Strong Leach Recoveries and Low Impurities Drive Halleck Creek Closer to Unlocking Its Rare Earth Potential
American Rare Earths (AMRRY) has announced significant progress in its Halleck Creek Rare Earths Project's metallurgical testing program. The company achieved notable leach recoveries for critical rare earth elements, including 85% for Praseodymium and 84% for Neodymium at optimal conditions.
The testing, conducted at SGS's laboratory in Lakefield, included 25 leach tests exploring various parameters. A key breakthrough was achieved with significantly lower impurity elements, with iron and aluminum concentrations 5.0x and 2.9x lower respectively compared to previous Scoping Study tests. The company has selected Atmospheric Tank Leach as the preferred method, noting its superior energy efficiency and cost-effectiveness.
These results represent a crucial milestone in the technical de-risking of the Cowboy State Mine Pre-Feasibility Study, establishing optimal leach conditions for producing rare earth magnet oxides.
American Rare Earths (AMRRY) ha annunciato progressi significativi nel programma di test metallurgici del progetto Halleck Creek Rare Earths. L'azienda ha raggiunto recuperi di lisciviazione notevoli per elementi delle terre rare critici, ottenendo l'85% per il Praseodimio e l'84% per il Neodimio nelle condizioni ottimali.
I test, condotti nel laboratorio SGS di Lakefield, hanno incluso 25 prove di lisciviazione analizzando vari parametri. Un risultato chiave è stato il drastico abbassamento degli elementi impurità, con concentrazioni di ferro e alluminio rispettivamente 5,0 e 2,9 volte inferiori rispetto ai test precedenti dello Studio di Fattibilità Preliminare. L'azienda ha scelto il metodo di Lisciviazione in Serbatoio Atmosferico come preferito, evidenziandone l'efficienza energetica superiore e la convenienza economica.
Questi risultati rappresentano una tappa fondamentale nella riduzione del rischio tecnico dello Studio di Fattibilità Preliminare della miniera Cowboy State, definendo le condizioni ottimali di lisciviazione per la produzione di ossidi magnetici di terre rare.
American Rare Earths (AMRRY) ha anunciado avances significativos en el programa de pruebas metalúrgicas de su proyecto Halleck Creek Rare Earths. La compañía logró altas recuperaciones por lixiviación de elementos críticos de tierras raras, alcanzando un 85% para Praseodimio y un 84% para Neodimio en condiciones óptimas.
Las pruebas, realizadas en el laboratorio de SGS en Lakefield, incluyeron 25 ensayos de lixiviación explorando diversos parámetros. Un avance clave fue la reducción considerable de elementos impurezas, con concentraciones de hierro y aluminio 5,0 y 2,9 veces menores respectivamente en comparación con pruebas anteriores del Estudio de Alcance. La compañía ha seleccionado la lixiviación en tanque atmosférico como método preferido, destacando su mayor eficiencia energética y rentabilidad.
Estos resultados representan un hito crucial en la reducción del riesgo técnico del Estudio de Prefactibilidad de la mina Cowboy State, estableciendo las condiciones óptimas de lixiviación para producir óxidos magnéticos de tierras raras.
American Rare Earths (AMRRY)는 Halleck Creek 희토류 프로젝트의 야금학적 시험 프로그램에서 중요한 진전을 발표했습니다. 회사는 최적 조건에서 프라세오디뮴 85%, 네오디뮴 84%의 중요 희토류 원소 침출 회수율을 달성했습니다.
Lakefield에 위치한 SGS 실험실에서 진행된 시험은 다양한 매개변수를 탐색하는 25회의 침출 시험을 포함했습니다. 주요 성과로는 철과 알루미늄 농도가 각각 이전 예비 타당성 조사 시험 대비 5.0배 및 2.9배 낮아진 낮은 불순물 함량을 기록한 점입니다. 회사는 에너지 효율성과 비용 효율성이 뛰어난 대기 탱크 침출법을 선호하는 방법으로 선정했습니다.
이 결과는 Cowboy State 광산 예비 타당성 연구의 기술적 위험 감소에 중요한 이정표로, 희토류 자석 산화물 생산을 위한 최적 침출 조건을 확립했습니다.
American Rare Earths (AMRRY) a annoncé des progrès significatifs dans son programme de tests métallurgiques pour le projet Halleck Creek Rare Earths. La société a obtenu des taux de récupération par lixiviation remarquables pour les éléments de terres rares critiques, atteignant 85 % pour le praséodyme et 84 % pour le néodyme dans des conditions optimales.
