Chrysos’ PhotonAssay analysis machine uses high-powered x-ray machines to atom count, or in layman’s terms to give a rapid, accurate, non-destructive and fully automated analysis of ore grades that is up to three times more accurate than conventional methods.
Samples are hit with high-energy X-rays produced by an electron accelerator that causes short-lived excitation of atomic nuclei of targeted elements. They emit a characteristic signature that can be detected and used to calculate metal grade.
During the process samples are sealed inside tamper-proof plastic jars and placed on a conveyor belt inside the machine.
Trial testing in Canada last year showed the machine could estimate the measurements of samples down to 30 parts per billion. While the level of precision depends on the amount of gold in each sample for the high-grade samples accuracy was within around 1%.
According to Chrysos chief technology officer and PhotonAssay founder James Tickner the process has the potential to boost assaying efficiency and also limit the environmental impact of mineral processing by negating the need for toxic chemicals such cyanide and sulphuric acid or heavy metals such as mercury or lead.
He said the company was setting up its first production unit in WA in partnership with Ausdrill and MinAnalytical, and has plans to build a smaller on-site model to be available next year to better support in-field exploration campaigns and exporting its technology.
Tickner believes the challenge for the industry at the moment is that the current methods for analysing gold ore are not fast enough and require too much work, and PhotonAssay will address those mineral processing inefficiencies.
He said the process itself was not new but PhotonAssay had developed it further to be more accurate and broadened it application so it also had the potential to assess silver, barium, hafnium, yttrium and selenium.
By adjusting operating conditions different ranges of elements can also be measured, such as copper, lead and zinc in complex polymetallic ores.
Ausdrill chief operating officer of Australian operations Andrew Broad said the destructive nature of contemporary assaying procedures such as fire assays and the obvious speed benefits of Chrysos’ machine led the company into its partnership.
He said fire assays were quite laborious and took between 24-48 hours to provide results, and it was often quite difficult to get skilled labour in that field anyway.
With PhotonAssay the waiting time is reduced to just minutes and further tests can be run on a sample at a later date.
Broad said Ausdrill would set up its first unit in Kalgoorlie by December, and then hopefully export the technology to other projects in Africa.
