HOYT LAKES, MINN. - After years of hard times for Minnesota's Iron Range, a Canadian corporation is offering a tantalizing mix of promises.

PolyMet Mining is planning a $600 million construction project on the site of a bankrupt taconite mine in Hoyt Lakes. The project would bring more than $80 million annually in tax revenue and 400 jobs in a lucrative new vein of mining -- for copper, nickel, cobalt, platinum and even gold.

But as Iron Range politicians plan for a prosperous leap out of the region's iron age, environmentalists are urging the state to reject nonferrous mining as too dangerous to lakes and rivers. They say metallic sulfide ore of the type that PolyMet and several other companies hope to mine has a notorious history. When it's exposed to air and water, it leaches sulfuric acid and toxic metals into nearby watersheds, poisoning wildlife.

The well-known phenomenon, called "acid mine drainage," can appear decades after companies have gone. Several abandoned mines in the West are now federal Superfund sites, with taxpayers footing the bill for cleanup and perpetual water treatment. Butte, Mont., was left with a pit lake so acidic that 340 migrating snow geese died after landing there in 1995.

Sulfide mining in Wisconsin caused so much controversy that in 1997 the state outlawed it unless a company can cite an example of a North American sulfide mine that operated 10 years without polluting ground or surface water, and one mothballed 10 years without leaching such pollution.

No company has tried to mine known deposits of sulfide ore in Wisconsin since such proof was made a requirement. "They're boring holes all over the Upper Peninsula of Michigan and in northern Minnesota, but no one is doing it here," said Philip Fauble, mining coordinator for the Wisconsin Department of Natural Resources.

Impact study due

Supporters of nonferrous mining for Minnesota say sulfur concentrations are lower here than in many places and are less apt to produce acid mine drainage.

PolyMet also says it will use some of the cleanest technology available to process the ore and manage the waste rock. The innovations include reducing ore in an enclosed "autoclave," an industrial pressure cooker that will consume much of the sulfur as fuel and produce very low emissions compared with old-technology smelters.

Waste rock with the potential to produce acid will be reburied and landscaped atop liners designed to catch runoff and divert it for treatment. The company also agreed to set up "bankruptcy proof" reclamation funds for water treatment and other potential cleanup costs.

"The ultimate goal of PolyMet's approach is to have a minimum impact on the environment and to protect our air and water resources," said LaTisha Gietzen, vice president of public, government and environmental affairs.

The company has spent more than $40 million so far proving the feasibility of mining the 800-foot-deep ore formation that geologists call the "Duluth Complex." About $15 million of that has gone toward a three-year environmental review coordinated by state, federal and tribal regulators who are working to complete a draft environmental impact statement as soon as this month.

Next: 45 days of comments

Publication of the environmental impact statement will trigger a 45-day comment period, after which the state will consider whether to issue mining permits to PolyMet.

Among the steps taken by the team of 25 experts working on the study was to visit sulfide mines in Ontario, where the climate and hydrology are similar to Hoyt Lake, and a mine in Nevada that is using an autoclave, said Stuart Arkley, coordinator of the review for the Minnesota Department of Natural Resources.

"PolyMet is proposing applying relatively new technology to a relatively low-grade ore body, so there isn't a lot out there to compare it to," he said.

Arkley said that, despite the diligence of PolyMet and the regulators, the public should not expect a benign mine.

"There's no such thing as an industrial site that doesn't cause some level of pollution, some level of impact," he said."

Environmental groups are considering legal action to block or at least alter the project. Last month, the Minnesota Center for Environmental Advocacy wrote the DNR that it would be illegal under the Minnesota Environmental Rights Act to permit the project without a thorough analysis of the feasibility of mining the ore underground rather than in an open pit. The organization said an underground mine would have a smaller footprint, and it warned that it would take "appropriate steps" to make sure that option is fully analyzed.

While the DNR has not formally responded, Gietzen of PolyMet and Arkley of the DNR said in e-mails that the underground option had been analyzed and so far doesn't appear feasible, in large part because the ore deposit comes within feet of the surface.

'Fear factor' debated

PolyMet's promises have made a believer out of Hoyt Lakes Mayor Marlene Pospeck, who watched 1,400 taconite miners lose their jobs when LTV Steel Mining Co. went bankrupt in 2001.

"The technology they plan to use is nothing like the methods that caused problems elsewhere," Pospeck said.

Iron Range legislators also have hailed the project, and in Congress, Sen. Amy Klobuchar and Rep. Jim Oberstar introduced bills that would allow the Superior National Forest to sell PolyMet 6,700 acres.

Democrats Klobuchar and Oberstar say that the legislation, requested by the Forest Service, would be good for the environment because the land has been mined and logged over, and the Forest Service would use the proceeds from the sale to buy better land. In an interview, Oberstar said that as long as state and federal regulators determine the ore can be mined safely, the project should proceed.

Opponents say politicians are too focused on the promised benefits of the project and not concerned enough about what Minnesota could lose.

Technology proving grounds

The Sierra Club, Friends of the Boundary Waters Wilderness, Minnesota Center for Environmental Advocacy and other groups argue that sulfide mining's history is too disastrous to allow any state watersheds to be used as proving grounds for new technology.

While any discharges from PolyMet would drain through the St. Louis River watershed to Lake Superior, other companies are test-drilling on sites that would drain through the Boundary Waters Canoe Area Wilderness to the Rainy River.

"The BWCA and the Superior National Forest cannot be used as guinea pigs," and John Doberstein of Two Harbors, chairman of the Mining Without Harm Campaign for the Sierra Club's North Star Chapter.

Larry Oakes • 218-727-7344