OD6 Metals (ASX: OD6) says magnet rare earths recoveries of up to 90 per cent have confirmed its Splinter Rock project near the port of Esperance in Western Australia as the nation’s “premier” clay-hosted deposit.
The company says its latest suite of results thrown up from testwork being conducted by ANSTO (the Australian Nuclear Science and Technology Organisation) compare favourably with others emerging from several leading Brazilian rare earths operations.
Brazilian Critical Minerals has reported an average recovery of 68 per cent total magnet rare earth oxides (MREO), with an average neodymium-praseodymium (NdPr) content of 69 per cent and combined terbium-dysprosium (TbDy) analysis of 48 per cent. Results from Brazil have been regarded as some of the best in the business and OD6 says its findings are “as good as or better than” other notable ASX-listed, South American-based rare earths operations including Viridis Mining & Minerals, Alvo Minerals, Meteoric Resources and Aclara Resources.
The company has today confirmed that its phase three metallurgical leach MREO recoveries on 71 new samples from its Centre and Prop prospects range overall from 41 to 90 per cent and average about 60 per cent. Analyses across the full spectrum of 16 rare earths from three zones at the Centre prospect highlight a remarkable uniformity of response to hydrochloric acid leach at a 25g/litre concentration from sample material.
Magnet rare earths command higher values due to their particular applications in the high-power, high-efficiency magnets used in motors for electric vehicles (EVs) and in a range of turbines used to generate electricity.
At the Centre, Inside Centre and Centre North prospects, the best recoveries are noted for (non-magnet) cerium at about 94 per cent, with NdPr achieving 90 per cent and terbium and dysprosium recovered at 84 per cent and 80 per cent, respectively. Average NdPr and TbDy recoveries sit at about 60 per cent.
Analyses across the full spectrum of rare earths from the company’s Prop prospect showcase a great uniformity of response to the same leaching method.
The best recoveries from Prop are noted for cerium at about 80 per cent, for neodymium and praseodymium at 76 per cent and 78 per cent, respectively and for terbium and dysprosium at 74 per cent and 72 per cent, respectively. Average neodymium and praseodymium results run at about 54 per cent and 56 per cent, respectively and at 55 per cent and 54 per cent for terbium and dysprosium, respectively.
Management says it is important to have similar recoveries for all MREO as that factor is a proven key to the overall project economics for any clay-hosted rare earths project.
The results continue to show that the Splinter Rock Recoveries are as good as or better than the Brazilian clay-hosted rare earth plays that have gained so much attention over the past 12 months and continues to affirm that we are Australia’s premier clay-hosted rare earth deposit. The Inside Centre recoveries of ~60%, when combined with grades of between 1400 to 2200ppm TREO across an extensive 2km-by-1km area, with substantial thicknesses between 20 to 77m, low stripping ratio, plus low acid consumption, continue to be a standout for the company. OD6 Metals managing director Brett Hazelden
The company says the 71 samples were taken from a wide range of clay types, locations and depths to help build its understanding of its two key Centre and Prop potential resource areas, which it plans to incorporate into its upcoming mineral resource estimate that is slated for this quarter.
OD6 and ANSTO have developed a project specific bottle-roll test procedure utilising a hydrochloric acid leach solution at a 25g/litre concentration, with recoveries being calculated based on the difference between the assayed solid head and solid residue using a 4-acid digestion method. A fourth phase of metallurgical leaching testwork and process optimisation studies is in progress with ANSTO.
OD6 will now look at building its results into the evolving resource model and updating the model and various metallurgical bench-scale processing tests to include a range of extraction and filtration methods and small-plant, pilot-scale testing on composite samples.
It will be accompanied by process and economic modelling and assessing a range of possible flow sheet alternatives, which will include examining the processing and economic merits of downstream conversion of mixed rare earths carbonates or hydroxide to a range of rare earth oxides.
It can often be misleading to compare projects on the basis of analytical results alone. For example, OD6 does not have to confront issues such as private royalties or private landholdings at Splinter Rock and it has the advantage of the operation sitting within an already-established renewable energy corridor with abundant wind and solar power – and it is just a stone’s throw from the Esperance port.
Management believes these and other considerations will be important factors when it comes to running out its imminent mineral resource estimate upgrade and ultimately, for any future feasibility studies.
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