The increase in our 22.5% share of Antamina's gross profit before depreciation and amortization in the fourth quarter was primarily due to significantly higher sales volumes as the benefits from the expansion project and resulting higher production levels were realized. Our 22.5% share of gross profit was affected by a one-time $10 million (US$43 million - 100% basis) labour settlement charge for the new three-year labour agreement ratified in the quarter.
Tonnes milled in the fourth quarter were 22% higher than a year ago and averaged approximately 128,000 tonnes per day, which reflects Antamina's expanded mill capacity. The mix of mill feed in the fourth quarter of 73% copper-only ore and 27% copper-zinc ore was the same as a year ago. Copper production increased by 28% to 121,600 tonnes compared with 95,000 tonnes in the fourth quarter of 2011, reflecting the additional mill throughput and slightly improved recoveries. Zinc production in the fourth quarter of 44,400 tonnes was 7% lower than the same period last year as lower ore grades offset the increased mill throughput. Molybdenum production decreased in the fourth quarter compared with a year ago as a result of lower molybdenum grades and recoveries.
The increased cost of sales in the fourth quarter compared with a year ago was due to substantially increased sales volumes in both copper and zinc and the one-time US$43 million charge for the new three-year labour agreement ratified in the quarter. Excluding the one-time labour settlement charge, total cash costs, before by-product credits, was similar to the same quarter last year.
Our 22.5% share of Antamina's copper production in 2013 is expected to be in the range of 90,000 to 100,000 tonnes and our 22.5% share of zinc production is expected to be in the range of 45,000 to 50,000 tonnes.
Quebrada Blanca (76.5%)
Operating results at the 100% level are summarized in the following table:
Three months ended Year ended December 31, December 31, 2012 2011 2012 2011----------------------------------------------------------------------------Tonnes placed (000's) Heap leach ore 1,495 1,796 6,625 6,621 Dump leach ore 5,668 6,030 25,361 23,288 -------------------------------------------------------------------------- 7,163 7,826 31,986 29,909Grade (TCu%) (note 1) Heap leach ore 0.96 0.84 0.89 0.90 Dump leach ore 0.54 0.43 0.50 0.46Production (000's tonnes) Heap leach ore 9.3 10.6 39.5 33.6 Dump leach ore 5.0 7.1 22.9 29.8 -------------------------------------------------------------------------- 14.3 17.7 62.4 63.4Sales (000's tonnes) 15.1 17.5 62.2 63.5Cost of sales (US$ million) Operating $ 122 $ 88 $ 410 $ 301 Distribution $ 2 $ 2 $ 7 $ 7 Depreciation and amortization $ 26 $ 29 $ 97 $ 96Gross profit (loss) summary ($ millions) (note 2) Before depreciation and amortization $ (5) $ 46 $ 82 $ 255 Depreciation and amortization (25) (29) (97) (95)---------------------------------------------------------------------------- After depreciation and amortization $ (30) $ 17 $ (15) $ 160----------------------------------------------------------------------------1. TCu% is the percent assayed total copper grade.2. Results do not include a provision for the 23.5% non-controlling interest in Quebrada Blanca.
