Ore

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Iron ore (banded iron formation) Banded iron formation.png
Iron ore (banded iron formation)
Manganese ore - psilomelane (size: 6.7 x 5.8 x 5.1 cm) Psilomelane-167850.jpg
Manganese ore psilomelane (size: 6.7 × 5.8 × 5.1 cm)
Lead ore - galena and anglesite (size: 4.8 x 4.0 x 3.0 cm) Anglesite-Galena-249200.jpg
Lead ore galena and anglesite (size: 4.8 × 4.0 × 3.0 cm)
Gold ore (size: 7.5 x 6.1 x 4.1 cm) Gold-Quartz-273364.jpg
Gold ore (size: 7.5 × 6.1 × 4.1 cm)
Cart for carrying ore from a mine on display at the Historic Archive and Museum of Mining in Pachuca, Mexico OreCartPachuca.JPG
Cart for carrying ore from a mine on display at the Historic Archive and Museum of Mining in Pachuca, Mexico

An ore is a natural occurrence of rock or sediment that contains sufficient minerals with economically important elements, typically metals, that can be economically extracted from the deposit. [1] The ores are extracted at a profit from the earth through mining; they are then refined (often via smelting) to extract the valuable element or elements.

Rock (geology) A naturally occurring solid aggregate of one or more minerals or mineraloids

A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed. Rocks are usually grouped into three main groups: igneous rocks, metamorphic rocks and sedimentary rocks. Rocks form the Earth's outer solid layer, the crust.

Sediment Particulate solid matter that is deposited on the surface of land

Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation. If buried, they may eventually become sandstone and siltstone through lithification.

Mineral Element or chemical compound that is normally crystalline and that has been formed as a result of geological processes

A mineral is, broadly speaking, a solid chemical compound that occurs naturally in pure form. Minerals are most commonly associated with rocks due to the presence of minerals within rocks. These rocks may consist of one type of mineral, or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases. Compounds that occur only in living beings are usually excluded, but some minerals are often biogenic and/or are organic compounds in the sense of chemistry. Moreover, living beings often synthesize inorganic minerals that also occur in rocks.

Contents

The ore grade, or concentration of an ore mineral or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the metal value contained in the rock to determine what ore can be processed and what ore is of too low a grade to be worth mining. Metal ores are generally oxides, sulfides, silicates, or native metals (such as native copper) that are not commonly concentrated in the Earth's crust, or noble metals (not usually forming compounds) such as gold. The ores must be processed to extract the elements of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes. The process of ore formation is called ore genesis.

Metal element, compound, or alloy that is a good conductor of both electricity and heat

A metal is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable or ductile. A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride.

Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications.

Silicate minerals Rock-forming minerals with predominantly silicate anions

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of the Earth's crust.

Ore deposits

An ore deposit is an accumulation of ore. This is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type. Most ore deposits are named according to their location (for example, the Witwatersrand, South Africa), or after a discoverer (e.g. the Kambalda nickel shoots are named after drillers), or after some whimsy, a historical figure, a prominent person, something from mythology (phoenix, kraken, serepentleopard, etc.) or the code name of the resource company which found it (e.g. MKD-5 was the in-house name for the Mount Keith nickel sulphide deposit).

Kambalda type komatiitic nickel ore deposits are a class of magmatic iron-nickel-copper-platinum-group element ore deposit in which the physical processes of komatiite volcanology serve to deposit, concentrate and enrich a Fe-Ni-Cu-(PGE) sulfide melt within the lava flow environment of an erupting komatiite volcano.

Mount Keith Mine mine in Australia

Mount Keith Mine is an open pit nickel mine in Western Australia. It is operated by BHP. The site's closest landmark is the town of Wiluna, 85 kilometres (53 mi) to the north.

Classification

Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. The classifications below are typical.

Ore genesis How the various types of mineral deposits form within the Earths crust.

Various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.

Hydrothermal epigenetic deposits

Lode part of a rock body that holds ore

In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fissure in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning dates from the 17th century, being an expansion of an earlier sense of a "channel, watercourse" in late Middle English, which in turn is from the 11th-century meaning of lode as a ‘course, way’.

