Twin Metals Announces Use of ‘Environmentally Friendly’ Dry Stack Method for Proposed Mine

The Company Says This Will Eliminate Need for a Storage Pond

ST. PAUL, Minn. – Twin Metals Minnesota announced Thursday morning that they plan to use the environmentally friendly dry stack method to store leftover rock for their proposed copper-nickel mine southeast of Ely.

The company says this method will eliminate the need for a storage pond and dam which are commonly used at conventional tailing facilities.

The dry stack method has been successfully used in four other mines in the northern United States and Canada.

“Dry stack tailing storage is the most environmentally friendly tailings management approach for our site,” said Kelly Osborne, chief executive officer of Twin Metals Minnesota. “The first key is that there’s no dam, no risk of dam failure. The moisture content of the filtered tailings is reduced to a material that we can compact and manage seasonally.

“Because there’s no risk of a dam failure, dry stack is considered the best available technology for tailings storage and, after a decade of study and consultation with concerned voices in our community, we determined that it will be an effective choice for our project.”

The company explains, in the dry stack method the tailings, which are crushed rock left over after target minerals are removed, are compressed into low-moisture, sand-like deposits and stored in a lined ground facility near the plant.

“Dry stack is one of the ways we are making a 21st century mine that will be the most technologically advanced mine in Minnesota’s history and a model of how copper mining can be done safely and sustainably,” said Osborne.

Today, Save the Boundary Waters National Chair Becky Rom issued the following statement on Twin Metals’ announcement:

“Antofagasta’s Twin Metals project should never have gotten this far. This US Forest Service unequivocally concluded in 2016 that sulfide-ore copper mining posed an unacceptable risk to the Boundary Waters, America’s most popular Wilderness. This conclusion has never been refuted. That unacceptable risk is in no way reduced by today’s announcement, and is actually made worse by the fact they are putting the tailings basin right next to the Wilderness. Minnesotan’s can’t rely on hollow promises from an international mining company with a history of environmental degradation and political corruption to protect the Boundary Waters.”

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