Oyu Tolgoi Underground

Oyu Tolgoi underground project

The Oyu Tolgoi copper mine in Mongolia is a world-class open pit mine and underground project. More than 80% of Oyu Tolgoi’s total value lies deep underground. We are building an underground mine complex, that will use block-caving mining techniques to extract the ore and transport it to the surface.

In January 2022, the Oyu Tolgoi Board approved the beginning of underground mining operations, and the project fired the first and second drawbells of the Hugo North underground mine in June 2022. We expect sustainable underground production in the first half of 2023.

At peak production, Oyu Tolgoi is expected to operate in the first quartile of the copper cash cost curve1. Oyu Tolgoi is expected to produce around 500,000 tonnes of copper per year on average from 2028 to 2036 from the open pit and underground, and an average of around 350,000 tonnes for a further five years2, compared to 163,000 tonnes in 20213.

By 2030 Oyu Tolgoi is expected to be the fourth largest copper mine in the world. It is a complex greenfield project comprising an underground block cave mine and copper concentrator as well as an open pit mine which has been successfully operating for almost ten years. It is one of the most modern, safe, sustainable and water-efficient operations globally, with a workforce which is more than 96% Mongolian. Since 2010, Oyu Tolgoi has spent $4.1 billion on national procurement, with total in-country spend of $13.4 billion, inclusive of taxes and salaries during the same period.

The capital forecast for the project is $7.06 billion, an increase of $0.3 billion against the 2020 Definitive Estimate, largely related to COVID-19 disruptions.


1 Wood Mackenzie copper equivalent cash cost curve (Q4 2021).

2 The 500ktpa target (stated as recovered metal) for the Oyu Tolgoi underground and open pit mines is underpinned 17 per cent by Proved Ore Reserves and 83 per cent by Probable Ore Reserves for the years 2028-2036. The 350kpa production target for the following 5 years is underpinned 18 per cent by Proved Ore Reserves and 82 per cent by Probable Ore Reserves. These production targets have been scheduled from current mine designs by Competent Persons in accordance with the requirements of the Australasian Code for Reporting of Exploration Results, Minerals Resources and Ore Reserves, 2012 Edition (the JORC code).

3 Rio Tinto Annual Results, published 22 February 2022.