Facility nearing operation date
MICHIGAMME TOWNSHIP – Seventy days. That’s about how much time remains until Lundin’s Eagle Mine moves from preparation to operation.
Meanwhile, the company is offering free public tours of the facility throughout the summer.
Even in the preparatory stage, though, the mine looks and sounds active. Haul trucks carry full loads of rock from below ground – none of which yet contain the valuable nickel and copper they’ll bring to the surface once the mine is operational – to the coarse ore storage area building, the largest of a handful of rectangular, beige-sided structures on site.
There, the rock is dumped, then loaded onto highway-ready semi tractor-trailers, which go through a truck wash before departing for the mine’s mill in Humboldt.
Underground, in contrast to the iron-rich red soil found throughout much of the rest of Marquette County, the earth underfoot is gray and soft, mixed with fist-sized chunks of siltstone. The walls and ceilings of tunnels are studded with 8-foot metal bolts injected into the surrounding rock for additional support. And the exposed rock faces are finished with a wire mesh cemented in place with “shotcrete” – a type of sprayable concrete.
The tunnels are as loud and windy as they are dark, with the reverberating sounds of heavy machinery and a steady flow of air from two vertical shafts, enormous in diameter, bored about 500 feet down into the mine; separated by an airlock, one provides 450,000 cubic feet of fresh air per minute into the tunnels while the other acts as the mine’s exhaust. And each double as a secondary means of escape in an emergency.
Should the mine’s main portal become blocked off, the fresh-air shaft features an elevator to the surface and the exhaust shaft is fixed with ladders up to the airlock that leads to the fresh-air side.
Farther down, about 1,000 feet below the surface, one of two multimillion dollar Swedish Sandvik “jumbos” – a giant piece of machinery with long, insect-like hydraulic drill arms on the front – drills four-meter-deep holes in a computer prescribed pattern at the end of one of the mine’s “development laterals.” The holes will be filled with explosives to blast the section into manageable-sized chunks for removal. From these horizontal tunnels, vertical “stopes” will be created once the mine starts to drill into the actual body of ore.
“You do an undercut, you undermine the bottom (of the stope), then you mine the top off so you can get onto the top with these drills, which drill long holes down through the ore,” explained Wil Greuer, a geotechnical mining engineer at Eagle.
“Then it’s charged with explosives and it’s blasted so that whole block is rubblized, and then you just have ‘muckers’ – or scoops – which take it out from the bottom level. And so once you’ve undermined it, it all collapses easily and it comes out and you’re just basically drilling and shooting the ore from the top and then scooping it out from the bottom.”
All the bustle in the mine is to get Eagle ready for the fast approaching date when it will begin mining the 360 million pounds of nickel and 295 million pounds of copper the mining company hopes to remove from the ore body.
Even the rock currently being extracted is put to use. It’s either crushed on-site and mixed with concrete that will be used to fill the emptied stopes, or it’s driven to the Humboldt Mill and put through the equipment there as a means to calibrate, test and troubleshoot the machinery before the mill starts to get truckloads of the sought-after minerals.
Those interested in going on one of the tours can sign up in advance for any of the weekly Friday dates through the middle of October. Participants will be bused out to the mine from the Eagle Mine Information Center on West Washington Street in Marquette.
While the tours are surface only, the four to five hour experience will offer a view and explanation of the mine’s above-ground facilities. The minimum age for the tour is 16 and anyone under 18 must be accompanied by an adult.
About 400 people take part in the tours each year, said Dan Blondeau, senior adviser of communication and media relations at Eagle.
“Actually being able to come up here and see the facilities, (makes the tours) probably the biggest perception-changer” for the public, Blondeau said.
For more information, visit eaglemine.com/minetours.
Zach Jay can be reached at 906-486-4401.