Taking the world’s fourth-largest copper mine underground.
About 1.3 kilometres beneath the remote Gobi Desert, you’ll find a hive of activity.

For the past decade, thousands of Mongolians and their international colleagues have been working to access the underground orebody at the Oyu Tolgoi (OT) copper mine, a partnership between Rio Tinto and the Government of Mongolia.

Today we celebrated the start of production from the underground mine, which will make OT one of the most important producers of copper in the world. At full production, OT’s underground and open cut mines will produce enough copper annually for more than 6 million electric vehicles.

Since 2013, OT has been producing copper concentrate using the ore mined from the open pit, while building the underground mine and readying it for production.

At every stage of the project, the team has been finding better ways to provide copper – a material the world needs for the energy transition. It’s a story of continuous improvement – from the way we manage water resources to trialling new technology to improve safety to creating partnerships, like the Tri-Partite Council, to make sure community voices are heard. And we know there is still more we can do.

As we celebrate this milestone, we’ve chosen some of our favourite images from OT so far. Here are the stories behind them.