Name: Bogoso Prestea mine.
Location: The operating Bogoso gold mine and processing operations are located in western Ghana near the town of Bogoso, about 35 km northwest from the town of Tarkwa.
Controlling Company: Golden Star (Bogoso Prestea) Limited (GSBPL) is 90% owned by Golden Star Resources (GSR) and 10% by the Ghanaian government, which receives a 5% royalty on gross revenue on all GSBPL gold production.
Brief History: Gold was first commercially mined at Bogoso during the 1930s. Until its closure in 1955, this operation produced more than 900 000 oz of gold at an average grade of 3.73 g/t. By 1991, construction and processing facilities were completed by Billiton International BV, which had taken over the concessions during the late 1980s. Their plant was designed to process oxide ore using a conventional carbon-in-leach (CIL) method, while the sulphide ore was processed through a flotation, fluid-bed roasting and CIL technology. In 1999, Golden Star acquired the majority interest in the mine and, since that time, it has operated a nominal 1.5-million-tonne-a-year CIL processing plant to process oxide and other nonrefractory ores. In July 2007, GSBPL completed the construction and development of a new nominal 3.5-million-tonne-a-year processing facility that uses bio-oxidation (BIOX) technology to treat refractory sulphide ore.
Brief Description: Bogoso and Prestea comprise a collection of adjoining mining concessions that collectively cover a 40 km section of the Ashanti gold district, with the processing facilities situated about 10 km south of the town of Bogoso. The ore production in recent history at Bogoso Prestea has been at an estimated rate of three-millon tonnes a year.
Geology/Mineralisation: The Bogoso, Prestea, Mansiso and Asikuma properties lie within the southern portion of the Ashanti greenstone belt along the western margin of the belt. The geology of the mine site is divided into three main lithostructural assemblages, which are fault-bounded and steeply dipping to the west. This suggests that the contacts are structurally controlled and that the lithostructural assemblages are unconformable. These packages are from the eastern footwall to the western hanging wall of the Tarkwaian lithostructural assemblage, and the tectonic breccia assemblage – comprising sheared graphitic sediments and volcanic flows – which is commonly referred to as the main crush zone, the last assemblage comprises undeformed sedimentary units of the Kumasi basin, located to the west of the Ashanti fault zone.
Reserves: Total proven and probable reserves as at December 31, 2013, were estimated at 19.42-million tonnes grading 3.17 g/t of gold.
Resources: Total measured and indicated resources as at December 31, 2013, were estimated at 28.72-million tonnes grading 3.28 g/t of gold. Inferred resources were 5.27-million tonnes grading 6.25 g/t of gold.
Products: Gold.
Mining Method: The mining methods used at the Bogoso main and satellite pits are conventional excavator and truck methods, which are typical for this style of gold mineralisation.
Major Infrastructure and Equipment: Bogoso has two ore processing facilities: a refractory processing plant with a capacity of 2.7-million- tonnes a year, which uses BIOX technology and a conventional CIL processing plant with a capacity of 1.5-million tonnes a year.
The main production fleet comprises excavators, haul trucks and rotary drill rigs, principally sourced from the Liebherr, Caterpillar and Atlas Copco manufacturers respectively. In addition to the main equipment units, graders, water trucks and various support and service equipment are in use.
The pits are dewatered using in-pit pumps placed in sumps located towards the lowest point of the pit and wet season arrangements include drainage channels to protect against inflows.
Prospects: Numerous satellite deposits can potentially provide additional ounces.
Contact Person: Investor relations, Angela Parr.
Contact Details:
GSR,
tel +1 416 583 3800,
email investor@gsr.com, and
website http://www.gsr.com.