HIDDEN VALLEY – PRODUCTION AND RESOURCES
The total production statistics for the Hidden Valley project, from commissioning in July 2009 and commercial production from October 2010 to September 2013, is shown in Table 4. Unfortunately, no data has been published concerning waste rock produced during the construction phase, although it is expected to be more than 30 million tonnes1 (see SMEC, 2010a,b).
Annual processing capacity is presently about 3.5 Mt of ore, grading ~2.1 g/t Au and ~25 g/t Ag, to produce about 5,500 kg Au and 50,000 kg Ag per year. The MMJV is currently working towards optimising the existing mining infrastructure and mill and increasing the processing rate to about 4.7 Mt of ore per year. As of December 2012, reported total mineral resources remaining are 117.9 Mt grading ~1.5 g/t Au and ~27 g/t Ag – (~5.61 million ounces Au, 102 million ounces Ag) (Newcrest, 2013). At present processing rates, this gives a mine life of some 45 years.
A detailed site map is shown in Figure 5, outlining all major site features (open cuts, power station, processing plant, tailings storage facility, waste rock dumps and rivers and streams). Recent aerial views of the main part of the project site are shown in Figure 6 (the Hamata open cut mine, processing plant and tailings storage facility) and Figure 7 (looking from the Hidden Valley open cut to Hamata).
Figure 5: Detailed site plan of the Hidden Valley Au-Ag mine (SMEC, 2010a)
Figure 6: Hidden Valley Au-Ag mine, Papua New Guinea, showing the Hamata pit (centre), tailings storage facility (centre left) and processing mill in between (photo: Gavin Mudd, Mineral Policy Institute, February 2011).
Figure 7: Hidden Valley Au-Ag mine, Papua New Guinea, showing the Hidden Valley pit (front) looking towards the tailings storage facility (centre left) (MMJV, 2011).