Mongolia

Oyu Tolgoi Mine

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Overview

Mine TypeOpen Pit & Underground
StatusActive
Commodities
  • Copper
  • Gold
  • Silver
  • Molybdenum
Mining Method
  • Truck & Shovel / Loader
  • Block caving
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SnapshotOyu Tolgoi mine is one of the world’s largest copper-gold mines.

Rio Tinto delivered first sustainable underground production from Panel 0 in March 2023.

Oyu Tolgoi underground spend expected to be complete by end-2025.

The commissioning of infrastructure for ramp-up to full capacity remains on target: Rio Tinto expect shafts 3 and 4 and the conveyor to surface in the second half of 2024, while the concentrator conversion is expected to be progressively completed from the fourth quarter of 2024 through to the second quarter of 2025. Construction of primary crusher 2 commenced in December 2023 and is due to be complete by the end of 2025.
Related AssetHugo North Lift 1 Expansion

Owners

SourceSource
CompanyInterestOwnership
Erdenes Oyu Tolgoi LLC 34 % Indirect
Rio Tinto plc (operator) 66 % Indirect
Rio Tinto owns a 66% interest in Oyu Tolgoi LLC; the remaining 34% interest is held by the Government of Mongolia through Erdenes Oyu Tolgoi LLC.

Contractors

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Deposit type

  • Porphyry
  • Vein / narrow vein

Summary:

Oyu Tolgoi mine consists of a series of porphyry deposits containing copper, gold, silver, and molybdenum.

The mineral deposits at Oyu Tolgoi lie in a structural corridor where mineralization has been discovered over a 26 km strike length. Four deposits hosting Mineral Resources have been identified: Oyut, Hugo North, Hugo South, and Heruga.

Tolgoi copper-gold deposits currently comprise, from north to south:
• Hugo North – The Hugo Dummett Deposit north of approximately 4766300 N (or the 110 Fault).
• Hugo South - The Hugo Dummett Deposit south the 110 Fault.
• Oyut - The Oyut Deposit includes the Southwest Oyu, South Oyu, Wedge, Central Oyu, Bridge, Western, and Far South zones within mining licence MV-006709.
• Heruga – is within the area governed by the arrangements between Oyu Tolgoi LLC and Entrée LLC except for a small northern portion that lies within the Oyu Tolgoi mining licence MV-006709.

The Oyut deposit is currently being mined as an open pit using conventional drill, blast, load, and haul methods. The Hugo North deposit is currently being developed as an underground mine using the block caving mining method. A staged approach is envisaged for developing the Hugo North deposit, involving mining two block cave lifts (Lift 1 and potentially Lift 2). Mineral Reserves have been estimated for Lift 1, which comprises three panels (Panel 0, Panel 1, and Panel 2).

Hugo South and Hugo North
The Hugo Dummett deposits, Hugo North and Hugo South, contain porphyry-style mineralization associated with quartz-monzodiorite intrusions, concealed beneath a sequence of Upper Devonian and Lower Carboniferous sedimentary and volcanic rocks. The deposits are highly elongated to the north-northeast and extend over 3 km.

The Hugo North zone is virtually contiguous with the Hugo South zone and lie within a similar geological setting. The two deposits are separated by a 110°-striking, 45° to 55° north-dipping fault that displaces Hugo North vertically down a modest distance from Hugo South. The dividing line between the two deposits is approximately 4766300 N, a location marked by the thinning and locally discontinuous nature of the high-grade copper mineralization (defined by greater than 2% copper). The east-striking 110° Fault for the projections of the major faults in the area of the Hugo Dummett deposits), delineates the gold- and copper-rich zone hosted in augite basalt and quartz?monzodiorite of the Hugo North deposit from the more southerly, goldpoor, ignimbrite- and augite basalt-hosted mineralization at Hugo South.

The quartz monzodiorite bodies are contemporaneous with alteration and mineralization. The quartz monzodiorite is considered to be the progenitor porphyry, and two zones are distinguished on the basis of alteration characteristics and position within the deposit.

The highest-grade copper mineralization in the Hugo North deposit is related to a zone of intensely stockworked to sheeted quartz veins known as the QV90 zone, so named because >90% of the rock has >15% quartz veining. The high-grade zone is centred on thin, east dipping quartz monzodiorite intrusions or within the apex of the large quartz monzodiorite body and extends into the adjacent basalt. In addition, moderate-to-high grade copper and gold values occur within quartz monzodiorite below and to the west of the intense vein zone, in the Hugo North gold zone. This zone is distinct and has a high Au (ppm) to Cu (%) ratio of 0.5 to 1.

