerns from locals about the risks its proposed Twin Metals underground copper-nickel mine and processing facility would carry.

In January, the company lost its battle. The US Department of the Interior cancelled two mineral leases for Antofagasta’s proposed mine in Minnesota, effectively killing the project and handing a major win to environmentalists.