Mining Intelligence and News

Wetar Mine

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Mine TypeOpen Pit
  • Copper
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Production Start2010
Mine Life2027
SnapshotThe Wetar Copper Mine is the only mine in Indonesia that directly produces and exports copper cathodes.

With the development of the AIM project, the focus going forward will be on extracting maximum value from the Wetar ore including the production of copper at Wetar and the sale of ore to the AIM project to be used to produce acid, iron, steam, copper, gold, and silver.


PT Merdeka Copper Gold Tbk 100 % Indirect
Wetar Copper Mine is indirectly held by Merdeka through PT Batutua Tembaga Raya(BTR) and PT Batutua Kharisma Permai(BKP). BKP is in charge of copper mining, while processing and refining is conducted by BTR as the holder of industrial business license for industry of making noniron base metal.

Deposit type

  • VMS


Wetar Island is composed of Neogene volcanic rocks and minor oceanic sediments and forms part of the Inner Banda Arc. The island preserves ~4.7 million-year-old precious metal-rich volcanogenic massive sulphide and barite deposits.

The polymetallic massive sulphides are dominated by pyrite, with minor primary chalcopyrite and lesser bornite cut by late fractures infilled with sulphosalts, tennantite-tetrahedrite and enargite. The sulphosalts have replaced primary chalcopyrite and bornite to varying extents across Kali Kuning, Lerokis and Partolang, and these have in turn been replaced by supergene chalcocite and covellite to varying extents.

Barite-rich orebodies are developed on the flanks of the sulphide units and locally overly the massive sulphides.

Sulphide mounds showing talus textures are localised onto faults, which provided the main pathways for high-temperature hydrothermal fluids and the development of associated stockworks.

Known orebodies are closely associated with quartz-porphyry dacites which occur within the basalts/andesites and are surrounded by widespread propylitic and argillic alteration haloes. Hydrothermal alteration around the various orebodies is zoned and dominated by illitekaolinite- smectite with local alunite and pyrophyllite.

The sulphide mounds and related barite bodies were covered and preserved by post-mineralisation chert, gypsum, calcareous siltstone, limestone, lahars, subaqueous debris flows, volcaniclastic rocks and locally fresh dacitic lava flows at Partolang.

Gold-silver mineralisation occurs predominantly within barite-rich units, including sands, tuffs and breccias (after original dacitic rocks), which are strongly ferruginised locally. In some of the dacitic rocks, barite and hydrated iron minerals have completely replaced the host units, with original breccia textures no longer visible.

The economic copper mineralisation occurs predominantly within coherent massive sulphide units and locally in dacitic breccia units which, have been almost completely replaced by sulphides, with some minor lower-grade material occurring in fractures and as stockworks within intensely altered andesitic and dacitic tuffs and volcanics in the footwall and lateral extent of the massive sulphides. Not all massive sulphides are mineralised.

The contact between the massive sulphides, barite, footwall and hangingwall units is generally quite sharp.

Reserves at December 31, 2022

Mineral Resources are reported inclusive of Mineral Reserves.
CategoryOre TypeTonnage CommodityGradeContained Metal
Proven 1.1 Mt Copper 1.55 %
Proven Heap leach 2.6 Mt Copper 1.18 %
Proven 1.1 Mt Gold 0.48 g/t
Proven 1.1 Mt Silver 19 g/t
Probable 12.8 Mt Copper 1.09 %
Probable Heap leach 2.9 Mt Copper 1.55 %
Probable 12.8 Mt Gold 0.59 g/t
Probable 12.8 Mt Silver 24 g/t
Proven & Probable 13.9 Mt Copper 1.28 % 178.4 kt
Proven & Probable Heap leach 5.6 Mt Copper 1.38 % 76.4 kt
Proven & Probable 13.9 Mt Gold 0.58 g/t 258.3 koz
Proven & Probable 13.9 Mt Silver 24 g/t 10,711 koz
Total Resource 37.3 Mt Copper 0.91 % 340 kt
Total Resource 36.18 Mt Gold 0.41 g/t 480 koz
Total Resource 36.2 Mt Silver 17.1 g/t 19.9 M oz

Mining Methods

  • Truck & Shovel / Loader


Wetar Copper is a copper mine located on Wetar Island, Maluku Barat Daya Regency, Maluku Province.

Commercial production of Wetar Copper started in 2010, consists of open pit mine, associated heap leach operation and solvent extraction-electrowinning (SX-EW) plant which produces copper metal.

Wetar comprises three open pits: Lerokis, Kali Kuning and Partolang. Mining activities at Lerokis and Kali Kuning pits were completed. Since October 2020, mining operations commenced at the Partolang Pit.

