Test of new mining technique set for Minn. manganese deposit

Town of Emily
Experts believe 1 billion pounds of high-grade manganese can be found underground within the city limits of Emily.
MPR Photo/Tom Robertson

Test mining is set to begin in central Minnesota this fall on what could be one of the largest manganese deposits in North America.

Mineral experts believe 1 billion pounds of high-grade manganese can be found underground the small town of Emily, Minn., about 35 miles northeast of Brainerd.

A significant, extractable lode of manganese would be a big deal, since the United States imports virtually all of the manganese it uses. The mineral is used in steel production and the manufacture of batteries.

The deposit sits under a five-acre site just a couple miles from the center of town. Crow Wing Power officials bought the land and created a subsidiary called Cooperative Mineral Resources, or CMR, to pursue a locally based mining operation.

CMR will try a mining technique never used in Minnesota called borehole extraction mining, in which a device inserted into a wellshoots out a jet of high-pressure groundwater. Because manganese is a crumbly ore, the process should flush it out and pump it to the surface. It will then be trucked about 60 miles north to a minerals lab in Coleraine.

The company plans to test the method this September, spokesman Mike Zipko said.

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"The scale of this is going to be dramatically different than what anybody in Minnesota thinks of when they think of mining," Zipko said. "This is going to be done on an extremely small site. They're going to drill one well that will be 14 inches in diameter."

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The state Department of Natural Resources and the Minnesota Pollution Control Agency have concluded the test operation won't hurt the environment. But not everyone is convinced.

Among those worried is Elizabeth Heck, who lives about six miles north of the mine site.

"I think there's a lot of environmental concerns," Heck said. "I think there is concern for the aquifer. If I was down on Ruth Lake or any of those surrounding lakes, personally, I would probably be selling my property right now."

Ruth Lake and several other spring-fed lakes are within a few miles of the mine site. Two aquifers feed the lakes and supply well water for the whole city of Emily.

Heck said she believes the state isn't being tough enough to ensure the water that's filtered and put back into the ground is clean. She's also concerned about dust from trucks that would haul the material.

"This project is highly experimental ... I think there's a lot of environmental concerns."

There's good reason to be cautious. According to the U.S. Centers for Disease Control and Prevention, exposure to high levels of manganese, through inhalation or ingestion, can cause neurological damage in humans. Heck said most locals don't share her concern.

"This project is highly experimental," she said. "Manganese has never been mined through borehole extraction before, and the company that's actually doing this has never mined anything before."

Company officials say their operation will be safe. Brad Moore, a senior advisor for a Minneapolis consulting firm hired by Crow Wing Power, said dust won't be an issue because material hauled by trucks will be wet and the trucks will be covered.

The company has a plan in place to make sure groundwater isn't harmed, said Moore, former head of the MPCA.

"We have monitoring in place during the project that's real-time monitoring," he said. "In addition to the borehole, there's a series of seven other wells surrounding that that are being monitored for water movement and quality. In addition, we also monitor residential wells."

If the test project moves to full-scale mining, profits will go back to the cooperative's 40,000 members.

Emily Mayor George Pepek said it would also generate taxes and create jobs. Pepek said he's confident the permitting and approval process protects local residents and the environment.

"We've kind of looked at all aspects of it. It's been a long, long haul. And I guess we'll learn more as we go along as they do the demo project," Pepek said. "It may turn out that it's not even feasible for them, but we'll see."

The borehole test project will take about 12 weeks. Company officials will then decide whether a full-scale operation is feasible. The state would then require a full environmental review, which would take about two years.