Source:
p. 94
Eldorado Gold Corp. indirectly owns 100% interest in Lamaque mine through Integra Gold (Triangle) and Or Integra (Sigma), wholly owned subsidiaries of Eldorado Gold.
Deposit Type
- Breccia pipe / Stockwork
- Vein / narrow vein
- Orogenic
Summary:
The Lamaque Project is located in the southeastern Abitibi Subprovince of the Archean Superior Province in the Canadian Shield. The region has several large-scale strike faults and/or shear zones, trending W to WNW and dipping steeply to the north. The Cadillac Tectonic Zone (“CTZ”) is one of the most prolific structures in terms of gold mineralization.
Current gold resources at the Lamaque Operations are defined in the Triangle, Plug No. 4 and Parallel deposits, with most resources occurring in the Triangle Deposit.
The Triangle deposit is hosted by volcaniclastic rocks and minor volcanic flows of the Val-d’Or Formation, which have been intruded by numerous intrusions, dykes and sills of compositions varying from mafic to intermediate.
Gold mineralization at Triangle occurs within quartz-tourmaline-carbonate and pyritic gold veins in the Triangle Plug and in the adjacent massive mafic lapilli-blocks tuffs. The veins are localized in a series of shear zones and fractures that cut both units. The thickest and most continuous veins are localized with E-W striking ductile-brittle reverse shear zones dipping 50-70° south. Veins also occur as extensional shear vein splays dipping 20-45° south as well as subhorizontal extension veins. The latter generally are not volumetrically significant. Gold also occurs in sericite carbonate-pyrite alteration selvages along the veins, which are commonly foliated to schistose within fault zones.
The Plug No. 4 deposit is located 550m north of the Triangle deposit. No. 4 Plug is a fine- to mediumgrained magnetic gabbro intrusion measuring roughly 100 to 150 m in diameter. A series of E-W striking reverse shear zones dipping between 45° and 75° to the south cuts all units at Plug No. 4. The shear zones are spaced roughly 25 to 50 m apart and have been identified to a depth of more than 1000m from surface in the gabbro. Gold mineralization at Plug No. 4 is found in quartztourmaline carbonate-pyrite veins. Sub-horizontal extensional veins also occur in this deposit as vein arrays or clusters that extend for tens of meters down the center core of the gabbro intrusion. At Plug No. 4 these vein clusters can carry significant but quite erratic gold concentration.
The Parallel Deposit is located 650 m northwest of the No. 3 Mine and 900 m east-southeast of Lamaque Mine main shaft. Gold mineralization at Parallel is hosted within fine- to medium-grained porphyritic diorite, similar to the host rock at the Sigma Mine. The ore zones at Parallel occur as subhorizontal extension veins at shallow depths (70-200 m) and as east-west striking shear veins dipping approximately 30° south at deeper levels. The mineralized veins consist of quartz and carbonate with lesser amounts of tourmaline, chlorite and sericite.
Gold mineralization is also documented in numerous zones which are peripheral to, but show similar styles of vein control and host rock characteristics to, the three above deposits. The principal zones currently defined at the project include: Fortune Zone; No. 5 Plug (including No. 35 Vein); No. 3 Mine (including No. 1 and 2 Veins); South Triangle Zone; Mylamaque Zone; No. 4 Vein; No. 6 Vein; Sixteen Zone and Sigma East Zone. In addition, both the Sigma Mine and Lamaque Mine contain significant zones of residual mineralization not exploited during the historical mining of these deposits.[2019 AR F-40, p.99]
The volcanic sequence at Lamaque strikes E-W and dips steeply south, with tops facing south. It consists of andesitic basalt lapilli tuffs mixed with lesser andesite flows and flow breccia and mafic lavas. The oldest intrusive rocks at Lamaque are porphyritic diorite dykes and stocks.
