Oyu Tolgoi: engineering a Mongolian caving dynasty

Abstract

Oyu Tolgoi, located in the South Gobi region of Mongolia, is a world-class mining and processing complex jointly owned by the Government of Mongolia (34%) and Turquoise Hill Resources (66%). Rio Tinto owns 50.8% of Turquoise Hill Resources and is the Manager. Rio Tinto provides extensive and critical management services and support for the operation. Oyu Tolgoi comprises multiple copper, gold and molybdenum deposits located within a more than 23 kmlong structural corridor, the bulk of the known deposits requiring underground extraction. Surface mining commenced at Oyu Tolgoi in 2011 and first copper concentrate was produced in 2013. Mining operations have now started from underground following the commencement of production ramp-up in January 2022 of the 95,000 tonnes per day Hugo North Lift 1 block cave mine. Whilst surface mining will continue into the future, underground mining operations are expected to underpin the business for many decades to come and will make Oyu Tolgoi amongst the largest copper producers in the world. Production from Hugo North Lift 1 is the culmination of more than 20 years of investment in the project. To date, more than 100 km of underground development has been completed, three shafts have been sunk and a significant crushing and material handling infrastructure has been installed to support the initial stages of underground production. Construction of the remaining infrastructure (additional two ventilation shafts, second primary underground crusher, conveyors systems to surface and concentrator upgrade) is continuing in parallel with production ramp-up. The underground project has been complex; including sourcing and developing the technical, project management, construction and operational capability from around the world that is required to undertake a project of Oyu Tolgoi’s magnitude and complexity, addressing the impacts of the COVID-19 pandemic and changes to the extraction level design in the initial underground mining area during construction. Fundamental to the project’s success has been the commitment of the more than 20,000 people who have been involved in the project, but especially the Oyu Tolgoi’s investment in Mongolian capability, including the establishment of a world-class Mongolian underground mine workforce and supporting mining and construction service industry and in-country engineering and technical capability. Oyu Tolgoi establishes Mongolia as the next centre of large-scale block cave mining in the world.