Twin Metals proposes alternative tailings system
4 Aug 2019
Twin Metals Minnesota has announced plans to use the dry stack method to store leftover rock from its proposed underground copper-nickel mine nine miles southeast of Ely.
The dry stack method eliminates the storage pond and dam associated with conventional tailings facilities, the nonferrous mining company said Thursday. It has been successfully used in four mines in the northern United States and Canada having similar climates and has been permitted at two mines in the western United States, Twin Metals said.
The process, Twin Metals explained, involves removing target minerals and then compressing the remaining tailings into low-moisture, sand-like deposits that are stored on a lined ground facility near the plant site. Reclamation of the tailing site can occur in stages and can be capped or covered with natural vegetation.