Numerous chimney or plug-shaped intrusions varying from mafic to felsic compositions occur at Lamaque, with the Main Plug being the most productive host rock. The Main Plug is roughly elliptical (250 m E-W by 100 m N-S), plunges northeast at 70° and has been traced to a depth of 1,800 m. The core of the Main Plug is medium to fine grained, dark grey and homogeneous tonalite-diorite, which grades outward to quartz diorite and finally diorite. The West and East plugs have the same composition as the Main Plug, but the West plug is coarser grained.
Gold mineralization at Lamaque consists of pyritic quartz-tourmaline-carbonate (QTC) veins, stringers and stockworks. These gold bearing veins occur within all rock types, but are mostly abundant in intrusions. Roughly 85% of the gold mined historically at Lamaque was from veins hosted by the Main Plug. The QTC veins, as at Sigma, are associated with brittle-ductile reverse shear zones, and occur in multiple orientations and styles. Historical nomenclature for the different veins sets include i) “major veins” (strong subvertical shear vein), ii) “lesser veins” (extensional shears or Riedel shears), iii) “stockworks and stringers” (horsetail structures) and iv) three types of “flat veins”, each distinguished by their host rocks or their spatial and temporal relationships with the shear zones.
Mining Methods
- Longhole stoping
- Longitudinal retreat
- Room-and-pillar
- Cemented backfill
Summary:
Commercial production was declared on March 31, 2019. Underground mining and underground ramp development were sufficiently established to produce 500,000 tonnes of ore in 2019. The mining plan for the Lamaque Operation calls for a predominantly mechanized mining by long-hole open stoping. Waste material generated from drift development will be used to backfill part of the long-hole open stopes. [2019 AR F-40, p.101]
The Lamaque Operation includes an underground ramp system currently extending to over 450 m depth, with approximate dimensions of 5.1 m x 5.5 m that provides access to the ore zones on 18 m and 25 m vertical intervals. A ventilation system with two 1500 hp surface fans and multiple 3.4 m - 5.5 m diameter raisebored connections to levels in the mine are capable of providing air for the operations including heating with natural gas in winter months. A cement slurry mixing and distribution system is for use in the backfilling of stopes with cemented rockfill. [2019 AR F-40, p.102]
The Triangle Zone will be the only area of extraction representing the most advanced part of the property.
From the early phases of the project it was recognized that the reserves in Triangle would be optimally recovered through a haulage ramp system to surface, as opposed to a vertical shaft which could not be economically justified at this time. The ramps will be used to haul ore and waste and provide access for personnel, equipment, materials and services, and form part of the exhaust air circuit.
The Triangle Zone long-hole stopes are designed within four sub-parallel major zones (the C zones) dipping 50-70° to south. Approximately 95% of all reserves are located within these zones, whereas a minor portion (5%) of the reserves are located in low-dipping (20-45°) splays off the main shears (C-splays). Each of the C-zones (C2 West, C1-C2 East and C4) will be serviced by a dedicated haulage ramp. A total of 36 levels are required to extract the reserves over the vertical extent of the orebody. The total lateral development requirements are estimated at 54,000 meters over the LOM. Sector C2 West and C1-C2 East are connected via level 184 and 148. Sector C2 West and C4 are tied together at level 328.
A longitudinal retreat long-hole mining method was selected for the Triangle zone based on the orebody characteristics, including grade, dip, continuity, thickness, etc. Although some part of the C-zones have hanging walls dipping shallowly (as low as 43 degrees), the approach in this study has been to promote the application of long-hole mining where possible.
Long-hole Method:
Sublevels will be developed along the vein strike with an 18.0 m vertical separation.
The stope preparation sequence involves marking all the reference lines on the walls for drilling, followed by raise boring an initial opening raise using a V-30 boring head1. Production drilling is then carried out following a pattern defined by the engineering group. The blasting sequence will generally involve two separate firings; the first blast will increase the initial void according to the available volume for broken material whereas the second will encompass the remaining stope volume. Production blast holes will be typically 64-mm (2.5”) or 76-mm (3.0”) in diameter following a pattern parallel to the walls. Mucking will be performed longitudinally from the ore drift using remote controlled loades. Each stope will be filled with a combination of cemented rock-fill and free running waste material.
