Newcrest Mining is investing A$1.91 billion to develop an underground panel cave mine to extract the Cadia East orebody as the next major ore source for its Cadia Valley operations in central western New South Wales, 250 km west of Sydney. The orebody is one of the world’s largest gold deposits, with a current reserve of 961 million mt grading 0.61 g/mt gold and 0.33% copper and containing 18.7 million oz of gold and 3.16 million mt of copper. Indicated and inferred resources total 2.3 billion mt grading 0.44 oz/mt gold and 0.28% copper for 33 million oz of gold and 6.59 million mt of copper. The Cadia East mine will become Australia’s largest underground mine. Production from the mine is expected to underpin Newcrest’s Cadia Valley operations for at least the next 30 years.
Construction at Cadia East began upon receipt of board approval in early April 2010. The construction schedule includes underground mine development, modifications to the existing processing plant to increase capacity from 24 million mt/y to 26 million mt/y, and further development of bulk underground mining technologies, including the application of automated remote loaders. First production is expected in 2012, to be followed by commissioning and appreciable production during 2013. Provisional mine scheduling calls for production of about 4 million mt in year three of operations and buildup to a design production rate of 27 million mt/y in year nine of operations. Total production costs for Cadia East are expected to come in at under A$250/oz over the first 10 years of operations.
The Cadia East project will enable Newcrest’s Cadia Valley operations to increase production to between 700,000 and 800,000 oz/y of gold and 75,000 and 100,000 mt/y of copper in concentrate over a period of 10 years. Combined production from the existing Cadia Hill and Ridgeway mines during Newcrest’s fiscal 2009, ending June 30, 2009, totaled 532,000 oz of gold and 57,000 mt of copper.
The Cadia East deposit is a porphyry zone of gold-copper mineralization extending up to 2.5 km east of the existing Cadia Hill mine. The system is up to 600 m wide and extends to 1,900 m below surface. Mining will extend from 500 m to approximately 1,650 m below surface. Underground infrastructure will include crushers, declines, production/undercut levels, ventilation shafts, and an ore handling and conveyor system. The panel cave will be conducted in three lifts, with mining to commence at the base of the orebody.