Resolution Minerals Ltd (ASX:RML, OTCQB:RLMLF, FRA:NC3) has reported high antimony recoveries from initial 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 was achieved from lower-grade composite samples grading 10.5% antimony, suggesting the process may still recover stibnite effectively where high-grade material is diluted by surrounding waste or gangue during any 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 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,” Resolution’s In-house Senior Metallurgist, Dr. Adam Roper said.
Supports processing pathway
Resolution said the recoveries supported 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 supported 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.
Cleaner flotation work underway
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.
