Larvotto Resources has made gravy from the overlooked leftovers at its Hillgrove antimony-gold project in New South Wales, confirming it can successfully recover valuable antimony and gold from a 1.4 million-tonne pile of historic tailings at the soon-to-be operational project.
The company says initial metallurgical testwork on material from the site’s old tailings storage facility (TSF) has delivered impressive flotation recoveries of between 80 and 95 per cent for antimony and 40 to 75 per cent for gold. The results have given the company a green light to treat the old waste as a supplementary feed source for its main Hillgrove processing plant, which is slated for a production restart in August.
The historic tailings were deposited before 2002 at a plant designed primarily to recover antimony. Larvottto says its tailings carry an indicative head grade of 1.8 per cent antimony and 1.6 grams per tonne (g/t) gold, similar numbers to those at many other operating gold-antimony operations.
The company’s testwork produced concentrates from the coarser material grading between 15 and 45 per cent antimony and 4 to 12g/t gold, opening up a potential further revenue stream on top of the pricey antimony-gold mining and an unfolding tungsten kicker.
The testwork also confirmed the tailings material is amenable to the same conventional flotation methods being deployed in the upgraded Hillgrove plant.
The ability to reprocess the tailings offers a threefold benefit. Not only does it provide a potential new revenue stream and additional ore source optionality, but it also delivers a substantial environmental dividend.
The TSF1 facility sits adjacent to a 500-metre-deep gorge and reprocessing the material will form part of a progressive rehabilitation of the site, reducing long-term management requirements and, no doubt, pleasing the locals.
Adding another layer of potential value, the company says tungsten metal, whose price is skyrocketing, is also present in the tailings and could be recovered.
While dedicated testwork for tungsten has yet to be completed, management says the flowsheet designed to treat gold flotation tailings should be directly applicable, as it now considers blending material options.
Larvotto Resources managing director Ron Heeks said: “The pathway is becoming very clear; reprocess the tailings, recover the metals, and simultaneously rehabilitate a facility that sits adjacent to a 500-metre gorge. That environmental outcome matters both to the project and to the broader community.”
While the August restart remains front and centre, Larvotto is also expanding its high-grade resource base at Hillgrove, which currently totals 8.76 million tonnes at 4g/t gold and 1.1 per cent antimony.
According to the company’s feasibility study, the operation is expected to produce an average of 85,710 ounces of gold equivalent annually across its eight-year mine life, comprising 40,556 ounces of gold and 4878 tonnes of antimony.
On the ground, the processing plant’s A$70 million refurbishment is advancing towards wet commissioning in August. Development has been backed by a substantial funding package, including a second US$31.5 million (A$47.5 million) drawdown in March from the company’s US$105 million (A$160 million) Nordic Bond facility.
For an old mine with a new lease on life, there is a certain satisfaction in seeing a company turn old waste into new money. Larvotto’s move to re-evaluate the Hillgrove tailings looks like a shrewd piece of business, potentially lowering the barrier to a mine restart while cleaning up an old environmental headache.
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By Andrew Todd
