ASX: AT4 | OTCQB: ATALF | 17 September 2026

Del Sol Restart Campaign Commences Ahead of Schedule

American Tungsten & Antimony Limited has commenced a restart campaign for the leach and electrowinning circuit at the Del Sol Hydromet Refinery in Amargosa Valley, Nevada, using material from the White Spar Antimony Mine in Yavapai County, Arizona. The Company describes the campaign as the first physical demonstration of the US mine-to-metal pathway underpinning its strategy.

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States in the chain: Arizona mine to Nevada refinery
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Stibnite hauled White Spar to Del Sol
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DOE award negotiations ongoing
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EO 14415 waiver cutoff, 1 January

Why This Announcement Is Different

Every prior AT4 announcement described intent, engineering or federal process. This one describes a circuit being brought back online with US ore in it. Executive Chairman Timothy Morrison put the distinction plainly, stating that the ability to demonstrate physical production from US material differentiates AT4 from projects that remain at the development stage.

That distinction has a specific commercial function. Product qualification is a prerequisite for defence and industrial supply arrangements, and qualification cannot begin without physical samples. A development plan cannot be qualified. A drum of antimony flake can.

  • Fast-tracked and ahead of schedule. The restart was previously targeted to commence by the end of the September quarter.
  • No new infrastructure. The campaign is conducted within the facility’s existing permitted feed envelope, avoiding new build and further permitting delay.
  • Independently supervised. The restart is overseen by independent process engineering specialists engaged by the Company, working alongside AT4’s technical team and the site operating crew.
  • Third-party verified assays. Assaying is undertaken in the on-site Del Sol laboratory with third-party laboratory verification performed on keepsake samples.

Inside the Campaign

The restart is a confirmatory campaign on the Del Sol Refinery’s existing configuration. Feed preparation, hot water commissioning and final checks have commenced as the campaign proceeds. Conducting it within the existing permitted feed envelope allows the restart to be executed quickly while minimising capital expenditure.

The campaign is processing White Spar mineralisation recovered from the existing small-scale extraction zone at the mine, together with material upgraded in a gravity beneficiation circuit. Antimony metal flake will be collected, washed, dried, weighed and assayed. Remelting and fire refining test work using the recovered flake is planned to follow the leach and electrowinning campaign, with product quality confirmed by XRF and ICP analysis on site.

A comprehensive sampling and assay protocol covers head samples, intermediate samples, tailings and final product.

The campaign has been designed to pursue five outcomes:

Production of antimony flake for product qualification, sampling and technical discussions with prospective offtakers, strategic partners and government agencies.

Production of Regulus II antimony ingot through remelting of Company-produced flake, together with fire refining test work to assess achievable product quality.

Verification of process parameters, reagent consumption, antimony recovery and the antimony flake grade achievable through the existing Del Sol configuration on White Spar feed material.

Generation of feed material for planned test work on specialty antimony products.

Advancing the technical basis for applications and submissions under United States federal programs supporting domestic critical minerals processing.

A second, larger campaign is proposed to build on these results and to generate the engineering data required to support scoping study cost estimates for expansion of Del Sol’s antimony capacity.

Tungsten test work is continuing at Del Sol on samples from Dutch Mountain, Tennessee Mountain and third-party sources, assessing the upgrading of scheelite and informing flowsheet selection for the proposed APT circuit. Analytical work is being completed in the on-site laboratory by ICP, with sample splits submitted to an independent umpire laboratory for verification.

Tungsten drilling commenced at Dutch Mountain on 4 September 2026. Metso Finland Oy was engaged on 1 September 2026 to complete a scoping study for an ammonium paratungstate circuit at Del Sol. APT is the principal traded tungsten intermediate.

The two metals are being advanced on parallel tracks through the same facility. Antimony is at the physical restart stage; tungsten is at the test work and engineering study stage.

Antimony and the US Defence Industrial Base

Antimony flake produced at Del Sol can be used as feedstock for antimony trisulphide, an essential component of primer compositions for small arms and medium calibre ammunition. Antimony is further used as a hardening agent in projectiles, in military grade lead acid batteries, in flame retardant systems, and in night vision and infrared guidance systems. It is also emerging as a critical raw material for the United States semiconductor and advanced electronics sectors. Despite that criticality, the United States remains overwhelmingly dependent on imports, with China the dominant global supplier.

