OD6’s reports impressive metallurgical recoveries from Splinter Rock

13 May 2024 14:55

OD6 Metals’ (ASX:OD6) Splinter Rock Project near Esperance in WA is consistently achieving high metallurgical recoveries of Magnetic Rare Earth Elements (MagREE), crucially contributing to the Project’s comprehensive Mineral Resource Estimate (MRE).

These MagREE recoveries, encompassing neodymium, praseodymium, dysprosium, and terbium, serve as the cornerstone for any clay-hosted rare earth project.

Test Work

The metallurgical selection process involved gathering 71 samples from diverse clays, locations, and depths, with the aim of enhancing the understanding of metallurgy across different regolith types at Splinter’s two primary prospects.

Criteria for sample selection encompassed factors such as location, Rare Earth Element (REE) grades, colours, chemical compositions, AEM conductivity, proximity to granite, basin position, and inferred geological genesis.

These criteria proved instrumental for OD6, enabling the attainment of an average metallurgical recovery rate of 60% MagREE, with a peak grade reaching 90% MagREE.


Figure 1: Splinter Rock Scrum and Centre metallurgical sample drill hole locations on AEM model clay thickness.

Centre Prospect

The Centre Prospect, boasting the most impressive grade, is a large clay basin situated within an elevated tableland, characterised by multiple feeder channels and Booanya granite to the north.

Divided into three geological locations – Inside Centre, Centre North, and Centre – Inside Centre features a significant feeder channel heading northeast towards the Centre Basin, extracting MagREE at rates ranging between 44% and 76%.

Centre North, described as a large Clay basin to the north and western edge of the main Prospect, showcases MagREE elements ranging between 42% and 90%, with prevalent carbonaceous shale in some areas, believed to be remnants of a historic estuary, resulting in typically lower grades and higher sulphur levels.

However, below the carbonaceous shale, recoveries often witness a significant increase.

Centre, covering most of the main Prospect’s southwestern area, extracts MagREE recoveries ranging between 48% and 68%, while experiencing lower recovery rates on the clay basin consequential of the transition between clay and saprock due to weathering, much like Centre North, where carbonaceous shale is also present.

Prop Prospect

Prop, situated at Splinter Rock’s lowest elevation and encompassed by Booanya granite to the north, is interpreted as a clay-filled paleo-valley with multiple feeder channels.

MagREE recoveries within this Prospect were deemed more feasible, ranging from 41% to 77%, with the highest extractions occurring at the centre of the deposit along a central northwest-southeast channel.

However, lower recoveries were observed at the margin of the clay basin to the west, attributed to the transition between clay and saprock induced by weathering. Additional elements, displaying wide recovery ranges, were also obtained.

Nevertheless, akin to geological features at the Centre Prospect, black carbonaceous shales were present in certain areas of the basin.


Figure 2: Splinter Rock Prop and Flanker metallurgical sample drill hole locations on AEM Model clay thickness.

4-acid digestion method

Recoveries were determined by comparing the assayed solid head and solid residue through 4-acid digestion, the chosen assay method for this round of testing at Splinter Rock by OD6 Metlas.

This method was preferred over the alternative borate fusion digest method due to its better alignment with the company’s MRE and reporting standards for geological drill assays.

It’s important to interpret these test results within the geological context of both OD6’s objectives and the sample extraction locations to identify significant areas of geology and metallurgy effectively.


Graph 1: Centre Prospect REE Recovery by Element (>40% MagREO recovery).

Next steps

OD6 plans to assess and potentially enhance its MRE based on these results, which are anticipated to be disclosed this quarter.

Despite this focus, the company is actively conducting further phase 4 metallurgical leaching and processing optimisation work in collaboration with the Australian Nuclear Science and Technology Organisation (ANSTO) to maintain production efficiency.

Managing Director Brett Hazelden emphasised the significance of Splinter Rock compared to the growing number of Rare Earth plays hosted in Brazil.

“The results continue to show that the Splinter Rock Recoveries are as good as or better than the Brazilian-hosted Rare Earth plays that have gained so much attention over the last 12 months and continue to affirm that we are Australia’s premier clay-hosted rare earth deposit,” he said.

“The Inside Centre recoveries of ~60% when combined with grades of between 1,400 to 2,200ppm TREO, across an extensive 2km by 1km areas, with substantial thicknesses between 20 to 77m, a low stripping ratio, plus low acid consumptions continue to be a standout for the company.

“These metrics align closely with the essential value drivers we believe are crucial for the economic viability of clay-hosted rare earth projects both in Australia and globally.”

Mr. Hazelden expanded on Splinter Rock’s potential by highlighting the importance of its location.

“At the Splinter Rock Project we have no private royalties, do not sit over farming land, are located in a known wind and solar renewable energy corridor, plus we are only a short distance to the major port of Esperance.

“We look forward to these factors being considered as part of our future Mineral Resource Estimate upgrade scheduled for later this quarter.”

OD6’s Australian Security Exchange-listed share price is currently trading at $0.071 (02:30 pm UTC+ 8 hours).

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