Develop Global has doubled its projected free cash flow for its Sulphur Springs zinc-copper project in Western Australia’s Pilbara to $1.5 billion after releasing its definitive feasibility study, showing strong returns driven by higher metal prices and a larger mine plan.
The definitive feasibility study (DFS) puts Sulphur Springs back on track for a final investment decision and construction, with all major project approvals granted.
Develop’s updated DFS pre-tax net present value at 8 per cent (NPV8) rose to $921 million, a 76 per cent increase from the 2023 DFS. Its pre-tax internal rate of return stepped up to 59 per cent in 2025 with a roughly three-year payback, followed by the $1.5b free cash flow.
Develop managing director Bill Beament said that the outstanding results from the DFS confirmed that Sulphur Springs is a significant mine “by any measure” and can generate “outstanding financial returns” and value for the company and its shareholders.
“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,” he said.
Beament added this would happen before the beginning of production mining, significantly de-risking the project and maximising the overall mining opportunity at Sulphur Springs.
The project will be developed as an underground operation, which Develop said would allow for flexibility in the mine plan and scheduling sequence.
The company will be using a bottom-up long-hole stoping sequence with cemented paste fill, with nameplate throughput increasing to 1.5 million tonnes per annum (Mtpa), up from 1.25Mtpa, enabling a two-year ramp-up and five years at a steady state within an approximately eight-year mine life.
Beament said Develop is planning on leveraging the project’s significant untapped geological upside, and they are confident in its potential to deliver substantial mine life growth.
“Develop now has two projects in Sulphur Springs and our Woodlawn Copper-Zinc mine in NSW, 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.”
Sulphur Springs holds an unchanged ore reserve of 8.8 metric tonnes (Mt) at 1.1 per cent copper and 5.4 per cent zinc; zinc and copper concentrate grades are targeted at roughly 50 per cent Zn and 21 per cent Cu respectively.
Upfront capital costs for Develop are $329 million, with $289 million for plant and infrastructure and $40 million for pre-production; with costs estimated at +/- 15 per cent for Q4 in the 2025 calendar year.
Life of mine (LOM) onsite operating costs are at an average of $114 per tonne once processed, with the forecasted LOM revenue sitting at $3.42 billion, with the average annual pre-tax cash flow of approximately $252 million.
Meanwhile, there is no offtake agreement for the copper metal over the LOM and only a residual zinc offtake beginning after year five of production, therefore leaving offtake capacity available.
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