By Jack Parker*
BALTIC -- In February 2006, Kennecott submitted their application for a mining permit. We will not discuss it here because it should have been rejected as incomplete, but it was not rejected. They still do not have a suitable permitted haul road.
We will not discuss that either. They intend to get one, one way or another. Too many dollars are at stake to let the Eagle fall by the wayside. Let’s say $4.7 billion for a start.
But is a new haul road from the mine to the mill at Humboldt necessary?
THE FACTS, AS PRESENTED TO US. We don’t have to believe them but that’s all we have. There is good reason to believe, for example, that the tonnage, the values and the duration of the mining on and around the Yellow Dog Plains are not just the 4,050,000 tonnes of high-grade ore worth around $4,700,000,000 at Eagle West, to be mined out in six years. There’s more.
We are told that only the high-grade massive sulfides and semi-massive sulfides will be extracted, as follows:
1,477,000 tonnes of "Massive," more than 80 percent sulfides.
2,573,000 tonnes of "Semi-massive," 30 to 80 percent sulfides, average around 55 percent.
Weighted average would be 4,050,000 tonnes of 64 percent sulfides, i.e, 2/3 valuable minerals.
The predominant sulfide is pyrrhotite, a weakly-magnetic iron sulfide. Copper and most of the precious metals come with the chalcopyrite, a copper/iron sulfide. Nickel comes in pentlandite, a nickel/iron sulfide.
Roughly $1,700,000,000 worth of lower-grade ore will be abandoned. It runs less than 30 percent sulfides and average value is around $200/tonne.
The rate of mining will be around 2,000 tonnes per day, to be hauled to the mill at Humboldt for conventional crushing, grinding and flotation, with tailings being pumped into the existing lake.
According to the application for permits for milling, tests showed that recovery of copper would be 75 to 97 percent and recovery of nickel would be 60 to 90 percent. Those are wide ranges, since even 90 percent recovery is not high by industry standards. But nobody objected.
They seem to have missed the point that this is direct-shipping ore, ready to be refined, either by fire or by water. The copper, nickel and precious metals alone are worth more than $1,000/tonne, and the remainder -- mostly sulfur and iron -- are now recoverable and marketable too. So why crush and grind and float them before shipping?
There exists no good drilling and blasting plan; but the industry has the expertise to produce blocky ore, to minimize dust losses.
If there is some dilution by wall rocks it might be worthwhile to hand-pick the ore on a conveyor belt.
If there is a significant portion of fines they could be concentrated by taking advantage of the greater density of the sulfides -- using tables, spirals, cyclones or heavy-media treatment, and perhaps magnetism -- so avoiding the witches' brew of chemicals in the flotation process.
Two crowd-pleasing advantages would be that there would be fewer tailings by far to dispose of -- and that the somewhat undesirable refining processes would take place elsewhere.
Development rock, coming from access tunnels in wasterock, would go into empty stopes.
The ore would be trucked eastward to the railhead for shipment, to Sudbury perhaps, or stockpiled for boatloads to be shipped to the Far East. (Iron ore worth less than $200/tonne is currently shipped to the Far East for around $20/tonne.)
After the mining activity is completed any haul roads should be returned to logging-road status, not freeways.
* Keweenaw Now guest writer Jack Parker is a Mining Engineer. Emphasis in bold is Parker's.
Editor's Note: Opinions expressed by our guest writers are not necessarily the views of Keweenaw Now.