ASX-listed Cobalt Blue has outlined in an updated scoping study on the Halls Creek project, in Western Australia, the viability of recovering silver.

The study outlines a sequential development of the Onedin and Sandiego deposits using a common processing plant at Onedin to produce copper cathode, zinc oxide and silver doré.

By incorporating silver recovery at both deposits, the updated scoping study delivers a before-tax net present value of about A$317-million and a before-tax internal rate of return of 47%, which can generate A$618-million free casfhlow over the mine life, for an initial capital cost of A$75-million. From first production, this development pathway has an estimated payback period of three years.

With the silver recovery being incorporated for Halls Creek for the first time, it establishes a third revenue stream from metal already contained in both the Onedin and Sandiego deposits.

The updated scoping study envisions average production of 4 000 t/y of copper cathode, 13 000 t/y of contained zinc as zinc oxide and 130 000 oz of contained silver in doré over 11 years of production.

On this basis, Halls Creek's revenue will be split 56% from copper, 37% from zinc and 7% from silver. The updated scoping study uses conservative long-term pricing of $13 000/t for copper, $3 100/t for zinc and $50/oz for silver.

Cobalt Blue is working to ensure capital efficiency at Halls Creek by using one plant to produce three saleable metals. A common processing pathway for Onedin and Sandiego replaces the previously proposed Sandiego flotation concentrator.

The common plant also provides a platform to incorporate additional regional feedstock that can support increased production, longer mine life and stronger project economics. “This study is a significant step for Halls Creek. It brings silver into the picture from both Onedin and Sandiego, alongside copper and zinc, and it does that with a single  processing plant and a staged development, which makes for a simpler, more capital-efficient pathway to three saleable metals, with a lower external funding requirement," comments Cobalt Blue CEO Dr Andrew Tong.

Cobalt Blue is advancing Halls Creek through a preliminary feasibility study which is targeted for completion in the first half of 2028.