Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit / Underground |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Blast Hole Stoping
|
Processing |
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 7 years (as of Jan 1, 2015) |
Source:
p. 84,85-86
Pursuant to an amended and restated partnership agreement entered into with Premier Gold Mines Limited dated March 9, 2015, Centerra and Premier formed a 50/50 partnership (the “Greenstone Partnership”) for the joint ownership and development of the Greenstone Gold Property (formerly known as the Trans-Canada Property).
939 unpatented cells and mining leases and totaling 18,944 ha. It is located 14 km northeast of the town of Beardmore, Ontario. The Greenstone Partnership owns 100% of 1 lease that comprise the Brookbank project with the remaining portion (18 leases) of the Brookbank project subject to a joint venture agreement with Metalore Resources Limited (“Metalore”). The joint venture is between the Greenstone Partnership (74%) and Metalore (26%). The Brookbank project hosts the Brookbank, Cherbourg and Foxear deposits and the Irwin prospect.
Deposit Type
- Breccia pipe / Stockwork
- Vein / narrow vein
- Hydrothermal
Summary:
The 6.5 kilometre long Brookbank shear zone hosts the Brookbank, Cherbourg, and Foxear deposits. The deposits occur along lithological contacts between mafic volcanics and metasediments. Other areas of gold mineralization are present in one or more of the localized deformation bands within the hanging wall mafic volcanics, which are generally parallel to the Brookbank main zone within the Brookbank shear zone structure.
The zones of mineralization at Brookbank, Cherbourg, and Foxear occur within one of several bands of intense deformation and hydrothermal alteration at or near the contact between domains of mafic flows and polymictic conglomerate. Hydrothermal alteration in the vicinity of the mineralization consists of silicification, carbonatization, sericitization, chloritization, hematization and sulphidization. This alteration is commonly marginal to quartz-carbonate veins, fractures, and stockworks and may exceed 50 metres in width locally.
Mineralogical studies indicate that the precious metal mineralization consists of goldsilver particles with an approximate gold to silver ratio of 80:20. The gold occurs primarily as late fracture-controlled mineralization. The mineralization forms elongate lenticular particles associated with grain boundaries and possibly crystallographic planes. The gold generally consists of fine grained free gold particles, although there is very little visible gold even in areas of plus 30 g/t Au assays. Gold values are highest in the quartz–carbonate veinlets/stringers.
Sulphide mineralization (pyrite and minor chalcopyrite) is also present within the sheared host and quartz veinlets.
Economic concentrations of gold in the Geraldton area are typical of Archean epigenetic hydrothermal gold deposits normally considered to be mesothermal lode gold deposits. The gold mineralization is primarily located in areas of high strain and deformation with brittle structures providing a pathway and also hosting mineralization as veins or replacement zones with associated alteration. There are also low grade zones that locally have less obvious structural control, less veining, and less intense hydrothermal alteration on a hand specimen scale, but these clearly have strong deposit scale structural controls.
The mineralization on the Brookbank Project occurs within quartz-carbonate veinlets/stringers, fractures and/or stockworks associated with hydrothermal alteration. The latter is generally located within bands of intense deformation at the contacts between domains of mafic flows and polymictic conglomerate.
Mining Methods
- Truck & Shovel / Loader
- Blast Hole Stoping
Summary:
Based on the orientation, size, and suggested competence of the rockmass, open pit and underground longitudinal blasthole stoping have been selected as the most suitable mining methods. As Brookbank is located in Northern Ontario, personnel with mining experience are assumed to be available. The mining method requires mobile equipment that is commonly used in the industry.
Processing
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Run of mine material will be fed via a conveyor belt to a 0.81 metre (32 in.) x 1.14 metre (45 in.) jaw crusher located at the mine site. The run of mine material will be crushed to minus 89 mm (3.5 in.) and will be rehandled with a front end loader into 40 tonne capacity trucks. Trucks will travel 27 kilometres along the mine access road and Highway 11 to the mill where a second crushing step, consisting of a cone crusher, will further reduce the rock size to minus 32 mm (1.25 in.). The crushed product will be conveyed and stored in a 500 tonne capacity bin.
The crushed rock reclaimed from the bin will be conveyed to a 3.90 metre (12.8 ft.) x 5.18 metres (17 ft.) ball mill driven by a 1,043 kW (1,400 HP) motor equipped with a variable speed drive. The ball mill will be operated in closed loop with a cyclone. The underflow will return to the ball mill and the overflow will feed the trash screen. The trash screen undersize will feed an 11 metre diameter pre-leach thickener t ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 5.3 |
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Projected Production:
Commodity | Units | LOM |
Gold
|
oz
| 370,758 |
Operational Metrics:
Metrics | |
Daily milling rate
| 900 t * |
Daily ore mining rate
| 900 t * |
Annual mining capacity
| 328,500 t of ore * |
Ore tonnes mined, LOM
| 2,161,596 t * |
* According to 2015 study.
Reserves at December 31, 2018:
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
In-Situ (OP)
|
2,638 kt
|
Gold
|
2 g/t
|
172 koz
|
Indicated
|
In-Situ (UG)
|
1,852 kt
|
Gold
|
7.2 g/t
|
430 koz
|
Inferred
|
In-Situ (OP)
|
86 kt
|
Gold
|
2.4 g/t
|
14 koz
|
Inferred
|
In-Situ (UG)
|
404 kt
|
Gold
|
4.1 g/t
|
54 koz
|
Commodity Production Costs:
| Commodity | Units | Average |
Assumed price
|
Gold
|
CAD
|
1,316 / oz *
|
* According to 2015 study / presentation.
Operating Costs:
| Units | 2015 |
Total operating costs ($/t milled)
|
CAD
| 109.48 * |
* According to 2015 study.
2015 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Total CapEx
|
$M CAD
|
......
|
OP OpEx
|
$M CAD
|
......
|
UG OpEx
|
$M CAD
|
......
|
Total OpEx
|
$M CAD
|
......
|
Gross revenue (LOM)
|
$M CAD
|
......
|
Pre-tax Cash Flow (LOM)
|
$M CAD
|
......
|
Pre-tax NPV @ 5%
|
$M CAD
|
......
|
Pre-tax IRR, %
|
|
......
|
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Corporate Filings & Presentations:
- Subscription is required.
- Subscription is required.