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3 August 2021 4 min read

In the mining industry, CSIRO researchers are developing Gamma Activation Analysis (GAA) methods to enable bulk ore sorting on gold mines; and in the security industry, work is taking place to adapt Magnetic Resonance (MR) techniques, originally developed for mineral detection, to identify security-sensitive substances such as explosives and narcotics.

Both these innovative applications of sensing technology demonstrate the significant real-world impacts that can be achieved – human, environmental and economic - when science moves beyond the lab.

Using sensing technology for efficiency in gold mining

Gold is one of Australia's most precious commodities, with annual production of more than $20 billion. But with ore grades declining, there's an appetite within the industry for a rapid analytical technology that can work at scale to improve productivity and reduce costs.

That technology may be Gamma Activation Analysis (GAA).

Box like machine with cables protruding sitting on a packing crate
Coarse gold ore sample in position for linac activation tests

GAA uses high-energy x-rays to bombard ore samples and activate any gold contained within them. A detector then picks up the unique gamma-ray signature from the gold and determines its concentration.

The method was originally used for small-scale assay analysis in laboratories, and has been successfully commercialised by CSIRO spin-off company Chrysos, which was established in 2016 and has since marketed the technology as PhotonAssay.

Leveraging off this expertise, researchers now believe that GAA could also be an effective method for sorting bulk ore. In contrast to particle-based ore sorting, bulk sorting involves the measurement of conveyed material in real time, on site, and at much high quantities: up to 1000 tonne/hr.

According to Dr Peter Coghill, Group Leader for Magnetic Resonance at CSIRO, the technology offers the potential to capture significantly more value in the processing stage.

"Using GAA for bulk ore sorting – directly and rapidly measuring the concentration of gold at ppm levels as it’s coming down the conveyer - represents a major breakthrough for gold processing. It could potentially remove 30-40% of unviable rock from being processed, which equates to a saving of $80-$110 in mill costs for every ounce of gold produced. You’re cutting back on unnecessary time, money, water and energy use, which makes it a very appealing prospect."

The team working on the development of GAA for bulk ore sorting have completed a full-scale static bulk ore sample laboratory trial in China; a trial that was designed to validate the performance of the GAA measurement system, meet the performance hurdles for sorting, and reduce the risks for further investment.

Looking to the future, they are hopeful that CSIRO’s ability to demonstrate proof of concept will attract strong partners who bring manufacturing capabilities and bulk ore sorting capabilities to the table. That combination will provide a clear path to market and a meaningful opportunity to support Australia’s gold mining industry.

"One requirement for GAA sorting to be successfully deployed on a mine is that there must be lower levels of uranium and thorium,” says Dr Coghill. "Western Australia fits the bill from that perspective, and is one area we would certainly be keen to explore the potential for implementation and trial at a mining site."

Using magnetic resonance to boost global security

Hand-held magnetic resonance sensor for rapid high-explosive detection © 

Magnetic Resonance (MR) technology is a form of spectroscopy in which radio waves are used to excite materials, and the resulting signals are analysed to detect or identify the composition of the material.

A similar technique will be familiar to many of us from our experiences in the medical sector, where MRI scans are commonly used to try and achieve the best clinical outcomes.

Over the last fifteen years, CSIRO has developed MR technology for use in the mining industry.

"It can't detect the magnetic resonance signature of every mineral," explains Dr David Miljak, Research Program Director for Sensing and Sorting at CSIRO.

"But copper minerals are especially amenable to the technique, which allows bulk measurement through many metres of rock. When we worked that out back in 2005, it was a very exciting discovery."

Since that initial breakthrough, significant work has taken place to advance the technology within the mining sector: first by taking what was essentially a lab technique out into the field, then by trying to improve the accuracy of the measurements and by analysing ever larger volumes of material.

The MR mineral sensing technology is now commercialised through NextOre: a joint venture established in 2017 between CSIRO, leading advisory firm RFC Ambrian and global engineering company Worley.

More recently, researchers have been examining whether MR may have a role to play in other industries, such as security.

"We have discovered that we can use similar techniques to identify security sensitive substances, such as explosives and narcotics," says Dr Miljak.

"It's a great opportunity to build on the expertise that we have gained through applying the technology in the mining sector. One area we're focusing on is de-mining. Land mines are a huge issue in some parts of the world: they compromise the safety of communities and restrict travel across many areas. MR allows us to detect those mines deep below the surface."

Throughout its history, CSIRO has built a culture around the idea of impact: investing in research and using science to deliver real-world, tangible improvements to the economy, environment and people. In some cases, that means investigating models for the most efficient way to get technology out of the laboratory and into the hands of the people who can use it.

It also means that an application designed with one purpose in mind can sometimes be adapted for another: such as in the case of a technology that was developed for more efficient mineral extraction and is now being developed for saving lives.

"It's been a long path, but it’s very rewarding to know there is going to be a value to this work beyond the environmental and financial," says Dr Miljak. "A humanitarian value. It's really nice to be associated with it."

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