Geologists keep abreast with Oyu Tolgoi mine development project

Economy | Mining
2019-11-06 11:33:32

Mongolian geologists crucial part of discovery of Oyu Tolgoi

An establishment of the first national mining and mineral fund at the then-Ministry of Industry and Construction in 1939 marks the beginning of history of the Mongolian geological sector, which has grown as an independent industry of the country up to the present moment, providing coverage of various geographical exploration and studies encompassing the whole territory of Mongolia. As results of the explorations made in the past eight decades, more than 1900 deposits comprised of around 80 types of minerals, including world-class mineral deposits, have been discovered in Mongolia. One of such accomplishment made by Mongolian geologists along with foreign experts is the major discoveries of Oyu Tolgoi that continued for several decades.

Today, the exploitation of the currently estimated 20.8 million tons of copper and 23.5 million ounces of gold from the Southern Oyut open pit and underground deposits of Oyu Tolgoi, have moved forward already to complex phases of currently-active extraction and ore concentrate shipments of the open pit as well as construction of underground mine, stretching over 12 kilometers from the Hugo Dummett, down to the Oyut Deposit, extending to the Heruga Deposit. 

Mongolian geologists played an important part in the history behind the remarkable discovery of the Oyu Tolgoi deposits on a vast area of land located remotely in the Southern Gobi Desert of Mongolia, which unfolded for half a century. Regardless of being observed for its mineral resources by locals and geologists for a long time, this exact land had long remained untouched by no formal geological surveys up until 1957 when an early exploration was performed on the soil of the Oyu Tolgoi. The first geological survey of collaboration of Mongolian and Soviet geologists was headed by Soviet geologist Ya.Petrovich, who detected the possible existence of copper mineralization in the Oyu Tolgoi area.

Comparison of Ulaanbaatar city with Oyu Tolgoi underground deposits’ ore body, containing high contents of gold and copper

Notwithstanding the survey conclusion, which could have led to discovery of huge amount of gold-copper resources under the surface, in all likelihood at the same time of the historic discovery of the copper-molybdenum ore resources of the Erdenet, one of the country’s largest mining developments, no further explorations have been conducted until another Mongolian-Soviet joint geochemical mapping research team had a field study in the beginning of the 1980s to discover circular land formations, which indicated a vast amount of ore bodies.

The study prompted Mongolian geologists D.Garamjav and E.Chagnaa­dorj to continue the study on the area and noted the possible presence of ore-body, followed by a number of extensive but inefficacious explorations with US Company Magma Copper in 1996 and later with Australian BHP Billiton. Thanks to the consistent efforts of the exploration teams in spite of ‘not-so-successful’ attempts to identify significant ore grade mineralization paved the way for further discovery of a batch of quartz veins indicating the mineralization of the deposit. However, BHP Billiton decided to leave the country due to financial setbacks and insufficient amount of mineralization identified.

Oyu Tolgoi named open pit after geologist D.Garamjav, who discovered the deposit 

After Canadian exploration company Ivanhoe Mines took over on the area with exploration license in 2000, the exploration works intensified for about a year again before the company ran run out of financial source to conduct more exploration drills. Under the guidance by the experienced geologist D.Garamjav, the company performed the final drilling holes on the south western area of Oyu Tolgoi in 2001-2002, one of which precisely hit into the spot on porphyry zone containing highest-grade gold, copper and molybdenum, bringing about an extraordinary discovery of the Oyu Tolgoi deposit.

The rest is history with more discoveries of massive deposits, namely Heruga, a series of official talks with the Government of Mongolia on the development and investment of the deposits and arrival of international mining giant Rio Tinto to the project. A memorial monument is now standing beside the Oyu Tolgoi’s Oyut open pit mine named after the late D.Garamjav to commemorate his everlasting legacy and pivotal role in the exploration and survey of the Oyu Tolgoi deposits.

The 80th anniversary of the establishment of the geology sector was celebrated by Mongolians, with conferences and award ceremonies of merit geologists and miners. On the occasion of the jubilee, Oyu Tolgoi LLC, a company in charge of the operations of the Oyu Tolgoi mine development, has invited representatives of the Mongolia’s mineral and geology fields and senior geologists to Oyu Tolgoi project site in Khanbogd soum of Umnugobi aimag for a tour around the tremendous mine development to get acquainted with current operations.

Geologist S.Sanjdorj has been with Oyu Tolgoi since the very beginning of the exploration almost 40 years ago

Welcoming the visitors of the Oyu Tolgoi mine tour, general manager of the Oyu Tolgoi mine site S.Sanjdorj, who has been with Oyu Tolgoi since the very beginning of the exploration almost 40 years ago, delivered the most recent news on the development activities of the Oyu Tolgoi underground mine, where 80 percent of Oyu Tolgoi's total resources lie in. 

