Operations and productivity at PT Freeport Indonesia have continued to improve following the first-quarter 2012 work interruptions in connection with efforts to resume normal operations. PT Freeport Indonesia's milling rates averaged 179,500 metric tons of ore per day in second-quarter 2012, compared with the first-quarter 2012 average of 114,800 metric tons of ore per day. Mining operations in the Grasberg open pit are approaching normal levels and underground mining operations at the DOZ underground mine continue to be ramped up following the 2011 work stoppages. Mining rates at the DOZ underground mine averaged 45,400 metric tons per day in second-quarter 2012 and are expected to reach 80,000 metric tons per day in fourth-quarter 2012.
At the Grasberg mine, the sequencing of mining areas with varying ore grades also causes fluctuations in the timing of ore production resulting in varying quarterly and annual sales of copper and gold. FCX expects sales from Indonesia to approximate 750 million pounds of copper and 960 thousand ounces of gold for the year 2012, compared with 846 million pounds of copper and 1.3 million ounces of gold for the year 2011. PT Freeport Indonesia's revised sales estimates for 2012 are lower than previous estimates reported in April by approximately 50 million pounds of copper and 60 thousand ounces of gold because of a deferral of access to high-grade material in the open pit to future periods and a slower than expected ramp-up of the DOZ underground mine. FCX expects sales from Indonesia to increase in 2013 as PT Freeport Indonesia gains access to higher ore grades.
Indonesia's unit net cash costs (including gold and silver credits) of $1.37 per pound of copper in second-quarter 2012 were higher than unit net cash costs of $0.22 per pound in second-quarter 2011 primarily reflecting lower sales volumes.
Because of the fixed nature of a large portion of Indonesia's costs, unit costs vary from quarter to quarter depending on volumes of copper and gold sold, as well as average realized gold prices during the period. FCX estimates Indonesia's average unit net cash costs (net of gold and silver credits) would approximate $1.24 per pound of copper for the year 2012, based on current sales volume and cost estimates and assuming an average gold price of $1,600 per ounce for the second half of 2012. Projected unit net cash costs for 2012 are higher than previous estimates reported in April primarily because of lower copper sales volumes and lower by-product credits. Indonesia's unit net cash costs for 2012 would change by approximately $0.04 per pound for each $50 per ounce change in the average price of gold for the second half of 2012. FCX expects Indonesia's unit net cash costs to decline significantly in future years, compared to the year 2012, because of higher projected copper and gold volumes.