Overview
Status | Closing / Closed |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Heap leach
- Counter current decantation (CCD)
- Carbon in pulp (CIP)
- Merrill–Crowe
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Lichkvaz, Oroch, Sopka Kvartsevaya, Dalneye and Irbychan mines are classified as discontinued operations. |
Source:
p. 59
Polymetal International plc held Oroch through its 100% subsidiary Omolon Gold Mining Company LLC.
Summary:
Oroch was discovered in 1979 and was extensively explored from 1980 to 2005 through diamond drilling. It is located 110 km from Kubaka and approximately 20 km from the Kubaka-Sopka winter road. Oroch is an epithermal gold-silver deposit. The ore bodies are mainly composed of quartz and carbonate. They have a steep dip and an average width of 6 m.
The Okhotsk-Chukot volcanic belt formed over 25 Ma (middle Albian-Cenomanian) at the boundary between the continental Verkhoyansk-Chukot and Koryak-Kamchatka terranes (Fig.1). This giant belt is 3000 km long is composed of subaerial volcanic rocks.
Relative to the oceanic margin, the Okhotsk Chukot belt is divided into the inner, outer, and perivolcanic zones. The intricate structure of terranes of the basement and the Okhotsk Chukot belt produced a diversity of epithermal deposit types. The inner zone of the belt mainly accommodates porphyry Cu-Mo deposits. The outer and perivolcanic zones include gold silver and silver-tin ore deposits. The gold silver subtype is more widespread in the outer zone (Karamken, Valunisty, Kupol, and Dvoinoi). Deposits of the silver subtype (Dukat, Lunnyi, Arylakh, Golcovy and others) are confined to the volcanic rift located between the Yana Kolyma and Omolon terranes of the Okhotsk Chukot belt.
Summary:
At Oroch, open-pit mining commenced with a total of 400 Kt of ore mined, ahead of original schedule. The additional volumes will enable optimised throughput at the Kubaka mill in 2016.
Processing
- Heap leach
- Counter current decantation (CCD)
- Carbon in pulp (CIP)
- Merrill–Crowe
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Source:
Summary:
The Kubaka plant currently uses only conventional CIP cyanidation technology. Run-of-mine ore is crushed in a jaw crusher, followed by two-stage milling (SAG mill and ball mill), thickening, CIP leaching, desorption, electrolysis, carbon regeneration and doré smelting. This processing option will continue to be utilised in the long term for ores with low silver content, such as ores from the Birkachan and Tsokol mines.
Combined production numbers are reported under
Omolon hub Operation
Operational Metrics:
Metrics | 2017 |
Ore tonnes mined
| ......  |
Waste
| ......  |
Reserves at December 31, 2018:
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
Stockpiles
|
250 kt
|
Gold
|
3.7 g/t
|
29 koz
|
Proven
|
Stockpiles
|
250 kt
|
Silver
|
155 g/t
|
1,229 koz
|
Proven
|
Stockpiles
|
250 kt
|
Gold Equivalent
|
5.3 g/t
|
42 koz
|
Measured
|
Stockpiles
|
480 kt
|
Gold
|
1.2 g/t
|
19 koz
|
Measured
|
Stockpiles
|
480 kt
|
Silver
|
51 g/t
|
795 koz
|
Measured
|
Stockpiles
|
480 kt
|
Gold Equivalent
|
1.7 g/t
|
27 koz
|
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