AngloGold Ashanti has announced the successful test of its deep-earth mining robot at the company’s Tau Tona gold mine, the world’s deepest mine. The new automated system, known as “South African technology,” successfully drilled multiple 30-meter holes and extracted gold ore at depths in excess of 5 km (3 miles).
The new system, which has so far cost between $30 million and $40 million to develop, eliminates hard-rock blasting, and works 24/7 with no people present. The CEO of AngloGold estimates that the new technology will allow mining of over 100 million ounces of gold that were inaccessible to manual mining, doubling the company’s mineable reserves. Ore grades of 25g/tonne have been successfully mined at the 5km depth.
Hard rock mining usually involves the drilling of holes into the face of the mine, filling them with explosives, and detonating the charges. This is not only extremely dangerous at deep depths, but is inefficient, with much waste rock mixing in with the ore.
Due to the infrastructure needed to transport and support humans more than 2.5 miles beneath the Earth’s surface, millions of ounces of gold have thus far been impossible to mine. Most of each work shift is spent either traveling down shafts to the work area or returning to the surface, in addition to the area having to be evacuated each time a blast is set off. The new mining robots do not use explosives, and can work around the clock, mining 20 meters a day, compared to 3 meters a day by humans.
Human miners will still be used in shallower shafts, but AngloGold has already started introducing the new robots in more of its mines. Labor costs account for more than half the expenses of mining in South Africa, which until now has not seen the level of mechanization in mining that other nations have.