United States Antimony Corporation formally began wet commissioning its Radersburg Flotation Mill on Monday, marking a significant step in the company’s effort to build a domestic antimony supply chain independent of Chinese exports. Governor Greg Gianforte attended a ceremony at the Radersburg facility, located at 151 Keating Gulch Road, which ran from 11:00 a.m. to 2:00 p.m. MST.

A Facility Acquired and Upgraded in Under a Year

The company purchased the Radersburg site in January 2026 for $3.58 million, ending what had previously been a leasing arrangement with a third party. Since taking full ownership, the company has invested an additional $2 million in capital expenditures, covering equipment upgrades, refurbishments, and a new on-site laboratory that alone cost $1 million to build.

The laboratory is equipped with full sample preparation capabilities, a 3-kilowatt XRF analyzer, fire assay, and wet chemistry tools. Full commissioning of the laboratory alongside concentrate production is expected by mid-July.

The mill is now positioned to process an initial 800 tons of antimony ore sourced from the company’s Stibniite Hill Operations in Thompson Falls, Montana. Through gravity and flotation circuits, the facility is designed to produce high-grade concentrate of at least 80% antimony — a key specification for downstream smelting into finished antimony products.

Three-Stage Production Model

The company’s production strategy is built around three integrated stages. The mining stage at Stibniite Hill targets ore with at least 10% antimony content and minimal impurities. That raw ore then travels to Radersburg for concentration, where the flotation mill upgrades material to the 80% antimony threshold. Final smelting removes remaining impurities to produce finished goods ready for commercial or industrial use.

Stibniite Hill is currently producing raw antimony ore in anticipation of the Radersburg mill reaching full operation. With the wet commissioning now underway, the company is moving toward closing the loop between its mining and concentration stages.

Federal Funding Application and Broader Strategic Context

Beyond the flotation mill, the company has set its sights on a significantly larger expansion at the Radersburg site. In January 2026, it filed a direct application to the U.S. Department of Energy for funding to support construction of a Hydrometallurgical — or HydroMet — Refinery, estimated to cost approximately $66 million to build. The broader HydroMet project, classified as a Critical Materials Byproduct Recovery effort, was listed at $547.5 million in federal program requests.

The timing of the company’s growth reflects a major shift in the global antimony market. China began restricting antimony exports in September 2023, triggering a supply shock that sent prices surging more than 500%. Antimony is used in flame retardants, semiconductors, ammunition, and battery technologies — placing it firmly among the critical minerals that U.S. policymakers have prioritized for domestic sourcing.

Montana’s role in that domestic supply chain has been expanding. The state’s general fund revenue outpaced projections by a wide margin in fiscal year 2026, and resource-sector activity has been a component of that economic performance. Projects like the Radersburg mill represent the kind of capital investment and job creation that state officials have pointed to as evidence that Montana’s business climate is attracting industry in sectors aligned with national security priorities.

What Comes Next

With wet commissioning now launched, the company expects to reach full milling and laboratory operations by mid-July. Progress on the DOE funding application for the HydroMet Refinery will be a key development to watch in the months ahead, as that project would substantially expand the Radersburg site’s capacity and role in the domestic antimony supply chain.

Governor Gianforte’s presence at Monday’s ceremony signals continued state-level interest in critical mineral development as Montana works to position itself as a supplier in industries where foreign supply disruptions have exposed significant vulnerabilities.