Ahafo gold mine in Ghana is owned Newmont Mining, one of the world’s largest gold mining company. The Ahafo mine is located in the Brong Ahafo region of west-central Ghana west africa, about 30 km south of Sunyani and 307 km northwest of the capital city of Accra. Gold mine production in Ahafo started 2006 and in 2010, produced 545,000 oz of gold at a cost of $450/oz. Ahafo has two primary ore zones: Ahafo South and Ahafo North. Mining is currently underway at Ahafo South.
Ahafo gold mine’s property covers three segments of the granodiorite - metasediment contact. Gold mineralisation is generally associated with a brecciated and hydrothermally altered shear-zone of granodiorite lying in thrust/wrench contact with underlying graphitic phyllites of the Birimian Supergroup. The phyllities also contain scattered pods of gold mineralisation, but these appear to be limited to a zone lying no more than 20 m from the granodiorite. The thrust contact always dips east at angles varying from 30° to 65°. Gold mineralisation is also associated with a shear zone about 1.2 km east of the granodiorite - metasediment contact that was expressed by a low-level soil geochemical target. The granodiorite hosted shear zone is subparallel to the main trend and dipping from 60° east to sub-vertical.
Mining Operations And Mining Methods In Ahafo Mine In Ghana
Newmont mining in Ghana currently operates four open pits at Ahafo gold mines with reserves contained in 13 pits, over a strike length of 40 km. The operation is currently only operating in the Ahafo south open pits. There is much more gold available in the North section. At Ahafo North there are reserves of 3.2 Moz – an upside with multiple pit and underground opportunities Newmont mining in ghana spend between $15 and $20 million on drilling at Ahafo North
Open pits at Ahafo mine is currently using standard shovel and truck operations to transport the mineral rock from the open pit mine area. The wheel loading fleet is comprised of four Cat 992Gs. Caterpillar supplied most of the rest of the mobile equipment, including a 32-strong fleet of 785 haul trucks. The haul roads are kept in good condition by eight Cat D10T track dozers and Cat 834 wheel dozer, four Cat 16H graders and one Cat 14H grader. There are also two Cat 777 water trucks.
Sandvik supplied the drilling fleet of 10 Driltech D45 blasthole drills and one Pantera 1500. The primary hydraulic excavator loading units are four Liebherr 994Bs. These are supported by one Caterpillar 385, a 345 and a 330. There is also one O&K (Bucyrus, and becoming Caterpillar) 170B hydraulic shovel.
Mineral Ore Processing In Ahafo Mine Ghana
The processing of ore in Ahafo mine hauled to the concentrator in the south by either trucks or an overland conveyor system. A blend of both primary and oxide ore is fed to the mill to balance the head grade and recovery in the leach circuit.
To isolate pure gold, mining companies use a complex extraction process. The first step in this process is breaking down large chunks of rock into smaller pieces. At a mill, large machines known as crushers reduce the ore to pieces no larger than road gravel. The gravel-like material then enters rotating drums filled with steel balls. In these drums, feed ore into a series of crushers and grinding mills to reduce the size of the ore particles and expose the mineral.
Ahafo mine operates a 54 x 75” gyratory crusher for primary ore and an MMD Sizer for oxide ore. This is followed by a SABC circuit comprising a 34 x 16.4’, 13 MW SAG mill in closed circuit with two MP800 pebble crushers. SAG milling is followed by a 24 x 39’, 13 MW ball mill in closed circuit with a cluster of 26” cyclones. After classification, the milling product is thickened and the overflow is fed to CIL tanks.
The processing of ore in Ahafo mine, mill operators thicken the slurry with water to form pulp and run the pulp through a series of leaching tanks. Leaching dissolves the gold out of the ore using a chemical solvent. The solvent is cyanide, which must be combined with oxygen in a process known as carbon in leach. As the cyanide and oxygen react chemically, gold in the pulp dissolves.
Gold Production In Ahafo Mine Ghana West Africa
Newmont Mining in Ghana plans to expand mining and processing of its Ahafo Mine project in the Brong Ahafo Region from the current annual production volume of between 300-330,000 ounces to about 400-500,000 ounces.
The expansion has the potential to increase mill capacity from 7.5 million tonnes per annum to 12 million tonnes per annum, and will increase gold production at a lower cost; extending the lifespan of the Ahafo Mine to 2028.
The new development will be done within the mine’s concession without any additional acquisition of lands. Construction works are expected to begin in August 2015 and will last for 24 months, while expansion works on the mining pits are also expected to be carried out from 2016 to 2028.
Open pits at Ahafo mine is currently using standard shovel and truck operations to transport the mineral rock from the open pit mine area. The wheel loading fleet is comprised of four Cat 992Gs. Caterpillar supplied most of the rest of the mobile equipment, including a 32-strong fleet of 785 haul trucks. The haul roads are kept in good condition by eight Cat D10T track dozers and Cat 834 wheel dozer, four Cat 16H graders and one Cat 14H grader. There are also two Cat 777 water trucks.
Sandvik supplied the drilling fleet of 10 Driltech D45 blasthole drills and one Pantera 1500. The primary hydraulic excavator loading units are four Liebherr 994Bs. These are supported by one Caterpillar 385, a 345 and a 330. There is also one O&K (Bucyrus, and becoming Caterpillar) 170B hydraulic shovel.
Mineral Ore Processing In Ahafo Mine Ghana
The processing of ore in Ahafo mine hauled to the concentrator in the south by either trucks or an overland conveyor system. A blend of both primary and oxide ore is fed to the mill to balance the head grade and recovery in the leach circuit.
To isolate pure gold, mining companies use a complex extraction process. The first step in this process is breaking down large chunks of rock into smaller pieces. At a mill, large machines known as crushers reduce the ore to pieces no larger than road gravel. The gravel-like material then enters rotating drums filled with steel balls. In these drums, feed ore into a series of crushers and grinding mills to reduce the size of the ore particles and expose the mineral.
Ahafo mine operates a 54 x 75” gyratory crusher for primary ore and an MMD Sizer for oxide ore. This is followed by a SABC circuit comprising a 34 x 16.4’, 13 MW SAG mill in closed circuit with two MP800 pebble crushers. SAG milling is followed by a 24 x 39’, 13 MW ball mill in closed circuit with a cluster of 26” cyclones. After classification, the milling product is thickened and the overflow is fed to CIL tanks.
Gold Production In Ahafo Mine Ghana West Africa
The expansion has the potential to increase mill capacity from 7.5 million tonnes per annum to 12 million tonnes per annum, and will increase gold production at a lower cost; extending the lifespan of the Ahafo Mine to 2028.
The new development will be done within the mine’s concession without any additional acquisition of lands. Construction works are expected to begin in August 2015 and will last for 24 months, while expansion works on the mining pits are also expected to be carried out from 2016 to 2028.
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