Iduapriem

Overview 

Iduapriem gold mine, wholly owned by AngloGold Ashanti since September 2007, comprises the Iduapriem and Teberebie properties on a 110km² concession. The mine is situated in the western region of Ghana, some 70km north of the coastal city of Takoradi and 10km southwest of Tarkwa.

The mine is bordered to the north by Gold Fields Ghana Ltd’s Tarkwa Mine and to the east by Ghana Manganese Company (GMC) which is a manganese mine opened in the 1920s.

Iduapriem is an open-pit mine and its processing facilities include a carbon-in-leach plant. In 2011, the mine produced 199,000 oz gold.  Work is planned in 2012 to determine if there is an economic resource sufficient to support underground mining.

Location

The mine is located some 70 kilometers north of the coastal city of Takoradi, and 10 kilometers south west of Tarkwa in the western region of Ghana in West Africa.

Ghana is one of the world's top gold producers and mining is an important activity for its economy. Other  exports such as cocoa, crude oil, natural gas, timber, electricity, diamond, bauxite, and manganese are major sources of foreign exchange, even though Ghana continues to experience electricity and gas shortages, and remains a developing nation after 55 years of independence from the declining British rule.

The company has title to the 33km2 Iduapriem mining lease which was granted on 19 April 1989.

Geology & Mineralization

Iduapriem is located within the Tarkwaian Group of rocks that form part of the West Africa Craton which is covered to a large extent by metavolcanics and metasediments of the Birimian Supergroup. In Ghana, the Birimian terrane consists of northeast/southwest trending volcanic belts separated by basins. The Tarkwaian Group was deposited in these basins as shallow water deltaic sediments.

The gold mineralisation at Iduapriem is hosted in the Proterozoic Banket Series conglomerates that were developed within these sediments.

The Banket Reef Zone (BRZ) comprises a sequence of individual beds of quartz pebble conglomerates, breccia conglomerates, quartzites and grits. The outcropping Banket Series in the mine lease area forms prominent curved ridges that extend southwards from Tarkwa, westwards through Iduapriem and northwards towards Teberebie.

All known gold mineralisation within the Banket Series is associated with the conglomerates and is found within the matrix that binds the pebbles together. The gold content is a function of the size and amount of packing of the quartz pebbles within the conglomeratic units. At Iduapriem, the gold mineralisation is unrelated to metamorphic or hydrothermal alteration events and the gold is coarse grained, particulate and free milling. Mineralogical studies indicate that the grain size of native gold particles ranges between 2 and 500μ and averages 130μ. Sulphide mineralisation is present only at trace levels and is not associated with the gold.

As of December 2011, Iduapriem gold mine contained 55.44 million tonnes ore as proven and probable reserves grading 1.43 g/t gold for 2.55 million ounces of gold.

Mining & Operation

The Iduapriem gold mine is a conventional open pit mining operation.

While the mine has limited growth prospects on surface, the higher gold price led to renewed interest in evaluating the considerable low-grade Mineral Resources in the Tarkwaian conglomerates that extend below the economic limits of the existing pits. Work is planned in 2012 to determine if there is an economic resource sufficient to support underground mining.

In addition, the Ajopa project, which was anticipated to start in 2010, is now scheduled to start in mid-2012 and is expected to cost an estimated $12m. Ajopa hosts an ore reserve estimated at 4.97 Mt at a grade of 2.05 g/t, equivalent to around 363,000 oz of gold.

Processing

Ore from the mine is crushed, grounded (SAG & ball mills) and then subjected to cyanidation in an carbon-in-pulp circuit.

 A plant extension was successfully commissioned in 2011, which ensures that the operation can release excess water while fully meeting effluent discharge standards. Also a new facility for making up cyanide was commissined.

A new water treatment plant was built  during 2011 - it uses reverse osmosis to convert used process water from the plant in safe water which is discharged back in the river.

 In 2011, it produced 199,000 oz gold at $853 total cash cost per ounce.

Environment & Community

In 2009, the mine applied for temporary withdrawal from the certification to the cyanide code due to the non-compliance of its existing cyanide mixing and storage facility. Construction of the new cyanide storage facility is in progress and a new application will be made to the International Cyanide Management Institute (ICMI) during 2011. During 2010, the original water treatment plant installed in 2009 was upgraded. This work was undertaken to ensure full treatment of contaminants in process water in order to achieve the discharge standard for release of excess water from the operations.

Iduapriem achieved its ISO 14001 certification following a surveillance audit completed in November 2010.

Iduapriem’s alternative livelihood programme continued in 2010, with strong support from the communities, local chiefs and local authorities. The programme includes crop, fish and palm farming and processing. In addition, a mushroom farming project is being piloted as part of a broader economic development strategy. Women from local communities will operate the mushroom farms as standalone businesses, selling and marketing their produce in and around the Tarkwa region.

Key outstanding issues from previous years, in particular cracks in houses in Teberebie village, were addressed in 2010. Work is still in progress to finalise land-for-land compensation. This would improve an already strong relationship with the mine’s surrounding communities.