OD6 Metals Ltd (ASX:OD6) made important progress on its critical minerals strategy during the June quarter with the highlights being a doubling of the mineral resource estimate (MRE) at the Splinter Rock Rare Earths Project in Western Australia and continuing success with metallurgical tests.
The Splinter Rock MRE now stands at 682 million tonnes at 1,338ppm total rare earth oxides (TREO) in the indicated and inferred resource categories at a 1,000ppm cut-off grade including a high-grade indicated MRE at the Inside Centre deposit of 119 million tonnes at 1,632ppm TREO.
Strong Magnet REO content
This equates to approximately 910,000 tonnes of contained TREO and, importantly, 205,000 tonnes of higher value contained magnet rare earth oxides (MagREO), which represents an average of about 23% of the TREO grade.
Test-work continued to provide encouragement for OD6 Metals with recoveries of up to 90%, of magnet rare earth elements (MagREE) in multiple prospect areas.
This work resulted in average MagREE recovery of approximately 60% at 25g/l hydrochloric acid (HCl), with equivalent recoveries achieved for all MagREOs, including neodymium, praseodymium, dysprosium and terbium. These key magnet REEs attract the highest price and demand, and are likely drivers of the future economics of the project.
The size and grades of the resource and the metallurgical successes have led to the company describing Splinter Rock as “Australia’s premier clay-hosted rare earth deposit”.
“Another excellent quarter”
Managing director Brett Hazelden said: “It has been another excellent quarter of progress at OD6, which culminated in a doubling of our mineral resource estimate at Splinter Rock, in conjunction with continued metallurgical success.
"The Inside Centre Prospect will be the basis of our Phase 4 metallurgical test program being conducted at ANSTO with the aim of producing a mixed rare earth carbonate (MREC), which will form the basis of a scoping study scheduled for completion by the end of the calendar year.”
Splinter Rock comprises 2,579 square kilometres of granted Exploration Licences located about 150 kilometres northeast of Esperance in WA’s south.
The project is located on Unallocated Crown Land and the company has a strong working relationship and agreements with the traditional owners via the Ngadju and the Esperance Tjaltjraak Native Title Aboriginal Corporations.
READ: OD6 Metals higher on doubling rare earths resource estimate at Splinter Rock
Upside potential
Providing optimism for OD6 Metals is that there are substantial areas of identified clay basins with the potential to further expand the MRE through future exploration drilling.
OD6 has identified four main prospect areas from drilling and geophysics that contribute to the MRE:
- Centre - Large clay basin within an elevated tableland. Clays have potentially pooled in this area from Booanya granite to the north. Sub-prospects include Inside Centre and Centre Northwest
- Scrum - Magnetic dipole, with the northern area, located over a magnetic high in Booanya granite grading to a magnetic low in the south.
- Prop - Located at the lowest elevation and is surrounded by Booanya to the north and south and interpreted to be a glacial paleo-valley filled with clay.
- Flanker - Sits on top of a magnetic high on the Booanya granite and most likely to comprise some transported clays but is potentially related to a localised weathered granite profile.
READ: OD6 Metals achieves more high recoveries affirming Splinter Rock as “Australia’s premier clay-hosted rare earth deposit”
Strong recoveries
The metallurgical leaching tests conducted by the Australian Nuclear Science Organisation (ANSTO) achieved excellent metallurgical recoveries of up to 90% of MagREE in multiple prospect areas, across 71 new samples.
While the average MagREE recovered at 25g/l HCl, excluding basin edges and carbonaceous shales, was ~60%, the following MagREE results were obtained from prospects:
- Centre Prospect - 42% to 90% recovery;
- Inside Centre Prospect - 44% to 76% recovery; and
- Prop Prospect - 41% to 77% recovery .
OD6 said that importantly, recoveries for all MagREOs, inclusive of neodymium, praseodymium, dysprosium and terbium, were similar and this was the key to overall project economics for any clay-hosted rare earth project.
Further testing
Further Phase 4 metallurgical leaching and processing optimisation work is underway at ANSTO and this is based on two composite metallurgical samples originating from multiple holes at Inside Centre and Prop.
During the quarter OD6 also reported that simple beneficiation testing by ANSTO had lowered acid consumption at Splinter Rocks, which would also reduce costs. This work found that:
- Removal of coarse material (greater than 75um) improves TREO grades by up to 224% (157% average);
- Metallurgical testing of screened material delivered up to 79% reduction in HCl consumption (35% average reduction) to approximately 10kg HCl/t total screened ore; and
- Opportunity exists for screening size to be further optimised to maximise rare earth recovery while reducing acid consumption.
- Lowering acid consumption improves future potential project economics. A single chlor-alkali electrolyser is indicatively capable of treating more than 5 million tonnes per annum of REE-bearing clay.
Also, during the June quarter, the company was notified of its success in applying for the Western Australian Government’s Exploration Incentive Scheme (EIS) co-funded drilling program.
OD6 has been offered the maximum of $180,000 under the co-funded drilling program with this funding for the Tighthead and Loosehead prospective targets.