United States Antimony Corporation has started wet commissioning at its Radersburg flotation mill in Montana, moving the facility closer to processing domestically mined antimony and strengthening the company’s US supply-chain position.
The company purchased the processing facility for US$4.75 million in January 2026 and has since invested approximately US$2 million in refurbishment, equipment improvements and a new laboratory. Total acquisition and upgrade spending disclosed to date therefore stands at roughly US$6.75 million.
First 800 Tonnes to Test Processing Circuit
The initial commissioning campaign will process approximately 800 tonnes of antimony-bearing ore from US Antimony’s Stibnite Hill operations near Thompson Falls. Wet commissioning is designed to test the plant under operating conditions, including ore handling, grinding, reagent addition, flotation performance, concentrate recovery and water circulation.
The milestone goes beyond mechanical completion, but it does not yet represent stable commercial production. Early operating campaigns can expose problems with pumps, instrumentation, thickening, filtration and concentrate quality that may not be identified during dry commissioning.
Radersburg Adds Domestic Antimony Processing Capacity
The facility could strengthen US Antimony’s vertical integration by adding domestic flotation capacity to its existing antimony processing and marketing activities. This would potentially allow the company to process lower-grade or more complex US antimony ores before further conversion into saleable products.
The initial 800-tonne campaign is too small to establish sustainable operating costs or long-term metallurgical performance. Future economics will depend on the grade and variability of ore supplied to the mill, flotation recovery rates, concentrate quality and penalties, as well as the amount of economically accessible material available from the company’s mining operations.
Antimony Supply Security Raises Strategic Importance
The commissioning comes as restrictions on Chinese antimony exports have increased interest in alternative sources of the critical metal. Antimony is used in a range of industrial applications, including alloys, flame retardants and specialised technologies, making domestic production strategically important for the United States.
Radersburg could therefore have significance beyond its initial production volumes. Establishing a domestic route from US antimony ore to concentrate and downstream products could reduce dependence on overseas processing. The immediate priority, however, is proving that the flotation mill can operate consistently. The most important indicators will be repeatable recovery rates, concentrate quality, operating costs and a reliable long-term ore supply. Until those factors are demonstrated, the Radersburg commissioning remains an important development milestone rather than proof of sustained commercial production.
