Just read an interesting article on the Kinross Fort Knox mine...

Just read an interesting article on the Kinross Fort Knox mine which recently poured its 8m oz  of gold and is using a heap leach facility to now mine the lower grade gold.

"Heap leaching is an efficient means of recovering gold that involves stacking ore on a lined pad and using a mildly acidic leaching agent to dissolve the gold into a solution that is pumped through a facility for recovery.
Crews at Fort Knox recently finished lining the Barnes Creek Heap Leach Pad, a new facility that will be used to process the ore mined from Gilmore in the coming years.
With the Barnes Creek Heap Leach Pad ready and crews actively mining ore from the Gilmore deposit, the Oct. 9 gold pour seems to be a golden milestone that marks a transition into a new era for Fort Knox, which could be considered a third phase of mining at this Alaska gold mine.
The first Fort Knox era got underway when the mine went into production with about 4 million oz of gold in reserves in 1996. The next phase began in 2009, when Kinross added the Walter Creek Heap Leach Facility to recover gold from lower grade ore at the mine."

Heap leach is also used at Victoria Gold's new Eagle mine too.

Interestingly I was told separately that one of the costs of using a heap leach is that they need to be "flushed out" each year but with a cold climate heap leach you get that naturally in the spring thaw which results in a big cost saving.

Here's the link to the full article https://www.miningnewsnorth.com/sto...rt-knox-passes-8m-oz-gold-milestone/5958.html