Twin Metals Minnesota submits mine plan

December 19, 2019

Twin Metals Minnesota has submitted a mine plan to state regulators for its proposed underground copper-nickel mine near Ely, MN.

By submitting the plan, the environmental review process begins for what would be the second copper-nickel mine in Minnesota. However, The Associated Press reported that Twin Metals Minnesota continues to face significant opposition to its proposed mine that would be upstream from the Boundary Waters Canoe Area Wilderness.

Julie Padilla, Twin Metals’ chief regulatory officer, said the company hopes to complete the environmental review process in five to seven years which could be optimistic, given that the PolyMet project took well over a decade to clear those hurdles.

Twin Metals Minnesota officials have said that the mine is designed to prevent pollution from reaching the wilderness while creating about 765 full-time mining jobs and more than 1,500 spinoff jobs, plus thousands of construction work hours for union labor.

“For those communities, this is going to be an incredible opportunity for development, for generations to come, really,” Twin Metals spokeswoman Kathy Graul said.

Twin Metals, which is owned by Chilean mining giant Antofagasta PLC, says it has spent more than $450 million developing the project.

In November, the state agency said it would prepare its own environmental impact statement for Twin Metals, independent of the federal review by the Interior Department’s Bureau of Land Management.

The independent review would be a departure from how the Minnesota Department of Natural Resources (DNR) approached the PolyMet copper and nickel mine. For that project, the DNR partnered with the U.S. Forest Service and U.S. Army Corps of Engineers to oversee the project’s Environmental Impact Statement (EIS).

The state approved the PolyMet project in 2017. State and federal regulators worked for more than 10 years to complete the EIS for that project. The project has since continued to wind its way through court and legal challenges.

Twin Metals’ opponents called on Democratic Gov. Tim Walz to block even the opening of the environmental review process.

Opponents to the Twin Metals and PolyMet mines argue that the minerals are bound up in sulfide minerals that can leach sulfuric acid and other pollutants when exposed to air and water.

But Graul said the company’s design would avoid acid mine drainage by preventing the exposure of sulfide-bearing rock to the elements. The company plans to bury the waste bedrock in old portions of the underground mine, and to remove nearly all sulfides from ore-bearing rock during processing.

About half of the sandy tailings remaining after processing would be returned to the mine and cemented as backfill, she said, while the rest would be compacted above ground into a “dry stack,” a hill that would reach 37 m (120 ft) and get covered with soil and native vegetation. The stack would be impervious to precipitation, she said, and the remaining traces of sulfides would be too low to generate any acid.

The processing plant, connected by 2-km (1.25-mile) long tunnels to the mine itself, would produce copper, nickel-cobalt and palladium-platinum-gold concentrates that would be trucked away in containers and probably shipped via the Duluth harbor to Canada for refining, Graul said.
 

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