I am surprised that you did not answer that comparison yourself. I do not know FNI well to answer, but they and NOT are on opposite ends of scale as to which should be operating and not.

Just off the cuff:
Part of the answer is in the first lines of the Mining.com page.

"Canadian miner First Nickel (TSX:FNI) announced Monday it is idling its Lockerby nickel and copper mine near Sudbury, Ont., after current supplies of ore are used up, which it is expected to happen in the fall this year.
The Toronto-based company said that while it was planning further development at the mine weak nickel prices and low production levels at Lockerby made them re-think the decision."

Quantity of ore has little to do with profitability, the quality does it.That is a near exhausted mine by lack of ore. I suspect the quality of the ore probably leaves someting to be desired hence low metal prices have a huge impact.

Eagle on the other hand has a rich ore and I do not speak of the nickel in it alone but the copper, platinum and palladium additions. This combination and quantity of it per ton means that most nickel mines of the world would have to close before Noront's would.
The only thing other global producers can have over NOT's mine is labour costs. Canadian labout rates are high no doubt.

Five years ago I was cheering because Eagle's ore should return 5 dollars of profit per dollar spent, before taxes etc. Well now it may be on the rage of 4:1. Nothing to snicker about nor a reason to compare to any one else.
We are in a good position, Ed.