Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Cut & Fill
- Transverse stoping
- Longitudinal stoping
- Cemented backfill
|
Processing |
- Calcining
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 5.75 years (as of Jan 1, 2017) |
Source:
p. 15
July 1, 2020 /CNW Telbec/ - SEMAFO Inc. (TSX: SMF) (OMX: SMF) ("SEMAFO") is pleased to announce the successful completion of the previously announced plan of arrangement (the "Arrangement") involving SEMAFO and Endeavour Mining Corporation ("Endeavour") effective July 1, 2020. The SEMAFO shares will be delisted from the Nasdaq Stockholm and from the Toronto Stock Exchange.
Semafo Burkina Faso S.A. (“SEMAFO BF”), a corporation held 90% by SEMAFO and 10% by the Republic of Burkina Faso.
Deposit Type
- Vein / narrow vein
- Orogenic
Summary:
The Mana district is located in the northern part of the Houndé greenstone belt. Based on current knowledge, it is the most gold-rich portion of the belt. Five gold deposits, WonaKona, Nyafé, Fofina, Yaho and Siou, are hosted in different rock types. The lithostratigraphic succession is typical of greenstone belts and is characterized at the base by a major tholeiitic basaltic suite with some intercalations of argillic sedimentary rocks that are overlain by predominant pelagic and detrital sedimentary rocks (shale, sandstones, greywacke and volcaniclastics). The Mana district basalt unit has undergone submarine hydrothermal alteration with epidote, chlorite and local albite, and shows zones of strong silicification, some of which are anomalous in gold. Accessory minerals include rutile and disseminated pyrite.
All deposits on the Mana Property are characterized as typical West African, shear- hosted orogenic gold deposits.
The major sulphides associated with the gold mineralization are pyrite and arsenopyrite. Free visible gold is encountered at the Wona-Kona and Siou deposits. Magnetite occurs as small millimetric prisms along schistosity planes in the walls of mineralized zones.
the Siou deposit is a typical shear-hosted quartz vein deposit. The two principal zones are the Siou and No. 9 zones. The Siou zone is hosted in a single quartz vein located within the Siou Granitic Intrusive, but near the contact with sandstones and shales to the west. The No. 9 zone is located at the contact between the sediments and the Siou Intrusive and generally consists of quartz veining and veinlets intruding the granitic intrusive. Both the Siou and No. 9 zones are north-striking and moderately east-dipping.
The Siou deposit is made of eight mineralized structures (namely, Zones 9, 17, 18, 20, 25 Siou, 55, 56 and 57) extending over a distance of 2 km with an average north-northeast to south- southwesterly strike and dipping 45° to 60° to the east. The main structures are Zones 9, 25, 55 and 56 but are not easily discernable on the figures due to the small scale.
Mineralized structure Zone 9 straddles the contact between the sediments and the intrusive. It generally dips 40-45° to the east, increasing to 60° as it approaches the surface. True thickness varies between 0.5 and 13.6 m, averaging 3.1 m. The structure is mainly characterized by a stockwork of relatively thin quartz veinlets. Zone 25 is a massive, continuous quartz vein averaging 4.2 m in true thickness. It is located within the intrusive and dips 40-45° to the east. Locally it is in contact with the basalts. Mineralized structures Zones 55, 56 and 57 occur as a conjugate shear vein system between Zones 9 and 25. Average true thickness varies between 1.7 m and 1.9 m.
Mining Methods
- Cut & Fill
- Transverse stoping
- Longitudinal stoping
- Cemented backfill
Summary:
Two underground mining methods will be used at Siou: long hole (longitudinal retreat and transversal) and cut and fill mining. These were selected because of the inclination of mineralized lenses and ore (stockwork) thickness. Long hole mining will be used when a stope can be mined economically above a dip of 50o degrees and cut and fill below 50o. Most of the areas where the Siou orebody is located in the hanging wall will be mined cut and fill.
Long Hole Mining
Two different approaches will be used in long hole mining, depending on the width of the ore zone. Where stopes are wider than 10 m, a transversal approach will be used; where they are narrower, a longitudinal approach will be used. The longitudinal approach will be used mainly at the extremities of the ore zone.
Consolidated backfill and loose rock will be used to ensure safe ore recovery. Cemented rock fill at 4% cement will fill the primary stopes of the transversal stoping to ensure stability, and secondary stopes will be backfilled with loose rock. For the longitudinal stope, only a wedge close to the next stope will be backfilled with cemented rock fill, the rest will be loose rock.
For the longitudinal retreat, drives will be developed at the bottom and top of the stope. Mine geologists will align the development to follow the ore, map the heading and collect samples to confirm the stope with geological model.
Cut and Fill Mining
The minimum mining size has been set to 4.5 m by 4.5 m. In this case, 0.2 m of dilution from the wall was used to evaluate the tonnage and grade of the cut. An overall dilution for the cut and fill stope was estimated with the MSO calculation at 37.9%. Saprolite, which has a yellowish colour, will be used for backfill to easily distinguish broken ore and the backfill material.
Processing
- Calcining
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The Mana flowsheet comprises a standard SABC comminution circuit, CIL circuit, Zadra elution circuit and tailings disposal.
The comminution circuit consists of an open primary jaw crusher circuit followed by SAG and ball mills. The SAG mill operates in closed circuit with a pebble crusher and the product from the SAG is also screened classified prior to feeding the ball mills. The ball mill product is in closed circuit with hydrocyclones to produce a product P80 of 74 µm. Product from the grinding circuit is leached through a CIL circuit with a retention time of ±28 hours depending on throughput. Loaded carbon from the CIL is stripped through a pressurized Zadra system. The pregnant solution from the Zadra circuit is pumped to the gold room where electrowinning and smelting of the electrowon sludge occur in order to produce a gold doré. Slurry tails from the CIL circuit are pumped to the tailings storage facility (TSF) and surnagent water is recycled back to the mill. ........

Recoveries & Grades:
Commodity | Parameter | 2019 |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 4.6 |
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Production:
Commodity | Units | 2019 |
Gold
|
oz
| ...... * |
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Operational Metrics:
Metrics | 2019 |
Ore tonnes mined
| ......  |
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Reserves at December 31, 2018:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
1,047,000 t
|
Gold
|
5.1 g/t
|
171,600 oz
|
Probable
|
1,988,000 t
|
Gold
|
5.38 g/t
|
344,200 oz
|
Proven & Probable
|
3,035,000 t
|
Gold
|
5.29 g/t
|
515,800 oz
|
Measured
|
513,000 t
|
Gold
|
3.23 g/t
|
53,200 oz
|
Indicated
|
787,000 t
|
Gold
|
3.25 g/t
|
82,300 oz
|
Measured & Indicated
|
1,300,000 t
|
Gold
|
3.24 g/t
|
135,500 oz
|
Inferred
|
1,852,000 t
|
Gold
|
3.91 g/t
|
232,900 oz
|
Corporate Filings & Presentations:
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Aerial view:
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