The United States currently imports upwards of 80 percent of its palladium/platinum, over 80 percent of its cobalt, 60 percent of its nickel and 40 percent of its copper. That’s why PolyMet says it wants to open a mine north of Hoyt Lakes at the east end of the Mesabi Iron Range in St. Louis County. According to Brad Moore, a senior advisor at Barr Engineering, a consulting firm to PolyMet Mining, the Duluth Complex formation is estimated to rank very high as a world class source for these metals.
Moore gave a power point overview and status report on the PolyMet open pit mine venture to Cook County Commissioners Tuesday. He said the proposed mine would annually produce 36,000 tons of copper, 7,700 tons of nickel, 360 tons of cobalt and about 7,200 pounds of precious metals such as platinum and gold.
The valuable minerals PolyMet plans to tap into are part of sulfide rock, making this type of mining different from the more commonplace taconite mining on the range. A chief concern brought forward by critics of the mining proposal centers around what happens after the sulfide rock is brought to the surface. Runoff from the rock forms sulfuric acid which can cause acidity in water making it difficult and even impossible for anything to live in the streams or wetlands where the runoff flows.
Moore acknowledged resistance to the new mine proposal and attempted to address concerns in his presentation. One such concern has been possible pollution of lakes in the Boundary Waters Canoe Area Wilderness. Moore responded saying, “The watershed flow is south to Lake Superior, not north to the Boundary Waters.” He added that taconite mining is going on above the proposed PolyMet site and no pollution has been detected in boundary waters.
As for flowage to Lake Superior, Moore was a little less specific. According to PolyMet about 3 percent of the excavated waste rock will have increased acidity above normal stream water levels. He said the Minnesota Pollution Control Agency has stream monitors in place. He also said the affected rock will be stockpiled in such a way as to minimize drainage and once the operation is complete all the excavated material will be put back into the pit.
A member of the public in attendance asked if it was true the open pit would be the size of 200 football fields.
“I’m not sure of the 200 football field size,” he said, “but the pit will be large, but smaller than many other pits in the area. And it will be filled in when closed and converted to wetlands.”
Moore emphasized that the Environmental Impact Study currently underway, addresses the loss of wetlands from mining. He said mining always affects wetlands and where the impact cannot be avoided, the plan is to replace them.
“When the project is finished there will be more wetlands replaced than were lost,” said Moore.
Moore added although there is probably 100 years of minerals available in the Duluth Complex, the estimated life of the mine is 20 years, after which it will be closed and filled in.
“Unlike other open pit mines you see – lakes and so forth, this will be much different,” said Moore.
Moore’s appearance before the county board was at the same time the Minnesota Department of Natural Resources began opening new bids submitted by mining companies that want to prospect for minerals on state lands in the northeast. The DNR acknowledged the progress PolyMet is making through the environmental review process has increased non-ferrous mining interest.
For example Vermilion Gold has submitted a bid to look for gold under state land just west of the Iron Range. Dozens of test mine shafts have already been drilled on DNR and Forest Service lands in recent years. But opponents say non-iron mining is much riskier for the region’s environment because the minerals are found in rock with high sulfur content. When exposed to air and water, that rock can cause sulfuric acid runoff that can leach heavy metals into local waterways and cause problems for wildlife.
Supporters of these mines note they would help the region’s economy. The PolyMet project, for example, is projected to employ about 400 people for the life of the mine and have a $240 million dollar economic impact on St. Louis County according to PolyMet’s figures.
The county board agreed by consensus to write a letter to submit during the public comment period. The board will discuss the content of the letter during its next meeting on Tuesday, Jan. 19. The meeting begins around 9:30 a.m., after the Human Services Board meeting.