Source:
p. 44
Company | Interest | Ownership |
Government of Burkina Faso
|
10 %
|
Indirect
|
Teranga Gold Corp.
|
90 %
|
Indirect
|
The Wahgnion Mining License is held by WGO, formerly Société Minière Gryphon SA, a Burkina Faso entity, which is indirectly owned 90% by Teranga and 10% by the State of Burkina Faso.
Deposit Type
- Breccia pipe / Stockwork
- Vein / narrow vein
Summary:
Mineralization at the Wahgnion Gold project is structurally controlled and is widely associated with hematite, iron carbonate, sericite, pyrite and locally, with albitic alteration. Higher gold grades are commonly associated with stylolitic laminated quartz veins or pyrite veinlets. Coarse- grained gold is found in fractures within pyrite veins or in quartz-carbonate vein selvages. Mineralization is predominantly of a lode-style gold type, associated with discrete structures. The mineralization is interpreted to have formed from the same mineralizing system, with variations in style reflecting the difference in local lithological and structural settings.
Nogbele Deposit
Basement exposure in the Nogbele area is generally poor, with outcrop information limited to occasional exposure in shallow creek beds, shallow mining pits, road cuts, and quartz vein outcrop. Surficial regolith varies from a shallow residual granitic profile to a competent laterite ferricrete ridge that traces the contact of the Nogbele pluton and the host rocks in the Nogbele North area.
The Nogbele area is underlain by a package of metamorphosed and variably deformed volcano- sedimentary units and three distinct suites of intrusive rocks. A foliation or lineation is well developed in the oldest of the granitoids and the sedimentary rocks but is absent from the two younger granitoids.
Extensive packages of variably deformed and metamorphosed volcano-sedimentary rocks are the oldest rocks in the Nogbele area and include: Massive fine-grained mafic volcanic flows, tuffs and volcanic siltstones with few remaining primary textures; finely bedded mafic volcanic siltstones, sandstones, and possible tuffs in which centimetre-scale bedding is still well preserved and a variety of plagioclase-porphyritic rocks of intermediate to siliceous composition, which are interlayered with the more mafic lithologies listed above.
A large pluton of massive, medium to coarse grained, equigranular, and relatively leucocratic biotite granite forms bedrock in the Nogbele Central area. A broad halo of pegmatite and aplite dykes surrounds the northwest side of the granite pluton, where the upper contact of the pluton dips the shallowest. The moderate to steeply dipping margins of the main granite pluton, as well as the dyke in the Nogbele Northwest area, are surrounded by narrower halos of pegmatite and aplite dykes. Dykes of biotite granite, pegmatite, and aplite cut across the foliation in the adjacent volcanosedimentary rocks, as well as the lineation in the deformed biotite granitoids.
An extensive pluton of massive, equigranular, medium-grained, hornblende-biotite-epidote bearing quartz diorite-tonalite forms bedrock in the Nangolo area.
Fourkoura Deposit
The Fourkoura deposit is located in the south-central Wahgnion Gold project area, six kilometres to the southeast of the Nogbele deposit. There is limited but useful outcrop at the Fourkoura deposit, however, good structural information is available from a series of shallow artisanal pits.
The Fourkoura deposit is located on a north-northeast trending shear zone within a quartz-gabbro unit that intrudes a volcano-sedimentary package. There are two distinct areas of mineralization observed at Fourkoura:
- Northern Zone: The northern zone of mineralization is essentially a lens shaped lode dipping approximately 40° to the west-northwest. The lens is moderately plunging to the northeast and remains open down plunge. Significant mineralization is formed on the sheared contact and within a narrow granitoid unit, with sheared volcanics on the footwall. Near the southern end of the northern lode, more diffuse mineralization is hosted within a quartz-gabbro body. There are two discrete hanging wall lodes present.
