Oyu Tolgoi’s chief development officer, underground, Marco Pires, said: “This contract is another major milestone as we progress with the underground development and demonstrates our commitment to further strengthening national supply chain and skilled workforce. Dayan brings together the strength of a Mongolian company with international expertise in underground development, and will bring long-term benefits by creating world class expertise and capability in Mongolia.”

The contract entails the sinking of Shaft 2 and Shaft 5 at Oyu Tolgoi. The two separate vertical shafts will reach a total depth of 1,284m and 1,178m respectively. Shaft 2 with 10m diameter is among the largest of its kind in the world. Shaft 5 is for ventilation purposes and will measure 6.7m in diameter.

The contract also includes underground development services, which will cover lateral development, large excavations and mine services of the underground mine; and also mining support services, which will cover development and provision of a skilled Mongolian workforce for the underground project.