Engineering & Mining Journal

APR 2019

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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Page 33 of 83

LEACH PAD DESIGN 32 E&MJ • APRIL 2019 duced more than 100,000 oz gold. Active operations concluded in June 2016. Re- sidual leaching continued and the mine produced 65,000 and 34,000 oz of gold in 2016 and 2017, respectively. The company said in its annual report for 2017 that prices would determine fu- ture residual leaching at the site. By the end of September 2018, the mine had produced roughly 9,500 oz gold for the year. After a recoverability analysis, the company wrote down $13.1 million of heap leach inventory at the mine and dis- continued adding cyanide to the stacks. As a result of the write-down, costs rose roughly $400/oz and the mine was expected to "exceed full-year revised 2018 cost guidance," New Gold reported. Also, as a result, residual leaching there entered its final phase. The pad there is a success story, An- gel Chung, general manager of the mine, told E&MJ. From the outset, the sys- tem has performed as intended, he said. "Up until closure, there has been no ev- idence of instability, sinking, leaks, mud slides or cracks." The single-use pad was built in phases, Chung said. "The first phase was built in 2006-2007 and the last one in 2014," he said. "First ore load was placed in 2007 and the last load in 2016." The underfill is a clay of low permea- bility. "It was moisture controlled to pro- vide the required compaction specs with a minimum of 25 cm height," Chung said. The channel collection ditch liner is made of 2-mm-thick HDPE. A 1.5-mm LLDPE liner lines the rest of the pad. Overfill is 0.75-in. crushed barreno, be- gonia, and hospital limestone stacked to a height of at least a meter in most plac- es, Chung said. "Ore types and quantity, haul truck capacity; and total estimated Cerro San Pedro writes down $13.1 million in heap-leach inventory last year as gold prices teetered around bear territory. The mine runs a problem-free, 12-year-old heap leach pad. (Photo: New Gold) On-belt analysis to manage ore variability Intelligent multi-elemental and moisture analysis *NEW* SizeScan 3D IR camera PSD anaylsis & volume High performance customised systems Specialists in sensing for bulk sorting - accurate measurements for each 30 seconds of conveyed flow Safe, robust, proven, reliable Still processing more waste than you need to? Measure, Control, Improve ... minute by minute. See us at booth 2107 at CIM in Montreal.

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