Outstanding Rare Earth Purity in Larger-scale Tests

We previously announced that ANSTO tests on 300 g sub-samples from a 100 kg bulk sample from our Deep Leads deposit showed very high extractions (above 60%) for dysprosium and terbium, the two most crucial heavy rare earth elements. This level of extraction is very unusual under the benign conditions used, which is ambient temperatures and pressures with minimal acid for a short time.

We’re now reporting that ANSTO has performed impurity removal tests from rare earth enriched leach solutions produced from fresh sub-samples of the 100 kg bulk sample. A ‘sweet spot’ was identified at about pH 6 where the key impurity, aluminium, was fully removed and over 98% of the rare earths were retained. This outstanding result is because there was clear separation between the pHs at which the aluminium and rare earths precipitated. Many, perhaps most, clay-hosted rare earth deposits do not exhibit this degree of separation, meaning that more rare earths are lost during impurity removal.

The combination of high extractions during leaching and high rare earth retention during impurity removal means that a high proportion of rare earths in the resource should report to the MREC product, indicating very favourable process economics.

ANSTO will now finalise the process conditions for impurity removal, before producing an MREC sample.

The overall program is on schedule, with ANSTO’s production of a MREC product sample expected in Q4 2025. Results and samples will be provided to prospective customers, who are keenly anticipating these outcomes.

Crucially, the ABx Deep Leads deposit is the only clay-hosted rare earth resource in Australia with high proportions of dysprosium and terbium that can be extracted at ambient temperatures and pressures with minimal acid in a short time.