US Antimony Smelter Expansion Delay Tests Domestic Antimony Supply Strategy

USAC

US Antimony smelter expansion delays are testing the pace of America’s effort to rebuild domestic antimony processing capacity. US Antimony expects completion of the Thompson Falls smelter expansion in Montana to be delayed after supplier and third-party setbacks affected construction work.

The delay matters because Thompson Falls is the only antimony smelter in the US. It is also one of only two North American antimony smelting assets operated by the company, alongside the Madero smelter in Mexico.

US Antimony smelter expansion plans are designed to lift Thompson Falls capacity to more than 500 tonnes per month. That added capacity is central to the company’s 2026 revenue outlook and its ability to serve government and commercial contracts.

Thompson Falls Capacity Is Critical for US Defense Supply

Antimony is a strategic mineral used in flame retardants, alloys, ammunition, defense applications, batteries, and other industrial products. The Thompson Falls expansion therefore carries national security significance beyond ordinary smelter growth.

US Antimony has secured a five-year fixed-price contract worth up to $245 million to supply antimony ingots to the US Defense Logistics Agency for the national defense stockpile. The company expects to deliver its first $75 million of antimony ingots in 2026.

The company ended 2025 with a record 465 tonnes of processed and unprocessed antimony inventory, up from 78 tonnes a year earlier. Part of that inventory will support its DLA obligations while the company works to expand processing capacity.

Imported Feedstock Still Defines Near-Term Antimony Risk

US Antimony currently sources all of its antimony from international suppliers. That dependence shows why domestic mining claims in Montana and Alaska are strategically important to the company’s long-term supply position.

The company reacquired mining claims adjacent to its Montana smelting operations in July and also acquired claims in Alaska in January 2025. However, Alaska operations have faced delays from permitting issues and weather conditions.

Revenue more than doubled to $39.3 million in 2025 from $14.9 million in 2024, but losses widened to $4.3 million. This shows that growth is accelerating, but execution costs, expansion delays, and feedstock security remain key risks.

The Metalnomist Commentary

US Antimony smelter expansion is a test case for whether the US can convert critical mineral policy into real processing capacity. The company has the contracts and strategic relevance, but execution speed and domestic feedstock development will decide how much supply security it can actually deliver.