ANSTO Advances Metallurgical Test Work Unlocking Korsnäs Rare Earth Value

• Historical concentrate assays 2.3% TREY including 0.7% magnet rare earths
• Monazite and apatite identified as primary rare earth hosts
• Allanite contributes minimally to magnet rare earths Nd and Pr
• Next phase targets calcite removal and controlled apatite dissolution
• ANSTO’s work refines downstream processing strategy for Korsnäs

ANSTO’s Test Work Clarifies Rare Earth Mineral Hosts

Australian Nuclear Science and Technology Organisation’s minerals division (ANSTO Minerals) has provided a crucial update on metallurgical test work for European Resources Limited’s (ASX:ERE) Korsnäs rare earth project in Finland. The initial assays from historical lanthanide concentrate stockpiles returned a total rare earth oxide (TREY) grade of 2.3 wt%, including 0.7 wt% magnet rare earths, the prized neodymium and praseodymium critical for permanent magnets.

Mineralogical analysis using QEMSCAN revealed monazite as the dominant rare earth host mineral, accounting for 60% to 70% of the rare earth inventory. Apatite also contributes meaningfully, particularly enriched in yttrium and heavier rare earths, while allanite’s role is limited, hosting little of the key magnet rare earths. This mineralogical clarity shifts the processing focus towards monazite-apatite assemblages, which are more amenable to established extraction techniques than allanite-dominant systems.

Optimising Pre-Leach Conditions to Preserve Valuable Rare Earths

ANSTO’s pre-leach tests highlighted a delicate balance: calcite removal is achievable at a pH of 4, but apatite dissolution starts around pH 1. This is critical because yttrium and heavier rare earths, enriched in apatite, risk early loss if leaching conditions are not carefully controlled. The next phase of test work will focus on refining these pre-leach conditions to optimise rare earth recovery, particularly through acid bake processes targeting the refractory monazite-rich fraction.

Managing Director Jason Beckton emphasised the significance of this progress, stating, "ANSTO is delivering real progress. We now have a better-defined framework for the next phase of test work and for moving ahead with a downstream treatment route that can properly unlock the value of the historical concentrate." The company’s approach aligns with its recent efforts to expand and refine the Korsnäs resource, which was more than doubled to 15.4 million tonnes at 1.00% total rare earth oxides in April, supported by drilling and metallurgical advances Korsnäs Rare Earth Resource to 15.4Mt.

Next Steps in Process Flowsheet Development

ANSTO has commenced the next stage of flowsheet development, including multiple acid systems to complete calcite removal and apatite pre-leach testing at pH levels of 1 and 1.5. Direct acid bake tests on untreated concentrate will assess extraction from the monazite-rich fraction. These steps aim to define the preferred downstream process for recovering magnet rare earths efficiently.

This metallurgical work dovetails with ongoing beneficiation test programs at Korsnäs, which recently reported strong flotation results upgrading TREO grades and recoveries under the EU-funded REMHub program Strong Korsnäs Rare Earth Beneficiation Results. Together, these efforts are building a more integrated and technically robust processing pathway for the project.

Technical and Investor Implications

Consulting metallurgist Dr Mark Steemson highlighted the importance of managing apatite dissolution to avoid losing yttrium and heavier rare earths, which could materially impact overall recovery. The identification of monazite as the main host mineral simplifies downstream processing prospects, as industry experience with monazite extraction is more established.

While the results are preliminary and based on laboratory-scale testing, they provide a critical technical foundation for European Resources to advance its rare earth extraction strategy. The company’s clear articulation of next steps and the involvement of a respected institution like ANSTO enhance confidence in the project’s metallurgical pathway.

Bottom Line?

ANSTO’s refined mineralogical insights and targeted test work mark a pivotal step in unlocking Korsnäs’ rare earth value, but the challenge remains to optimise recovery without sacrificing key heavy rare earths.

Questions in the middle?

• How will ANSTO’s next phase of acid bake testing impact overall rare earth recovery rates?
• What are the potential processing cost implications of managing apatite dissolution carefully?
• Can the integration of beneficiation and downstream hydrometallurgical flowsheets deliver a commercially viable extraction route?