OZ Minerals fired the first production holes in the first stope of the Ankata underground mine at its Prominent Hill operations in South Australia. Development of the underground mine at Prominent Hill began in November 2010 to access the higher-grade Ankata deposit. The access decline reached the Ankata orebody in August 2011, and the first development ore was hauled to surface in September 2011.

The underground Ankata operation will ramp-up over 2012 and is anticipated to reach its full 1.2 million-mt/y mining rate in the third quarter. The mine is expected to contribute 0.8 million to 1 million mt of ore in the 2012 ramp-up year. The average grade of the Ankata ore to be mined in 2012 is expected to be in the range of 2.3% to 2.8% copper.

The Ankata resource is located 800 m from Prominent Hill’s Malu open-pit. The higher-grade ore from the underground mine is expected to contribute an average of 25,000 mt/y of copper and 12,000 oz/y of gold production each year for five years. Mining will be via sub-level open stoping techniques. The ore has metallurgical characteristics similar to the ore in the open-pit, and the material can be blended with the open-pit feed for processing.

“This is an excellent milestone for Prominent Hill, delivering on our commitment to achieve first production from stoping in the first quarter of 2012. We now have an open-cut and underground mine in operation that should enable OZ Minerals to maintain production at 100,000 to 110,000 mt/y of copper in concentrates,” said OZ Minerals CEO Terry Burgess.

OZ Minerals is exploring around the Prominent Hill area for further copper-gold deposits. The company has access to a highly prospective, 7,000-km2 tenement package in its own right and through its joint venture with IMX Resources. The company has committed to spending A$70 million on near-mine and regional exploration in 2012.