ST. PAUL, Minn. (AP) — PolyMet Mining and Teck Resources finalized a joint venture Wednesday to complete the copper-nickel mine that PolyMet has been developing in northeastern Minnesota, and the partnership hopes to eventually build a separate mine next door in an even larger ore body that Teck controls.

The long-planned PolyMet mine near Babbitt will now be known as NewRange Copper Nickel, the name of the 50-50 joint venture. Combined, the joint venture’s mineral resources are more than quadruple the size of what PolyMet had on its own.

Under the newly closed deal, NewRange now controls about half of the known copper, nickel, cobalt and platinum-group metal reserves in the geological formation known as the Duluth Complex, one of the world’s largest untapped resources of the critical minerals.

“Successful closing of the joint venture moves NewRange Copper Nickel to the forefront of responsible development of American-sourced critical minerals for the manufacture of clean energy and clean transportation technologies such as battery storage, wind and solar generation and electric vehicles,” Jon Cherry, PolyMet chairman, president and CEO, said in a statement.

Environmental groups that have long fought PolyMet raised concerns when initial plans for the joint venture were announced last summer, saying it potentially could lead to even bigger threats to the water-rich region. But NewRange says it will be a conscientious steward of the area’s water, air and natural resources.

The name NewRange pays homage to the mining heritage of northeastern Minnesota’s Iron Range. The joint venture’s first task is to bring the open pit mine that PolyMet had been developing in its NorthMet ore body over the finish line. That project remains on hold because three key permits, which were issued over four years ago, are still tied up in challenges in courts and regulatory agencies. Because of those, NewRange still isn’t projecting a date for major construction to begin.

Environmentalists have opposed the mine because the copper and nickel in the Duluth Complex are bound up in sulfide minerals that can leach sulfuric acid when exposed to water and air. For that reason, President Joe Biden’s administration is trying to kill another proposed mine nearby, Twin Metals near Ely, which sits in a watershed that flows into the pristine Boundary Waters Canoe Area Wilderness. While the administration last year committed itself to expanding domestic sources of critical minerals for electric vehicles and renewable energy, it says the Boundary Waters merit special protections.

The joint venture controls both the NorthMet deposit and Teck’s Mesaba deposit a few miles to the east. The lower-profile Mesaba project hasn’t progressed past the exploratory stages. NewRange plans further studies. A formal proposal for the envisioned open pit mine would have to go through a full environmental review and permitting process. That process would take at least several years. It hasn’t been decided whether a mine at the Mesaba site would use the former LTV Steel processing plant near Hoyt Lakes that will handle NorthMet’s ore.

The combined indicated and inferred resources of the two deposits adds up to nearly 4.8 billion tons (4.4 billion metric tons) — over 1.1 billion tons (1 billion metric tons) from NorthMet and over 3.6 billion tons (3.3 billion metric tons) from Mesaba, the companies said.

While the NorthMet deposit is in a watershed that eventually flows into Lake Superior, the Minnesota Center for Environmental Advocacy has pointed out that the Mesaba ore body sits mostly in the Boundary Waters watershed, like Twin Metals. But unlike Twin Metals, the Mesaba mineral rights leases are from the state, not the federal government.

Also in the early stages is the proposed Talon Metals mine near Tamarack, which has a deal to supply nickel to electric-carmaker Tesla Inc. It’s about 90 miles (145 kilometers) to the southwest, in the Mississippi River watershed. Talon plans to submit its application to kick off the review process in the next few weeks.

Both St. Paul-based PolyMet Mining Corp. and Vancouver, British Columbia-based Teck Resources Ltd. will remain publicly traded companies listed on both the New York and Toronto Stock Exchanges. PolyMet’s majority shareholder is Swiss commodities giant Glencore, which owns 71% of its common stock plus rights to acquire 78%, and has pledged continued financial support for the project. Teck’s largest shareholder is the China Investment Corp., the sovereign wealth fund of the Beijing government, with a 10% stake.

Tannice McCoy, who had been Teck’s Mesaba project manager since 2018, will be general manager of NewRange, responsible for day-to-day operations. Cherry will remain chairman, president and CEO of PolyMet and will chair the management committee of the joint venture.

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