Resolution Minerals has achieved 99.5% recovery of stibnite from lower grade Antimony Ridge samples, reinforcing the project's potential as a key US antimony source. Further flotation and hydrometallurgical test work is underway alongside a major drilling campaign at Golden Gate.
- 99.5% stibnite recovery in rougher flotation tests
- High recoveries from ~10% antimony lower grade samples
- Cleaner flotation stages targeting >50% antimony concentrate
- Supports prior 99.38% antimony trioxide production results
- FAST-41 permitting and 13,700m Golden Gate drilling underway
Near-Complete Antimony Recovery from Lower Grade Samples
Resolution Minerals Ltd (ASX:RML) has reported metallurgical test work from its Antimony Ridge project that achieved a striking 99.5% recovery of stibnite, the primary antimony sulphide mineral, during rougher flotation tests. Conducted by IMO Labs in Perth, the tests used composite samples with approximately 10.5% antimony, demonstrating that even lower grade material can yield near-complete sulphide recovery. This bodes well for future operations, where dilution by surrounding waste or gangue is inevitable during extraction.
These results suggest the rougher flotation stage effectively captures virtually all stibnite, providing a robust foundation for downstream processing. The company is now advancing cleaner flotation stages designed to upgrade the concentrate grade from around 30% to over 50% antimony, aiming to produce a high-grade product suitable for market requirements.
Validation of High-Purity Antimony Trioxide Production
The new flotation data strongly supports prior findings from Resolution's pyrometallurgical test work, which produced a 99.38 wt.% antimony trioxide intermediate from Antimony Ridge stibnite samples. This high-purity product, manufactured via volatilisation, underscores the amenability of the ore to conventional processing routes. The flotation results, combined with the earlier pyrometallurgical success, strengthen the case for Antimony Ridge as a viable source of domestic antimony supply for the US.
Resolution’s Antimony Ridge lies within the broader Horse Heaven Antimony-Tungsten-Gold-Silver Project in Idaho, adjacent to Perpetua Resources’ Stibnite Gold Project, which is currently under construction. The historical significance of Antimony Ridge is notable, having supplied the majority of US antimony during World War II, a fact that underscores its strategic importance in critical metal supply chains.
Strategic Importance and Permitting Acceleration
The US Permitting Council has selected Antimony Ridge for FAST-41 Transparency Coverage, a status aimed at expediting federal permitting processes. This recognition reflects the project's potential to supply antimony, a critical metal for defence, energy, and industrial applications, from a domestic source. The permitting acceleration aligns with Resolution’s broader strategy to establish a processing hub in Idaho, addressing the current lack of modern antimony processing options in the US.
Meanwhile, Resolution is progressing hydrometallurgical test work at ANSTO in Australia, which may offer alternative or complementary processing pathways. The company is also preparing for a substantial 13,700-metre diamond drilling campaign at the Golden Gate target, part of the Horse Heaven project, to delineate gold and tungsten mineralisation and support resource estimation efforts. This drilling program is scheduled to commence on 7 May 2026, following the company’s recent capital raise to accelerate exploration and development activities.
Metallurgical Test Work Details and Next Steps
The composite sample tested contained 10.5% antimony, with significant silicon, sulphur, aluminium, and gold content. Rougher flotation tests conducted at natural and adjusted pH levels showed improved antimony grade and recovery at neutral pH, with sulphide recovery consistently near complete. Notably, about 24% of antimony in the sample exists as oxides rather than locked stibnite, which may influence processing strategies.
Following the rougher flotation stage, the company plans to conduct rougher-regrind-cleaner flotation tests to enhance concentrate grade above 50% antimony. These efforts are complemented by ongoing hydrometallurgical studies. The combined test work aims to establish a simple, robust processing flowsheet for Antimony Ridge ore, supporting the project’s development potential.
Resolution’s metallurgical progress dovetails with its broader exploration momentum, including the imminent 13,700m drill campaign at Golden Gate and recent A$20 million capital raise to fund accelerated US critical minerals projects. These initiatives collectively advance the company's ambition to become a significant domestic supplier of antimony, tungsten, gold, and silver from Idaho.
Bottom Line?
Resolution’s near-complete stibnite recovery from lower grade samples marks a pivotal step in proving Antimony Ridge’s processing viability, but upcoming cleaner flotation and hydrometallurgical results will be crucial to confirm commercial-grade concentrate production.
Questions in the middle?
- Will cleaner flotation stages consistently achieve >50% antimony concentrate grades at scale?
- How will the presence of antimony oxides affect hydrometallurgical processing efficiency?
- Can Resolution leverage FAST-41 status to expedite permitting and commercialisation within a tight timeframe?