Ghana

Wassa Southern Extension Project

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Categories

Overview

Mine TypeUnderground
StagePreliminary Economic Assessment
Commodities
  • Gold
Mining Method
  • Longhole open stoping
  • Longitudinal stoping
  • Transverse stoping
Backfill type ... Lock
Mine Life... Lock
SnapshotWassa Mine of Golden Star Resources made full use of the processing capacity of the existing concentrator, and obtained the open-pit mining licenses in Benso I Area and DMH Area in July and November 2022, respectively, which quickly provided supplementary ore for the concentrator and provided the foundation and guarantee for the further development of Wassa Gold Mine.
Related AssetWassa

Owners

SourceSource
CompanyInterestOwnership
Government of Ghana 10 % Indirect
Chifeng Jilong Gold Mining Co., Ltd. 90 % Indirect
Golden Star holds a 90% interest in the Wassa gold mine through its 90% owned Ghanaian subsidiary, Golden Star (Wassa) Limited. The remaining 10% interest in Wassa is held by the Government of Ghana in accordance with applicable laws.

Contractors

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Deposit type

  • Orogenic
  • Vein / narrow vein

Summary:

The Wassa property lies within the southern portion of the Ashanti Greenstone Belt along the eastern margin of the belt within a volcano-sedimentary assemblage located at proximity to the Tarkwaian basin contact. The eastern contact between the Tarkwaian basin and the volcanosedimentary rocks of the Sefwi group is faulted, but the fault is discrete as opposed to the western contact of the Ashanti belt where the Ashanti fault zone can be several hundred meters wide. Deposition of the Tarkwaian sediments was followed by a period of dilation and the intrusion of late mafic dykes and sills.

The Wassa lithological sequence is characterized by lithologies belonging to the Sefwi Group and consisting of intercalated meta-mafic volcanic and meta-diorite dykes with altered meta-mafic volcanic and metasediments which are locally characterized as magnetite rich, banded iron formation like horizons.

The Wassa mineralization is subdivided into a number of domains: F Shoot, B Shoot, 242, South East, Starter, 419, Mid-East and Dead Man’s Hill. Each of these represents discontinuous segments of the main mineralized system which extends approximately 3.5 km along strike from surface and is still open at depth. The SAK deposits are located approximately 2 km to the southwest of the Wassa Main deposit on the northern end of a well-defined mineralized trend parallel to the Wassa Main trend. The SAK deposits are also located on the western side of a major regional east dipping fault which separates the Wassa main mineralization from this trend. The mineralization is hosted in highly altered multi-phased greenstonehosted quartz-carbonate veins interlaced with sedimentary pelitic units.

Three vein generations have been distinguished on the basis of structural evidence, vein mineralogy, textures and associated gold grades. Evidence further relates the majority of gold mineralization to the earliest recognized vein generation which is believed to be syn-Eoeburnean. Gold grades broadly correlate with the presence of quartz-dolomite/ankerite-tourmaline bearing quartz veins and the presence of sulphide minerals (predominantly pyrite) within and around the quartz veins. Gold grades appear to be spatially restricted to the quartz veins, vein selvages and the immediate wall rocks. The alteration haloes developed around the veins and pervasively developed within the core of the deposit scale Wassa fold contain lower grade mineralization.

HWINI-BUTRE
The Hwini-Butre deposits can be characterized as mafic intrusive hosted, orogenic shear zones. The deposits are hosted within diorite and granodiorite intrusive rocks of the Mpohor complex.

The Hwini-Butre concession is underlain by three deposits: Adoikrom, Dabokrom and Father Brown, which are all characterized by different styles of mineralization. The Hwini-Butre deposits are hosted within the Mpohor mafic complex, which consists mainly of gabbroic and gabbrodioritic intrusive horizons. . At Father Brown and Dabokrom, mineralization is associated with quartz vein systems which are locally surrounded by extensive, lower grade, disseminated quartz stockwork bodies, especially at Dabokrom. The Father Brown deposit is characterized by well-developed fault-filled quartz veins which are, as is the case for Dabokrom, light grey with carbonate and mica accessory minerals and minor tourmaline and feldspar.

BENSO
The Benso deposits can also be characterized as mafic intrusive hosted, orogenic shear zones deposits, which are hosted by Birimian metavolcanics into which coarse plagioclase porphyry units have intruded and are generally conformable with the volcaniclastic units.

The Benso concession is underlain by four main deposits: Subriso East, Subriso West, G Zone and I Zone. All the deposits are characterized by similar style of mineralization. As with Hwini-Butre, the Benso deposits are hosted within mafic intrusive rocks of gabbroic to dioritic composition, which intrude a thick volcano-sedimentary sequence mainly composed of mafic volcanic flows. Mineralization at Benso is associated with late deformational stages of the Eburnean orogeny and deposits are shear hosted along subsidiary structures.

CHICHIWELLI
The Chichiwelli deposits can also be characterized as mafic intrusive hosted, orogenic shear zones, the deposits are hosted within diorite and granodiorite intrusive rocks

The Chichiwelli deposit consists of two sub-parallel mineralized trends which hosts two distinct types of mineralization. The Chichiwelli West trend is a shear zone hosted deposit with a quartz, carbonate, sericite and potassic alteration assemblage, the mineralization is associated with pyrite. The Chichiwelli East trend is a quartz vein associated deposit with an ankerite and sericite alteration assemblage. Mineralization is also associated with pyrite along vein selvages and in the wall rocks.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Production

CommodityUnitsAvg. AnnualLOM
Gold koz 2943,456
All production numbers are expressed as metal in doré.

Operational metrics

Metrics
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Daily ore mining rate  ....  Subscribe
Daily processing capacity  ....  Subscribe
Annual ore mining rate  ....  Subscribe
Annual processing capacity  ....  Subscribe
Waste tonnes, LOM  ....  Subscribe
Ore tonnes mined, LOM  ....  Subscribe
Total tonnes mined, LOM  ....  Subscribe
Tonnes processed, LOM  ....  Subscribe
* According to 2020 study.

Production Costs

CommodityUnitsAverage
Cash costs Gold USD  ....  Subscribe
All-in sustaining costs (AISC) Gold USD  ....  Subscribe
Assumed price Gold USD  ....  Subscribe
* According to 2020 study / presentation.

Operating Costs

Currency2020
UG mining costs ($/t mined) USD 39.3 *  
Processing costs ($/t milled) USD  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2020 study.

Project Costs

MetricsUnitsLOM Total
Expansion CapEx $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
Total CapEx $M USD  ......  Subscribe
UG OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 520.8
Backfill costs $M USD  ......  Subscribe
Refining costs $M USD  ......  Subscribe
Transportation (haulage) costs $M USD 21.6
G&A costs $M USD 203.1
Total OpEx $M USD  ......  Subscribe
Income Taxes $M USD  ......  Subscribe
Royalty payments $M USD  ......  Subscribe
Gross revenue (LOM) $M USD  ......  Subscribe
Net revenue (LOM) $M USD  ......  Subscribe
EBITDA (LOM) $M USD  ......  Subscribe
Pre-tax Cash Flow (LOM) $M USD  ......  Subscribe
After-tax Cash Flow (LOM) $M USD  ......  Subscribe
Pre-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 10% $M USD  ......  Subscribe
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Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Sep 12, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 12, 2023

Aerial view:

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