The Minnesota Court of Appeals has rejected another permit for PolyMet Mining Corp.'s proposed copper-nickel mine, this time for its air emissions.
The Minnesota Pollution Control Agency (MPCA), which issued the air permit in 2018, should have looked harder at whether PolyMet plans to expand the state's first copper-nickel mine well beyond the limits imposed by the permit, the three-judge panel concluded in its unanimous decision released Monday.
Writing for the court, Judge John Rodenberg said the regulator should have clearly addressed whether PolyMet "is engaged in sham permitting" to avoid a permit requiring greater review and more stringent controls.
PolyMet's Canadian securities filings indicate it may actually be planning a mine nearly four times larger than operation covered by the air permit, which limits the mine to producing 32,000 tons of ore per day, the court noted.
The court remanded the permit back to the MPCA for further review.
The MPCA said it's reviewing the decision and will soon decide its next steps.
The decision is another setback for PolyMet's proposed copper-nickel mine, which is already tied up in litigation and investigations into how regulators handled its water quality permit. If it gets built, the open-pit mine, near Babbitt and Hoyt Lakes, would be the state's first nonferrous mine, known as a hardrock mine.
The publicly traded company, majority owned by global mining and trading conglomerate Glencore in Switzerland, said it's reviewing its legal options.