Turquoise Hill Resources Ltd.'s Oyu Tolgoi mine in Mongolia exceeded 2018 production guidance for both copper and gold by 2.6% and 1.8%, respectively.
The company was targeting to produce between 140,000 and 155,000 tonnes of copper in concentrates and between 240,000 and 280,000 ounces of gold in concentrates in the full-year.
For full-year 2018, copper output and sales rose 1.1% and 5%, respectively, to 159,100 tonnes and 156,700 tonnes.
Gold production jumped 150% to 285,000 ounces, while gold sales saw a 123.4% increase to 248,000 ounces. The company's silver production fell 6.2% year over year to 914,000 ounces, but sales inched up 1.5% to 873,000 ounces in the full-year period.
For the fourth quarter of 2018, copper production slipped 8.4% year over year to 41,500 tonnes, while gold production jumped 234.3% to 117,000 ounces. Silver output, meanwhile, fell 16.5% to 238,000 ounces.
The yearly jump in the fourth-quarter gold production was driven by significant increases in both grades and recovery, while the dip in the copper output was attributed to lower throughput, which was partially offset by higher grades and recovery.
Copper sales in the period climbed 12.6% to 40,200 tonnes. Gold sales soared 311.1% to 111,000 ounces, with silver sales rose by 5.4% to 216,000 ounces.
Turquoise Hill sees its full-year 2019 copper output ranging between 125,000 and 155,000 tonnes, while gold output is estimated at between 180,000 to 220,000 ounces, both lower than full-year 2018 targets.
Open-pit operations at Oyu Tolgoi are expected to mine phase four throughout the year, while underground lateral development is expected to advance 15 to 16 kilometers during 2019.
The company added that it is updating the latest developments on power study costs following the recent signing of the a power source framework agreement between the Oyu Tolgoi and the government of Mongolia for construction of a Tavan Tolgoi-based power project.