Develop’s foundational asset now stands at a 13.8 million tonnes grading 9.3% zinc equivalent, up from 13.4Mt at 8.1%, following the completion of a multi-million drilling program designed to expand mine life beyond a decade.
Contained metal in the volcanogenic-hosted massive sulphide deposit has increased to 1.3Mt zinc equivalent, including 786,000t zinc grading 5.7%, 153,000t copper at 1.1%, and 10.4 million ounces silver grading 22.5 grams per tonne.
The zinc grade is up over 50%, while silver grades are up some 15% delivering 260,000t and 2.4Moz in additional ore metal, but 56,000t less contained copper.
Lead and gold are also present as by-products.
Indicated resources are 32% larger at 1.16Mt zinc equivalent, accounting for 90% of the resource that will inform the optimised definitive feasibility study due for release early next year.
Sulphur Springs was subject to a DFS that suggested capital costs of $169 million, for an operation to produce about 15,000tpa copper and 35,000tpa zinc over a decade with a pre-tax net present value of $472 million based on prices of US$6300 per tonne copper and $2650/t zinc. Pricing is around $7650/t and $3200/t respectively today.
Develop managing director Bill Beament said the new resource was “pivotal” for Sulphur Springs as a combined open pit and underground development, positioning it as a significant producer of zinc and copper, but he cautioned its assumptions were conservative.
Permitting is nearing completion.
The project was first discovered in the 1980s. Despite decades of work, Develop considers the area underexplored, and anticipates further resource growth over time given the lenses are not closed off, and the potential for VHMS discoveries to cluster.
Develop also owns the Woodlawn zinc-copper mine in New South Wales, where it revised resources to 7.3Mt at 13.2% zinc equivalent last month, having recently completed its A$30 million upfront acquisition, leaving it with more than $40 million in the bank, and cash being generated from its mining services division.
