Australian gold explorers have been given the world-first option to access X-ray technology to detect and analyse unseen gold, cutting turnaround times significantly.
The photon assay technology was developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) over a period of 15 years, and was spun off into a public company called Chrysos, which is Greek for ‘gold’, in 2016.
The company’s investors include the CSIRO, investment adviser RCF Ambrian and a network of experienced mining executives.
During the photon assay procedure, a sample is put into a plastic screw-top jar weighing about half a kilogram. The jar is then placed on a conveyor belt inside Chrysos’ analysis machine and subjected to powerful X-rays to excite gold atoms in the sample.
The gold atoms give off a unique atomic signature, which is then identified by a highly sensitive detector that determines the concentrations of the gold atoms.
Although the basic principles of this method of analysis have been known for decades, the complex nature of the technology has meant that the technique has found only limited commercial application to date, the CSIRO says.
“In an industry facing declining ore grades, rapid analytical technology has the potential to unlock substantial productivity gains in gold mining and production and open up a significant new market for real-time analysis services in on-site applications,” says the CSIRO’s lead inventor of the technology and Chrysos chief technology officer, Dr James Tickner.
“We have focused on improving the accuracy, sensitivity and simplicity of the technology to make it useful for low-grade Australian operations,” Tickner said.
The technology is able to decrease the time it takes to analyse a drilling sample through traditional fire assaying of up to 48 hours to less than ten minutes. This means that mining companies have the opportunity to monitor their operations in real time and to identify possible issues as they arise.
In addition, the Chrysos technology is also safer and more environment friendly, as it is unlike the fire assay technique, which requires the complete destruction of the samples, produces lead-contaminated waste and has health and safety risks for fire assay technicians.
“Fire assay is laborious, dirty and environmentally unfriendly, and it is a very, very old technique,” Chrysos CEO Dirk Treasure tells Mining Weekly, noting that the Chrysos alternative offers a faster turnaround time at comparable prices, if not cheaper.
Further, the Chrysos technology is extremely sensitive and has two- to three-times improved accuracy on fire assays, and requires minimal sample preparation and no toxic or caustic reagents are required.
Since the sample is not destroyed, a further benefit of the Chrysos technology is that the sample could be tested repeatedly, if required.
In May, Australian mining services company Ausdrill announced the installation of a Chrysos photon assay machine at its facility in Perth, with the capacity to analyse up to 50 000 samples a month.
Australia is the world’s second-largest gold producer, and its miners of the yellow metal will benefit from the opportunity to capture more value from mined resources, as well as increased operational efficiencies, revenue and productivity.
“For Australian mining companies, this technology delivers . . . a fast turnaround, which has never been available to the market before, and does so with less sample preparation and in a nondestructive fashion,” says Ausdrill’s COO for Australia, Andrew Broad.
“This opens up a whole range of possibilities for our clients to review their processes to take advantage of the accessibility to results, which ultimately will deliver cost savings to their business.”
An estimated $1-billion is spent each year by global gold producers on fire assay services, giving Chrysos a serious incentive to break into the market.
Treasure notes that the company has rapid growth plans in place.
“With the first system now up and running at Ausdrill, we have successfully progressed the photon assay technology from concept to a deployed product in just 16 months,” Treasure says.
A further two units will be rolled out by Ausdrill, with the first unit to be operational at the company’s Kalgoorlie premises from January next year. The units will have capacity to analyse about 70 samples an hour, and about 650 000 a year.
Chrysos is also working on applying the technology to a range of other minerals, including silver and copper.
Treasure says the technology will likely be calibrated to detect silver by-products in gold samples within the next few months, with copper by-product calibrations likely to be completed by year-end.
However, Treasure says further development of the technology to detect other minerals will be driven by market demand.
“Largely, our market in the near future will be around gold. But, once we deploy units into companies that are using copper analysis techniques, we could start [seeing] more interest in the base metals space.”
In the longer term, Chrysos also plans to infiltrate the international market. Treasure says the international focus will initially be on Africa and North America, and on the gold projects in the two regions.
Australia’s Golden Goose
Australia’s yearly gold production is valued at about A$15-billion in a global market worth over A$150-billion, with the country currently ranked the second-largest producer, after China.
Australia’s economic gold resources are estimated at nearly 10 000 t, while its total Joint Ore Reserves Committee- (Jorc-) compliant resources are estimated at nearly 15 000 t. It is believed the country hosts the world’s largest percentage of gold resources, accounting for 18% of the global gold total.
In 2016, total Jorc-compliant gold ore reserves totalled 3 826 t, 27% of which was attributable to 130 operating mines, which produced 288 t of gold that year.
Exploration for gold is undertaken in every state and territory in Australia, with Western Australia and the Northern Territory accounting for 75% of the exploration activity. In 2012, Minerals Council of Australia (MCA) estimated that there were more than 2 000 active gold exploration projects in the country.
Despite Australia’s abundant gold endowment, deposits have become harder to find and delineate, with the number of significant discoveries declining each year. The deposits that are discovered also tend to be at greater depths or of lower grade, MCA says, which means that the capital investment required to bring these assets into production is greater.
The difficulty in discovering new gold projects, along with complex regulatory processes, has increased the cost of gold exploration in Australia, while also increasing the time required to bring projects into production.
During the 2016/17 financial year, Australian miners spent A$689.2-million on gold exploration, out of a total exploration spend of A$1.55-billion, Geosciences Australia reports. This represented an increase from the A$617.5-million spent in 2016 and the A$141.7-million spent in 2015.
Much of the exploration expenditure for gold has been targeted at existing deposits, rather than greenfield exploration.