Australian miner St Barbara has accelerated its decision-making process by selecting the saleable concentrate flowsheet option for its Simberi sulphides expansion project, three months ahead of schedule.

The latest testwork has also shown that Simberi’s Sorowar ore possesses lower competency than earlier assessments indicated. This finding reduces the average life-of-mine ore competency by 20%, which in turn decreases the energy needed for crushing and grinding.

“We are excited by the improvements in the recoveries-to-concentrate and overall recovery being achieved in the flotation testwork we have completed to date,” said MD and CEO Andrew Strelein on Wednesday.

“The results have allowed us to take an early decision in favour of the saleable concentrate flowsheet, three months earlier than anticipated.”

Strelein noted that the confirmation of Sorowar ore’s consistent crushing and grinding characteristics – matching those of Simberi’s other ore zones – represents a significant breakthrough.

“The simplification of the RoM pad and crushing circuit was just the first ‘value-unlock’ that we anticipate from this important clarification of the Sorowar ore properties. The testwork programme is revealing enormous potential for flexibility in the sequencing of the openpits, pit backfill strategies to reduce waste dump construction and potential savings in waste haulage costs, as well as dramatically simplifying mine closure and reclamation planning.”

St Barbara said that the company was well funded to complete the next phases of work and beyond, including the investment in pre-expansion growth capital. This will enable the firm to deliver the clearest possible scope of work for the final investment decision anticipated in the December quarter next year. 

Current oxide production at Simberi is expected to operate at around breakeven cashflow for the 2025 financial year, inclusive of funding a significant sustaining capital investment. Accordingly, the investment in pre-expansion growth capital is being funded from the St Barbara’s balance sheet.