RE: Confidence6 Jun 2023 16:10
For context on the RNS, here is a Telegram post from Donald Pond, the representative from PXC:
"There has been a little comment about the lack of detail in today’s RNS, so after speaking to one of the directors I thought I would add a few comments.
The RNS mentioned “robust” metal recoveries similar to those we achieved at bench level. The reason why we haven’t given percentages is simple: that would need a Qualified Person to sign off, and Zach Black, our QP, is currently on a family holiday.
So when the results came back from the lab, we had a choice of either issuing an RNS so that we could talk about ATS at the AGM, or disturbing Zach and getting him to cross check everything and sign off, which would both take a big chunk out of his holiday and delay the RNS. The whole point of being a QP is that you don’t simply rubber stamp stuff but do your own verification, so that wasn’t an option.
So what does “robust” mean? In June 2020 we mentioned using ATS on gold and silver. That RNS said
“Precious metals tests performed on samples from the Empire open pit deposit using non-toxic ammonium thiosulfate ("ATS") reagent resulted in high gold recoveries of 97.8% and 97.7%, and silver recoveries of 69.8% and 78.2%, respectively”
That provides a benchmark for what is meant by “robust” in this context. I think we have previously mentioned recoveries above 90% in a corporate presentation too, and linked them to the word “robust”, but I can’t lay my hands on that right now.
As far as copper is concerned, using a heap leach generally gives around 70% recovery. It is the law of diminishing returns, in that the longer you leach, the lower the recovery rates become.
Recovery from ATS is almost certainly going to be better than that, as we are operating in a closed system. It may be that there ends up being a small drop off in one metal to increase production of another, but the company is confident that when Zach is back and we are able to give details on the actual recovery rates, everyone will be very happy.
The upshot is, producing 3 metals from day 1, and getting recovery rates in those sort of regions, will be financially much better than the original approach in every way."