The Dukat deposit covers 11 sq km and comprises 87 distinct ore veins (only eight of them are fully depleted) and 34 ore zones. Ore bodies dip steeply, with an average width of 0.6 to 21 m. The five largest ore zones display continuity over several hundred metres and account for 85 per cent of ore reserves of the deposit. The largest ore body has a maximum thickness of up to 21 m, a strike length of approximately 1.2 km. Major ore minerals include silver sulphides and silver sulphasalts, as well as native silver and native gold associated with sulphides.

Goltsovoye is a typical narrow-vein deposit of multiple ore bodies with an average width of 4.6 m. In addition to silver, the ore also contains amounts of lead as well as traces of zinc and copper. The distribution of silver in the veins and geometry of ore bodies is highly irregular and requires a substantial amount of in-fill drilling to convert resources to reserves. Most ore bodies have a medium dip (35 to 45 degrees). They can be traced for up to 565 m along strike and are open down dip. The major ore minerals are sulphides, including galena, freibergite, and other silver sulphides.

Zone 9 comprises five ore bodies with a total strike length of approximately 1,900 m and width varying from 2 m to 12 m. Vertically dipping mineralisation is structurally adjacent to the Lunnoye fault (located in its footwall) and is heavily brecciated in places. The most important ore mineral is quartz. Silver is present in the form of sulphides and sulphosalts, while gold is mostly found in free form. The quartz has a distinct white colour and is easy to identify visually. Silver and particularly gold grade distribution within the ore body are highly erratic, requiring significant in-fill and grade control drilling.

At Dukat, underground mining is now the only source of ore. The conditions for underground mining activites are favourable, with competent ore and host rock made more stable by the permafrost extending to a depth of 300 to 350 m. As a result, very little support is required and a mostly sub-level open stoping mining method is used with minor amounts of ore extracted from manual shrinkage stopes. Underground mining at Dukat is characterised by wide, steeply dipping ore bodies with good wall stability and consistent geometry down-dip and along strike. The Dukat underground mine is accessible by multiple adits located near main ore zones and is relatively shallow, with all current and planned working levels located less than 100 m below the valley floor.

Both underground development and stoping at Dukat are fully mechanised, with the use of trackless equipment. The ore is delivered by trucks to a centralised underground railway. The railway transports the ore to the crusher, which is located immediately at the exit of the railway from the underground mine. Ore from the crusher and the adjacent ore storage yard is then transported to the Omsukchan concentrator by contractors.

Underground conditions at Goltsovoye are generally favourable, with competent host rock. The ore is of variable competency, with some weak stopes closer to the surface. All underground workings are located in permafrost, with limited support being provided by steel anchors and wire mesh. The mining methods include sub-level open stoping (50 per cent. of ore, used for steeply dipping relatively wide ore bodies), shrinkage stoping (25 per cent., steeply dipping narrow veins), longwall mining (15 per cent., shallow-dip narrow veins) and inclined room-and pillar (10 per cent., shallow-dip wide ore bodies).

The Lunnoye mine is accessible by two declines driven from the flanks of the ore body. A 10 m crown pillar separates the underground mine from the depleted pit. Underground conditions at the Lunnoye mine are challenging due to the proximity of the fault and, in some places, the significant brecciation of ore and hanging wall, which necessitate significant support structures. Most permanent underground workings are supported either by steel frames, where stability is poor, or by steel anchors and shotcrete, where conditions are moderate. Open stopes are supported by wire mesh and anchors. Ground conditions tend to improve at the lower levels of the mine as the ore body becomes more distant from the fault.

Both underground development and stoping at Lunnoye are fully mechanised, with the use of trackless equipment for drilling (long-hole production drill rigs and development jumbos), mucking (LHDs), and trucking (underground trucks). Ore is transported directly to the surface and then to the processing plant by contractors.

The Omsukchan concentrator uses conventional sulphide flotation technology, with each section designed to treat different types of feedstock. To achieve optimal results, extensive geotechnological testing is employed to determine the suitability of a particular ore for one of the sections and to assist in the selection of technological parameters (feed rate and reagent addition).

Section 1 is designed to treat simple metallurgical ores from the Dukat mine which typically yield higher recoveries with lower reagent consumption and generate concentrate that is amenable to cyanidation. The processing circuit comprises three-stage grinding (one SAG mill and two ball mills) followed by flash flotation and conventional flotation.

Section 2 is designed to treat ores that are technically more complicated, including feedstock from Goltsovoye, Lunnoye and old stockpiles. The processing circuit comprises two-stage grinding (one SAG mill and one ball mill) followed by gravity ........