Overview
Stage | Permitting |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Inline Leach Reactor (ILR)
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 14.5 years (as of Jan 1, 2016) |
Latest News | Premier Reports Optimized Positive Feasibility Study for Hardrock December 16, 2020 |
Source:
p. 84,11
The managing partner of the Greenstone Partnership is Greenstone Gold Mines GP Inc. (“GGM”), which is owned 50/50 by Centerra and Premier. GGM is the current owner of all claims and leases comprising the Greenstone Gold Property.
Deposit Type
- Banded iron formation hosted
Summary:
Gold deposits in the Hardrock deposit area are classic examples of epigenetic non-stratiform BIF-hosted gold deposits (historical North Zone and West Zone). Gold mineralization has resulted from the introduction of hydrothermal fluids in zones of high crustal permeability. Most mineralized occurrences in the Hardrock deposit area lie in a zone of deformation to the immediate north of, and genetically linked to, the Tombill-Bankfield Deformation Zone. Numerous Z-folds on various scales were formed in the deformation zone. Auriferous vein systems in the MacLeod-Cockshutt and Hard Rock mines are hosted by one of the Z-folds. This structure plunges shallowly west and is mimicked by minor parasitic folds in the BIF. The mineralization is found in upright sub-vertical axial planes that trend roughly east-west. The fold axes are shallowly west-plunging.
Two main styles of mineralization at the Hardrock deposit are quartz-carbonate stringer mineralization and sulfide replacement mineralization. Quartz-carbonate stringer mineralization generally consists of a series of narrow, tightly asymmetrically folded gold-bearing quartz-carbonate stringers, which are usually attenuated, transposed and dislocated in hook-like segments. The stringers are accompanied by a gold-bearing quartz-sericite-pyrite (±arsenopyrite) alteration halo about the stringers. Sulfide replacement mineralization occurs as variable pyrite, arsenopyrite and pyrrhotite replacement of Fe oxide within the hinge zones of folded BIFs. The auriferous sulfide replacement appears to have migrated outwards along the iron oxide bands from gold-bearing quartz-carbonate stringers occupying brittle axial planar tension fractures; this replacement mineralization yields grades of 7 g Au/t or greater.
Summary:
Mining will be carried out using conventional open pit techniques with 10 m benches. An Owner mining open pit operation is planned with hydraulic shovels and mining trucks and includes outsourcing of certain support activities such as explosives manufacturing and blasting.
Production drilling of the 10 m benches will be by blast hole drill rigs with both rotary and down-the-hole (“DTH”) drilling capability. Blast holes are loaded with bulk emulsion. The majority of the loading in the pit will be carried out by three hydraulic face shovels, two 26 m3 and one 19 m3 and two front-end wheel loaders (21 m3). The shovels and loaders will be matched with a fleet of 181 t payload mine trucks. The presence of underground stopes was considered when designing the pits mainly for the void in the F-Zone, which is 150 m high and 30 m wide. Most of the other underground openings are backfilled with sand fill or rock fill.
Mining of the Hardrock main pit will occur in four phases (including the borrow pit) with a single phase for the smaller satellite pit to the east. Waste rock will be disposed of in four distinct waste dumps with three located around the pit and one further to the south. The open pit generates 548.9 Mt of overburden and waste rock (inclusive of historic tailings and underground backfill) over the life of mine (“LOM”) for an average LOM strip ratio of 3.87:1.
The LOM plan details 14.5 years of production, with a four month ramp up and commissioning period, followed by eighteen (18) months at a processing rate of 24,000 t/d ore, increasing to 27,000 t/d ore for the remainder of the mine life.
Processing
- Gravity separation
- Inline Leach Reactor (ILR)
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The gold recovery process for the Hardrock Project consists of a crushing circuit (gyratory and cone), a grinding circuit HPGR and ball mill, pre leach thickening, a leach and carbon-in-pulp (“CIP”) circuit, cyanide destruction and tailings disposal, carbon elution and electrowinning, carbon regeneration and a gold refinery.
The crushing plant is a two-stage circuit consisting of a primary gyratory crusher and a secondary cone crusher. The crushing plant is expected to operate 67% of the time in order to achieve the daily throughput. A 30% design factor has been selected for the crushing circuit equipment so that the conveyors, crushers and other crushing equipment are sized to handle up to 2,194 t/h.
The run-of-mine ore is delivered by mine haulage trucks or by loader to the crushing plant. The ore is dumped into a 300 m3 concrete receiving hopper that feeds the primary crusher. A rock breaker will be used to break oversized rocks. The 652 kW gyratory crusher c ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 1.02 |
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Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
koz
| 288 | 4,193 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 3.87 * |
Daily ore mining rate
| 27,000 t * |
Waste tonnes, LOM
| 548.94 Mt * |
Ore tonnes mined, LOM
| 141.71 Mt * |
Total tonnes mined, LOM
| 690.65 Mt * |
Daily processing capacity
| 27,000 t * |
Tonnes processed, LOM
| 141.71 Mt * |
Annual processing capacity
| 9,855 kt * |
* According to 2016 study.
Reserves at December 31, 2019:
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Probable
|
In-Situ (OP)
|
70,858 kt
|
Gold
|
1.02 g/t
|
2,324 koz
|
Indicated
|
In-Situ (OP)
|
5,722 kt
|
Gold
|
0.36 g/t
|
66 koz
|
Indicated
|
In-Situ (UG)
|
6,846 kt
|
Gold
|
3.91 g/t
|
860 koz
|
Inferred
|
In-Situ (OP)
|
85 kt
|
Gold
|
0.88 g/t
|
2 koz
|
Inferred
|
In-Situ (UG)
|
85 kt
|
Gold
|
3.57 g/t
|
1,235 koz
|
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