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Finding the next Kambalda, home of Australia’s sulfide nickel mining industry, will be a lot harder than the original discovery, but to aid the process a new indicator mineral exploration technique is emerging from CSIRO research. TIM TREADGOLD reports

Fieldwork in Serpentine Bay. CSIRO geologists Siyu Hu and Steve Barnes

Back in the 1960s nickel at Kambalda was discovered the old-fashioned way with nickel-rich surface rock samples (gossans) providing the encouragement for a drilling campaign which returned a world class 8.3% nickel over a 2.75 metre intersection in the first hole.

Within 12-months of the discovery, shaft sinking had started and the Kambalda nickel industry was born, and continues to operate – though the era of kicking a surface rock and finding a nickel-rich gossan is almost certainly over.

Clues from the diamond hunters

New ways of discovering nickel, especially in its most keenly sought-after form as a sulfide, are needed with an indicator mineral technique similar to that used in the hunt for diamonds showing considerable potential.

Diamond explorers were among the first to notice that near-surface indicator minerals, such as garnet, chromite and ilmenite, could lead them to their deeper target, while nickel explorers wanting to "see" beneath the surface mainly used geophysical tools such as electromagnetic surveys followed immediately by drilling.

That could change as three years of laboratory research starts to move into the field following a call for mining industry engagement in a collaborative project focused on case studies.

Dr Louise Schoneveld, a CSIRO research scientist specialising in ore deposit petrology, said the laboratory work had been refined to a point where it was ready to be more broadly tested.

"The aim is to develop practical and useful tools based on indicator minerals to help discover magmatic nickel systems," Dr Schoneveld said.

Those systems, such as the komatiite structures around Kambalda, are the remnants of highly liquid lava flows and are one of the best sources of the sulphur rich nickel preferred by companies making batteries for electric vehicles (EVs).

Searching for indicator minerals to uncover nickel

X-ray Fluorescence (XRF) image of indicator minerals, taken on the CSIRO Maia mapper

Nickel, which is currently used mainly in the production of stainless steel, can be obtained from other sources, but it is sulfide nickel which has emerged as a key ingredient in the chemistry of long-life, rechargeable EV batteries.

Measures of the importance of sulfide nickel can be found in comments from Elon Musk, founder of electric vehicle maker Tesla, and revitalised interest in nickel at Australia's biggest resources company, BHP.

"A shortage of nickel is our biggest concern," Musk said earlier this year when talking about Tesla’s expansion plans, a comment which sits perfectly alongside BHP's vision for nickel as one of its preferred "future facing" commodities.

Looking for sulfide nickel deposit

The challenge for explorers is that sulfide nickel deposits, often found in magmatic nickel systems (cooled volcanic lava), are not as common as other sources of nickel, such as material found in near-surface, low sulphur, laterite and saprolite deposits.

Converting the nickel found in low sulphur orebodies into a product suitable for use in batteries is technically challenging and while there are reports of a new process being developed in China and Indonesia the preference of battery makers is likely to remain with nickel from the high sulphur magmatic orebodies mined in Australia and Canada.

Dr Schoneveld said the work of her team was based on analysing chemical signatures trapped in the crystal structure of certain minerals with those signals potentially pointing to the formation of mineralisation in a particular location and whether it is favourable for intrusion hosted or komatiitic sulfide deposits.

"We have been measuring and observing these signals in the lab over the past few years and now we’re ready to test our work in the field," she said.

Partners required to test nickel indicator approach

"What we need are corporate partners to determine the robustness and practical use of known indicators to see whether they lead to an ore deposit."

Dr Schoneveld said most nickel explorers applied tried and proven techniques which started with coarse geophysics followed by fine geophysics and then straight to drill.

Missing from the tool kit of magmatic nickel sulfide explorers is a geochemical process to complement data collected by geophysical devices such as electromagnetics.

In effect, geochemistry is a missing link which analysis of indicator minerals using recently development technologies can now provide.

Core of dunite. Olivine is one of the possible indicators being tested

The geochemical missing link

"What we're trying to do is fill the gap between geophysics and drilling by looking for and analysing minerals which might indicate a sulfide nickel deposit," she said.

"We're using the indicator mineral theory by looking for chromite, magnetite, pyroxene, olivines and arsenides.

"By looking at the chemical signals from those minerals we've proven in a laboratory setting that the theory works in that we can see the difference between barren and mineralised systems.

"So far, the cases we've look at are all binary, which means identifying that one sample is mineralised while another is not through a comparison of indicator mineral.

"Doing that in a lab is encouraging, but now it's time to undertake more extensive testing in the field."

Dr Schoneveld said that while indicator minerals were first used in diamond exploration advances in technology made it possible to look for signals in magmatic nickel systems.

Applying new analytical technologies

Technologies being applied in the nickel sulfide search include laser ablation, X-ray fluorescence (XRF) and laser inductive breakdown spectroscopy (LIBS).

Dr Louise Schoneveld at the XRF beamline at the Australian Synchrotron to develop tools for use with desktop XRF technologies

Those technologies represent unprecedented analytical advances over the past decade permitting accurate and precise determination of trace element concentrations in mineral phases from heavy minerals resistant to weathering which will enable new pre-screening techniques as well as a reduction in sample volume.

"Testing potential indicator minerals with the new tools will provide a faster and easier flow of information to better target more detailed exploration," Dr Schoneveld said.

Describing herself as a "lab rat" after three years of working on signals emitted by potential nickel sulfides in magmatic structures Dr Schoneveld said it was time to turn them into something of practical value.

A number of nickel explorers have already indicated that they are keen to work with the CSIRO team to get a greater understanding of the technology and how it might be applied to their projects.

But Dr Schoneveld said there was room for additional partners so that a broad-based data set could be developed to demonstrate to the exploration industry that there is a new technology emerging to help with the search for magmatic nickel systems.

For more information, contact Dr Louise Schoneveld (louise.schoneveld@csiro.au), Research Scientist, CSIRO Mineral Resources

A visit to the Black Swan mine, hosted by Poseidon Nickel. (L-R) Graham Leaver (Poseidon Nickel) and CSIRO researchers Jens Klump, Steve Barnes, Siyu Hu, Louise Schoneveld and Helen McFarlane

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