“The construction of the underground mine, which is to be developed with a challenging, yet effective method of block-caving mining techniques to extract the ore and transport to the surface to the concentrator, is currently around 60 percent complete, ensuring compliance with work schedules. Several different immense development works are underway in the underground mine construction, namely installing belt conveyor technology and equipping with maintenance service and fuel facilities”.

According to Oyu Tolgoi, up to 200 kilometers long tunnels under construction at depths of up to 1300 meters below the surface to allow safe mining of the deepest parts of Oyu Tolgoi’s ore body, containing high content of copper and gold. “All necessary activities to be carried out to the great depth of the underground mine, including transportation of heavy equipment and mechanisms to the deep underground, are ongoing with the help of fully operational Shaft 1 at 1385 meters under strict schedule” said S.Sanjdorj.

 About 94 percent of Oyu Tolgoi’s over 17 thousand employees are Mongolians

Underground mine’s 1300-meter Shaft 2 construction completed 

Because of demanding conditions of the underground mine construction, the Oyu Tolgoi LLC allowed a short delay in the completion of the Shaft 2 construction, which will be one of the world’s deepest mine shafts at 1300-meter depth and 96-meter-high to transport ore from the underground mine. S.Sanjdorj mentioned that the announcement of commissioning of the Shaft 2 most likely to happen this December. One of five lifts equipped for the Shaft 2 will have a daily extraction capacity of 30 thousand tons with another one of the lifts being able to move machinery and heavy equipment at 60-ton capacity and the other two lifts are for moving workers and maintenance supplies below the surface. “The Shaft 2 will enormously facilitate and speed up future ore extraction processes in the underground mine”.

In terms of open pit development, S.Sanjdorj informed that the daily ore extraction from the open pit, which is presently about 340 meter deep, reaches 120-130 thousand tons, and 110 thousand of which are shipped to the Oyu Tolgoi concentrator, which can process up to 100 thousand tons of ore and one thousand tons of copper concentrate each day. The depth of open pit will be not added in the next 2 to three years as the open pit has been dug up downward for mineral excavation, only the edges of the pit will be expanded.

Senior geologists S.Tseren-Ochir, S.Selembaatar and A.Gotovsuren, who took part in the tour, familiarizing with the development and extraction works of the largest mining development in Mongolia were delighted with what they witnessed at the Oyu Tolgoi mine site. Expressing their satisfaction with the project achievements and processes as well as well-planned and effective organizational structure and management systems, how the standard work procedures and safety performance and culture are maintained and followed perfectly by everybody of thousands of employees at the Oyu Tolgoi mine site to the fullest extent practical and the efficient use of the most advanced technologies and mechanisms in all mine areas, the senior geologists excitingly shared their stories of geological exploration journeys.

Furthermore, Doctor of Geological and Mineralogical Sciences, Mashkov­tsev Grigory Anatolyevich, General Director of the All-Russian Scientific Research Institute of Mineral Raw Materials named after. N.M. Fedorovsky (VIMS) also witnessed the tour. The prominent Russian scientist in the field of geology of ore deposits talked to his fellow senior geologists from Mongolia about his participation in a joint Mongolia-Soviet geological expedition to Mongolia at the end of the 1980s. Noting his pleasure with the fast complex growth of the Mongolian geological and mining field, G.A.Mashkovtsev remarked on the great capacity of mining-specialized human resources and utilization of the latest technologies in the activities of the mine development, with the exception of financial and economic gains from the enormous project.

Indian Ambassador to Mongolia M.P.Singh, who was among the guests of the tour to the Oyu Tolgoi site visit, shared his impression of the Oyu Tolgoi project by “Oyu Tolgoi project being the largest development in Mongolia and the fifth in the world are big number. But if you come here to see your own eyes, you will realize the massive scale of project, including the impressive open pit mine. The project’s very economical use of water, adherence to safety precautions and measures, quiet efficient transportation system, leveraging technologies and support for local economy of the Umnugobi aimag are the first things that made a great impression on me today. Moreover, I would like to mention that when we entered the Oyu Tolgoi facility, we saw three wild asses within the fence d-off site area, which shows the project’s respect for wildlife, herders and for livelihoods of the local people. I really look forward to come back here too see the underground mine once it is done”.

In terms of the water use efficiency mentioned by Mr. M.P.Singh, Oyu Tolgoi is one of the most water-conservative mines in the world, recycling 100 per cent of domestic waste water, and around 80-90 percent of processing water taken from the underground aquifer more than 150-400 meters below surface. As of this year, Oyu Tolgoi used an average of 0.42 cubic meters of water per ton of ore processed – significantly better than the global average of 1.2 cubic meters per ton, and achieved a recycling rate of 85 per cent, according to their performance report. Fully committed to mitigating impact on the wildlife, Oyu Tolgoi mine will be using approximately 20 percent (918 liters per second) of the water from the aquifer during a minimum of forty years of its operations, so that it can never be exhausted and affect herder communities and ecosystem.

Photo by B.Chadraabal

The article originally published on the Mongol Messenger issue No. 43 for November 1, 2019.