June 25, 2019

A return to Ontonagon County’s copper roots

Photos Department of Natural Resources A stamp sand reef among the drifting sands that is causing an environmental threat to the Buffalo Reef area, that will be part of a project of the P.M. Power Group to extract the remaining copper from the tailings, while rendering the residual safe for other uses.

WHITE PINE — P.M. Power Group (PMPG), owner of White Pine Copper Refinery in Ontonagon County, announced last week that it has been working for some time on developing a lab scale project to extract copper from the stamp sands causing problems on Keweenaw County’s Buffalo Reef, near Gay.

Currently working under a Michigan Rural Development Fund Grant, PMPG, along with Subterra, Greensands, and Michigan Technological University, is in the process of taking the lab scale project to a full pilot project to process full size copper cathode from the stamp sands during the summer months.

A cathode is produced when pure copper is separated from unwrought copper in an electrolytic refining process. They are typically 99.9% in purity and may be used as melting stock for mills or foundries. They may also be cast into wire rod, billets, cakes or ingots, generally, as pure copper or alloyed with other metals. The main application of cathodes is as raw material for the production of electrolytic copper rods, copper shields, and in the composition of a series of alloys.

According to the Michigan Department of Natural Resources, Buffalo Reef is a 2,200-acre natural cobble feature beneath the waters of Lake Superior, located off the eastern edge of the Keweenaw Peninsula. The reef is vitally important for lake trout and lake whitefish spawning. Nearly a quarter of the annual lake trout yield from Lake Superior’s Michigan waters comes from within 50 miles of Buffalo Reef.

In September of last year, the Army Corps of Engineers, Detroit District, announced a $2,779,257 contract award for dredging of the stamp sands. Peterson Companies of Minocqua, Wisconsin received the award to dredge roughly 27,500 cubic yards of stamp sand from in and around the Grand Traverse Harbor, and an additional 80,000 cubic yards of the mill tailings from the ancient riverbed area north of Buffalo Reef, known as “the trough,” in order to delay further sedimentation by the drifting of the stamp sands in the reef. Dredging is expected to be completed during this summer.

The goal of the PM Recovery System pilot project is to determine the economics of cleaning the copper from the sands and placing it in an environmentally sound state to ensure it will never reach Lake Superior of impact the ecosystem again.

“We are also evaluating the residual sands for vegetation and beneficial reuse once the copper is safely removed from the sand,” PMPG stated in a release. “PMPG is of the opinion that the long-term benefit to the region and cleanup of the stamp sands in the Keweenaw is to maximize beneficial reuse of the stamp sands by recovering the copper, utilizing as much of the stamp sands in reuse, whether it be road fill, sand blasting, or other beneficial reuse that can be coordinated on White Pine’s plant site, then permanently store the remaining residual in an appropriate storage site.”