The use of fire assay to determine the precious metal content of ore has been traced back to around 2600BC Troy.

The process involves the addition of a chemical flux to an ore sample that is heated to around 1200 degrees Celsius before the gold is recovered via the addition of highly corrosive nitric acid.

Now, it is being sidelined by the much cleaner, safer, CSIRO-developed PhotonAssay^TM.

ASX-listed, Adelaide-based Chrysos Corporation gained the rights in 2016 to commercialise the technology and are initially focusing on gold miners.

Chrysos CEO Dirk Treasure said the company leases the equipment to laboratories and miners for use on-site.

“We’re providing them with this faster, safer, more accurate gold analysis,” he said.

“Analysis for the gold mining industry, or for any mining industry for that matter, is a non-discretionary spend.

“The incumbent technique, fire assay, ends up with a lot of waste. You’ve got hazardous lead waste that comes out of it and it’s a high consumer of energy.

“We have drastically reduced our environmental footprint compared to that technique.”

He said the company’s new mining technology is also more accurate, with the lower detection limit for PhotonAssay^TM is currently twelve parts per billion, equal to 0.012 grams per tonne.

For reference, imagine a box measuring one metre high, wide and deep that is filled with sand from Henley Beach. There are 96 grains of coloured sand in that box, which need to be found. The photon assay can do it.

PhotonAssay^TM can be used at every stage of sample analysis, from drill core to rock chip to process slurry, and is non-destructive.

Treasure said for a small gold mine, a one per cent improvement in gold recovery could add an additional $2 million to a mine’s bottom line, calculated at a gold price of around US$2000 per ounce.

“We’re leasing our equipment to miners and labs for between $2 and $3 million,” he said.

“If they can then get that optimisation, their process plant will improve the recovery and they’re effectively getting the service for free.”

The much faster turnaround is also of value to the mining industry.

By having almost real-time analysis for the process plant – reduced from upwards of six hours for fire assay to just two or three minutes with PhotonAssay^TM – plants can also optimise their reagent consumption and gold recovery rates.

“You have a material that comes in at say five grams per tonne, and then two hours later, another truck has come along and it’s running [at] two grams per tonne,” explained Treasure.

“You would need to know that grade to be able to control your process plant and ensure that you’re recovering all of your gold. So, any volatility in the feed grade would lead to volatility in tailings and that would impact your recovery.”

While the focus for now is on gold miners, PhotonAssay^TM is also being used for copper at Barrick’s Bulyanhulu mine site in Tanzania.

Chrysos has fourteen units deployed globally, with contracts for a further 35 units.

“We’re in the process of expanding our manufacturing capacity at the moment from 12 units per year to 18 units per year [from] the middle of 2023,” said Treasure.

He said the mining industry was ready and hungry for the novel technology.

“If you send the same sample to two different fire assay laboratories, you’re likely to get two different results.

“We’re coming in with this modernised form that is better in every way than that incumbent technique.

“That’s why we’re getting such market uptake around the world.”

Chrysos Corporation debuted at 53 on the South Australian Business Index 2022, garnering the Best New Entrant award, sponsored by HLB Mann Judd.