While iron-ore mining has a long history in the “Iron Range” region of northeastern Minnesota, the Center’s Minnesota Mining campaign is focused on an entirely different type of mining being proposed in the same region. The Duluth Complex, which stretches from the Canadian border south to Duluth, may contain the world’s largest untapped copper deposit — an estimated 4 billion tons of copper-nickel ores that may be worth more than $1 trillion.
MINNESOTA’S COPPER RUSH
The untapped potential of the Duluth Complex has triggered widespread exploration for copper, nickel and other heavy metals across the region. Since 2008, mining companies have applied for more than 100 permits to conduct exploratory drilling on the Superior National Forest of northeast Minnesota. The state of Minnesota owns the mineral rights of much of this region, and in 2010 about 145,000 acres of state mineral rights were under leases for exploration. Besides the heavy level of exploration in and around the Superior National Forest, additional exploration is underway elsewhere, including extensive drilling to the west in Aitkin and Carlton counties.
THE CONCERN OVER HEAVY-METALS MINING IN NORTHEASTERN MINNESOTA
The main concern with this new type of mining can be summed up in one word: water. Northeastern Minnesota is defined by its lakes, rivers and wetlands, with the northern half of the region draining into the Boundary Waters on its way to Hudson Bay and the southern half flowing into the St. Louis River before entering Lake Superior.
Mining for copper, nickel and other heavy metals is often referred to as “sulfide mining,” because these metals are found bonded to sulfur in sulfide ores. This type of mining would produce millions of tons of waste rock containing sulfides, which when exposed to air and moisture will generate sulfuric acid that can leach into the surrounding streams, wetlands and lakes. This phenomenon is known as “acid mine drainage,” and is responsible for massive water pollution problems at mine sites throughout the western United States.
POLYMET’S NORTHMET MINE
The first proposed copper mine in the state to reach the environmental review stage is PolyMet’s proposed NorthMet mine, which is located on the Superior National Forest. According to the draft environmental impact statement, the mine would generate 400 million tons of waste rock over 20 years, directly affect more than 800 acres of high-quality wetlands and destroy two square miles of lynx and wolf habitat. Major environmental concerns triggered critical comments from the Environmental Protection Agency, which resulted in the need for a supplemental draft statement that is now being prepared.
THE TWIN METALS PROJECT
The second proposed copper mine that is expected to reach the environmental review stage is the Twin Metals Project, which is a joint venture targeting what were originally four separate ore bodies: the Nokomis, Birch Lake, Maturi and Spruce Road deposits. The potential mining area covers 25,000 acres and could become one of the largest copper-nickel mines in the world. The project begins just south of the Boundary Waters Canoe Area Wilderness, and much of the ore is located under Birch Lake.
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