- Southern Zone: Mineralization hosted entirely within a quartz-gabbro unit is more northerly striking, with multiple lodes defining the deposit. Continuity on the structures is not as well defined and it is likely that mineralization is being controlled by crosscutting features that are poorly defined by current drilling. Mineralization is currently still open to the south.
Stinger Deposit
The Stinger deposit is hosted by dioritic, granitoid, and mafic metavolcanic rocks located within largely coincident swarms of diorite and granitoid dykes, both of which cut the older Birimian mafic volcanic country rocks. Diorite dykes and elongate plugs form the earlier swarm, whereas a more extensive and in-part coincident swarm of granitoid dykes form the later swarm. The intrusive margins of these dykes are the most widespread penetrative structure within the Stinger deposit, and one of three features that defined the structural grain of the rocks at Stinger prior to mineralization. Weak foliation and bedding within the Birimian mafic volcanic rocks also contribute to the structural grain of rocks at the Stinger deposit.
Intrusive contacts, foliation, and bedding in the southwest part of the deposit strike northeast and dip steeply, more commonly towards the northwest. Dykes in the central part of the deposit tend to strike north-northeast rather than northeast. A wider range of dips are also apparent, suggesting folding of the dykes about gently northeast or southwest plunging axes.
Samavogo Deposit
Samavogo is located in the northeast part of the Wahgnion Gold project area, approximately 18 km to the northeast of the Nogbele deposit. The Samavogo deposit is associated with a northeast trending shear zone that cuts volcanic rocks and occurs along the western contact of an early tonalite/quartz-diorite intrusion. It appears that the granitoid has been thrust into a hanging wall position and the current interpretation is that the contact is tectonic. A series of discrete structures are essentially parallel to the local amphibolite facies metamorphic fabric, and the mineralization is associated with movement on these faults.
Summary:
An open pit mining operation is planned. Material will be drilled and blasted where required, then loaded by backhoe excavators into haul trucks dispatched to the PCA, WRDs, or stockpiles. Various material types are considered in the mine planning and open pit design and there is a significant emphasis on mine sequencing to optimize WGO economics.
The total surface footprint area of all the pit designs is 399.6 ha. The maximum pit depth in each area is as follows:
• Nogbele Nangolo – 93 m
• Nogbele North Central – 145 m
• Nogbele South – 133 m
• Fourkoura – 110 m
• Stinger – 231 m
• Samavogo – 135 m.
Pre-split drill and blast operations are estimated for final pit walls in primary rock.
In general, in-pit haul roads were designed for two-way traffic at a maximum continuous gradient of 10%. In certain instances, the bottom 10 m to 20 m of pits may employ a narrower ramp width suitable for one-way traffic.
Two-way traffic pit wall haul road widths are 12 m wide, which includes provision for a single shoulder berm that is three quarters the height of the truck tires. The operable width is approximately nine metres, which is three times the truck width of approximately three metres. One- way traffic pit wall haul roads are nine metres wide.
In the bottom bench of pit areas, trenches were designed to excavate ore where appropriate. Trenches were excavated to a depth of up to 7.5 m, which is within the working depth reach of the specified excavator.
In larger or elongated pits, multiple haul road alignments were incorporated into the final pit walls to improve mining flexibility and reduce haulage times, which will offset the additional waste stripping required for the relatively narrow haul roads.
All haul roads are to be suitably crowned to allow for efficient drainage of surface water, where operations experience will determine the appropriate level of crowning (typically between 1% and 3%).
In general, development of main haul roads and permanent structures, such as the WRDs, around the open pits assumes a minimum setback of 25 m and 50 m respectively from pit rims.
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
1
|
SAG mill
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Summary:
CRUSHING CIRCUIT
RoM ore will be loaded into the RoM bin by direct tipping from the mining trucks or by FEL from the stockpiles. A grizzly will be fitted to the RoM bin to protect the downstream equipment from oversize material and will be inclined for easy removal of oversize to minimize stoppages. A rock breaker will be utilized to break oversize rocks on the grizzly or RoM pad.
