American Tungsten & Antimony (ASX:AT4) begins restart and expansion planning for Del Sol Refinery and White Spar Antimony Mine
American Tungsten & Antimony has provided an operational update following site visits to the Del Sol Refinery in Nevada and the White Spar Antimony Mine in Arizona, outlining planned restart, expansion and technical work programs across the assets.
The activities remain subject to completion of the share sale and purchase agreement announced on 28 July 2026, which has not yet completed.
Highlights
AT4 Chief Executive Officer Casper Adson and the Del Sol operating team commenced ramp up and expansion planning at the Del Sol Refinery and White Spar Antimony Mine, subject to completion of the acquisition.
Restart of the Del Sol antimony flake circuit using White Spar feedstock is intended to commence in the September 2026 quarter, subject to completion of the acquisition.
Operating data from Del Sol is intended to support expansion studies and planned applications for US Government funding programs, including Defense Logistics Agency programs.
Requests For Proposal have been issued to international engineering firms covering antimony flake capacity expansion and the addition of Regulus II antimony metal, antimony trisulphide, sodium antimonate and ammonium paratungstate circuits at Del Sol.
AT4 held a pre application meeting with the Nevada Division of Environmental Protection regarding an application to expand permitted capacity from 18,500 short tons of feed per year to approximately 100,000 short tons of feed per year and add APT production.
The Del Sol site visit focused on plant condition and readiness, reagent and consumable requirements, staffing and shift structure, laboratory capability and the sequencing of expansion works within the existing building and permitted site footprint.
AT4 stated that the Del Sol facility is constructed, permitted and connected to established infrastructure.
The company considers that constraints to increased output are principally equipment additions within existing site space.
The company also confirmed that no scoping study, pre feasibility study or feasibility study has been completed for any expansion of the facility and no capital or operating cost estimate has been prepared.
The existing processing building houses the current alkaline leach and electrowinning circuit, with unused floor space available for potential additions including further caustic leach tanks, filter presses and electrowinning cells.
AT4 has also identified antimony trisulphide and sodium antimonate as target products for the facility, subject to confirmation during an independent technical review.
Subject to completion of the acquisition and available funding, AT4 intends to initiate the restart of the Del Sol plant in the September 2026 quarter.
The restart is planned to occur on a phased basis, with initial batches used to establish circuit performance before throughput is progressively increased.
The company intends to collect operating data during the restart program covering batch cycle time, throughput, antimony recovery, reagent and consumable consumption, power draw, cathode quality, product purity, labour requirements and maintenance intervals, with the data intended to inform engineering and design work for any expanded facility.
At White Spar, AT4’s Chief Executive Officer and company geologist completed site visits to review existing infrastructure and historical workings.
The property hosts on site accommodation, an office, heavy machinery, haulage trucks and excavators.
No Mineral Resource or Ore Reserve has been estimated for the White Spar Antimony Mine in accordance with the JORC Code 2012.
Mineralised material has previously been extracted from the small scale extraction zone and hauled to the Del Sol Refinery for processing.
Subject to completion of the acquisition and obtaining required approvals, AT4 intends to extract a bulk sample from the existing extraction zone to assess the metallurgical performance of White Spar material through the Del Sol flowsheet.
The planned work program across the assets includes White Spar metallurgical test work, bulk sample extraction and processing, exploration program design, Del Sol restart and baseline data capture, engineering engagement for capacity and product expansion, and permitting activities.
AT4’s planned workstreams remain conditional on completion of the Del Sol Refinery and White Spar Antimony Mine acquisition, along with the availability of equipment, personnel, laboratory capacity, funding and regulatory approvals.
The company has stated that the acquisition has not completed and shareholders should not assume that completion will occur or that the described work programs will proceed.