Sound Problem Fix High Resolution Reupload = https://www.youtube.com/watch?v=HrA-tegCkhE
Mponeng is a gold mine in South Africa's Gauteng province. It extends over 4 kilometres (2.5 mi) below the surface and is considered to be one of the most substantial gold mines in the world. It is also currently the world's deepest mine from ground level. The trip from the surface to the bottom of the mine takes over an hour.
Over 5400 metric tonnes of rock are excavated from Mponeng each day. At a price of $19.4 per gram of gold the mine only needs to extract 10 grams of gold per ton excavated to remain profitable. The mine contains at least two gold reefs with the deepest one metre thick.
The temperature of the rock reaches 66 °C (151 °F) and the mine pumps slurry ice underground to cool the tunnel air below 30 °C (86 °F). A mixture of concrete water and rock is packed into excavated areas which further acts as an insulator. Tunnel walls are secured by flexible shotcrete reinforced with steel fibers which is further held in place by diamond-mesh netting.
Danny Forster visited the mine for Build It Bigger
With the world getting better and better every second the quest for perfection is at its limit and beyond. The quest of perfection is getting insatiable and there are some insanely big and ambitious projects underway. Here are the mega projects which promise to further enhance the world we currently live in.
Engineering projects around the globe keep getting bigger and more ambitious. there are structures being designed and built that will dwarf anything that has come before. Plans are on the drawing board for projects so huge – not only in scale but in their implications for society – they’re almost beyond imagination. This documentary that eyes the largest construction projects ever imagined – 'Extreme Engineering'.