HOYT LAKES, Minn. – PolyMet’s plan to construct an enormous earthen dam to hold back mining waste from its proposed copper mine in northern Minnesota may soon clear the first of many regulatory hurdles.
The road to approve the PolyMet mine has been a long and hard one, as state and federal regulations hold up a project expected to cost over $500 million to construct, and which will employ about 300 Minnesotans once constructed.
The PolyMet mine would be the state’s first-ever copper-nickel mining operation. Now Minnesota’s Department of Natural Resources (DNR) so far seems satisfied with its plans for dams needed for the waste management aspect of the mine, as two permits for the dams have been opened up for public review, reports the Pioneer Press. The DNR will take comments from the public through Oct. 16, and make a final decision on the permits afterwards.
These two permits are just the first of more than 20 across the state and federal levels that PolyMet must get before opening the mine.
The dam would be several miles long and reach 252 feet in height when finished, reports the Pioneer Press. It will hold millions of gallons of water mixed in a slurry with the finely ground rock that results from the mining process of crushing material to extract copper, nickel, and other valuable metals.
Much of that fine ground rock is expected to settle into the bottom of the basin, necessitating a rising of the dam walls in 20 foot increments over the course of the mine’s expected 20-year lifespan, reports the Pioneer Press.
The other DNR draft permit covers PolyMet’s hydrometallurgical residue facility. This facility would handle residue generated from use of intense pressure and temperature reactions in an attempt to extract additional precious metals aside from what can be extracted via more standard extraction techniques, reports the Pioneer Press.