Alaska’s Red Dog zinc mine has purchased two M3000, 1.5 MW IsaMills.
Red Dog produces over 1.0 Mt/y of zinc concentrate and 0.23 Mt/y of lead concentrate, and the new IsaMills will improve grinding capacity and zinc recovery.
The mine’s circuit currently uses up to 10 vertical tower mills for regrinding intermediate flotation streams, but the new IsaMills will allow for seven of these tower mills to be shut down.
The mills will regrind intermediate flotation streams, one to a product size of 13 microns, and the other to 25 microns.
“While we expect some flotation benefits from inert media, energy efficiency was the prime consideration,” Red Dog Chief Metallurgist, Brigitte Lacouture, said.
“The remote arctic location means that all of our power is diesel generated, and the diesel can only be shipped in during the brief arctic summer.”
According to IsaMill Technology Manager Greg Anderson, the reason IsaMills achieve high energy efficiency is because they use fine ceramic grinding media.
“In practice, operating ball mills and tower mills are limited to about 12 mm ball size, whereas the IsaMills are designed to efficiently use 2 mm or 3.5 mm media,” he said.
This is especially important for grind sizes below 70 microns, such as Red Dog’s.