American Rare Earths Ltd (ASX:ARR, OTCQB:ARRNF) has begun a major optimisation program at its Halleck Creek Rare Earths Project in Wyoming, United States, with a multi-pronged strategy designed to improve mineral recoveries and support a future demonstration plant.
Key activities include:
- Parallel optimisation testing of mineral processing routes to enhance magnet rare earth element recoveries
- Procurement of long-lead magnetic separation equipment for use in a pilot-scale demonstration facility
- Immediate commencement of test mining at Cowboy State Mine to secure bulk samples for processing studies.
The efforts will support the Halleck Creek Project’s Pre-Feasibility Study (PFS) and are expected to strengthen the technical and economic viability of the development.
The company will mobilise extraction equipment at the Cowboy State Mine under its approved exploration licence to collect bulk samples. While only 8 tonnes are required for immediate comminution testing, ARR plans to extract approximately 3,200 tonnes to serve both the optimisation program and as feedstock for its future demonstration plant.
Comminution testing targets reduced fines, higher efficiency
Three comminution methods — Vertical Roller Mill (VRM), High Pressure Grinding Rolls (HPGR) with Air Classifier, and HPGR Tower Mill — will be tested.
These approaches aim to minimise fines (material below 50 microns) in the beneficiation circuit. Reducing fines can improve ore concentration, increase total rare earth oxide (TREO) grades in leach, and reduce reagent consumption, ultimately lowering operating costs.
Beneficiation program focuses on primary separation upgrades
ARR will also use Induced Roll Magnetic Separators (IRMS) to isolate allanite from gangue, with additional work underway to refine the primary separation stage. Techniques under assessment include:
- Reflux Classifier Concentrator (RCC), which shows improved selectivity and reduced mass yield over traditional gravity spirals.
- Magnetic Drum and Rare Earth Drum (RED), both dry methods that may eliminate the need for intermediate ore drying, offering cost and operational benefits.
- Hydrometallurgy testing progresses with impurity removal trials
- Leach conditions are well established from earlier testing, and current work focuses on impurity removal.
Six neutralisation agents were initially assessed at SGS’s Lakefield lab in Ontario, with two candidates undergoing further testing. These results will guide larger-scale leach and purification trials using optimised grinding and separation methods.
Demonstration plant preparations underway
ARR has ordered two full-scale IRMS units for delivery in early 2026 and will incorporate findings from ongoing optimisation into the full process flow-sheet. This facility will allow for larger-scale validation and de-risking of the processing design.
Strategic position in US critical mineral supply chain
Through its wholly owned subsidiary Wyoming Rare (USA) Inc., American Rare Earths aims to establish Halleck Creek as a flagship US source of magnet rare earths, reducing reliance on imports.
With cost-effective open-pit mining and access to state-level permitting, the project is poised to become a critical pillar in US economic and national security supply chains.