SAMPLING , ANALYSIS AND LAB ASSAY
Around 10,000-20,000 samples have now been processed through the PhotonAssay unit at Kirkland Lake ’ s Fosterville mine , with Chrysos ’ Dirk Treasure expecting this number to be closer to 100,000 by the end of 2021
“ When it comes to moisture analysis , typically plant samples would come into the lab , be dried , crushed , pulverised and fire assayed ,” Treasure explained . “ With PhotonAssay , the sample simply comes into the lab as a wet filter cake and is placed into the sample jar that goes directly into the PhotonAssay unit . We never need to dry the sample .
“ Those gold and moisture analysis results could then be back with the process operators in less than an hour .”
Around 10,000-20,000 samples have now been processed at Fosterville , with Treasure expecting this number to be closer to 100,000 by the end of 2021 .
It is the expansion into other complementary elements outside of gold that saw Chrysos seal another significant deal in 2020 .
In November , PhotonAssay was chosen as part of the Capital Ltd ( Capital Drilling ) and MSALABS service expansion program at Barrick Gold ’ s Bulyanhulu gold mine in Tanzania .
When deployed in the June quarter , the PhotonAssay unit being run by MSALABS on site at Bulyanhulu will include gold , silver and copper and moisture analysis , according to Treasure .
The signing of such a contract may be considered a ‘ watershed ’ moment by Chrysos ’ investors , yet the team has been working on a move into other complementary elements for some time .
“ Bringing the technology into other elements was always on the radar since acquiring the technology ,” Treasure said .
“ What we have done during the last four-or-so years is really crystallise the ‘ why ’ surrounding the move into other elements . You really have to find the overlap between what elements are difficult , expensive and laborious to analyse today where PhotonAssay can competitively provide a precise and accurate measurement .”
Treasure says PhotonAssay is extraordinarily competitive with the incumbent technology for gold analysis based on the ‘ price per sample ’ business model Chrysos employs but adding complementary elements around gold will enable the company to expand its market reach .
“ The technology , in itself , might not prove enough to get us on site for just copper , for example , but when you have copper and gold analysis lined up , we become very competitive ,” he explained .
This price per sample model includes more than just the sampling process ; it also covers installation of the unit , commissioning , servicing and maintenance . “ We also guarantee performance and availability all within that model ,” Treasure said .
“ This means the customer doesn ’ t have to fork out any capital expense whatsoever ,” he added . “ What that enables us to do is compare ourselves directly on an operating cost basis with other technologies .”
Such a comparison highlights the speed , accuracy and environmental benefits already mentioned , but Treasure sees even more industry advantages being realised with the increased uptake of PhotonAssay technology . This is where he draws parallels with the arrival of XRF analysers in the base metal flotation plant close to four decades ago .
“ The ability to optimise your flowsheet , eke out a little more recovery , control your reagent consumption a bit better , tweak the throughput in your plant , etc could have significant impacts ,” he said .
“ In the base metals industry , this has been a reality since the late 70s / early 80s . You no longer have a base metals flotation plant operating without an online XRF analyser for this very reason . If you look back at the Outokumpu reports from that time , they were getting a 2-5 % recovery improvement on copper recovery with XRF analysers . We don ’ t think we ’ ll get a 2-5 % improvement in gold recovery with PhotonAssay , but even a tiny amount of improvement – when you are coming in on a like-for-like basis with the incumbent technology – is a huge value add .”
Guaranteed sample turnaround times as small as two-to-three hours , on top of the ability to recalculate resources and reserves more accurately in coarse gold deposits are just some of the ‘ value adds ’ Treasure mentions .
“ It is a matter of understanding what the industry can do with this information and data if they had it more quickly ,” Treasure said .
The most sophisticated PhotonAssay setup to date
is in Kalgoorlie , Western Australia , at MinAnalytical ’ s lab . A three-cell facility has been established , in tandem with Scott Automation , to fully automate the gold sampling process – from gold sample preparation to sample analysis .
The first of these three automated cells is already operating , according to Treasure , and , after some finetuning , the process will be rolled out across the remaining cells leading to a facility with a 100,000 per month automated sample throughput capacity .
Treasure sees automation as a big part of the laboratory and sampling processing industry , yet “ semi-autonomous ” operation currently has the strongest business case across the wider sector , he believes .
“ If you want a fully-automated solution , you need to have the throughput to justify it – a big miner or a big lab ,” he said . “ Meanwhile , you can have a degree of automation that can help simplify and streamline operations ; make it so you can operate with just a couple of operators .”
With Chrysos ’ PhotonAssay technology looking to cater to a range of labs and miners – from those producing 40,000 oz / y of gold to those with more than 500,000 oz capacity – this degree of automation is easy to justify .
As the company expands further , the benefits of this novel process will gain further recognition . This is where an expansion into North America with MSA Laboratories in Quebec , Canada , in the second half of 2021 , will help .
“ From then , this will no longer be an Australian technology story that is only known about on the other side of the world ,” Treasure said .
And he is clear about the company ’ s long-term focus .
He said : “ Our long-term business model is all about getting the equipment onto the mine sites themselves and providing a solution that needs minimal expertise to operate , is simple and transparent from a costing point of view and has enough latent capacity to manage the volatility of a three- or six-month drilling campaign overlapping
with your normal grade control process .”
IM
64 International Mining | FEBRUARY 2021