Tri Origin Minerals has doubled resources at its flagship projects in New South Wales with JORC-compliant base and precious metals exceeding 25 million tonnes.

Tri Origin managing director Bruce Robertson says resources at the company's main zinc-copper project at Woodlawn, near Goulburn, have been boosted by 8.6 million tonnes which represent tailings from the west and south tailings dams.

This adds to the previously announced JORC resource of 10.1 million tonnes for Woodlawn's underground project. Another 2.5 million tonnes is anticipated to be added from a third tailings dam at Woodlawn after it has been drilled and evaluation studies are completed.

In addition, Tri Origin had previously outlined 6.6 million tonnes of base and precious metals resources at the Lewis Ponds project, near Orange.

"This is a significant resource base for the company, particularly at Woodlawn, and leads to the potential to develop a 2 million tonne per annum operation," Bruce Robertson says.

He says the company is on track to deliver an economic evaluation and commercial framework for Woodlawn through a bankable feasibility study in the first quarter of 2008, with broad capital cost estimates of around $150 million.

"A positive economic evaluation from the bankable feasibility study would likely result in a tailings re-treatment project in the order of 1.5 million tonnes per annum and an underground operation producing 440,000 tonnes per annum."

Bruce Robertson says Tri Origin will establish an integrated project to blend a low grade concentrate from tailings dams re-treatment at Woodlawn, with higher grade concentrate from the underground project.

"Combined tonnage throughput would give us the benefit of significant operating economies of scale with the potential to produce 120,000 - 130,000 tonnes of concentrates at the site per annum."

Bruce Robertson says the zinc focused Woodlawn project is underway during a time of continued buoyant prices for base metals, with plenty of scope for smelters within the Asian region to consume further zinc concentrate from international suppliers.