Overview
Stage | Preliminary Economic Assessment |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Longitudinal retreat
- Paste backfill
|
Processing |
- Flotation
- Carbon in leach (CIL)
- Cyanide (reagent)
|
Mine Life | 9 years (as of Jan 1, 2012) |
Summary:
The Deposit has been described as an Archean gold lode deposit where mineralized zones are structurally controlled and consist of brittle to ductile discontinuous, anatomising structures.
Not-typical for the Kirkland Lake camp is the copper-gold association at Upper Beaver with the widespread and pervasive development of magnetite-feldspar-actinolite-epidote and carbonate-sericite. These features are more consistent with some deposits in the Timmins camp (such as the McIntyre Mine) along the Destor-Porcupine Fault Zone. Kontact, Dube and Benham (personal communication) have suggested that the Upper Beaver deposits are consistent with an alkali porphyry copper-gold model.
Mineralization at Upper Beaver, as described by Queenston (Kontack, Dube and Benham, unpublished):
- Occurs both in flat and steeply dipping zones;
- Is of replacement-type with rare vein-type mineralization;
- Is associated with minor to pervasive alteration which includes feldspar, epidote, carbonate, sericite, silica and magnetite with trace hematite; and
- Has an element association of Cu, Au, or Au-Cu with associated molybdenum.
Queenston classifies the mineralization as three main groups of zones (from south to north):
- South Contact Zones;
- Beaver North Zones; and
- North Basalt Zones.
The South Contact Zones disseminated mineralization consists of two, relatively flat-lying zones. These occur below and south of the mine workings in the Upper Tisdale contact area, marked by the roll in the stratigraphy from a north-westerly to north-easterly strike. Gold and copper contents increase where steeply dipping quartz-chalcopyrite-quartz veins and stringers intersect the flat-lying disseminated zones. The host is mafic breccia and volcaniclastic conglomerate with variable silica, epidote and calcite alteration, along with magnetite, chalcopyrite, pyrite, pyrrhotite, and visible gold.
The Beaver North Zones include a series of east-northeast striking, north-dipping, fracture, vein and stringer systems containing chalcopyrite, magnetite, pyrite and visible gold. They occur below and north of the mine workings near the south contact of the large (600 m) syenite plug. The fracture systems crosscut a variety of rock types and are tentatively named by their position in the stratigraphy when first identified as: Syenite Zones, North Contact Zone (the basalt/syenite contact area), Porphyry Zones (associated with feldspar porphyry), Syenite Breccia Zones, and Lower Gauthier Zone (in Upper Tisdale assemblage rocks).
The North Basalt Zones are located at the north contact of the 600 m, syenite plug. They are also characterized by a series of fractures and stringers with chalcopyrite and magnetite crosscutting syenite to mafic syenite and basalt.
Mining Methods
- Longitudinal retreat
- Paste backfill
Summary:
The mining method selected for the extraction of the mineralized rock is Longhole Longitudinal Retreat mining. Sublevels would be driven in the mineralization every 35 vertical metres to allow access for drilling, blasting and mucking operations. Access to the sublevels would be provided by drifts driven either from the shaft access drifts on every third sublevel or from the internal ramps.
Stope dimensions would nominally be 65 metres long by 35 metres high by 5.6 metres wide. A slot/ventilation/backfill raise would be driven at the extremity of each stope. Successive rows of boreholes would be blasted into the slot raise and the resulting open stope.
Cemented paste backfill and development waste would be placed in the stopes as they retreat from the slot raise to the entrance to the stope. The life of mine (LOM) schedule includes 217 stopes which would produce an average of approximately 1,750 tonnes per day (tpd) of mill feed. Typically, this corresponds to mining four sublevels concurrently (i.e. approximately 440 tpd / sublevel).
Processing
- Flotation
- Carbon in leach (CIL)
- Cyanide (reagent)
Source:
Summary:
Gold and copper mineralization would be processed in a 2,000 tpd expandable mill and paste backfill plant using conventional crushing, grinding, flotation and CIL processes. The current flow sheet does not include a gravity circuit as more testing is required to determine if this step is warranted, particularly as the design considerations would examine this mill as a future central facility for all of Queenston?s Projects within the Kirkland Lake gold camp. P&E has included the capital cost of a gravity circuit in the process plant estimate. Metallurgical testwork completed by SGS Lakefield Research Limited indicates gold recovery of 98% and copper recovery of 90% using simple floatation and cyanidation. Payable gold and copper are estimated at 95% for gold and 90% for copper. Approximately, 80% of the gold is recovered in flotation with the balance being recovered from CIL. The projected gold-rich copper concentrate would be shipped to a smelter off site.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 5.1 |
Copper
|
Recovery Rate, %
| ......  |
Copper
|
Head Grade, %
| 0.37 |
Copper
|
Concentrate Grade, %
| ......  |
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Projected Production:
Commodity | Product | Units | LOM |
Gold
|
Payable metal
|
oz
| 1,055,200 |
Copper
|
Metal in concentrate
|
t
| ......  |
Copper
|
Concentrate
|
t
| ......  |
Gold Equivalent
|
Payable metal
|
oz
| ......  |
Operational Metrics:
Metrics | |
Daily milling rate
| 2,000 t * |
Daily ore mining rate
| 2,000 t * |
Waste tonnes, LOM
| 1,562 kt * |
Ore tonnes mined, LOM
| 6,839,800 t * |
* According to 2012 study.
Reserves at December 31, 2018:
Category | Tonnage | Commodity | Grade | Contained Metal |
Probable
|
7,992 kt
|
Gold
|
5.43 g/t
|
1,395 koz
|
Probable
|
7,992 kt
|
Copper
|
0.25 %
|
19,980 t
|
Indicated
|
3,636 kt
|
Gold
|
3.45 g/t
|
404 koz
|
Indicated
|
3,636 kt
|
Copper
|
0.14 %
|
5,134 t
|
Inferred
|
8,688 kt
|
Gold
|
5.07 g/t
|
1,416 koz
|
Inferred
|
8,688 kt
|
Copper
|
0.2 %
|
17,284 t
|
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Corporate Filings & Presentations:
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Aerial view:
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