United States Antimony Corporation has started wet commissioning at its Radersburg flotation mill in Montana, advancing the facility toward processing antimony ore from the company’s domestic mining operations. US Antimony acquired the processing facility for US$4.75 million in January 2026 and has since spent approximately US$2 million on refurbishment, equipment upgrades and a new laboratory. Total disclosed expenditure on the acquisition and improvements is therefore about US$6.75 million.
Initial campaign to process Stibnite Hill ore
The first commissioning campaign will treat approximately 800 tonnes of antimony-bearing ore from the company’s Stibnite Hill operations near Thompson Falls. The wet run is designed to test ore handling, grinding, reagent addition, flotation performance, concentrate recovery and water circuits under operating conditions with material in the system.
Wet commissioning represents a step beyond mechanical completion, but the plant has not yet reached stable commercial production. Operating campaigns can identify issues involving pumps, instrumentation, thickening, filtration and concentrate quality that may not emerge during dry testing.
Radersburg adds domestic processing capacity
The mill forms part of US Antimony’s vertically integrated operating model. The company already processes and sells antimony products, while the additional flotation capacity could enable treatment of lower-grade or more complex US ore before downstream conversion. The initial 800-tonne feed campaign is not sufficient to establish long-term operating costs or sustained metallurgical recovery rates.
Future commercial performance will depend on ore grade and variability, flotation recovery, concentrate penalties and the volume of accessible mine feed available to the facility. The commissioning comes as restrictions on Chinese antimony supply increase strategic interest in production outside China. The contribution of Radersburg to US Antimony’s operations will depend on repeatable recovery results and the establishment of a reliable multi-year ore supply.