Room-and-pillar method:
A minor portion of the reserves in shallow dipping areas such as the upper part of C1 will be mined using the room-andpillar mining method, and backfill will not be required.
The proposed room-and-pillar stope configuration is based on typical industry practices for currently operating mines with similar vein geometry. The typical mining height will vary from 1.8 m to 3.0 m. The room and-pillar mining method involve the excavation of a series of “rooms” following the vein, leaving “pillars” (columns) of rock in place to support the mine roof. In conventional room and pillar mining, drilling is achieved using hand held drill equipment and holes are loaded with explosives. After blasting, bolts are then installed in the mine roof to ensure the roof is properly supported. The broken rock is moved to either a raise or a drawpoint using an electric slusher with a scraper. The broken material is the recovered by an LHD to be hauled to surface by truck. A room-and-pillar design is proposed for the upper part of the C1 Zone using 6 m wide rooms with 3 m x 6 m pillars. Mechanized sublevel development from which the blasted material is loaded by LHDs will be completed at 60 m intervals along the vein.
Ore will be hauled by 45 tonnes underground mining trucks via the main access ramp to the surface ore pad. The broken ore will then be transported by a local contractor via an off road route from the Triangle ore pad to the Sigma mill site.
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
.......................
|
|
|
1
|
Ball mill
|
|
|
1000 HP
|
1
|
Ball mill
|
|
12' x 14'
|
1250 HP
|
1
|
Rod mill
|
|
9' x 12'
|
400 HP
|
1
|
Processing
- Gravity separation
- Agitated tank (VAT) leaching
- Counter current decantation (CCD)
- Carbon in pulp (CIP)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The ore from the Triangle site is currently processed at the re-furbished and operating Sigma Mill.
Fixed infrastructure at the Sigma Mill site includes the primary crushing circuit, fine ore bins, a rod and ball milling circuit followed by a series of cyclones, a gravity concentration circuit, a pre-aeration tank, a cyanide leach circuit, a carbon in pulp circuit, ADR process circuit and equipment, a gold refinery and associated infrastructure including piping, pumps, electrical connections, motor controls, instrumentation and automation and monitoring equipment. [2019 AR F-40, p. 103]
The gravity circuit is currently composed of two static screens and two 20-inch Knelson gravity concentrators operating as parallel units to recover free gold. For the first year of operation, the XD20 unit will be rehabilitated and the CD20 unit dismantled. The Knelson concentrate will be treated on the existing shaking table. The table concentrate is then further processed in th ........

Recoveries & Grades:
Commodity | Parameter | 2019 |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| ......  |
Production:
Commodity | Units | 2019 |
Gold
|
koz
| ......  |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2019 |
Tonnes milled
| ......  |
Daily milling capacity
| ......  |
- Subscription is required.
Reserves at September 30, 2018:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
215 kt
|
Gold
|
7.12 g/t
|
49 koz
|
Probable
|
3,872 kt
|
Gold
|
7.26 g/t
|
904 koz
|
Proven & Probable
|
4,087 kt
|
Gold
|
7.25 g/t
|
953 koz
|
Measured
|
239 kt
|
Gold
|
9 g/t
|
69 koz
|
Indicated
|
4,837 kt
|
Gold
|
8.26 g/t
|
1,285 koz
|
Measured & Indicated
|
5,076 kt
|
Gold
|
8.3 g/t
|
1,354 koz
|
Inferred
|
8,397 kt
|
Gold
|
6.78 g/t
|
1,830 koz
|
Commodity Production Costs:
| Commodity | Units | 2019 |
Cash costs (sold)
|
Gold
|
USD
|
......
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
......
|
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Operating Costs:
| Units | 2019 |
UG mining costs ($/t milled)
|
USD
| 66.6 |
Processing costs ($/t milled)
|
USD
| ......  |
Total operating costs ($/t milled)
|
USD
| ......  |
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Financials:
| Units | 2019 |
Sustaining costs
|
M USD
| ......  |
Revenue
|
M USD
| ......  |
Earnings
|
M USD
| ......  |
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Corporate Filings & Presentations:
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News:
Aerial view:
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