The Oyu Tolgoi mine, also (, ; "Turquoise Hill"), is a combined open pit and underground mining project in Khanbogd sum within the south Gobi Desert, approximately east of the Ömnögovi Province capital Dalanzadgad. The site was discovered in 2001 and is being developed as a joint venture between Turquoise Hill Resources (a majority owned subsidiary of Rio Tinto) with 66% ownership and the Government of Mongolia with 34%. The mine began construction as of 2010 and shipped its first batch of copper on 9 July 2013.
The Oyu Tolgoi mining project is the largest financial undertaking in Mongolia's history and is expected upon completion to produce of copper annually. Financing for the project has come in part from the Rio Tinto Group and an investment agreement between Ivanhoe Mines and the government of Mongolia.
Rio Tinto reached an agreement with the government in January 2022 to move the joint Oyu Tolgoi copper and gold project forward and resolve outstanding issues, which is key for Mongolia to significantly increase its copper exports to China in 2023.
History
In 2001, Canadian-based Ivanhoe Mines estimated the resource gold-copper ore deposit in the Gobi Desert of Mongolia, which Soviets had discovered officially before 1990. It is in an area known as Oyu Tolgoi (Mongolian for Turquoise Hill), where in the time of Genghis Khan outcropping rocks were smelted for copper. The place was suspected to have mineralization by Mongolian geologists since the 1950s. By 2003 there were 18 exploration drill rigs on the property employing approximately 200 people, and Oyu Tolgoi was the "biggest mining exploration project in the world." In January 2013 Oyu Tolgoi started producing concentrate from the mine.
Description
The Oyu Tolgoi mine is in the South Gobi Desert of Mongolia, north of Mongolia's border with the People's Republic of China, where the mined copper is expected to be shipped. Oyu Tolgoi deposits contain an estimated 2.7 million tonnes of copper and of gold. It also contains 1,900 tonnes of silver and 205,000 tonnes of molybdenum. Production began in 2013 and is scheduled to reach full capacity in 2021. Over the anticipated lifespan of the mine (>50 years), Oyu Tolgoi is scheduled to produce of copper per year, an amount equal to 3% of global production. Oyu Tolgoi is also expected to produce of gold annually, with "by-product silver and molybdenum". Rio Tinto intends to employ 3,000–4,000 people from Mongolia.
In January 2022, Rio Tinto reached an agreement with the government to move the joint Oyu Tolgoi copper and gold project forward and resolve outstanding issues. The agreement is key for Mongolia to significantly increase its copper exports to China in 2023 and attract more investment.
Geology
The deposits are Late Devonian quartz monzodiorite igneous intrusions, and include the Southwest Oyu, South Oyu, Central Oyu, Hugo Dummett, and Heruga gold and porphyry copper deposits. The central portion of the deposit consists of hydrothermal breccia that crosscuts a feldspar porphyryr. The regional geology consists of middle to late Paleozoic Gurvansaihan island arc terrane.
Mining and milling
Oyu Tolgoi will use both underground and open pit mining techniques. Initially the mine will process 70,000 tonnes of rock per day, ramping up to 85,000 tonnes from both the open pit and the underground mine (underground mining is to be done by block caving). The yield from the first phase of mining will be ground through one semi-autogenous grinding mill (SAG mill). Expansion to new underground areas will result in an additional increase of up to 140,000 tonnes per day with a possible increase to 170,000 tonnes per day.