The magazine depth problem

The war in Ukraine, now in its fifth year, and the war with Iran that began on 28 February 2026 have together placed sustained pressure on United States munitions inventories and on the industrial base that supplies them. Analysis by the Center for Strategic and International Studies reported Patriot interceptor inventories falling from 2,330 in February 2026 to as low as 759 by July, and THAAD interceptors from 452 to as low as 234 over the same period. Defense Secretary Pete Hegseth has stated that replenishment will take months and years depending on the weapon system, and CSIS analysis projects that return to pre-war inventory levels would not be reached until 2029 or 2030 for several systems.

Those specific figures concern interceptors rather than the conventional ammunition categories in which antimony is consumed. The relevance to antimony is indirect but real: the depletion has forced a broad reassessment of magazine depth, surge capacity and input material sourcing across the entire munitions industrial base, and has moved domestic supply of critical materials from a policy preference to a procurement requirement.

Executive Order 14415, Securing America’s Defense Supply Chains and Ensuring Domestic Acquisition of Critical Materials, was signed on 20 July 2026. It states that it is the policy of the United States that not only the finished equipment deployed by the military, but also the critical materials and components necessary to manufacture, maintain, sustain and repair that equipment, are sourced domestically or from allied nations.

The order directs the introduction of requirements for defence contractors to trace their supply chains back to the origin of raw materials, to vet their suppliers, and to qualify and utilise an alternative source where they rely on an unreliable foreign supplier. From 1 January 2027 the availability of waivers under 10 U.S.C. 4872 is substantially curtailed.

Most of the order’s broader contractor requirements are not immediately effective and must first be implemented through Department of War policy, regulation or contract clauses. The order does not appropriate funding, make awards or establish procurement quantities. It creates a sourcing obligation and a timetable.

Product qualification is a key requirement in defence and industrial supply arrangements, and it cannot begin without physical samples. Against a background of contractors being required to trace and qualify domestic sources ahead of a fixed deadline, the ability to present physical, domestically refined antimony product produced from United States material in a permitted United States facility is materially different to presenting a development plan.

The restart campaign is intended to produce that sample material and to allow qualification discussions to commence with prospective offtakers, strategic partners, United States government agencies and defence primes.

Federal Engagement Continues in Parallel

AT4’s wholly owned United States subsidiary was selected by the Department of Energy to enter award negotiations under the Mines & Metals Capacity Expansion program in respect of the ASCEND-Sb Project, a potential award of up to US$18 million. The Company states that discussions with the Department of Energy on that funding package are ongoing, and that it is progressing existing applications with other agencies and initiating new applications following the program of meetings recently completed in Washington D.C.

The Company has been explicit that references to US Government policies, programs and engagement do not imply that AT4 will receive government funding, enter into a supply arrangement or become a qualified supplier, and that selection to enter award negotiations does not constitute a funding commitment.

Next Steps

  • Apply for funding and open offtake discussions for production of antimony from US sources on US soil.
  • Complete an extended campaign to collect operating data for the refinery antimony expansion study.
  • Conduct test work on specialty antimony products such as antimony trisulphide using Company-produced flake.
  • Complete the APT tungsten scoping study for the proposed expansion of Del Sol into tungsten production.

The Position

Across five announcements since late July, AT4 has moved from a conditional acquisition to federal shortlisting, gravity trials, an engaged international engineer, tungsten drilling and now a refinery restart campaign. The logic is consistent: use an existing permitted facility to produce physical domestic product quickly, use that product to open qualification discussions, and use the resulting operating data to support expansion studies and federal funding applications.

The near-term gate is corporate, not technical. Shareholders vote on the acquisition on 21 September 2026, and if the conditions precedent are not satisfied or waived by 27 September 2026 any party may terminate the agreement. Everything described at Del Sol and White Spar is being conducted under arrangements with Nexus Metals that do not confer on AT4 any legal or beneficial interest in those assets.

This article is general information only. It is not financial product advice and does not take into account any person’s objectives, financial situation or needs. Investors should read the Company’s ASX announcements in full, including those dated 28 July, 19 August, 21 August, 1 September, 4 September and 16 September 2026, together with the cautionary and forward-looking statements contained in them, and obtain independent advice before making any investment decision.