Oyut deposit
The Oyut deposit includes the most mineralized domain called Southwest Oyu (Southwest), but also includes South Oyu (South), Wedge, and Central Oyu (Central) domain and several smaller, fault- bounded zones. The open pit incorporates most of these domains. They form contiguous sectors of mineralization representing multiple mineralizing centres, each with distinct styles of mineralization, alteration, and host rock lithology. The boundaries between the individual zones coincide with major faults. Faulting has resulted in different erosional histories for the zones, depending on the depth to which a zone has been downfaulted or uplifted relative to neighbouring zones.

Southwest Oyu zone
The Southwest Oyu zone is a gold-rich porphyry system characterized by a south-west–plunging, pipe-like geometry that has a vertical extent of as much as 700 m. The high-grade core of the zone is about 250 m diameter; the low-grade shell (0.3% Cu) surrounding the core may extend for distances as much as 600 m by 2 km.

Over 80% of the deposit is hosted by massive to fragmental porphyritic augite basalt of the Upper Devonian Alagbayan Group, with the remainder hosted by intra-mineral, Late Devonian quartz- monzodiorite intrusions. The quartz-monzodiorite intrusions form irregular plugs and dykes related to several distinct phases:
• Early, strongly altered quartz-veined dykes mainly limited to the high-grade central Central deposit core.
• Superimposed younger fragmental dykes entraining early quartz vein clasts but lacking strong sulfide mineralization.
• Voluminous massive quartz-monzodiorite (informally referred to as QMD) containing weaker mineralization, flanking and underlying the high-grade deposit core.

Several phases of post-mineral dykes cut the Southwest zone. Most of the dykes belong to the rhyolite, hornblende-biotite andesite, or biotite granodiorite intrusive phases. Dykes commonly have steep dips, and many are localized along faults. The rhyolite dykes tend to strike west to west-northwest in the deposit core and north-east when emplaced along major faults. Hornblende- biotite andesite dykes strike east-north-east except where they intrude along the major north- east trending faults.

Central zone
The Central zone is about 2,300 m wide and tapers from about 200 m long in the east to more than 600 m to the west. Mineralization extends to depths of over 500 m. The Central zone is hosted within a swarm of feldspar-phyric quartz-monzodiorite intrusions, emplaced into porphyritic augite basalt and overlying basaltic tuff of the Alagbayan Group. The basaltic tuff is in turn overlain by unmineralized sedimentary and mafic volcanic rocks of the Alagbayan Group unit DA4, which dip moderately to the east (30–60°).

South Oyu zone
The South Oyu zone is developed mainly in basaltic volcanics and related to small, strongly sericite altered quartz–monzodiorite dykes. Zone dimensions are about 400 m by 300 m in area, and mineralization extends to depths of more than 500 m.

Heruga
The Heruga deposit is the most southerly of the currently known deposits at Oyu Tolgoi. The deposit is a copper–gold–molybdenum porphyry deposit and is zoned with a molybdenum-rich carapace at higher elevations overlying gold-rich mineralization at depth. The top of the mineralization starts 500–600 m below the present ground surface. The deposit has been drilled over a 2.3 km length, is elongated in a north–northeast direction and terminates to the north on an east– northeast-trending regional fault with 500 m of apparent dextral displacement. The deposit is transected by a series of north–northeast trending vertical fault structures that step down 200 m to 300 m at a time to the west and have divided the deposit into at least two structural blocks.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityProductUnits202320222021202020192018201720162015
Copper Metal in concentrate kt  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe146159157201202
Copper Concentrate kt  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe675725722
Gold Metal in concentrate koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe242285114300653
Silver Metal in concentrate koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe8679149741,4201,223

Operational metrics

Metrics202320222021202020192018
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe40,777 kt38,738 kt
Total tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe101,316 kt91,310 kt

Production Costs

CommodityUnits2021202020192018
All-in sustaining costs (AISC) Copper USD  ....  Subscribe  ....  Subscribe 2.08 / lb **   2.2 / lb **  
C1 cash costs Copper USD  ....  Subscribe  ....  Subscribe 1.37 / lb **   1.59 / lb **  
** Net of By-Product.

Operating Costs

Currency2021202020192018
OP mining costs ($/t mined) USD 2.24  1.8  1.88  2.13  
Processing costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe

Financials

Units2023202220212020201920182017
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 1,289   1,284   901  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 1,166   1,180   940  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe -2,137   139   22  
Earnings M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 160   25  
EBITDA M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 357   375   256  
Operating Cash Flow M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe

Heavy Mobile Equipment

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EV - Electric

Personnel

Mine Management

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Aerial view:

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