Obuasi Gold mine (Obuasi)

 mine, gold mine

Obuasi is owned and operated by Anglogold Ashanti and in 2004 Anglogold and Ashanti Goldfields merged. Ashanti Goldfields Company (AGC) was established in London in 1897 and started underground mining at Obuasi in 1907.

he Obuasi deposits occur along a zone of intense shearing and faulting within precambrian greenstones. Mineralisation comprises two main types: quartz veins containing high-grade free gold and the main sulphide ore in which narrow veins contain gold trapped within arsenopyrite.

The mine has worked surface and underground mineralisation along an 8km north-south strike length but mining is now mainly underground, extending to depths of 1,600m. The mainly flat-back, cut-and-fill stopes used to exploit several ore blocks are being converted to mechanised open stopes. There are 15 shafts but the main hoisting shafts are modern – George Cappendell, Kwesi Mensah, Kwesi Renner (Stonewall) and Sansu. Obuasi has made extensive use of raise boring in developing the underground mine and has one of the world's larger fleets of raise boring machines. During 2002–03, AGC upgraded the Brown sub-vertical shaft and bored a new ventilation shaft. Total hoisting capacity will remain at 6.2Mt/y between the Kwesi Renner, Kwesi Mensah and Sansu shafts.

The shafts are linked by an electric rail haulage system serving six dump stations on the 41 level. Designed by Nordic Mining Technology, this system comprises two eight-car trains of 14m³ side-hinged cars, hauled by 15t locomotives supplied by British manufacturer Clayton. The dump stations are fed by conveyors from ore passes to the haulage level. Late in 2004, Obuasi took delivery of new LHDs and haul trucks from Atlas Copco.

About the time of the Ebola problem the mine went on standby, many were laid off, and developement of a decline from the surface was started. In August, 2015 a new partner joined Ashanti with plans to reactivate the mine if certain goals were reached.