RoM ore will be drawn from the RoM bin at a controlled rate by a variable speed apron feeder and will discharge onto a vibrating grizzly. The grizzly oversize will report to the jaw crusher. The crusher product and grizzly undersize will discharge onto the primary crusher discharge conveyor feeding directly to the crushed ore stockpile.
Under normal operating conditions, the crushing rate to the stockpile will exceed the rate of withdrawal of ore to the milling circuit. Crushed ore will be reclaimed from the stockpile by FEL into the emergency feed hopper to maintain mill feed when the reclaim apron feeders are off line.
Crushed mill feed will be withdrawn from the stockpile at a controlled rate by variable speed apron feeders and fed via the mill feed conveyor directly to the SAG mill. A weightometer will indicate the instantaneous and totalized mill feed tonnage.
Quicklime, used for pH control, will be added directly onto the mill feed conveyor. Quicklime will be stored in two lime silos and will be metered onto the belt using a variable speed rotary feeder. Quicklime will be delivered to site in bulk tankers and transferred to the lime silos using a pneumatic conveying system. The silos will be fitted with a dust collector.
Grinding media will be added directly onto the SAG mill feed belt via the emergency feed hopper as required to maintain the required SAG mill load.
Coarse spillage in the crusher area will be cleaned up by FEL and transported to the RoM pad for drying or fed directly to the primary crusher. Coarse spillage in the reclaim tunnel will be cleaned up by hand and then transferred by FEL and loaded into the circuit via the emergency feed hopper.
Water sprays and/or dust collectors will be installed for fugitive dust at the primary crusher, surge bin, and quicklime addition point.
The crushing circuit will be controlled from the local control station.
GRINDING AND CLASSIFICATION CIRCUIT
The grinding circuit will consist of a SAG mill in closed circuit with a pebble crusher and a ball mill in closed circuit with hydrocyclones. Crushed ore will be fed directly to the SAG mill. Pebble crusher product will also be deposited on the SAG mill feed conveyor. Process water will be added to the SAG mill to achieve the required milling pulp density.
The SAG mill will be equipped with a variable speed drive and will be capable of operating between 60% and 80% of critical speed. During start-up, the mill speed will be reduced and the ball load increased to meet the requirements for treating high proportions of low competency oxide ore. As the amount of competent primary ore in the mill feed increases, the mill speed will be increased and ball charge reduced.
The SAG mill will discharge via a discharge assembly over a vibrating wet screen. Screen oversize, consisting of pebbles and worn steel grinding media, will discharge onto the pebble transfer conveyor. If required, screen oversize can be diverted to the pebble bunker.
A magnet mounted above the pebble transfer conveyor will remove the tramp steel grinding media. Any tramp metal not removed will be detected by a metal detector located above the pebble transfer conveyor prior to the pebble crusher. The metal detector will activate a diverter gate to prevent steel from reporting to the pebble crusher. This diverter gate will also allow bypassing of the pebbles for recycle to the SAG mill or to enable maintenance to be carried out on the pebble crusher without the need to shut down the milling circuit. A weightometer on the pebble transfer conveyor will indicate the mass of pebbles being recycled.
Pebbles will be crushed in the pebble crusher, which will discharge directly to the emergency feed/pebble product conveyor. This conveyor then discharges to the SAG mill feed conveyor.
The SAG mill discharge screen undersize will gravitate to the mill discharge hopper, where it will be diluted with process water and pumped to the classifying hydrocyclone cluster.
The combined cyclone overflow stream, with a nominal pulp density of 42% w/w solids, will gravitate to the trash screen. The cyclone underflow will be collected in the underflow launder and report to the feed chute of the ball mill. The design has made allowance for a future gravity circuit fed from the cyclone underflow launder with gravity tails reporting to the ball mill feed.
The ball mill will be equipped with a variable speed drive (VSD) and squirrel cage motor for soft starting only. No speed variation will be available for the ball mill.
