ASX-listed Vault Minerals has unveiled an update to its Leonora operating strategy, underpinned by a 33% increase in openpit ore reserves at its flagship King of the Hills (KoTH) operation and confirmation it will proceed with a Stage 2 processing plant upgrade.

The company said on Monday the expansion would create a “larger, longer life 2.2-million-ounce openpit ore reserve,” supporting an 18-year operating life and a production outlook of 215 000 oz/y over the next five years, peaking at 235 000 oz/y.

“Dovetailing the KoTH Stage 1 and Stage 2 processing upgrades increases Vault’s production from its Leonora operations and demonstrates the confidence Vault has in its strategic position,” the company said in a statement.

The revised plan will see throughput capacity increase by 50%, from five-million tonnes a year currently to 7.5-million tonnes a year late in the second quarter of the 2027 financial year. 

Stage 2’s capital cost is estimated at A$92-million and follows the already-committed A$80-million Stage 1 upgrade. The full A$172-million investment will be internally funded, aided by rising free cash flows as hedging rolls off.

The KoTH openpit ore reserve now stands at 110-million tonnes at 0.62 g/t for 2.2-million ounces, up from 1.65-million ounces a year earlier. The reserve update follows a remodel using a lower cutoff grade of 0.23 g/t and a higher gold price assumption of A$3 750/oz versus A$2 900/oz previously.

At the mineral resource level, KoTH now hosts 3.4-million ounces in the openpit, based on 116-million tonnes grading 0.91 g/t. This compares to 2.9-million ounces previously, with the new model incorporating a higher gold price (A$4 500/oz vs A$3 500/oz) and a lower reporting cutoff of 0.3 g/t.

Vault has also confirmed progress on site works for Stage 1, with crusher vault excavation largely complete and civil works for new adsorption tanks under way.

Enhancements from the two upgrades include a new crushing circuit, increased tankage, a 9 MW regrind ball mill, improved gravity and carbon-in-leach circuits, and expanded power and tailings capacity.

At the Darlot underground mine, drilling has increased confidence in life-of-mine extensions, while at KoTH, first-phase exploration from the W5000 drill drive has intersected mineralisation 300 m beyond the current underground envelope.

Both Darlot and KoTH underground ore reserves remain unchanged but will be updated in the first quarter of the 2026 financial year reporting cycle.