Prominent Hill copper resource grows

OZ MINERALS has released its Prominent Hill mineral resource and ore reserve statement for 2011 which shows an increase in copper resources, a fall in gold resources and a dip in both copper and gold reserves on the back of mining depletion.

OZ Minerals managing director and chief executive Terry Burgess at Prominent Hill.

Mineral resources now stand at 272.7 million tonnes at 0.98% copper, 0.7 grams per tonne gold for 2.68Mt copper and 6.3 million ounces of gold.

It compares to the previous year’s resource of 285Mt at 0.9% copper, 0.8gpt gold for 2.54Mt copper and 7.2Moz of gold.

Copper metal in resources increased thanks to the inclusion of the Kalaya resource as well as an increase in the Ankata resources.

It was despite a fall in copper metal as a result of the reclassification of some near-surface resource, reported in 2010, to an underground resource.

The reclassification involved a change in the cut-off grade from 0.3% copper to 0.5% copper.

In the 12 months to June this year, there was also a 6.5Mt fall in copper ore in the Malu pit resource from mining depletion.

Gold metal in resources have fallen due to additional surface drilling and reinterpretation in the Kalaya resource, as well as changing the cut-off grade for material previously classified as near-surface from 0.5gpt gold to 1gpt gold.

Meanwhile, ore reserves for 2011 came in at 72.3Mt at 1.13% copper and 0.64gpt gold for 818,000t copper and 1.5Moz gold.

It compares to ore reserves of 75Mt at 1.21% copper, 0.67gpt gold for 905,000t copper and 1.6Moz gold in 2010.

OZ managing director and chief executive officer Terry Burgess said the average copper grade was slightly lower due to the inclusion of further tonnes of gold reserves.

“Our focus for extending mine life is now on upgrading the resources in the upper levels of the Malu zone in the 300 metres immediately beneath the pit, with a view to development of a second underground mine to be developed in conjunction with the open pit,” Burgess said.

Burgess expects an exploration decline to access the area to be completed in mid-2012, after which drilling can begin.

“The next step in 2012-2013 will be to further investigate the potential in both the Kalaya zone and the deeper Malu mineralisation to assess mining possibilities after the life of the open pit,” he said.

Shares in OZ were trading 12c lower at $10.54 this afternoon.