Resolution Minerals Ltd (ASX:RML, OTCQB:RLMLF, FRA:NC3) has produced high-purity antimony trioxide from its Antimony Ridge deposit in Idaho, a key step forward in its metallurgical program and broader US-focused critical minerals strategy.
Conventional pyrometallurgical test work has successfully produced an intermediate antimony trioxide product grading 99.38% Sb₂O₃ from stibnite samples sourced from historical open pits.
This work was completed by Kingston Process Metallurgy in Canada and represents an early validation of a conventional processing pathway for the project.
Test work continues, with further refinement underway and final product results expected in the coming weeks.
“The initial pyrometallurgical results from processing Antimony Ridge samples are very encouraging with few impurities. This is a great start and I’m looking forward to discussing the final results in the coming weeks," Adam Roper, PhD, Resolution’s in-house senior metallurgist, said.
“Resolution’s goal is to develop a processing hub in Idaho for stibnite and I’m relishing the opportunity to bring this to fruition, from mine to product.
“The Johnson Creek Mill site, at the base of Antimony Ridge, is being considered as a fast-track option for potential development of a local processing site, given it has the necessary infrastructure on site, with power and water, and is on 10 acres of private land owned 100% by RML.”
Antimony Ridge – As part of Resolution’s larger Horse Heaven Antimony-Tungsten-Gold-Silver Project – Relationship of Antimony Ridge (Sb) with Golden Gate (Au) and Golden Gate Tungsten (W).
Processing pathways progressing
Resolution is advancing multiple processing routes in parallel:
- Pyrometallurgy identified as the base-case processing option, with third-party groups already engaged
- Hydrometallurgical test work underway at ANSTO in Australia
- Concentrate optimisation studies ongoing at IMO laboratories in Perth
The company is also targeting development of a domestic US processing hub in Idaho, highlighting the current lack of modern antimony processing capacity in the country.
“With the recent US Government Permitting Council provided via FAST-41 coverage to accelerate permits, Resolution is in parallel developing further local processing plans to enable antimony and tungsten supply for US demand. Our unique combination of critical minerals assets makes us well placed to deliver,” RML’s managing director, Ari Zaetz, said.
Strong underlying mineralisation
Metallurgical work is supported by high-grade mineralisation at Antimony Ridge, with previous results showing:
- Antimony grades consistently above 30% Sb, and up to 50% Sb
In addition, recent 3D modelling has outlined extensive vein swarms across an area of about 1,000m by 700m, pointing to significant scale potential for the system.
Strategic positioning
The project has also been selected for FAST-41 permitting coverage in the United States, a designation aimed at accelerating approvals for strategically important infrastructure and resource projects.
Management views this as a key enabler for advancing both mining and downstream processing plans in parallel.
What’s next
Resolution is preparing to ramp up activity across the broader Horse Heaven project, with near-term milestones including:
- Further metallurgical results from ongoing refining and hydromet test work
- A bulk sampling program targeting high-grade antimony ore
- Submission and approval of a Plan of Operations for up to 250 drill holes
- A Phase 2 drilling campaign at Golden Gate, commencing May 2026, comprising up to 13,700 metres of diamond drilling aimed at defining a maiden resource
Antimony Ridge is expected to play a central role in the company’s strategy to supply antimony, tungsten and gold into US markets, particularly amid growing demand for critical minerals tied to defence and energy applications.