20 August 2007
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TauTona to take ‘deepest mine’ accolade

Gold producer AngloGold Ashanti will celebrate a historical moment in July 2008 when its TauTona mine, in Carltonville, surpasses the current record to become the deepest mine in the world.

The Below 120 Carbon Leader project will take TauTona to a depth of 3 902 m.

Currently, the deepest-mine accolade belongs to Savuka mine, in the North West province, which descends to a depth of 3 774 km.

The TauTona project, which was initiated two years ago, has an approved expenditure budget of R1,2-billion. On completion of the mining area below 120 level, it is estimated that 1,2-million m2 will be mined and 26 km of develop- ment will be completed.

The Carbon Leader project will involve the sinking of the twin decline shaft, which will take the mine down another five levels to shaft bottom. This infrastructure will enable the mining of an addi-tional 1,2-million m2 and yield about 72 t of gold.

Currently, TauTona’s narrow reef tabular orebody produces about 550 000 oz of gold yearly. Current infrastructure is down to 3 600 m and in March 2007, the sinking of the twin decline shaft will take TauTona to a depth of 3 902 m. With the introduction of down-dip mining, the stoping date of the project has been moved ahead to April 2008. Murray & Roberts have already excavated the rock chamber and the man-and-material shaft, with civil work under way. This will be followed by the winder installation of the rock chamber. The sinking of the man-and-materials handling shaft will be completed in December 2009 and the sinking process for the rock shaft in March 2010. The 718,1-m-long man-and- material decline, with a 350-kW double drum winder, will have a rope speed of 3,5 m/s.

The Deilmann Haniel K313 decline loader will be used to sink the declines. The Deilmann Haniel drill rig will be used to advance the decline at a rate of three meters a blast.

Sinking and production will occur simultaneously owing to the existence of interboxes on the reef elevation. This will allow ore to be drawn into the shaft and hoisted to the 120 project site while sinking is under way. This will bring financial returns for AngloGold Ashanti, as gold will be recovered during the sinking process.

With 5 500 people employed at TauTona, those working on the project area will have to travel an additional four kilometres horizontally to reach their daily destination. It currently takes about an hour-and-a-half to travel to the face and, as the project reaches greater depths, travelling times will increase.

The existing shaft vertical system triple-deck cages carry about 120 people at a time. TauTona has a three-tier system of a main shaft, subshaft and tertiary shaft. Management at Tau-Tona has envisaged a new transport system that will maintain output at current levels. The system, a gondola, will transport workers on their decline down the mine. The gondola will have its own on-board driver, conventional winder brakes and a special design brake for use in emergencies.

The gondola personnel-carrying cassette will carry the same amount of people ensuring a consistent flow of workers through the four-shaft system. As personnel arrive at the Q shaft, the gondola will depart and the next group of workers will arrive. Decline equipment will also include a three-material car cassette, which is attached to the main driver conveyance, thus allowing for the transport of mate-rial bulk to the various levels when it is required for production and sinking. Other advances have also been made to ensure that production is maintained. The Hilti rock drills will replace the air-driven rock drills on the existing Below 120 area. TauTona is currently in the pro-cess of rolling out all stope panels that are being mined.

The average face advance is already 12 m. Three drillers and three assistants will be used in each panel on the pre-Hilti while two drillers and two assistants will be used on the post-Hilti.

Panel lengths are established at 28m and an increase in winch operating speeds from 1,1 m/s to 1,3 m/s, having one back-fill range for every two panels instead of one for every three panels and the use of the Hilti electric drills on all stope faces.

At a depth of 3 902 m, virgin rock temperatures will increase from the current 55 �C to 59 �C. Mining at greater depth induces higher temperatures and upgraded fridge plants will be used to maintain the mandatory 28 �C temperature.