Cyclone underflow returning to the ball mill will undergo further size reduction and discharge from the ball mill will be combined with the pebble dewatering screen undersize in the mill discharge hopper and undergo reclassification in the hydrocyclone cluster.
Cyclone overflow will be screened on a vibrating trash screen to remove any misreporting of coarse ore particles, wood fragments, organic material and plastics that would otherwise become locked up with the circuit carbon and 'peg' the intertank screens. Trash material will report to the trash bunker.
Processing
- Gravity separation
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The process plant design incorporates the following unit process operations:
• Single stage primary crushing with a single toggle jaw crusher to produce a crushed product size of P80 ranging from 100 mm to 140 mm, based on differing weathering types.
• A crushed ore stockpile with a live nominal capacity of 2,000 t.
• SAG and ball milling in closed circuit with a pebble crusher and hydrocyclones (SABC) to produce a P80 grind size of 106 µm.
• Leach and CIL circuit incorporating eight stages, with one stage of leaching without carbon and seven stages with carbon for gold adsorption.
• Split Anglo American Research Laboratory (SAARL) elution circuit, electrowinning, and gold smelting to recover gold from the loaded carbon to produce doré.
• Carbon reactivation utilizing a rotary kiln.
• Tailings thickening to recover and recycle process water and precious metal values from the CIL tailings.
• Tailings pumping to the TSF.
LEACH AND CARBON ........

Recoveries & Grades:
Commodity | Parameter | 2019 |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 1.63 |
- Subscription is required.
Reserves at December 31, 2019:
Mineral Resources are reported at cut-off grades ranging from 0.320 g/t Au to 0.403 g/t Au in oxide, and at cut-off grades ranging from 0.388 g/t Au to 0.541 g/t Au in transition and primary rock.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
2.89 Mt
|
Gold
|
1.37 g/t
|
0.13 M oz
|
Probable
|
27.43 Mt
|
Gold
|
1.61 g/t
|
1.42 M oz
|
Proven & Probable
|
30.32 Mt
|
Gold
|
1.59 g/t
|
1.55 M oz
|
Measured
|
3.27 Mt
|
Gold
|
1.36 g/t
|
0.14 M oz
|
Indicated
|
46.35 Mt
|
Gold
|
1.5 g/t
|
2.23 M oz
|
Measured & Indicated
|
49.62 Mt
|
Gold
|
1.49 g/t
|
2.37 M oz
|
Inferred
|
5.24 Mt
|
Gold
|
1.41 g/t
|
0.24 M oz
|
Commodity Production Costs:
| Commodity | Units | 2019 |
Total cash costs (sold)
|
Gold
|
USD
|
......
|
All-in sustaining costs (AISC)
|
Gold
|
USD
|
......
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
......
|
- Subscription is required.
Operating Costs:
| Units | 2019 |
OP mining costs ($/t mined)
|
USD
| 2.17 |
Processing costs ($/t milled)
|
USD
| ......  |
- Subscription is required.
Financials:
| Units | 2019 |
Capital expenditures (planned)
|
M USD
| ......  |
- Subscription is required
Proposed Heavy Mobile Equipment:
HME Type | Size | Quantity | Ref. Date |
Backhoe
|
5.7 cu. m
|
6
|
Jul 31, 2019
|
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2
|
Jul 31, 2019
|
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1
|
Jul 31, 2018
|
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2
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Jul 31, 2019
|
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5
|
Jul 31, 2019
|
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2
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Jul 31, 2019
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6
|
Jul 31, 2019
|
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3
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Jul 31, 2019
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1
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Jul 31, 2019
|
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3
|
Jul 31, 2019
|
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3
|
Jul 31, 2019
|
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29
|
Jul 31, 2019
|
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|
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|
3
|
Jul 31, 2019
|
- Subscription is required.
Aerial view:
- Subscription is required.