The Deepest Gold Mine on Earth - The Mponeng Gold Mine
Mining can be a dangerous business. Recovering minerals from the earth has never been an easy task, but the thirst for precious metals and stones has lead people to go to amazing lengths. New technology and growing rarity is pushing the industry to mine in more and more challenging situations and to dig deeper.
An example of this trend is the amazing Mponeng Gold Mine in South Africa. This mine complex is home to the deepest mine shaft on earth, the deepest is currently 2.4 miles deep (3.9 kilometres).
The first shaft was completed in 1986, but it is the sub-shaft that is the deepest. It was finished in 1993, and there are plans to take the shaft beyond the 4 kilometre mark in the next decade. This will allow the owners of the mine, AngloGold Ashanti, to continue to mine here until at least 2024.
Naturally, a mine like this employs a lot of people. There are around 35,000 people working at the mine, which means that the surrounding area has benefitted greatly. The town of Carletonville existed as a direct result of mining that started in 1937.
However, not all of the people who work in the mine are employed by AngloGold Ashanti. As well as the legal workers there are hundreds of people who live and work in the mine as illegal miners.
They spend weeks at a time in the mine extracting the ore and processing it into gold. Because these people do not see sunlight during that time, they take on a grey palor, which gives them a ghost like appearance.
As well as being the deepest mine on earth, it is also one of the hottest. The deeper you go the hotter it gets. At the bottom the rock reaches temperatures of 151F.
To cool the mine ice is mixed with slurry and pumped down into a lake below the shaft. Air is blown across the lake, which flows through the mine and brings the average temperature to a bearable 85F. Every day the mine's ice plant produces huge quantities of ice to help to cool the mine.
In addition, once an area has been excavated it is back filled with concrete and rock. This provides further insulation that helps to keep the temperature down.
In 2006, researchers found bacteria in the mine that lived without relying on photosynthesis. Instead, they used the radioactivity in the rock as their energy source. Before 2006 nobody realised anything could live in these conditions.
Currently, 5,400 metric tonnes of rock are extracted from the mine, which produces around 520,000ozs of pure gold. The ore is processed on site. It is estimated that reserves will last up to 2024. In places, the VCR reef is up to 3 meters thick, but smaller reefs could potentially be reached from the two existing shafts, so mining at Mponeng could potentially continue for longer.