With the development of the AIM project, the focus going forward will be on extracting maximum value from the Wetar ore including production of copper at Wetar and the sale of ore to the AIM project to be used to produce acid, iron, steam, copper, gold and silver.


Crushers and Mills

Milling equipment has not been reported.


  • Crush-and-stack plant
  • Heap leach
  • Solvent Extraction & Electrowinning


Partolang ore is processed via heap leaching SX-EW and incorporated into the existing 28 kt/a operation located in the Kali Kuning valley 2 km distant.

Nine columns in total are being prepared and eight of the column tests are underway for Partolang. Three of the columns have been active for 100 days, three other columns have been active for 83 days and 2 others for 46 days. The columns are designed to test each of the main ore units (i.e. MPY, PBX2 and SBX), run of mill composites, column height, high ferric/ferrous ratio in lixiviant, low acid, and low iron content in lixiviant.

Results from the initial columns suggest reasonable recoveries, with 75.2% recovered from SBX, 47.3% recovered from MPY, and 66.4% recovered from PBX2 etc after 100 days under irrigation. The columns that have been active for 83 days, testing ROM composites, high ferric and lower column height have recovered 58-65%, whilst those for 46 days testing lower acid and TDS have recovered 50-56%.

The AIM Project will purchase high-grade pyrite ore from Wetar. The AIM plant, under construction at IMIP, is designed to treat the pyrite ore from Wetar at a nominal rate of 1,060,000 tonnes per year. The plant will produce sulphuric acid, saturated steam, iron ore pellets, copper cathode, leadzinc hydroxides, gold and silver doré.

Recoveries & Grades:

Copper Recovery Rate, % 80
Copper Head Grade, % 1.461.982.062.852.582

Water Supply


Wetar Copper Mine manages water within a closed circuit system. The managed water comes from mineral processing residues and runoff water. Water from mineral processing residues is collected in Storm Water Ponds (SWP) 3, SWP 2, and KK SWP, utilizing former mining pits. Runoff water is collected in sediment ponds Sump 3, Sump 4, Sump 5, Wetland, and the newly added sediment ponds in 2022: sediment ponds SP-1 and SP-2.

Both runoff and mineral processing residue collection points are connected to several rivers. Sump 3, Wetland, and SWP 3 are connected to the Kuning River; SP-1 and SP-2 are connected to the Lurang River; and Sump 4 and 5 are connected to the Wetuk River and Koreng River, respectively. If it is necessary to release water into the river, the water collected in the sediment ponds is neutralized beforehand to ensure it meets the government’s quality standards when discharged. Each release at the compliance points is measured, monitored, and reported to the government on a quarterly basis.

Wetar Copper Mine also monitors the water quality in the rivers within the mining area and the coastal areas near the river estuaries. River and coastal monitoring is conducted quarterly by a third party, and the results are reported to the government.


Copper t 16,000-20,000 ^19,55119,0455,37716,77717,07122,969
All production numbers are expressed as cathode. ^ Guidance / Forecast.

Operational metrics

Annual production capacity 25,000 t of copper cathode25,000 t of copper cathode25,000 t of copper cathode25,000 t of copper cathode25,000 t of copper cathode25,000 t of copper cathode
Annual processing capacity 2.5 Mt2.5 Mt2.5 Mt2.5 Mt
Ore tonnes mined 2.2 Mt2.4 Mt0.5 Mt2.3 Mt1,587,951 t1,884,400 t
Waste 15.8 Mt11.1 Mt2.4 Mt3.8 Mt1,408,672 t650,279 t
Total tonnes mined 18 Mt13.5 Mt2.9 Mt
Tonnes processed 2.3 Mt2.4 Mt0.4 Mt

Production Costs

Cash costs Copper USD 2.64 / lb   1.7 / lb   3.41 / lb   1.29 / lb   1.49 / lb   1.05 / lb  
All-in sustaining costs (AISC) Copper USD 4.2 / lb ^   3.37 / lb   2.33 / lb   4.62 / lb   1.86 / lb   1.73 / lb   1.56 / lb  
^ Guidance / Forecast.


Revenue M USD 183.8  161.9  31.9   99.2   155   209.5  
Pre-tax Income M USD 9.9  19.2  -31.6   -5.6   20.7   57.3  
After-tax Income M USD 11.4   56.3  
EBITDA M USD 100  -12   41   38   73  

Heavy Mobile Equipment

Fleet data has not been reported.


Mine Management

Job TitleNameProfileRef. Date
General Manager Barend Knoetze LinkedIn Feb 19, 2024
Processing Manager Brian Swahadana LinkedIn Sep 15, 2023
Technical Services Manager Kell Monro LinkedIn Sep 15, 2023

Total WorkforceYear
2,800 2022
1,100 2021
1,100 2020
873 2019

Aerial view:


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