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.
During the 1990s, AngloGold boosted output by surface mining and surface tonnage overtook underground in the middle of the decade. Having ceased surface mining during 2000 to contain costs, Ashanti opened the Homase pit in 2002, completed mining it during 2003 and started two more surface operations at the Kunka and Adubrem deposits. During 2003, underground production totalled over 2.3Mt, surface mining added 476,000t, and tailings recovery almost 2Mt.
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