Eldorado Gold today provides an update on its 100% owned Kisladag gold mine in Turkey. Kisladag is a low-grade, bulk-tonnage, open pit operation that uses heap leach for gold recovery.
On June 27, 2017, the Company reported that, while placement of estimated recoverable gold on the leach pad proceeded as planned, the gold solution grade and consequently gold recovery from the leach pad had lagged internal expectations. Initial laboratory and in situ tests, where solution chemistry was adjusted, indicated normal recovery rates were still expected. The Company also believed that more time for solution to flow through the current stack height of the leach pad (approximately 80 meters at the highest point) was required.
During the third quarter, a significant amount of laboratory test work was undertaken, primarily focused on the zone of mineralization located around the base of the open pit where mining is currently underway. Monthly composite samples from material recently placed on the pad, even with adjusted solution chemistry, have indicated lower gold recoveries. Final recoveries in the low 40% range are now anticipated for this material. This will result in a reduction in the recoverable leach pad inventory by approximately 40,000 ounces of gold.
In light of the lower recoveries, the Company is revising its 2017 guidance for Kisladag to 170,000 to 180,000 ounces at cash costs of $500 to $550 per ounce. Guidance for 2018 and beyond is currently under review.
Further metallurgical test work on heap leaching is ongoing to determine the extent of the materiality of the impact on gold resources and reserves, and possible implications for the carrying value of the mine.
In parallel with ongoing laboratory heap leach test work, the Company is investigating alternative treatment methods for this material, which includes studies on finer particle breakage, either through milling or high pressure grinding roll (HPGR) crushers. The Company has previously contemplated construction of a mill at Kisladag and historic and ongoing test work using bottle rolls and other metallurgical tests indicates that milling should result in consistently higher recoveries compared to heap leaching throughout the orebody; the potential benefits from HPGR requires further studies and test work.