Les tests, réalisés au laboratoire SGS de Lakefield, comprenaient 25 essais de lixiviation explorant divers paramètres. Une avancée majeure a été réalisée avec des concentrations d'impuretés nettement plus faibles, le fer et l'aluminium étant respectivement 5,0 et 2,9 fois inférieurs à ceux des tests précédents de l'étude de faisabilité préliminaire. La société a choisi la lixiviation en cuve atmosphérique comme méthode préférée, soulignant son efficacité énergétique supérieure et son rapport coût-efficacité.
Ces résultats représentent une étape cruciale dans la réduction des risques techniques de l'étude de préfaisabilité de la mine Cowboy State, en établissant les conditions optimales de lixiviation pour la production d'oxydes magnétiques de terres rares.
American Rare Earths (AMRRY) hat bedeutende Fortschritte im metallurgischen Testprogramm seines Halleck Creek Rare Earths Projekts bekannt gegeben. Das Unternehmen erzielte bemerkenswerte Auslaugungsraten für kritische Seltene-Erden-Elemente, darunter 85 % für Praseodym und 84 % für Neodym unter optimalen Bedingungen.
Die Tests, die im Labor von SGS in Lakefield durchgeführt wurden, umfassten 25 Auslaugungstests mit verschiedenen Parametern. Ein entscheidender Durchbruch war die deutlich geringere Konzentration von Verunreinigungen, wobei die Eisen- und Aluminiumwerte 5,0- bzw. 2,9-mal niedriger waren als bei früheren Scoping-Studientests. Das Unternehmen hat die atmosphärische Tanklaugung als bevorzugte Methode ausgewählt und hebt deren überlegene Energieeffizienz und Kosteneffektivität hervor.
Diese Ergebnisse stellen einen wichtigen Meilenstein bei der technischen Risikominderung der Cowboy State Mine Vorstudie dar und legen die optimalen Auslaugungsbedingungen für die Herstellung von Seltene-Erden-Magnetoxiden fest.
- High leach recoveries achieved: 85% for Praseodymium and 84% for Neodymium
- Significantly reduced impurity levels: 5.0x lower iron and 2.9x lower aluminum concentrations
- Selection of more cost-effective Atmospheric Tank Leach method
- Technical de-risking milestone achieved for Pre-Feasibility Study
- Lower recovery rates for heavy rare earths: only 52% for Terbium and 46% for Dysprosium
- Requires higher acid dosage (400 kg/t) compared to Scoping Study (250 kg/t)
- Longer retention time needed (8 hrs vs 6 hrs in previous studies)
Highlights
- High Light Rare Earths Leach Recoveries
- Praseodymium (“Pr”) leach recoveries of
85% at optimal conditions - Neodymium (“Nd”) leach recoveries of
84% at optimal conditions
- Praseodymium (“Pr”) leach recoveries of
- Encouraging Heavy Rare Earths Leach Recoveries
- Terbium (“Tb”) leach recoveries of
52% at optimal conditions - Dysprosium (“Dy”) leach recoveries of
46% at optimal conditions
- Terbium (“Tb”) leach recoveries of
- Significantly lower impurity elements of iron and aluminum
- Concentrations of iron and aluminum impurities post leach are approximately 5.0x and 2.9x, respectively, lower than the tests previously performed for the Scoping Study1
- Atmospheric Tank Leach chosen as the preferred leach method
- Atmospheric tank leaching is typically more energy and reagent efficient and less costly than other rare earth leaching methods, such as an acid-bake (i.e. cracking)
DENVER, July 09, 2025 (GLOBE NEWSWIRE) -- American Rare Earths (ASX: ARR | OTCQX: ARRNF | ADR: AMRRY) (“ARR” or the “Company”) is pleased to announce the results of an extensive leach testing program undertaken on Cowboy State Mine ore, part of the Halleck Creek Rare Earths Project in Wyoming USA.
Twenty-five leach tests exploring various parameters and leach methods were completed at SGS’s laboratory in Lakefield, Ontario, Canada.
Why it matters? The leach tests provide key data for the on-going metallurgical testing and mineral processing flow-sheet development for the Cowboy State Mine Pre-Feasibility Study. The tests represent a significant milestone in the technical de-risking of the project as the results have established the optimal leach conditions and preferred arrangement for the PFS flow-sheet. Test results demonstrate leach parameters which may achieve favorable processing outcomes such as lower energy consumption and front end impurity removal. This is a key step forward in producing rare earth magnet oxides from Halleck Creek ore.
Metallurgical Testing Next Step
- SGS is performing scoping impurity removal tests, the next step in the mineral processing flow-sheet design for the Pre-Feasibility Study.
Additional Technical Details
The completion of the extensive leach testing campaign of Cowboy State Mine ore marks a major milestone for the project. The testing was completed at the Lakefield Ontario Canada location of SGS. All testing in this current campaign was conducted using sulfuric acid as the lixiviant (leaching agent). Previous leach testing completed at Nagrom (under the direction of Wood), and Virginia Tech demonstrated that sulfuric acid was the ideal lixiviant when optimizing for recovery, reagent cost, and shipping/logistics.
