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.
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.
Timberjay 6/25/2020, Marshall Helmberger
NMW attempting to pressure DNR to prohibit copper-nickel mine in Rainy River watershed
Duluth News Tribune 6/16/2020, Jimmy Lovrien
In March, the Court of Appeals sent the company's air permits back to the MPCA for review and said the agency should have considered a report that said the PolyMet is eyeing a much larger operation.
Timberjay 4/29/2020, Marshall Helmberger
Minntac tailings basins could be subject to Clean Water Act regulation under new court ruling.