Resolution Minerals delivers strong antimony recoveries from Antimony Ridge tests, boosting US domestic supply prospects
Resolution Minerals Ltd (ASX:RML, OTCQB:RLMLF, FRA:NC3) has reported strong antimony recoveries from early-stage metallurgical test work on samples from Antimony Ridge, part of its Horse Heaven Antimony-Tungsten-Gold-Silver Project in Idaho, USA.
Rougher flotation tests conducted by IMO labs in Perth achieved sulphur recovery of 99.5%, which the company said indicated near-complete recovery of stibnite—the primary antimony sulphide mineral—during the rougher concentration stage. The result came from lower-grade composite samples grading 10.5% antimony, suggesting the process can still effectively recover stibnite even when high-grade material is diluted by surrounding waste or gangue during future extraction.
At pH 7, combined rougher antimony recovery improved to 76.0% at a grade of 27.3% antimony, compared with 72.2% recovery at 23.6% antimony at natural pH. The company said these results point to a simple and robust processing flowsheet for antimony.
“The initial concentration results in rougher flotation test work are very encouraging from Antimony Ridge samples. Capturing virtually all the antimony sulphides is an excellent sign of a simple and robust processing flowsheet for antimony. I’m looking forward to discussing further results in the coming weeks,” said Dr. Adam Roper, Resolution’s in-house senior metallurgist.
The recoveries support previous metallurgical work that produced 99.38 weight percent antimony trioxide from large stibnite samples from historical open pits at Antimony Ridge using conventional pyrometallurgical volatilisation. The company said the combination of high sulphide recovery, earlier antimony trioxide results and 3D modelling of multiple antimony and silver-bearing vein swarms over a 1,000-metre by 700-metre area reinforces the project’s development potential.
Antimony Ridge was recently selected for FAST-41 Transparency Coverage by the US Permitting Council, reflecting its potential role as a domestic US antimony source—a critical mineral with growing demand for defense, electronics, and energy storage applications.
“This is exactly the kind of news the US critical minerals sector needs right now,” said Mark Chen, a mining analyst based in Denver. “The recoveries are solid, and the FAST-41 designation gives it a clear regulatory path. But the real test will be whether they can scale this economically.”
Not everyone is convinced. “Sure, the numbers look good on paper, but we’ve seen this movie before—great lab results, then nothing happens for years,” said Linda Torres, a former industry consultant now critical of junior miners. “Antimony prices are volatile, and unless they lock in off-take agreements, this is just another exploration story with a shiny headline.”
Further flotation test work is now underway, with cleaner stages designed to upgrade rougher concentrate from around 30% antimony to more than 50% antimony. Hydrometallurgical processing test work is also underway at ANSTO in Australia, with results to be released when available.
Resolution is also advancing broader Horse Heaven work, including test work on antimony, tungsten and gold-bearing samples, and plans to begin a 13,700-metre Phase 2 drilling program at the Golden Gate target to define the scale of gold and tungsten mineralisation and support a maiden mineral resource estimate.