Building on the previous leach testwork, SGS tested the following leaching types and arrangements during the recent trials:
- Atmospheric Tank Leach
- Acid-bake and Water Leach
- Counter-Current Leach
SGS conducted 18 atmospheric tank leach tests, 5 acid-bake/water leach tests and 2 counter-current leach tests. The atmospheric tank leach was chosen as the preferred arrangement with operating conditions providing the optimal revenue minus raw material cost.
The selected atmospheric leach (“AL”) conditions for AL16 are shown in Table 1. The AL16 parameters represents the recommended feed for ongoing plant engineering and piloting trials. AL16 is composed of
| Leach Condition | AL16 | |
| Feed | ||
| Regrind Particle Size | -53 μm | |
| Acid Dosage | 400 kg/t | |
| Retention Time | 8 hrs | |
| Temperature | 90°C | |
| % Solids | ||
| Leach Result | ||
| La Extraction | ||
| Pr Extraction | ||
| Nd Extraction | ||
| Tb Extraction | ||
| Dy Extraction | ||
| Fe Extraction | ||
| Al Extraction | ||
| Mg Extraction | ||
| Ca Extraction | ||
| Final Acidity | 20 g/L | |
Leachate Concentration
The Scoping Study concentrate was generated using WHIMS. The current concentrate was produced using gravity spiral followed by IRMS. The Scoping Study sulfuric acid tank leach test was performed at 250 kg/t and a 6 hr reaction time while the current spiral/IRMS concentrate was tested at 400 kg/t and a 8 hr reaction time.
Table 2 below compares the difference in leachate concentrate for the major impurity elements for the Scoping Study concentrate with the current concentrate. Concentrations of iron and aluminum impurities post leach are approximately 5.0x and 2.9x, respectively, lower than the tests previously performed for the Scoping Study.
It is theorized that the gravity spiral step removed some of the Fe and Al containing heavy minerals and the IRMS was able to separate out the highly magnetic minerals such as hematite and magnetite. These minerals were readily leached in the sulfuric acid tank leach tests for the WHIMS concentrate resulting in much higher impurity concentrations in the leachate. With greater proportions of Fe and Al removed from IRMS concentrate, downstream Impurity removal steps should use less reagent (i.e. potential for lower operating costs) and achieve lower concentrations of these elements in the leachate.
| Unit | SGS Spiral/IRMS Conc (AL16) | Scoping Study WHIMS Conc | % Change | |
| Si | mg/L | 1,250 | 3,627 | - |
| Al | mg/L | 1,300 | 3,748 | - |
| Fe | mg/L | 4,450 | 22,230 | - |
| Mg | mg/L | 74 | 210 | - |
| Ca | mg/L | 1,670 | 1,495 | |
| Na | mg/L | 92 | 292 | - |
| K | mg/L | 158 | 510 | - |
| Ti | mg/L | 231 | 562 | - |
| P | mg/L | 45 | 190 | - |
| Mn | mg/L | 111 | 541 | - |
| Zn | mg/L | 19 | 101 | - |
This release was authorized by the board of American Rare Earths.
Investors can follow the Company’s progress at www.americanree.com
For the full press release with additional technical information and the updated JORC Table please see the full release here.
About American Rare Earths Limited:
American Rare Earths (ASX: ARR | OTCQX: ARRNF | ADR: AMRRY) is a critical minerals company at the forefront of reshaping the U.S. rare earths industry. Through its wholly owned subsidiary, Wyoming Rare (USA) Inc. (“WRI”), the company is advancing the Halleck Creek Project in Wyoming—a world-class rare earth deposit with the potential to secure America’s critical mineral independence for generations. Located on Wyoming State land, the Cowboy State Mine within Halleck Creek offers cost-efficient open-pit mining methods and benefits from streamlined permitting processes in this mining-friendly state.
With plans for onsite mineral processing and separation facilities, Halleck Creek is strategically positioned to reduce U.S. reliance on imports—predominantly from China—while meeting the growing demand for rare earth elements essential to defense, advanced technologies, and economic security. As exploration progresses, the project’s untapped potential on both State and Federal lands further reinforces its significance as a cornerstone of U.S. supply chain security. In addition to its resource potential, American Rare Earths is committed to environmentally responsible mining practices and continues to collaborate with U.S. Government-supported R&D programs to develop innovative extraction and processing technologies for rare earth elements.
For additional information:
Susan Assadi
Media Relations US
sassadi@americanree.com
347 977 7125
Beverly Jedynak
Investor Relations US
Beverly.jedynak@viriathus.com
312 943 1123
1 Refer ASX Announcement titled ‘Full Updated Scoping Study’ released 7 March 2025
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