The Batu Hijau mine is an

open pit Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. This form of mining ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

mine Mine, mines, miners or mining may refer to: Extraction or digging * Miner, a person engaged in mining or digging *Mining, extraction of mineral resources from the ground through a mine Grammar *Mine, a first-person English possessive pronoun ...

operated by PT. Amman Mineral Nusa Tenggara (previously known as PT Newmont Nusa Tenggara). The mine is the second largest copper-gold mine in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

behind the

Grasberg mine The Grasberg mine has one of the largest reserves of gold and copper in the world. It is located in Mimika Regency, Central Papua, Indonesia near Puncak Jaya. It is operated by PT Freeport Indonesia (PTFI, ''see below''), a joint venture be ...

of PT. Freeport Indonesia. The mine is located east of the Indonesian capital

Jakarta Jakarta (; , bew, Jakarte), officially the Special Capital Region of Jakarta ( id, Daerah Khusus Ibukota Jakarta) is the capital and largest city of Indonesia. Lying on the northwest coast of Java, the world's most populous island, Jakarta ...

Sumbawa Sumbawa is an Indonesian island, located in the middle of the Lesser Sunda Islands chain, with Lombok to the west, Flores to the east, and Sumba further to the southeast. Along with Lombok, it forms the province of West Nusa Tenggara, but there ...

, an

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

West Nusa Tenggara West Nusa Tenggara ( id, Nusa Tenggara Barat – NTB) is a province of Indonesia. It comprises the western portion of the Lesser Sunda Islands, with the exception of Bali which is its own province. Mataram, on Lombok, is the capital and largest ...

Province, more precisely in the southern part of

West Sumbawa Regency West Sumbawa Regency ( id, Kabupaten Sumbawa Barat) is a Regency ('' Kabupaten'') of the Indonesian Province of West Nusa Tenggara. It is located on the island of Sumbawa and has an area of 1,742.27 km2. The regency was created on 18 December ...

. The mine is the result of a ten-year exploration and construction program based on a 1999 discovery of the porphyry copper deposit. Production began in 2000. The mine utilizes a "truck and shovel" open-pit mining method, with ore reporting to semi-Autogenous Grinding and ball mills, followed by a flotation circuit. The finished product is a thickened copper-gold concentrate, which is shipped via pipe to a storage facility on the Indonesian coast.

History

During 1984,

Newmont Corporation Newmont Corporation is a gold mining company based in Greenwood Village, Colorado, United States. It is the world's largest gold mining corporation. Incorporated in 1921, it owns gold mines in Nevada, Colorado, Ontario, Quebec, Mexico, the Domin ...

undertook conceptual studies and identified the island arc terrain to the east of

Bali Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and Nu ...

as being prospective for epithermal

mineralization. A joint venture was formed with PT. Pukuafu Indah in September 1985, and tenement applications lodged over the islands of

Lombok Lombok is an island in West Nusa Tenggara province, Indonesia. It forms part of the chain of the Lesser Sunda Islands, with the Lombok Strait separating it from Bali to the west and the Alas Strait between it and Sumbawa to the east. It is rou ...

and

. In 1986, a Contract of Work with the

Government of Indonesia The term Government of Indonesia ( id, Pemerintah Indonesia) can have a number of different meanings. At its widest, it can refer collectively to the three traditional branches of government – the executive branch, legislative branch and ju ...

was signed. During 1987, a regional geochemical sampling program commenced. Due to the mountainous and jungle-covered terrain, samples primarily comprised silt stream-sediment samples. A total of 36

anomalies were generated, and prioritized for additional exploration. In 1989, a significant

and

anomaly was identified in the Sejorong drainage located near the southwest coast of

. Field checking of the anomaly identified altered and Copper-stained diorite float samples in the river bed, and subsequently, strong quartz pyrite stockworking and abundant Copper staining in outcrops within Green Creek. In 1990

mineral exploration Mining in the engineering discipline is the extraction of minerals from underneath, open pit, above or on the ground. Mining engineering is associated with many other disciplines, such as mineral processing, exploration, excavation, geology, and ...

on the island of Sumbawa resulted in the discovery of copper mineralization that would be developed into the Batu Hijau mine. The deposit was named for the discovery outcrop, a bright-green oxide-copper occurrence; in

Indonesian Indonesian is anything of, from, or related to Indonesia, an archipelagic country in Southeast Asia. It may refer to: * Indonesians, citizens of Indonesia ** Native Indonesians, diverse groups of local inhabitants of the archipelago ** Indonesian ...

