Turquoise Hill Resources reported in early June that Oyu Tolgoi LLC has drawn down approximately $4 billion of a project finance facility signed in December 2015 for development of block cave underground mining at the Oyu Tolgoi copper-gold-silver mining complex in southern Mongolia. The boards of Oyu Tolgoi LLC, Turquoise Hill and Rio Tinto approved the restart of underground development at Oyu Tolgoi in early May (E&MJ, June 2016, p. 4).

The project finance facility is being provided by a syndicate of international financial institutions; export credit agencies representing the governments of Canada, the United States and Australia; and 15 commercial banks.

Turquoise Hill also reported the signing of a contract with Jacobs Engineering Group to provide EPCM services for underground development at Oyu Tolgoi, paving the way for construction to begin. The project is expected to be delivered over a five to seven-year period. The underground mine is scheduled to produce 95,000 mt/d of plant feed.

The current Oyu Tolgoi underground development program will build on work completed prior to August 2013. This work included completion of Shaft No. 1 to its full depth of 1,380 m in February 2008. The shaft is concrete-lined to a finished diameter of 6.7 m. The design allows for future conversion to permit the shaft to be used as a permanent hoisting facility.

Also prior to August 2013, underground lateral development had advanced approximately 16 km off Shaft No. 1. Sinking of Shaft No. 2, the primary operations access and initial production hoisting shaft, had reached a depth of 1,168 m below surface, 91% of its final depth of 1,284 m. Sinking of Shaft No. 5, a dedicated exhaust ventilation shaft, had reached a depth of 208 m, 17% of its final depth of 1,174 m. Surface facilities, including offices, mine dry, and workshop, are in place to support pre-production development and construction.