PERTH (miningweekly.com) – Minerals developer Heron Resources has updated the resource estimate at its Woodlawn tailings retreatment project, in New South Wales, to incorporate additional drilling done between 2008 and 2011.
A mineral resource of 9.83-million tonnes, grading 2.25% zinc, 0.51% copper, 1.33% lead, 0.31 g/t gold and 32 g/t silver has now been estimated for the tailings. This was a 4.6% increase in measured and indicated resource tonnage, but a 6.1% overall decline on the previously estimated tonnage, owing to a more conservative density estimate.
Heron said on Tuesday that the tailings retreatment project was an integral part of the ongoing feasibility study at Woodlawn. The retreatment project was based on the reprocessing of the tailings generated from the Woodlawn openpit and underground mining operations, which ran between 1978 and 1998.
The tailings are contained in three tailings dams and a number of drill programmes have been undertaken over the years, with the most recent resource estimate using 332 holes and 1 312 samples.
Further drilling on the tailings was planned as part of the Woodlawn feasibility study to provide additional material for metallurgical and paste-fill testwork.
Over an 11-year mine life, the Woodlawn project was expected to produce some 353 000 t of zinc, 77 000 t of copper, 112 000 t of lead, 8.9-million ounces of silver and 59 000 oz of gold.