Ore Daily PerspectivePaused Oyu Tolgoi underground carried 70% of copper fed to the mill
Rio Tinto has stopped underground mining at the mine that made 56% of its copper last quarter. The underground ore carries most of that copper. China's border checks were already slowing exports.
Where the copper comes from
Oyu Tolgoi produced 113.5 kt of copper in concentrate in the third quarter, up 27% on the year, Rio Tinto's Oct. 14 report shows. That is about 1.2 kt a day, or 8.6 kt a week, by Ore Daily's calculation. It was 56% of Rio's consolidated copper output.
The underground mine drives it. It sent 3.77 Mt of ore to the mill at 2.36% copper in the quarter. The open pit sent 7.39 Mt at 0.51%. The underground ore held about 88.9 kt of copper and the pit ore about 37.7 kt. That puts about 70% of the copper entering the mill on the underground side, by Ore Daily's calculation, up from 61% a year earlier.
Rio said this week it paused underground work after seismic activity on a fault zone shook the mine. Three employees were hurt and no one died, Reuters reported. Rio gave no restart date.


Two problems at once
Exports were already slowing. Truck convoys through China's Ganqimaodu crossing fell to about four a day from the usual 12–13 over the past two weeks, Oyu Tolgoi LLC told the AP. Concentrate exports are down about 70%. China introduced in-vehicle facial recognition for truck drivers there in August, and the port work could run to the end of December, AP reported.
Sales trailed output before either problem. Oyu Tolgoi sold 106.8 kt of copper in concentrate in the third quarter, 6.7 kt less than it produced, by Ore Daily's calculation. Local media put the export losses at about $300M, rising to $1.2bn if the checks last the year, AP reported. Oyu Tolgoi LLC did not confirm those figures.
What to watch
Rio kept its 2026 copper guidance of 800–870 kt on Oct. 14, before both events. It produced 646.3 kt in the first nine months, which leaves 154–224 kt for the fourth quarter, by Ore Daily's calculation. Rio's operations outside Oyu Tolgoi produced 91.0 kt in the third quarter.
Oyu Tolgoi ran at about 450 kt a year in the third quarter, Rio said. That is roughly 2% of the 23.0 Mt of copper mined worldwide in 2025, based on USGS estimates. Rio still targets about 500 kt a year from 2028 to 2036. Mongolia's finance minister, Mendsaikhan Zagdjav, said ministers were told to visit the crossing and meet Chinese officials, AP reported.
Sources: Rio Tinto Q3 2026 operations review (SEC) · Rio Tinto Q3 2026 (ASX) · Reuters via MINING.COM, Oct 29 · MINING.COM, Oct 29 · AP via Yahoo, Oct 29 · Australian Mining Review, Oct 30 · USGS MCS 2026
Ore Daily analysis of public data. Figures are as reported by the sources.



