American Rare Earths Ltd (ASX:ARR, OTCQB:ARRNF) has taken another step towards developing what it aims to be the United States’ next producing rare earths mine, releasing strong initial beneficiation optimisation results and a preliminary updated mineral processing flowsheet for its flagship Halleck Creek Rare Earths Project in Wyoming.
The update builds on recent hydrometallurgical test work and follows a quarter in which the company completed test mining, progressed comminution studies and strengthened the project’s technical foundations ahead of a planned pre-feasibility study (PFS).
New beneficiation test work shows improved recoveries
The headline results come from preliminary testing using a Reflux Classifier Concentrator (RCC) — a technology ARR says could replace spirals as the primary beneficiation method.
Testing completed by Nagrom in Perth on material from 10 drill holes at Halleck Creek delivered:
- 78.4% total rare earth oxide (TREO) recovery,
- 14% mass yield, and
- a 5.66× enrichment factor.
The reduced mass yield compares favourably with spirals, achieving a 44% decrease in mass yield while delivering similar TREO recoveries. Lower mass yields typically translate into lower capital and operating costs downstream, as less material requires hydrometallurgical processing.
The results also showed effective removal of gangue minerals, including strong separation of silica and aluminium, and meaningful reduction of iron.
American Rare Earths believes the RCC has potential to form the primary separation stage in a circuit used in series with the Induced Rolled Magnetic Separator (IRMS). Bulk RCC testing will now be carried out on material produced from the ongoing comminution program to validate these initial results.
Locations of RC cuttings holes.
Updated flowsheet nearing completion
ARR has incorporated the latest beneficiation and leaching results into a preliminary updated processing flowsheet, which outlines the path from crushed ore to a mixed rare earth oxide.
Upcoming steps include:
- Producing a mixed rare earth oxalate (MREO) via precipitation,
- Calcining the MREO to a mixed rare earth oxide — the precursor to separated oxides, and
- Running a bulk ore sample through the full flowsheet (except separation and finishing), generating the final data required for the PFS.
The flowsheet work is part of a broader optimisation program launched in mid-2025 to refine conventional processing routes and improve overall recoveries.
Updated Preliminary Halleck Creek Mineral Processing Flowsheet.
Comminution optimisation expected to further enhance recoveries
ARR is also testing multiple conventional milling approaches with industry experts to reduce fines generation during crushing and grinding. Excess fines can complicate early-stage beneficiation. If successful, the optimisation is expected to support stronger recoveries during primary concentration.
These combined optimisation streams — comminution, RCC testing and hydrometallurgical improvements — are designed to de-risk the Halleck Creek PFS and improve project economics.
Positioned as part of US supply chain strategy
Halleck Creek sits on state land in Wyoming and is designed for open-pit mining with onsite processing and separation, positioning American Rare Earths to support US ambitions to develop a domestic rare earths supply chain. The United States currently relies on imports, predominantly from China, for separated rare earth elements used in defence systems, clean energy technology and advanced manufacturing.
In recent quarterly reporting, ARR highlighted that milestones achieved at Halleck Creek — including test mining, data generation and initial hydrometallurgical success — have helped de-risk the project as it moves towards PFS.
Read more: American Rare Earths reports quarterly progress as Halleck Creek milestones de-risk US supply
With today’s announcement, the company says Halleck Creek is now “one step closer” to becoming a producing mine, describing the optimisation results as material to confidence in the project’s technical and economic viability.