Overview
Status | Closing / Closed |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Open stoping
- Cut & Fill
- Cemented (undefined) backfill
|
The Cosmo Mine ceased production in February 2020. Work commenced on the Cosmo Howley rehabilitation strategy in October 2020, under Kirkland Lake Gold ownership, and Agnico Eagle continued implemention of this closure strategy following the merger. Although reclamation is a legislative requirement, the manner it is executed is determined by the company that owns the property. The work at the site aligns with Agnico Eagle’s regulatory and risk based approach to remediate land in a manner that allows for future land use when possible.
Reclamation of a 100-year-old mining camp is underway. Acid generating waste rock was excavated and placed into the Cosmo Pit. This waste was layered with non-acid generating waste rock then submerged under 19 metres of water to inhibit acid rock drainage. |
Source:
p. 1
Company | Interest | Ownership |
Agnico Eagle Mines Ltd.
|
100 %
|
Indirect
|
NT Mining Operations Pty Ltd.
(operator)
|
100 %
|
Direct
|
February 8, 2022 – Agnico Eagle Mines Limited and Kirkland Lake Gold Ltd. are pleased to announce the successful completion of the previously announced merger of equals transaction (the “Merger”).
The combined company will continue as Agnico Eagle Mines Limited.
Contractors
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Deposit Type
- Vein / narrow vein
- Orogenic
Summary:
A variety of genetic models, ranging from magmatic through hydrothermal to syngenetic, have been postulated in the past for the formation of gold deposits in the Pine Creek Geosyncline. Gold and base metal mineralization in the Pine Creek Geosyncline is commonly associated with granite intrusions and have often been classified as high temperature contact aureole deposits. A secondary host rock control has also been suggested due to the association of gold mineralization with carbonaceous metasedimentary rocks, such as at Cosmo Mine.
Native gold is the main mineralization mineral and is commonly present as micron sized grains; coarse nuggets are rare. Gold is commonly associated with pyrite, arsenopyrite and pyrrhotite and in places with minor base metal sulphides. Quartz, chlorite, sericite and carbonates are the common gangue minerals in the gold-quartz deposits.
All gold deposits in the Northern Territory show some structural control at the regional and deposit scales, with most deposits within the Pine Creek Orogen trending northwest southeast.
Base metal mineralization in the Pine Creek Orogen strike significantly differently than the gold veins, suggesting different discrete mineralizing events. They are syngenetic.
Cosmo gold mineralization is hosted across a stratigraphic sequence (‘Cosmo Mine Sequence”) that lies between a major dolerite sill (‘Zamu’ dolerite unit) and a thick package of high sulfide, graphitic mudstone (‘Pm ........
Mining Methods
- Open stoping
- Cut & Fill
- Cemented (undefined) backfill
Summary:
The Cosmo Mine ceased production in February 2020.
The Company has mined the Cosmo Deposit as an underground mine at a depth of 600mRL. The Cosmo workings are accessed via a decline commencing from the southern wall of the Cosmo open pit. The mining activity at Cosmo has progressed from the Eastern Lodes utilizing Avoca-style cut and fill stoping to the Hinge Zone and Western Lodes where uphole open stoping is employed.
Ore was previously mined by a combination of Modified Avoca and Long-hole Open Stoping when isolated stopes were extracted. Mining is now focused on the Hinge Zone and Western Lodes where the uphole open stoping will speed up access to stope ore as upper stopes will be mined without the requirement to backfill.
Uphole Open Stoping is sequenced from the top down. As soon as the drill drive is completed, Stope development can begin. Rib pillars are left at intervals along the length of each panel to support the hangingwall without the requirement of back filling. Sill pillars are not required to regulate stope development. All underground production mineralization is trucked via the decline to the surface ROM stockpile adjacent to the Cosmo open pit. Mineralization is then loaded into on-highway haul trucks to be transported 67km to the Union Reefs processing plant.
Development waste is used for stope backfill as dictated by the production schedule. Waste not immediately required for backfill is typically stockpiled ........
Flow Sheet:
Source:
ROM ore is crushed at a rate of up to 2.5Mtpa in a three stage crushing circuit incorporating a primary jaw crusher operating in open circuit and a secondary and tertiary cone crushers operating in closed circuit with a double deck banana screen. Crushing circuit product, at a nominal size of 12mm is conveyed to the grinding circuit via the Fine Ore Bin (“FOB”).
The FOB, with a live capacity of 2,500 tonne, provides a buffer of approximately seven to eight hours between the crushing and grinding circuits. Ore is reclaimed via a slot feeder at a variable rate and is conveyed to the grinding circuit.
As the crushing circuit capacity exceeds that of the milling circuit, crushed ore is stockpiled and fed back into the grinding circuit using a front end loader into an emergency feed hopper and feeder arrangement.
Crushed ore is ground in the grinding circuit consisting of two ANI single stage rubber lined ball mills operating in closed circuit with a nest of Warman cyclone classifiers. A proportion of ball mill discharge is directed to the gravity circuit incorporating four Knelson concentrators, two per mill. Knelson concentrator tailings report back to the mill discharge stream whilst the concentrated coarse gold is sent to the gold room for further processing.
Flow Sheet:
Summary:
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Source:
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Production:
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | 2017 | 2016 |
Tonnes milled
| 259,729 t | 646,848 t |
Annual mining capacity
| | 2 Mt |
Reserves at December 31, 2020:
Northern Territory Open Pit Mineral Resources were estimated using a cut-off grade of 0.5 g/t Au.
Northern Territory Underground Mineral Resources were estimated using a cut-off grades ranging between 1.5 g/t Au and 2.0 g/t Au.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured & Indicated
|
25,200 kt
|
Gold
|
2.3 g/t
|
1,830 koz
|
Inferred
|
19,200 kt
|
Gold
|
2.3 g/t
|
1,390 koz
|
Commodity Production Costs:
| Commodity | Units | 2017 |
Cash costs (sold)
|
Gold
|
USD
|
1,661 / oz
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
1,996 / oz
|
Financials:
| Units | 2017 |
Capital expenditures
|
M USD
|
7.5
|
Revenue
|
M USD
|
27.4
|
Operating Income
|
M USD
|
-33.5
|
Pre-tax Income
|
M USD
|
|
After-tax Income
|
M USD
|
|
Corporate Filings & Presentations:
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