REE Survival Guide Part 2 – How metallurgical wizardry can make or break a project

Explorers need to decide the direction of their REE deposits early
Astute metallurgy makes a huge difference
ASX juniors making the right decisions

The West is transitioning away from what has long been single-source commodity production and refining out of China for a range of critical minerals – especially a suite of rare earths – and explorers are now popping up with deposits across the world to link into new diversifying supply chains. ASX juniors are chipping away at REE projects around the world, pioneering extraction techniques with metallurgical wizardry to get the best bang for their buck.

It’s our fault. Cheap labour costs and a keen eye for the future led the Chinese government to feed into domestic downstream processing through to manufacturing and exports, starting in the 1980s during what’s known as its ‘economic miracle’, an era of cheap-to-consumer products proffered around the globe.

Fast-forward a few decades and China’s monopoly on the production and refinement of REEs has made projects outside the Middle Kingdom difficult to get off the ground, as oversupply has generally kept prices down.

That is, until now.

Rocketing demand from a burgeoning EV market, the wind power industry and other advanced tech uses are now changing the landscape long term, and in this Part 2 of our REE Survival Guide, we look at the fundamental uses for rare earths and how to know if you’ve got a good resource on your hands.

Rare earths rundown

REEs are part of the lanthanide series of elements and are comprised of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

On top of this is yttrium (Y) and scandium (Sc) – both commonly found in HREE deposits. Here’s a few terms to get your head around:

HREE/HREO – heavy rare earth elements/oxides
LREO – light rare earths/oxides
MREO – valuable magnetic rare earth oxides – Nd, Pr, Dy, Tb, Eu and Y
TREO – total rare earth oxides

Particularly marketable REEs that most explorers are looking to prove up are the HREO and MREO types and come as a percentage of the TREO found in deposits – and while they’re all quite similar, each tends to have a couple of uniquely specific uses.

Neodymium is a key component in high-strength permanent magnets for hard drives, mobile devices and other electronics and high-technology applications.
Praseodymium is also used in high-intensity magnets and is an alloy agent for high-strength metals for EVs, generators and wind turbines, as well as glass and lighting.
Dysprosium is excellent at absorbing neutrons and are perfect for control rods in nuclear reactors to stop fission reactions getting out of control. They’re also used in magnets, fridges, infrared systems and storage devices.
Terbium is crucial for EVs, solid-state devices, low-energy lightbulbs and the photo-medical industry.

Metallurgy makes the difference

High concentrates of MREOs are often processed in pairs, such as NdPr or DyTb – these four are what miners look to primarily produce – with the rest of them predominantly classed as value-adding by-products.

HREO content (which contains the magnetic rare earths) is traditionally (and still to this day) split in the processing phase, and explorers need to decide if they can target them at scale to attract partners that will help drive development and get the commodities downstream through the supply chain.

Thus, many explorers are becoming much smarter earlier on in the way they navigate projects – and that’s often down to using innovative metallurgical practices.

Did you miss Part 1 of our REE Survival Guide? – Rare earths explorers are getting smarter – here’s what to look for

For instance, proving up its North Stanmore deposit in WA’s Mid West, Victory Metals (ASX:VTM) has found high concentrations of dyprosium and terbium, confirming ‘exceptional’ ratios of 7.75% DyTb with a combined value 900% higher than the most valuable light rare earths, while extending the exploration target zone by ~51km2.

With a whopping 250Mt resource for 130,000t of contained TREO, HREO makes up 33% of the total resource and also contains high-value NdPr.

VTM has discovered using a simple physical screen carried out by Core Resources delivering an average increase in the TREO grade by 63% to 1,526ppm across all samples, with increases of up to 187% noted.

The explorer says this low-cost technique demonstrated that 50% of the clay material can be rejected prior to processing, with the remaining 50% clay material hosting 70% of the REE mineralisation – an upgrade that’s expected to deliver substantial opex savings.

“These results not only exceed expectations but also underscore the exceptional potential of North Stanmore,” VTM chief exec Brendan Clark says.

“They demonstrate the important role of basic geochemical research and metallurgical test work to improve our understanding the influence of oxidation on rare earth element systematics in ionic clay-regolith rare earth systems.”

Characteristics to look out for in clay-hosted REE deposit include the:

Ionic proportion – Simple leach testing can determine the ionic component of REE mineralisation.
Acid leach proportion – additional acid leach and pH analysis can potentially increase the levels of extraction, but at added costs.
Refractory proportion – the more refractory materials as such those come in monazite and apatite minerals, the less likely the deposit it will be ionic.

OD6 Metals (ASX:OD6) is taking its own approach to its clay-hosted Splinter Rock and Grass Patch REE projects near Esperance and is collaborating, as others are, with the Australian Nuclear Science and Technology Organisation (ANSTO) and CSIRO on techniques to improve exploration and extraction.

The company is doing its due diligence to make sure its clay projects have the right characteristics and recovery potential, as it’s a relatively fresh exploration and development space as supply chains transition away from a reliance on Chinese production.

Knowing your clay

OD6 MD Brett Hazelden says that from a metallurgical point of view, there’s a base understanding of what does and doesn’t work when it comes to ionic absorption clay-hosted REE deposits (IAC).

“I think what investors are struggling to figure out is that with the nature of clay deposits, there’s an ionic proportion, an acid soak portion and a refractory portion,” Hazelden says.

“And when reporting the assay results, some don’t explain the difference at all. Some might report really good grades, but the reality is it could be all monazite and apatite and that means it’s refractory – and clay with all that refractory material means it won’t be ionic.”

Recent sample results from metallurgical work at OD6’s Splinter Rock averaged 62% MREO for all rare earth oxides inclusive of high grades of both NdPr and DyTb sets of REEs – indicating the resource base is not just reliant on high grades of just one type.

At Grass Patch, 11 samples returned average MREO recoveries of a whopping 69% using hydrochloric acid concentrations during metallurgical testing.

This will also enable the prioritisation of the best clay basins for economic studies.

“Whilst our focus over the last 12 months has been firmly on our world-class Splinter Rock project, we have continued to leverage that work and apply it at Grass Patch,” Hazelden says.

“It is pleasing to report that all 11 metallurgical samples sent to ANSTO have surprised us on the upside of our expected metallurgical leach recoveries, with each of the 15 rare earth elements also being broadly equally recovered which is one of our key tests for clay projects to be potentially successful.”

Stay tuned for a big Part 3.

At Stockhead, we tell it like it is. While Victory Metals and OD6 Metals are Stockhead advertisers, they did not sponsor this article.