Antofagasta's (LSE: ANTO) Twin Metals Minnesota has received formal notice that its planned copper-nickel-cobalt-platinum metals mine will be assessed through a federal environmental review. The U.S. government's Bureau of Land Management (BLM) notified the company at the end of June of its intention to scope and prepare an Environmental Impact Statement (EIS) for the proposed mine project in Minnesota.
Twin Metals' chief regulatory officer, Julie Padilla, said this is another important part of the company's long-term plans for an underground mine.
"It's really a significant milestone," Padilla told The Northern Miner. "Getting to this point means that we've submitted and answered enough questions on the mine plan of operations that the BLM feels it's prepared to enter into formal environmental review."
The project has been in development for a decade, and is located between the cities of Ely and Babbitt in northeastern Minnesota. The company is headquartered in St. Paul, with its operational base located in Ely.
Twin Metals envisions an underground mine that will target minerals within the Maturi deposit, part of the Duluth Complex geologic formation.
According to Twin Metals, the Duluth Complex contains some of the largest undeveloped deposits in the world, with more than 4.4 billion tonnes of mineralized material containing copper, nickel and other strategic minerals.
Padilla believes the region's deposits have not received enough attention. As the U.S. government looks to reduce reliance on foreign production sources, resources like those located in the Maturi deposit will take on increased strategic importance. These include copper for wind power and broadband networks, nickel for electric vehicles and cobalt for smart phones.
"This deposit overall - the Duluth Complex - hosts about 95% of the United States nickel reserves," she said. It also has "88% of the country's cobalt, a third of its copper, and about 75% of its platinum-group metals."
The company is mindful that its planned mine is located within the U.S. Forest Service Superior National Forest Plan and close to the Boundary Waters Canoe Area Wilderness. The project would be the first underground mining operation in Minnesota since 1967, an approach Twin Metals says will minimize surface disruption, noise and dust.
The proposed mine is not without its opponents, who worry about the potential environmental damage that could result from the project. But Twin Metals' plans foresee the overall project footprint to be only 15-20% the size of a traditional open pit mine.
The company anticipates the mine processing 20,000 tonnes of mineralized material per day, with extraction operations taking place between 120 and 1400 metres underground. Additionally, processing will remove most of the sulfide minerals, so tailings will not produce acid rock drainage, and crushing will occur underground.
While the U.S. federal government's BLM environmental assessment gets underway, Minnesota's Department of Natural Resources (DNR) is the other regulatory player that will soon be looking at the project.
"As we move forward, our next steps are to continue to respond to the state, the DNR's comments on our data submittal, to work towards a completeness determination there," Padilla says. "We are also out in the field doing a lot of baseline data collection on the environment. And we expect to do cultural resources data collection this year."
While Twin Metals has already drilled almost 610,000 metres on the deposit, Padilla notes that there is still a lot of work to be done before the project enters into an operational phase.
"My best guess on getting through both the state and the federal environmental reviews, and the permitting process which follows that, is five to seven years," Padilla says. "And then we'll see a two and half year construction period. So, we're a ways out, but hopefully it'll be at the more efficient end of that timeline."