The Hidden Valley open-pit gold-silver operations were officially opened on September 30, 2010, in Morobe province, Papua New Guinea (PNG) after having reached commercial production in May. The project is owned and operated by Morobe Mining Joint Ventures (MMJV), a 50:50 joint venture of Harmony Gold, of South Africa, and Newcrest Mining, of Australia. Harmony was the initial developer of the project. Newcrest bought a 30% stake in Harmony’s PNG assets in July 2008 for $229 million and sole-funded exploration, development, and construction costs in the joint-venture area totaling around $300 million to earn an additional 20%, reaching its 50% stake in June 2009.
Hidden Valley is located 210 km north-northwest of Port Moresby, the capital of Papua New Guinea, and 90 km south-southwest of Lae, a port on the Solomon Sea. Mining is from two open-pits located approximately 5 km apart: the Hamata pit, which exploits the Hamata gold orebody, and the larger Hidden Valley pit, which exploits the Hidden Valley and Kaveroi gold and silver orebodies. Based on current reserves, Hidden Valley operations are expected to produce about 255,000 oz/y of gold and 4 million oz/y of silver over a mine life of 10 years. Mill throughput will average about 4.2 million mt/y.
In addition to developing Hidden Valley, MMJV has an extensive exploration program in Morobe province that includes its advanced Wafi-Golpu porphyry copper-gold project about 60 km north of Hidden Valley. Ongoing drilling success has increased the mineral resource at Wafi-Golpu to 30 million oz of contained gold and 8 million mt of contained copper.
A prefeasibility study for Wafi-Golpu is in progress, targeting further increases in the tonnage and grade of the resource; optimization of production rates from panel caves; optimization of gold recovery from the refractory Wafi orebodies; and positioning of infrastructure, waste dumps and storage facilities to minimize environmental impacts and optimize costs.