Despite the lower gold price negatively impacting the extent of the final pit shell geometries, the Mineral Reserve grade from open pits is stable year-on-year at 1.24g/t.
Tarkwa is located in south-western Ghana approximately 300km by road west of Accra, the capital, at latitude 5°15’N and longitude 2°00’W. The Tarkwa gold mine is located 4km west of the town of Tarkwa with good access roads and an established infrastructure. The mine is served by a main road connecting to the port of Takoradi some 60km to the south on the Atlantic coast.
|Licence status and holdings||
The Tarkwa mine operates under mining leases covering a total area of approximately 20,825ha. Five mining leases, dated 18 April 1997, cover the Tarkwa property, while two mining leases, dated 2 February 1988 and 18 June 1992 respectively, cover the Teberebie property. The Tarkwa concession mining leases expire in 2027 and the Teberebie property mining leases expire in 2018. Application for an extension of the mining leases has been applied for and all required fees and documentation submitted to the Minerals Commission of Ghana. There is no reason to expect that these will not be granted. All necessary statutory mining authorisations and permits are in place for the Tarkwa Mine Lease and GFG is entitled to mine all material falling within the lease.
and processing capacity
Four large open pits currently exploit the stacked narrow auriferous conglomerates, similar to those mined in the Witwatersrand Basin of South Africa.
Ore is processed utilising a conventional CIL plant, with a gyratory crusher feeding a SAG mill and ball mill. Gold is recovered from solution by electro-winning and smelted in an induction furnace. Current plant capacity is 13.5Mtpa.
LoM tailings deposition requirements are catered for in the short term by wall raise sequences at the operating TSF 1, 2 and 3 facilities and in the medium term by TSF 5 whose construction commenced in 2016. In the longer term, LoM tailings deposition requirements will be catered for by planned TSFs 4 and 6.
A tropical climate, characterised by two distinct rainy seasons from March to July and September to November. Average annual rainfall near the site is 2,245m. Although there may be minor disruptions to operations during the wet season, there is no operating or long-term constraint on production due to climate.
The open pit surface operation currently exploits the tabular auriferous conglomerates from four open pits – Pepe-Mantraim, Teberebie, Akontansi and Kottraverchy.
It is estimated that the current Mineral Reserves will be depleted in 2031 (15 years).
|Environmental, health and safety||
Tarkwa retained its ISO 14001 environmental management system certification following an external audit during 2015. The mine also retained full compliance to the ICMC, as well as OHSAS 18001 in June 2014 respectively.
Brief history of Tarkwa
Sinking of the Abontiakoon vertical shaft was completed in 1935 and a central mill with a capacity of 30ktpm was constructed in the following four years. Several small mining companies operated the Abontiakoon concession, but in 1960 all workings were abandoned and allowed to flood.
In 1961, production restarted under the State Gold Mining Corporation and in 1963 the Tarkwa mines were renamed Tarkwa Goldfields Limited. The Apinto Shaft was sunk in the mid-seventies.
GFG signed a management contract with the Ghanaian Government to operate the mine in 1993, and in 1996 completed a feasibility study on an open pit/heap leach operation. In 1998, the initial Tarkwa Phase 1 development was completed for an open pit operation mining 14.5Mtpa, including 4.7Mtpa of heap leach feed ore. In 1999, the Tarkwa Phase 2 expansion was completed to increase the mining rate to 20.7Mtpa and heap leach feed ore production to 7.2Mtpa. All underground operations and the associated processing plant ceased production in this year. In 2000, GFG acquired the northern area of Teberebie and mining production was increased to 36Mtpa.
Tarkwa implemented owner mining in July 2004 and commissioned a CIL plant with a name plate capacity of 4.2Mtpa in October 2004. The expanded CIL plant was commissioned in January 2009 and a design throughput of 12.3Mtpa was achieved in September 2009. Conversion to owner maintenance was completed in 2010.
In 2011, GFG acquired the 18.9% IAMGold interest in Tarkwa and now holds 90%, with the remaining 10% held by the Ghanaian Government. At the end of 2013, all heap leach operations ceased.
The CIL plant capacity was increased to 13.5Mtpa late in 2014.
Key developments and material issues
- World-class, low-cost surface mine with a 6.1Moz Mineral Reserve and 15-year life (nine years mining, followed by processing of the surface stockpile and South Heap Leach material) that remains strongly geared to the gold price – strong potential for leveraging resource ounce conversion and driving larger pits with high gold prices
- Mineral Resources decreased by 4% and Mineral Reserves by 10%, mainly from a US$100/oz lower gold price and mined depletion
- Reserve grade from open pits remained stable year-on-year at 1.24g/t (1.25g/t 2015)
- The 60Mt of SHL ore at 0.4g/t for 771koz processed at the end of mine life remains value accretive, especially with the operating cost benefits delivered by the Genser gas power generation project
- On-lease palaeoplacer and hydrothermal style exploration continues with the intent of defining new higher-grade ore sources from the hydrothermal prospects
- Kottraverchy underground potential is undergoing assessment to profile any suitable options to turn the underground extensions of the palaeoplacer ore body to account
- Options for in-pit waste dumping are being assessed
Plan of the Tarkwa mining area