ASX-listed American Tungsten & Antimony's restart campaign at the Del Sol refinery has started ahead of schedule, with the company having launched the leach and electrowinning circuit on site using US-sourced material.

The restart campaign represents the first physical demonstration of the company's US mine-to-metal strategy.

The Del Sol hydrometallurgical refinery, in Nevada, is using material from the White Spar antimony mine, in Arizona.

Pending completion of American Tungsten's acquisition of Del Sol, which was announced late in July, the restart campaign is being undertaken in cooperation with Nexus Metals under arrangements that permit American Tungsten to progress agreed work programmes at the assets prior to completion of the deal.

The antimony flake produced by the Del Sol refinery is intended to enable qualification discussions with prospective offtakers and strategic partners, including US government agencies. It is a product that can be used to produce higher-value specialty antimony products such as Regulus II antimony ingot and antimony trisulphide.

American Tungsten aims to generate and use data from the restart campaign at Del Sol for further expansion studies. The company also continues with testwork on material from the Dutch Mountain, Tennessee Mountain and third-party sources of antimony.

“The [restart] campaign is an important step in our strategy to establish a vertically integrated US supply chain for antimony. Producing antimony in Nevada from material sourced in Arizona will allow us to demonstrate a domestic mine-to-metal pathway and provide physical product for qualification and engagement with prospective customers.

“US policy increasingly requires domestic and allied supply of critical materials used in defence supply chains, and antimony sits at the centre of these requirements. The ability to demonstrate physical production from US material differentiates American Tungsten from projects that remain at the development stage. Our objective is to build on that position in antimony and, in time, tungsten through the proposed ammonium paratungstate expansion at Del Sol," says executive chairperson Timothy Morrison.