Agglomerated oxide ore is stacked for heap leaching at Alacer Gold’s Çöpler mine in eastern Turkey. The company is studying the feasibility of building a facility for pressure oxidation of sulphide ore that currently is mined and stockpiled at Çöpler. (Photo courtesy of Alacer Gold)
Alacer Gold has reported the results of a definitive feasibility study (DFS) of the processing of sulphide ore through whole ore pressure oxidation at its Çöpler gold mine in Erzincan province, eastern Turkey, about 550 km east of Ankara. Alacer will conduct basic engineering and further optimization studies, as well as completing the permitting process, in advance of a construction decision for the sulphide operation, anticipated in the first quarter of 2015. Commissioning of the sulphide operation is currently planned for the fourth quarter of 2017.
“Together, the results of the DFS and our mineral resources and reserves update represent a material step forward for the company,” the Alacer statement said. “They demonstrate the viability of processing sulphide ore at the mine, thereby extending the mine life while generating attractive and robust financial returns.”
The Çöpler mine has been in production since late 2010, processing oxide ore via an open-pit, heap leach operation.
Alacer is forecasting the mine’s 2014 production to be in the range of 200,000 to 225,000 oz of gold.
The Çöpler pressure oxidation facility will have the capacity to process sulphide ore at 5,000 metric tons per day (mt/d) and will result in a 20-year life for Çöpler operations. Life-of-mine gold production is forecast at 3.2 million oz from July 1, including both oxides and sulphides. Total cash costs are forecast at $540/oz, and all-in costs are forecast at $801/oz.
In the course of mining oxides ores for the current heap leach operation, Alacer has mined and stockpiled more than 2 million mt of sulphide ore at a grade of 4.9 g/mt gold. Prior to the planned commissioning of the pressure oxidation plant in 2017, the sulphide ore stockpile is expected to grow to about 9 million mt at a grade of 3 g/mt gold.
Throughput for the pressure oxidation plant is planned at a nominal 5,000 mt/d.
Gold recoveries are expected to average 94% from sulphide ore. Long lead time and critical equipment items for the plant will include the oxygen plant (28 months), autoclaves and agitators (15 months), and SAG and ball mills (14 months).
The Çöpler DFS base-case economic analysis was predicated on a gold price of $1,300/oz, a copper price of $3.29/lb, and average annual copper production of 3.7 million lb, and a silver price of $22/oz and average annual silver pro- duction of 40,000 oz.
The Çöpler deposit will continue to be mined by a contractor using conventional truck-and-shovel methods. Three open pits are currently being mined for oxide ore. They will ultimately converge into a single pit over the life of the sulphide project. The mine design for the sulphide project was based on an optimized pit shell using a gold price of $800/oz.
The total mining rate will continue at current rates of roughly 33 million mt/y until 2018, when the rate will be halved to roughly 17 million mt/y. The mining rate is then planned to reduce further in 2020, averaging roughly 11 million mt/y from 2020 until mining ceases at the beginning of 2026. Processing of stockpiled sulphide ore is planned to continue until 2034.