ASX-listed Develop Global has delivered a value uplift for its Sulphur Springs zinc/copper project, in Western Australia, with an updated definitive feasibility study (DFS) showing free cashflow almost doubling to A$1.5-billion and project value surging 76% to A$921-million.

The updated study, published on Thursday, confirms that Sulphur Springs will be technically and economically robust, with a pre-tax internal rate of return of 59% and an 18% increase in project revenue to A$3.4-billion.

Develop said the DFS paved the way for a final investment decision and subsequent construction, with all major project approvals already granted. The company will now pursue offtake agreements, project financing and pre-development activities.

The mine will be developed from underground using a bottom-up approach, which the company said would allow an aggressive production ramp-up to a steady-state rate of 1.5-million tonnes a year.

“The outstanding results from the DFS confirm that Sulphur Springs is a significant mine by any measure and is set to generate outstanding financial returns and create substantial value for Develop shareholders,” said Develop MD Bill Beament.

“The case for accelerating Sulphur Springs is clear and compelling. We have a unique opportunity which we intend to maximise by building the underground decline and associated infrastructure at the start of the project, well before we start production mining, significantly derisking the project and maximising the opportunity at Sulphur Springs.”

Under the updated plan, preproduction capital has been estimated at A$329-million, up 11% from the 2023 DFS, while average annual pre-tax cashflow (excluding capital construction) is forecast at about A$252-million – a 71% increase.

The 8.8-million-tonne ore reserve remains unchanged, grading 1.1% copper and 5.4% zinc. Average yearly recovered metal over years three to seven is projected at 79 000 t of zinc and 11 500 t of copper, with life-of-mine recovered metal of 490 000 t of zinc and 75 000 t of copper.

Beament said Develop’s in-house mining services expertise and refined cost estimates from engineering partner GR Engineering Services had helped produce a more accurate and efficient project plan.

“Develop now has two projects – Sulphur Springs and our Woodlawn copper/zinc mine in New South Wales – which give us substantial exposure to what is set to be one of the great investment themes of a generation,” he said.

“Our people and our assets make Develop a perfectly positioned company for our times.”