Name and Location
Prestea gold mine project, Ghana.

Client
The mine was acquired by Golden Star in 2002 and placed on care and maintenance while evaluation and exploration activities continued.

Project Description
Prestea is an underground gold mine, which has been in existence for more than a century and has produced an estimated nine-million ounces of gold to date. It has an extensive infrastructure of surface and underground vertical shafts, inclined shafts, horizontal development, raises and stopes developed along the 9 km of strike length of the gold mineralisation.

Extensive drilling of the deeper deposit at the underground mine has identified and defined a new zone called the West reef. This is a high-grade, narrow-vein deposit that hosts nonrefractory free-milling gold.

A preliminary economic assessment (PEA) completed on the deposit has demonstrated positive economics for the extraction of ore on the West reef using shrinkage stoping, which was the mining method historically used at Prestea.

Metallurgical testwork results indicate that the Prestea West reef material is nonrefractory, with 90% metallurgical recovery greater than using carbon-in-leach (CIL) processing.  This material is likely to be well suited to processing through the CIL section of the existing Bogoso refractory processing plant, which will be available to process this ore after the completion of mining at the Bogoso North and Chujah pits in late 2015.

The Prestea surface deposits have proven and probable mineral reserves of 122 000 oz of gold at an average grade of 2.24 g/t of gold, and measured and indicated mineral resources of 454 000 at 2.57 g/t of gold inclusive of mineral reserves.

The West reef mineralisation is located about 2 km south of the Central shaft and 2 km north of the Bondaye shaft at a depth of between 570 m and 950 m below surface. The Central shaft will be used for personnel access, materials transport, dewatering and hoisting. The Bondaye shaft will be used as the secondary means of egress and for dewatering.

The main haulage level will be established on the existing 24 level to move mineralised and waste rock to the Central shaft for hoisting to surface. An incline/decline system will be developed in the footwall of the mineralisation to access sublevels at a vertical spacing of about 40 m between the existing levels 17 and 24.

The development of this deposit is expected to be concurrent with the development of the underground mine. Prestea underground mine has measured and indicated resources of 630 000 oz at an average grade of 14.82 g/t of gold.

Net Present Value/Internal Rate of Return
The PEA indicates an internal rate of return of 72%, a net present value at a 5% discount rate of $121-million and a payback period of 2.5 years from the start of development.

Value
Total capex is estimated at $94-million.

This forms the bulk of the initial capex and will be directed towards infrastructure rehabilitation, which includes shaft and hoist upgrades, electrical infrastructure, process plant upgrade, ventilation, compressed air and pumping.

The refurbishment and development overhead capital includes labour, power, consumables and refurbishment costs for items not directly related to the West reef project during the predevelopment and production ramp-up phase.

Duration
Not stated.

Latest Developments
Golden Star has confirmed that it has secured the necessary permits to develop openpit operations at its Prestea mine project. 

The surface deposits are expected to be in production by the end of 2015, a year earlier than production from Prestea was initially expected.

Combined with the redevelopment of underground operations, Prestea has the potential to deliver more than five years of low-cost production.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Golden Star Resources, tel +1 233 302 779 040, fax +1 233 302 779 041 or email siteoperations@gsr.com.