Is NVA a good bet?, page-27

Thinking a bit about the ore sorting, they wouldn't need to apply it to the whole deposit. They could apply it to the blocks that assay 0.1 g/t to say 0.15 g/t as well as blocks at the margins or perimeter of the pit shell ( blocks that could be marginal and approaching cut-off grade).

So selecting and ore sorting say the bottom 20 to 30% of blocks in the block model by grade. Even a 3x increase in head grade by ore sorting these blocks would increase these blocks to 0.3 g/t to 0.45 g/t. That would remove the amount of rock they need to move down to heap leach pads and also reduces the size of the heap leach pads.

They just need to do enough grade control drilling as part of mine planning to select which blocks of ore will be run through a sorting process.

The alternative approach is to select the highest grade blocks and run these through an ore sorter. Say blocks in the 0.4 g/t to 1.0 g/t range. Running these blocks through an ore sorter could lift the grade to 1.2 g/t to 3.0 g/t (at 3x improvement). Then run these blocks into a traditional grinding circuit and everything else gets gravity-fed to heap leach pads. So perhaps 25% to 30% of the deposit through traditional processing.

I've based my numbers on 3x improvement on a newcrest study.

Now NVA think the ore at Korbel is very amenable to ore sorting and think a 10x improvement in head grade is possible. Even a 5x improvement could dramatically help economics.


NVA have lined up this guy for the ore sorting study. He is now at https://www.abhengineeringinc.com/