
United States Antimony Corporation (USAC) has concluded a comprehensive review of its expansion strategy for the sole operational antimony smelter in the US.
The company has executed a definitive agreement with WSP USA to provide engineering and construction services to increase the smelting operations at Thompson Falls, Montana.
This development is expected to boost the facility’s production output to more than 300 standard tonnes per month, a sixfold increase from current levels.
The expansion is projected to cost less than $15m and is designed to proceed without disrupting ongoing smelting operations. The completion of the expansion is scheduled before the end of 2025.
USAC chairman and CEO Gary C. Evans said: “Over the last few months, management has been looking tirelessly at all options available to it regarding how to expand this facility with the understanding that we have a limited footprint on the property we own.
“Additionally, due to the limitations caused by difficult terrain around the perimeter of the property, our growth plans are constrained. We entertained conversations and bids from a number of different engineering and general contracting firms experienced in our business.

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By GlobalData“We chose WSP due to their size, their significant local presence in the State of Montana and their broad capability to handle all required parts of our expansion plans.”
The recent commencement of operations at US Antimony’s Madero Smelter in Mexico, coupled with the increased throughput capacity in Montana, is expected to advance the company towards the objective of attaining a production capacity of 500 tonnes per month by the end of the year.
WSP P.E., BCEE Randy Huffsmith said: “WSP is pleased to offer our expertise in support of US Antimony’s plans to expand and upgrade its existing processing facility located at Thompson Falls, Montana. We acknowledge the critical importance of enhancing production capacity while maintaining our industry standard of environmental compliance and operational efficiency.
“As a global leader in engineering and professional services, WSP has a mining team of over 5,200 dedicated professionals that bring unparalleled expertise to every project we undertake. We are excited about this opportunity to partner with US Antimony on these expansion plans with our experienced Montana team.”
In August 2024, USAC agreed to acquire a 100% ownership interest in 97 mining claims and three mining leases in the Sudbury district of Ontario, Canada.