, "Batu Hijau" means "green rock." Over the next ten years PT Newmont Nusa Tenggara delineate the resource and began developing the mine and building the required infrastructure. In 1991, core drilling commenced, and continued to 1996. A feasibility study was completed in February 1996. The feasibility study was amended in July 1996 to reflect an updated mine plan based on additional drilling data, a change from fresh water to sea water processing, and a change from distributed diesel power generation to a central, coal-fired power plant. A partnership agreement was entered into with Sumitomo in July 1996, under which Sumitomo became equity partners and co-managers of the Batu Hijau Project. The Indonesian government approved the feasibility study in 1997, allowing construction to commence in the same year. Additional drilling programs continued to define the deposit from 1996 to 1998. Total capital costs for the initial Batu Hijau Project were $1.8 billion. The Batu Hijau mine was the largest "green-fields" mining project ever built. In 1999 construction was completed and by the next year Batu Hijau was producing

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 April 2 ...

. In 2016, Newmont Mining Corporation successfully completed the sale of its ownership stake in PT Newmont Nusa Tenggara, which operates the Batu Hijau copper and gold mine in Indonesia, to PT Amman Mineral Internasional.

Geology and ore reserves

The orebody at Batu Hijau is a

porphyry copper Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of ...

type and includes a high gold component, which is common for such copper deposits in

southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

. The host rock for porphyry copper deposits in southeast Asia is typically

diorite Diorite ( ) is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-silic ...

and

quartz diorite Quartz diorite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz is present at between 5 and ...

. Copper sulphides such as

chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...

and

bornite Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5 Fe S4 that crystallizes in the orthorhombic system (pseudo-cubic). Appearance Bornite has a brown to copper-red color on fresh surfaces that tarnishes to v ...

are frequently associated with the gold component of these deposits. As of the end of 2008, Batu Hijau had an ore reserve of 968mt of ore at 0.41% Cu and 0.29g/t Au.

Mining & milling

Batu Hijau is an open-pit mine. Ore is removed from the mining face using P&H 4100 electric shovels (pictured) and loaded into

Caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...

793C haul trucks. Each haul truck can move a payload of ore. The trucks haul ore from the shovel to primary

crusher A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, sand or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce ...

s. Crushed ore is sent by a

conveyor A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transport of heavy or bulky materials. Conveyor systems allow ...

wide and long to the

mill Mill may refer to: Science and technology * * Mill (grinding) * Milling (machining) * Millwork * Textile mill * Steel mill, a factory for the manufacture of steel * List of types of mill * Mill, the arithmetic unit of the Analytical Engine early ...

. Daily production from the mine is an average of ore and waste combined. Ore from the mine has an average copper grade of 0.49% and an average gold grade of 0.39g/t. Crushed ore is further reduced in size by Semi-Autogenous Grinding and ball mills. Once milled it is sent through a flotation circuit which produces a concentrate with a grade of 32% copper and 19.9g/t gold. The mill realizes a copper recovery of 89%. The concentrate is thickened into

slurry A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped on a device such as a centrifugal pu ...

and piped to the port at Benete where water is removed from the slurry. The concentrate storage at the port can hold of copper-gold concentrate.

Environmental issues

Disposal of

tailings In mining, tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different to overburden, which is the waste rock or other material that overlie ...

from the processing operation of the Batu Hijau mine takes place in the

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

, using a process called Submarine Tailings Disposal (STD). Indonesia is currently the only location that PT. Amman Mineral Nusa Tenggara uses this process, claiming that it is more an environmentally sound practice despite being more costly to the company. The process involves piping the tailings off the coast to a drop-off of , which carries the waste down another . Waste rock from the Batu Hijau mine is disposed of in the

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

, with space for newly produced waste rock running out. Environmentalists are raising concern with the declining population of the

yellow-crested cockatoo The yellow-crested cockatoo (''Cacatua sulphurea'') also known as the lesser sulphur-crested cockatoo, is a medium-sized (about 34-cm-long) cockatoo with white plumage, bluish-white bare orbital skin, grey feet, a black bill, and a retractile y ...

References

External links

PT. Amman Mineral Nusa Tenggara
official website {{DEFAULTSORT:Batu Hijau Mine Copper mines in Indonesia Geography of Sumbawa Gold mines in Indonesia Open-pit mines Surface mines in Indonesia