Twin Metals

A second sulfide mine has been proposed for northern Minnesota by Twin Metals Minnesota LLC.

The ore deposit is two to three miles from the Boundary Waters Canoe Area Wilderness. Twin Metals was a joint venture of Duluth Metals Limited, a Canadian company, and Antofagasta PLC, a Chilean-based mining company. In January 2015, Antofagasta purchased Duluth Metals, and is now the 100% owner of Twin Metals. This proposal seeks to mine copper, nickel and other metals in an underground mine located near Birch Lake, southeast of Ely, Minnesota. The project is comprised of four mineral deposits, which the company refers to as “Maturi,” “Maturi Southwest,” “Spruce Road,” and “Birch Lake.”  The area of interest includes beneath Birch Lake (the company may propose to mine under the lake) and the area between the lake and the BWCAW, along the South Kawishiwi River.  The area is largely on public land on the Superior National Forest and contains two expired federal mineral leases.

These expired mineral leases are currently the subject of a public input period as the Forest Service considers whether to veto the extension of these leases. Learn more and take action

Twin Metals published a “prefeasibility study” in July 2014, which described more of the project details, such as engineering design and facility locations.  The prefeasibility study showed high capital costs (over $2.8 billion) and marginal profitability. When Antofagasta acquired Twin Metals in January 2015, their CEO announced that Antofagasta would “optimize” the plan for the mine, indicating that changes to the proposal are likely.

This project lies within the Rainy River watershed, an area where surface waters flow north through the Boundary Waters Canoe Area Wilderness and other parts of the Superior National Forest, as well as through Voyageurs National Park.  The route surface waters take (and potential pollution) are through the South Kawishiwi River, into Birch Lake, into the White Iron Chain of Lakes, and then into the BWCAW.