Our Operations

Open Pit

The open pit accesses the Southern Oyu deposit, one of three deposits discovered at Oyu Tolgoi. Extracting minerals involves a four-step process: blasting, excavation, removal and initial primary crushing.

The open pit is mined using a combination of excavator dump trucks and shovel dump trucks. Ore is removed from a series of benches which are linked to the top of the pit by a 40 metre wide trench road. Each truck transports around 290 tonnes of excavated soil and ore to the top of the pit where it is stockpiled or sent to the primary crusher. Hydraulic and cable operated electric excavators (Bucyrus RH 340B and 495HR shovels) are used alongside Komatsu 930Е-4SE dump trucks. A total of 28 dump trucks have been used on site since August 2012.

What happens?

1. Blasting

Explosives are placed in holes drilled into the ground and safely detonated. This loosens the earth, preparing it for excavation.

2. Excavation

After blasting, giant Bucyrus excavators scoop up ore from the loose ground. Geological surveys allow engineers to know how much metal can be found in each part of the open pit.

3. Removal

Between two and three shovels of ore are then dumped into giant, 290 tonne Komatsu haul-trucks. Oyu Tolgoi has a fleet of 28 of these giant machines. These operate in shifts, driving the ore out from the bottom of the open pit.

4. Primary crusher

Just outside the top of the open pit, the haul trucks dump the ore into the primary crusher. This breaks the ore up into volleyball sized pieces of rock which are then ready to be sent on a 2.7 km conveyer belt to the Oyu Tolgoi concentrator.


  • Stripping of the Southern Oyu deposits to prepare for open pit mining began in August 2011.
  • The first ore from Oyu Tolgoi was mined at the open pit in April 2012.
  • The open pit mine will eventually cover an area of 1.5x2.7 km and will be about 650 metres deep.

Equipment used at the open pit

There are more than 1,000 Komatsu 930Е-4SЕ trucks operating at mines around the world. With a horsepower of between 2,700 and 3,500, their key strength lies in their ability to travel uphill without losing power. As the mine goes deeper, the trucks will become even more productive. It is a high quality, durable and reliable vehicle with a strong electrical system. Each wheel has its own engine and coolant system. Two Bucyrus 495HR steel cable shovels are in operation at the mine. The Bucyrus 495HR shovel is a highly efficient vehicle with a bucket capacity of 56 cubic metres.