Aeris Resources has provided an update on the feasibility study underway on its 100% owned Stockman project in Victoria, Australia, guiding for a development path that includes ultrafine grinding and the Albion Process from Glencore Technology.

Andre Labuschagne, Aeris’ Executive Chairman, said: “We are very excited with the potential of the Stockman project. Since acquiring Stockman as part of the Round Oak acquisition in July 2022, our technical teams have materially advanced the project.”

With a recent update to the mineral resource estimate for the Currawong deposit, the company now intends to mine only Currawong for the first 12 years of operations, at a rate of up to 850,000 t/y of ore, he added.

“Mining Currawong simplifies the operation compared to the previous plan of mining Currawong and Wilga concurrently, whilst also reducing up-front capital,” he said.

The processing strategy will involve two stages: the mine site processing plant will have a simplified flowsheet producing a high-grade copper concentrate and a bulk concentrate containing copper, zinc, gold and silver. The copper concentrate will be transported to market while the bulk concentrate will be trucked to a regional offsite processing facility. The offsite processing facility will use ultrafine grinding and the Albion Process to produce separate copper, zinc and precious metals saleable products.

Labuschagne said: “The addition of the Albion Process has potential to provide a step change in metal recoveries and materially improve project economics. An initial desktop study has been completed with the technology vendor, utilising the recent feasibility study and metallurgical test work results. A number of potential locations for the off-site processing facility have already been identified.

“The Albion Process technology is in operation at multiple locations globally, processing copper, zinc and precious metals. This is well established, oxidative leaching technology proven to treat a wide range of concentrates with high metal recoveries.”

The Albion Process uses a combination of ultrafine grinding and oxidative leaching at atmospheric pressure to work. It also tolerates a more variable feed and lower grade than other processes, according to Glencore Technology, meaning it can make some projects feasible and profitable where alternative technologies could not. The sulphides in the feed are oxidised and valuable metals liberated, with the economic metals recovered by conventional downstream processing. Test work requires only small sample masses with no pilot plant, Glencore Technology says.

The process has produced high recoveries in refractory gold and in base metal concentrates at the six Albion Process plants in operation across the globe, according to the company.

Labuschagne says opportunities to further improve other aspects of the operations, its ESG footprint and project economics have also been identified, which are progressing.

He added: “The feasibility study will now focus on verification of the metallurgical, flowsheet and economic assumptions associated with incorporating the Albion Process into the project. We are targeting to finalise the feasibility study in the second (June) half of 2024.”

The Stockman project was acquired by Round Oak Minerals Pty Ltd (ROM) from Independence Group NL (IGO) in December 2017. Aeris subsequently acquired the ROM businesses, including the Stockman project, in July 2022.

In 2019, ROM completed a Selection Phase Study (SPS), consolidating and advancing earlier studies undertaken by previous owners of the project, IGO and Jabiru Metals Limited. The ROM SPS comprised the development of two underground mines (Wilga and Currawong), mining approximately 1 Mt/y, and an on-site flotation processing plant producing copper and zinc concentrates with precious metal by-products. Results from the SPS provided the basis for ROM to commence a Definition Phase Study.