What Is Sulfide Mining?

Sulfide ores are ores containing heavy metals (such as copper or nickel) that are bonded to sulfur, forming sulfide minerals. When exposed to air and moisture, a chemical reaction generates sulfuric acid that can leach into the surrounding environment and cause the release of the metals into streams and lakes at levels that are toxic to fish and other aquatic life. * This phenomenon is known as Acid Mine Drainage. In a surface mine like the one proposed by PolyMet, mining leaves huge piles of waste rock and a huge pit exposed to the elements. Like the ore that has been removed, the waste rock and the pit walls contain sulfide minerals. The potential for Acid Mine Drainage and for contamination of surface and ground water by heavy metals remains for centuries, and even millennia, into the future.

Sulfide Mining

Northern Minnesota's Waters and Forests Threatened by Sulfide Mining and Industrial Expansion

Located between the North Shore of Lake Superior and the Boundary Waters Canoe Area Wilderness, the Arrowhead Region is Minnesota's most loved recreation area and a place that millions visit for rejuvenation. This region faces an unprecedented industrial expansion that is certain to affect the qualities that draw people here. One of the worst threats from this expansion is from the mining of sulfide ores, a particularly harmful type of mining that has not been conducted in Minnesota before. PolyMet Mining's NorthMet Mine, located between Babbitt and Hoyt Lakes, is the first of what may become many sulfide mine proposals. 


Learn about the cases against PolyMet


People vs. PolyMet is a project of the

Minnesota Center for Environmental Advocacy



A view of the aftermath from a failed iron ore tailings dam owned by Brazilian miner Vale SA that burst, in Brumadinho, Brazil.

REUTERS/Adriano Machado



What's New

Minnesota Supreme Court weighs PolyMet air permits

Duluth News Tribune 11/5//2020, Jimmy Lovrien

The Court of Appeals had ordered the permits back to the MPCA and said the agency needed to consider the larger plans.


The DFL has adopted the resolution calling for a moratorium on Copper Nickel Sulfide Mining in MN  


 A moratorium gives us time to consider.  It's time to throw our strength behind what is good and right.  

DFL committee adopts resolution calling for moratorium on copper-nickel mining, again exposing rift within party

Duluth News Tribune 7/5//2020, Jimmy Lovrien

Iron Range DFLers and the party's legislative leaders opposed the resolution.


Responsible mining? Minnesota has a long way to go. 

MinnPost  8/21/2020, Janet Keough and Bill Hansen




Copyright © 2018 DFL Environmental Caucus  255 Plato Blvd, St Paul, MN 55107. Veda Kanitz, Chair.

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