Mponeng
Encyclopedia
Mponeng is a gold mine in South Africa
's North West Province. It extends over two miles below the surface, and is considered to be one of the deepest and most substantial gold mines in the world. The trip from the surface to the bottom of the mine takes over an hour.
6,000 tons of rock are excavated from Mponeng each day. At a cost of $550 per ounce of gold extracted, the mine needs to recover only 0.35 ounces of gold per ton excavated to remain profitable. The mine contains at least two gold reefs, with the deepest three feet thick.
The temperature of the rock reaches 140 degrees Fahrenheit (60 Degrees Celsius), and the mine pumps slurry ice
underground to cool the tunnel air below 85 degrees Fahrenheit (29.5 degrees Celsius) (. 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.
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
's North West Province. It extends over two miles below the surface, and is considered to be one of the deepest and most substantial gold mines in the world. The trip from the surface to the bottom of the mine takes over an hour.
6,000 tons of rock are excavated from Mponeng each day. At a cost of $550 per ounce of gold extracted, the mine needs to recover only 0.35 ounces of gold per ton excavated to remain profitable. The mine contains at least two gold reefs, with the deepest three feet thick.
The temperature of the rock reaches 140 degrees Fahrenheit (60 Degrees Celsius), and the mine pumps slurry ice
Slurry ice
Slurry ice is a phase changing refrigerant made up of millions of ice “micro-crystals” formed and suspended within a solution of water and a freezing point depressant. Some compounds used in the field are salt , ethylene glycol, propylene glycol, various alcohols and sugar...
underground to cool the tunnel air below 85 degrees Fahrenheit (29.5 degrees Celsius) (. 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
Shotcrete
Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....
reinforced with steel fibers, which is further held in place by diamond-mesh netting.