Opponents of planned Minnesota copper mine worry about environment

Opponents of planned Minnesota copper mine worry about environment

A draft Environmental Impact Statement is due soon for a proposed industrial copper mine with the potential of hundreds of jobs and millions of dollars in economic growth for the Iron Range.

As PolyMet Co. prepares to ready the mine for opening over the next two years, opponents are talking about the potential acidic runoff that could flow into lakes and streams.

Critics note that runoff from copper mines frequently brings heavy metals — arsenic, cadmium, mercury and lead — that are leached out of rock and can be deadly to stream ecosystems.

Consultants who did an economic feasibility study recently were optimistic that the open-pit mine and processing facility north of Hoyt Lakes would be a big success with metal prices near record highs and more copper, nickel, palladium, platinum and other metals on the site than had been expected.

Permits could be issued late next year allowing PolyMet to dig the mine pit, restart the idled LTV taconite plant to process the copper, fill wetlands and to release wastewater from the site. Production could begin in late 2008, and the mine could operate for 40 years.

PolyMet purchased the shuttered LTV taconite operations in 2005. The company plans to use much of the old processing plant as the primary concentrator for copper, as well as the railroad and other parts of the old LTV operation.

Another copper mine under nearby Birch Lake near Babbitt also is under discussion as higher prices make lower-grade Minnesota copper deposits more attractive.

Although there has been mining on the Iron Range over the past century, copper mining has more potential to do caustic environmental harm, said Jane Reyer of Grand Marais, an attorney for the National Wildlife Federation and a member of ACT NOW, a coalition opposing copper mining in northern Minnesota.

“Every single copper mine we’ve researched has had a problem with acid drainage. Environmental harm is an inevitable byproduct of sulfide mining,” Reyer said. “Every company talks about how they will do things differently. Then the same problems come up.”

Reyer cites Wisconsin’s near moratorium on copper mining that requires any prospective mining company to show where a copper mining operation anywhere else has been shut down for 10 years without acid runoff.

“We haven’t found a single copper mine in the world that meets the requirement,” Reyer said. Minnesota doesn’t have the same restrictions.

Opponents to copper mining in Minnesota are meeting in Duluth next Saturday to discuss strategy and raise public awareness. They hope to influence state and federal regulatory agencies to write tough permits that restrict acid runoff if PolyMet advances.

“Short of stopping the project, we want to get the best permits we can get,” Reyer said. “Our main goal right now is public education. We don’t think most Minnesotans know how close this is to happening, or how different copper mining is from taconite mining. This isn’t against PolyMet. We’re concerned about any sulfide mining, period.”

PolyMet officials said they understand the concerns and concede copper mines elsewhere have a poor track record. But they say the rock holding the copper in the NorthMet deposit the company plans to mine is unusually low in sulfur, showing only about .6 percent sulfur. By comparison, rock at the former Flambeau mine in Wisconsin was more than 30 percent sulfur, and rock at the proposed Crandon mine in Wisconsin was more than 10 percent sulfur.

“The acid-generating potential of this rock is much lower than the Wisconsin mines or mines we see in the southwest (U.S.),” PolyMet project manager Don Hunter said. “The technology exists to isolate the reactive waste rock, collect the runoff and treat it. This is not a project that’s going to leave a legacy of harm.”

Mine officials say virtually all rock taken from pit will be monitored. If the waste rock is acidic, the piles likely will be stored in a lined holding area with runoff collected and treated. Wastewater from the mining process will be treated and sent into the existing LTV Steel tailings basin, which is lined and has more than 20 years of storage capacity remaining.

Acidic runoff also can be neutralized by adding limestone or by running the water through a system of created wetlands, mine officials said.

Polymet officials added that their proposed processing system, a massive pressure-cooker called an autoclave, produces far less air pollution than traditional copper smelting and uses much less energy.

“This is the cleanest copper producing process in the world,” Hunter said. The autoclaves have been used in Canada and overseas, but it will be the first time the process will be used in Minnesota. Even environmentalists say they process is vastly cleaner than the smoke-belching smelters of past copper processing.

Share this post