Eagle Mine ore is transported by haul trucks to Humboldt Mill, located in Humboldt Township, Marquette County, for processing.
The Humboldt Mill facility was originally constructed in 1954 to concentrate low grade iron ore from the Humboldt Mine. The Humboldt Mine was developed in two stages over its life, beginning with underground ore removal, followed by open pit extraction. In the early 1980’s, the mill was converted to gold ore processing and operated until 1989 when the Ropes Mine, located about 10 miles from the mill, was closed. After reconstruction of the mill, Eagle Mine began crushing and processing ore to nickel and copper concentrates. As during the processing of Ropes ore, residual tailings are placed for permanent subaqueous disposal in the Humboldt Tailings Disposal Facility (the previously mined pit area).