Key facts

• 80 per cent of Oyu Tolgoi’s value lies beneath the surface
• Mining method: Block caving
• Operations: The mine will work 365 days a year with two 12-hour shifts.
• The total conveyor length (13.2 kilometres) is as long as the distance from the Sukhbaatar Square to Tolgoit station.
• The depth of the deepest shaft is equivalent of 12 Blue Sky Towers
• Total length of tunnels over the life of Hugo North Lift 1 – 203 kilometres (mostly with a height of 5.5m and a width of 5m)

What is block caving?

The block caving method of mining uses the force of gravity to extract ore from an underground deposit. A series of lateral tunnels are developed under the deposit with an undercut level and extraction level. The ore is undercut creating a void which allows the rock above to fall under its own weight into draw bells. Loaders on the extraction level then remove the fallen rock from the draw points, allowing more rock to feed into the draw bell and as the void created by the initial undercut propagates up through the deposit.