I had a question about your recent Premium Nickel comments. The topic is the prospect of only a 62% recovery of nickel in the ore. Assuming the downhole EM’s do in fact turn out decent tonnage, is the 62% recovery a deal killer? Also: any thoughts on how to assess the probability that they can meaningfully improve that number?

Reader CL

62% recovery is not ideal, to be sure. Is it a deal breaker? No. If the EM plates indeed represent massive sulphide deposits of good grade, then the scale of what’s at hand could handle 62% recovery.

But improvements would be lovely, of course.

The standard flowsheet they tested generated two tailings streams – one high volume/low sulphur and one low volume/high sulphur – and two concentrates (copper and nickel-cobalt). Copper recoveries are great. Nickel is only 62%. To improve that they’re testing different grind sizes. They are also seeing if there’s a way to second-process the low volume/high sulphur tailings, as that’s where the unrecovered nickel ends up. For example, would some kind of hydrometallurgical process liberate more nickel from the tailings?

It’s good it’s the low-volume tailings that would potentially need another round of work. Lower volume is less capital and operating expense.

Odds of success? I think it’s likely they will find a way to pull a good chunk (perhaps half?) of the remnant nickel from the tailings. The question will then be the cost and complexity of adding that step to the process plant. Since it’s hydromet (basic chemistry) of low volumes and not high-pressure chemistry of high volumes, costs are not likely going to be dramatic.

This is 20,000-foot arm waving at this point, based on general principles. Until PNRL says more about the met processes they’re testing, I can’t really say more!

But I do think (1) the targets here are big enough, and the precedents suggest they could be rich enough, to very much make 62% recovery work, even if higher recoveries would be better and (2) there is a good chance PNRL will find an economic way to improve from 62%.

Courtesy of Resource Maven