The property is located in volcanic rocks that are largely of intermediate composition which host the steeply dipping gold and silver bearing veins where most of the gold is spatially associated with zones of altered rocks, primarily those of propylites and metasomatites. The host rocks include andesites, tuffs of andesites and, rarer, tuffs ofdacite. The mineralization is a gold-quartz low sulphide type.
|Location||Khabarovsk Territory, Russia|
|Processing||600 Ktpa Merrill Crowe, 1000 Ktpa HL circuit at Svetloye|
|Reserves (JORC)||0.7 Moz GE, 3.3 g/t average grade|
|Resources (JORC)||0.8 Moz GE, 4.7 g/t average grade|
|Production start date||2003 (Khakanja), 2016 (Svetloye)|
|Life of mine||2019 (Khakanja), 2024 (Svetloye)|
Okhotsk is one of Polymetal’s more mature operations with both gold and silver production. The operation comprises the Khakanja 600 Ktpa Merrill-Crowe processing plant and the recently launched 1,000 Ktpa Svetloye heap leach circuit, which is set to become the key driver for sustaining production levels in the long-term. In addition to the ore sourced from the Svetloye and Avlayakan deposits, the Company processes 3rd party ore at the Khakanja plant. Exploration activities at several near-mine properties are ongoing and subject to positive results and are expected to extend the life-of-mine at the Khakanja processing plant.
The Okhotsk operation is located in the Khabarovsk region in a very sparsely populated area covered with taiga forest. It is approximately 1,100 km north of the city of Khabarovsk and 480 km west of the city of Magadan. The seaport of Okhotsk if situated approximately 118 km from the operation and can be accessed via all-year unpaved roads built by Polymetal between 1999 and 2002. Due to the site’s remote location, electricity is generated via diesel powered generators with a capacity of 6 MW.
The Avalayakan mine is located 893 km from the Khakanja processing plant, so the ore is first tracked to the port of Kiran and is then transported via ship to the port of Okhotsk during navigation season. From Okhotsk, the ore is trucked to the processing plant for processing.
Svetloye is located 240km south-west of Okhotsk, the access port for the Company’s Khakanja mine and approximately the same distance from Khakanja itself. It is accessible by a 380 km winter road from Okhotsk and by a 105 km winter road from the seaport of Unchi, which is used for delivery of fuel and supplies during the summer navigation period. Between May and November the site is accessible only via helicopter.
The Khakanja deposit was discovered in 1960 and extensive exploration took place from 1963 to 1971. Polymetal acquired the asset in 1998 and construction started in 2000 followed by the launch of mining activities in 2002. The processing plant was commissioned in 2003 with a capacity of 300 ktpa, which was subsequently expanded to 400 ktpa in 2005 with the addition of the ball mill, and to 600 ktpa in 2006, with the replacement of three-stage crushing by one-stage crushing and SAG milling.
The Yurievskoye deposit was developed as a satellite to Khakanja. It was discovered in 1975, and exploration was conducted between 1976 and 1980 by trenching, diamond drilling and underground development. Open-pit mining commenced in 2007 and was completed in 2010. Underground development to access mineralisation below the pit commenced in 2010. Mining and processing at Yuriveskoye stopped in 2012.
Polymetal acquired Svetloye exploration and mining license in December 2010 for the total consideration of US$ 9.25 million. In 2014, results of resources and reserves audit were announced following geological exploration, and in September the decision was made to construct and develop the project. Svetloye was finally launched in August of 2016, 9 months ahead of schedule. Total capital expenditures comprised US$ 60 million. The current life of mine for Svetloye is approximately 7 years during which it is anticipated to deliver more than 500 Koz of gold. Significant near-mine exploration activities are expected to result in material resource additions. At present, Svetloye is running at 100% of its design capacity.
Gold mineralisation at Svetloye is formed by vuggy silica (secondary quartzite) associated with a high-sulphidation epithermal system. Most of gold mineralisation is very fine grained and disseminated. Gold-bearing silicification occurs as flat lenses or pods, which outcrop at the surface and have true widths of between 20 and 120 m. Higher-grade zones are adjacent to breccias. The oxidation zone develops to a depth of 150 m.
At Avlayakan, open pit mining has been completed in the Central pit with current activity concentrated on stripping at the North-eastern pit. Mining is carried out by a conventional truck and shovel operation with drilling and blasting of ore and waste. High-grade ore (greater than 5 g/t) is trucked to the port of Kiran, shipped to Okhotsk and then transported to the Khakanja processing plant. Low-grade ore is stockpiled at the Avlayakan mine site.
The main purpose of the trial mining at Avlayakan is for the Group to better understand vein geometry and confirm run of mine grade when mining a narrow ore body by conventional open-pit methods. Extensive grade control and mine-to-model reconciliation are performed by the Group to try to ensure that accurate estimation techniques are employed in the future. The metallurgical properties of ore will also be studied in detail during batch processing at the Khakanja processing plant.
Three ore zones (Emmy, Elena and Tamara) are proposed to be mined at Svetloye. Open pit mining will be conducted by conventional drill-and-blast and truck haulage. The average strip ratio over the life of the mine is 1.4 t/t. The open pits will reach the maximum depth of 130 meters.
The Khakanja processing plant is based on conventional cyanide leaching technology, using the Merrill Crowe process to recover silver and gold content from the solution.
Prior to processing, run-of-mine ore is crushed in the jaw crusher and is followed by three stages of grinding (SAG mill, one first stage and two second stage ball mills), slurry thickening, agitated cyanide leaching, counter-current decantation in four thickeners and the Merrill Crowe process.
The precipitate is then dried, homogenised, sampled, packed and shipped to third-party refineries for toll processing into doré bars, which are then sold. Tailings are filtered and trucked to a dry-stacking tailings storage facility immediately adjacent to the plant. Currently, the plant processes material above nameplate capacity of 600 ktpa.
|Ore Reserves||Tonnage, Mt||Gold grade, g/t||Silver grade, g/t||Copper grade, %||GE grade, g/t||Gold, Koz||Silver, Moz||Copper, Kt||GE, Koz|
|Mineral Resources||Tonnage, Mt||Gold grade, g/t||Silver grade, g/t||Copper grade, %||GE grade, g/t||Gold, Koz||Silver, Moz||Copper, Kt||GE, Koz|
- 48.0 km of exploration drilling has been completed in the Okhotsk region in 2017, a 70% increase compared to the previous year.
- At Levoberezhny (35 km from Svetloye), in-fill drilling confirmed the continuity of mineralisation and the option of using heap leaching to extract gold.
- 12.8 km were drilled at Kundumi within the Central and Western ore zones resulted in a material increase in mineral resources. In 2018, the Company plans to undertake an additional 15 km of core drilling targeting both resource-to-reserve conversion and further resource growth.
- At Khotorchan and Gyrbykan, multiple new veins have been discovered during the year. In 2018, Polymetal plans to complete resource definition drilling and start open-pit mining on previously discovered veins.