Lundin Mining announced on November 24 that its Eagle mine in Michigan’s Upper Peninsula has achieved commercial production. Lundin Mining defines commercial production as the ability to maintain average production metrics of 75% of designed throughput, 75% nickel recovery, and production of target-grade nickel concentrate (11% to 16%) for a period of 30 days. The project includes the underground Eagle mine 53 km northwest of Marquette, Michigan, and the Humboldt mill 60 km west of Marquette (E&MJ, August 2014, p. 8).
Designed capacity of the Humboldt mill is 2,000 mt/d. Throughput at the mill averaged 1,536 mt/d during October and 1,865 mt/d from November 1-18. Nickel recovery during the November period averaged 85%, slightly more than the designed rate of 83%. Copper recovery averaged 95%, against a designed rate of 96%.
Eagle is a relatively shallow underground mine, with access via a ramp. The mine employs transverse bench-and-fill stoping, using both cemented and uncemented rockfill. Two ventilation shafts are in place, with the downcast shaft also equipped for emergency egress. Ore from the mine is stored in a covered coarse ore stockpile prior to transport to the Humboldt mill site.
Ore is trucked 105 km from the mine to the mill. The ore-haulage route passes through the city of Marquette. Ore shipments to the mill began in early July.
Lundin’s production guidance for the Eagle mine over the first three full years of operation (2015-2017) remains unchanged and is expected to average approximately 23,000 mt/y of nickel and 20,000 mt/y of copper contained in separate concentrates, plus precious metals and cobalt byproduct credits.