JOHANNESBURG (miningweekly.com) – Rio Tinto subsidiary Turquoise Hill Resources’ Oyu Tolgoi mine, in Mongolia, set an all-time high of 25-million tonnes of quarterly mined material in the third quarter of 2016, including stripping for Phase 4 of the project, which is the next area of high-grade ore.

CEO Jeff Tygesen said the project performed as expected during the quarter, as openpit operations focused on phases 3 and 6, after the high-gold Phase 2 was nearly complete in the second quarter.

In the quarter under review, Oyu Tolgoi’s concentrator throughput declined by 4% quarter-on-quarter owing to planned maintenance and conveyor belt repairs.

Copper production in the third quarter declined 9.9% quarter-on-quarter, owing to lower recovery from Phase 6 ore. As expected, gold production in the quarter declined 47.1% from the second quarter owing to lower grades from the completion of mining Phase 2.

Tygeson noted, however, that despite the lower copper and gold production in the quarter, Turquoise Hill was confident in its ability to achieve the higher end of its yearly guidance.

The Canadian company expects Oyu Tolgoi to produce between 175 000 t and 195 000 t of copper in concentrates and 255 000 oz to 285 000 oz of gold in concentrates in 2016.

UNDERGROUND DEVELOPMENT
Turquoise Hill said that underground development at Oyu Tolgoi was progressing well. During the third quarter, work began for Shaft 5 sinking and the convey-to-surface box cut excavation, while construction of critical on-site facilities continued.

The company further noted that Oyu Tolgoi had recently signed an additional underground mining and support services contract with Dayan Contract Mining, a joint venture between Hasu Megawatt and Redpath, for the sinking of Shafts 2 and 5.

At the end of the third quarter, the underground workforce comprised about 1 600 people and was expected to reach a staff complement of 2 400 people by the end of 2016.

Meanwhile, citing recent press speculation that the ramp-up period needed for the Oyu Tolgoi underground mine to reach full production would be seven to nine years, Turquoise Hill clarified that ramp up to full production was expected to take about seven years, according to a 2014 technical report.