The Lihir gold mine in Papua New Guinea (PNG) is one of the largest operational gold mines in the world.
The first gold at the mine was produced in 1997. The gold mine was managed by a subsidiary of Rio Tinto until late 2005, and the operatorship was then handed over to Lihir Gold.
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In 2010, Australian miner Newcrest Mining acquired Lihir Gold in a $9bn deal.
In November 2023, the mine became part of Newmont’s portfolio after it acquired Newcrest Mining for nearly $17bn.
According to a technical report published in December 2023, active mining at Lihir is expected to cease in 2039, with processing operations continuing until 2040.
The mine produced 614 kilo-ounces (koz) of gold in fiscal year 2024. The operation employs approximately 5,100 residential and fly-in-fly-out workers.
The Phase 14A layback project is currently underway at the mine and is expected to deliver approximately 30% more gold by 2028, driven by higher ore grades.
Lihir gold mine location
The Lihir gold mine is located on Aniolam Island in the New Ireland Province, within a geothermally active, extinct volcanic crater near the town of Londolovit. The site is around 900km north-east of Port Moresby.
The operation comprises a special mining lease, multiple mining leases, exploration licences and mining easements.
Geology and reserves of Lihir gold mine
Aniolam Island forms part of a 250km-long, northwest-trending alkalic volcanic island chain located in a complex tectonic setting involving several micro-plates.
The island comprises five main volcanic blocks, notably two Plio–Pleistocene units called Londolovit Block and Wurtol Wedge; and three Pleistocene volcanic edifices known as Huniho, Kinami, and Luise.
The Luise volcano features a 4km × 3.5km amphitheatre, elongated and breached to the north-east, interpreted as the remnant of an approximately 1.1km-high volcanic cone that underwent sector collapse.
Classified as an epithermal gold system, Lihir is situated in the footwall of the sector-collapse detachment surface.
The deposit measures approximately 1,500m × 3,000m, with a depth extent of 500m. It remains open at depth, along strike, and to the east where it is currently limited by the Pacific Ocean.
Mineralisation is described as complex and refractory, associated mainly with pyrite and marcasite in veinlets, disseminations, replacements and breccia fillings.
Gold occurs predominantly as a solid solution within pyrite, and locally as electrum, gold tellurides and native gold associated with quartz, calcite and bladed anhydrite.
Lihir’s reserves are estimated at 15.8 million ounces (moz) as of February 2025.
Lihir phase 14A layback project details
In January 2023, Newcrest approved the Lihir Phase 14A feasibility study (FS) and endorsed its implementation.
The study assessed the potential for growth and large-scale, long-life, low-cost production. The project involves a capital investment of around $280m.
The feasibility study estimated that Phase 14A ore will replace lower‑grade feed to the processing plant.
The project is expected to process 13 million tonnes (mt) of high‑grade and medium‑grade material through to FY26, generating approximately 400koz of incremental gold.
Lower‑grade ore will be stockpiled and treated progressively over the remainder of the mine life.
Mining details of the Lihir gold mine
Lihir is a large open-pit gold operation where mining is conducted using an owner-operated fleet and workforce, while a separate contractor, equipped with a smaller pioneering fleet, is responsible for opening up new working areas on the steep caldera slopes.
The conventional technique uses a fleet of 500t-600t class hydraulic face shovels that load ore and waste into 135t rear-dump haul trucks, supporting a proven ex-pit mining rate of approximately 30-35 million tonnes per year (mtpa).
Drilling and blasting are carried out on 12m benches, which are then mined in a single pass. Where conditions allow, pre-split drilling is employed to improve wall stability.
The high geothermal temperatures in parts of the pit often make standard explosives unsuitable, so specialised high-temperature products and tailored blasting procedures are used for hot-ground conditions.
Waste rock is either loaded into 1,500t barges for controlled offshore submarine disposal or stockpiled on land for later use as road base, bench sheeting, stemming material, or general construction fill.
Ore processing details at Lihir mine
Lihir predominantly treats refractory ore using pressure oxidation (POX) followed by conventional leaching to recover gold.
The plant, commissioned in 1997, has been repeatedly modified and expanded to increase throughput.
Primary crushing is carried out in two circuits, including a single circuit with a gyratory crusher and an MMD toothed rolls crusher, and a second circuit where two jaw crushers operate in parallel.
Three grinding lines (HGO, FGO, HGO₂) each comprise a semi-autonomous grind (SAG) mill followed by a ball mill in closed circuit with hydrocyclones.
As of December 2023, nominal capacities of the HGO, FGO and HGO₂ mills are 6.5mtpa, 5mtpa, and 6.5mtpa, respectively.
A thickened ore slurry, comprising flotation concentrate and whole ore, is pumped from six slurry storage tanks to four parallel autoclave trains. Oxygen for the autoclaves is supplied by three operating cryogenic oxygen plants.
The oxidised slurry, together with some fine flotation tailings, then passes through two parallel two‑stage counter-current decantation (CCD) circuits, where it is washed with process water and seawater and neutralised with lime.
Gold is extracted from the neutralised slurry by cyanide leaching in a conventional carbon-in-leach (CIL) circuit consisting of a series of agitated tanks.
Loaded carbon from the CIL tanks is treated in an elution circuit to remove the gold, producing a gold-bearing solution. This solution is passed through electrowinning cells, where gold is recovered as a sludge.
The gold sludge is subsequently dried and smelted to produce doré bars, which are then shipped to a refinery for further processing.
Infrastructure details of Lihir gold mine
The mine can be accessed through roads from the Put Put village, as well as an airstrip at Kunaye.
Run-of-mine stockpiles, crushing circuits and associated mine support infrastructure are situated in the Ladolam Creek valley.
Support infrastructure comprises a main administrative office, laboratory, training facility, warehouses, a plant workshop, and a combined emergency and security services building.
Workforce infrastructure includes residential housing, camp-style accommodation and associated community amenities.
Power for the operation is generated on site using a combination of heavy fuel oil (HFO) reciprocating engines and geothermal steam turbines.
Contractors involved
Fluor Daniel and Clough Niugini, a subsidiary of Clough, are some of the contractors involved in the original development of the mine.
MOSA, a joint venture between Vinci-owned Spiecapag and its sister company Menard Oceania, was responsible for the Lihir ground stabilisation project, which involved the construction of a benched retaining wall to enable continued mining in the adjacent pit.
Worley has been providing engineering, procurement and construction management services under a contract awarded in October 2020.
In December 2020, Wartsila signed a ten-year tailored Guaranteed Asset Performance Agreement to provide maintenance and operations advisory services for the Lihir gold mine’s critical 170MW power plant, which is powered by 22 Wartsila engines.
AECI won a five-year contract in October 2023 for the supply of explosives and related services to the Lihir operation.
Metso’s Geminex metallurgical digital twin was deployed at the mine to optimise material flows, manage ore feed variability, and maximise metallurgical performance, aiming for higher throughput, improved recovery, reduced operating costs, and lower energy and resource use.
In June 2024, Wood secured an $18m consulting and engineering contract to maintain and improve the condition and performance of the Lihir operation. The scope includes concept and feasibility studies, detailed design, and construction management services to support safe and efficient gold processing.
Telstra Mining Services implemented Papua New Guinea’s first private 4G LTE mobile network at the Lihir mine, enhancing safety and enabling remote operation and automation capabilities for vehicles and equipment.
Other suppliers and contractors involved in the project are EMtek, Fraser Osborn, Ausenco, HMR Engineering, Promech and GPA Engineering.