Kalgoorlie City in Western Australia

Kalgoorlie-Boulder, known colloquially as just Kalgoorlie, is a city in the Goldfields-Esperance region of Western Australia, located 595 km (370 mi) east-northeast of Perth at the end of the Great Eastern Highway. The city was founded in 1889 by the amalgamation of the towns of Kalgoorlie and Boulder, which developed in 1893 during the Coolgardie gold rush, on Western Australia's "Golden Mile". It is also the ultimate destination of the Goldfields Water Supply Scheme and the Golden Pipeline Heritage Trail.

The Archean Eon is one of the four geologic eons of Earth history, occurring 4,000 to 2,500 million years ago. During the Archean, the Earth's crust had cooled enough to allow the formation of continents and life started to form.

Tombstone, Arizona City in Arizona, United States

Tombstone is a historic city in Cochise County, Arizona, United States, founded in 1879 by prospector Ed Schieffelin in what was then Pima County, Arizona Territory. It became one of the last boomtowns in the American frontier. The town grew significantly into the mid-1880s as the local mines produced $40 to $85 million in silver bullion, the largest productive silver district in Arizona. Its population grew from 100 to around 14,000 in less than seven years. It is best known as the site of the Gunfight at the O.K. Corral and presently draws most of its revenue from tourism.

Magnetite iron ore mineral

Magnetite is a rock mineral and one of the main iron ores, with the chemical formula Fe3O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the naturally-occurring minerals on Earth. Naturally-magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism. Today it is mined as iron ore.

Skarn Hard, coarse-grained, hydrothermally altered metamorphic rocks

Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals. These minerals form as a result of alteration which occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin. In many cases, skarns are associated with the intrusion of a granitic pluton found in and around faults or Shear zones that intrude into a carbonate layer composed of either dolomite or limestone. Skarns can form by regional, or contact metamorphism and therefore form in relatively high temperature environments. The hydrothermal fluids associated with the metasomatic processes can originate from either magmatic, metamorphic, meteoric, marine, or even a mix of these. The resulting skarn may consist of a variety of different minerals which are highly dependent on the original composition of both the hydrothermal fluid and the original composition of the protolith.

Magmatic deposits

A cross-section of a typical Volcanic hosted massive sulfide|volcanogenic massive sulfide (VMS) ore deposit Classic VMS Deposit2.png
A cross-section of a typical Volcanic hosted massive sulfide|volcanogenic massive sulfide (VMS) ore deposit

Metamorphically reworked deposits

Sedimentary deposits

Magnified view of banded iron formation specimen from Upper Michigan. Scale bar is 5.0 mm. MichiganBIF.jpg
Magnified view of banded iron formation specimen from Upper Michigan. Scale bar is 5.0 mm.

Sedimentary hydrothermal deposits

Extraction

Some ore deposits in the world Simplified world mining map 1.png
Some ore deposits in the world
Some additional ore deposits in the world Simplified world mining map 2.png
Some additional ore deposits in the world

The basic extraction of ore deposits follows these steps:

  1. Prospecting or exploration to find and then define the extent and value of ore where it is located ("ore body")
  2. Conduct resource estimation to mathematically estimate the size and grade of the deposit
  3. Conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work.
  4. Conduct a feasibility study to evaluate the financial viability, technical and financial risks and robustness of the project and make a decision as whether to develop or walk away from a proposed mine project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of the ore concentrates, engineering, milling and infrastructure costs, finance and equity requirements and a cradle to grave analysis of the possible mine, from the initial excavation all the way through to reclamation.
  5. Development to create access to an ore body and building of mine plant and equipment
  6. The operation of the mine in an active sense
  7. Reclamation to make land where a mine had been suitable for future use

Trade

Ores (metals) are traded internationally and comprise a sizeable portion of international trade in raw materials both in value and volume. This is because the worldwide distribution of ores is unequal and dislocated from locations of peak demand and from smelting infrastructure.

Most base metals (copper, lead, zinc, nickel) are traded internationally on the London Metal Exchange, with smaller stockpiles and metals exchanges monitored by the COMEX and NYMEX exchanges in the United States and the Shanghai Futures Exchange in China.

Iron ore is traded between customer and producer, though various benchmark prices are set quarterly between the major mining conglomerates and the major consumers, and this sets the stage for smaller participants.

Other, lesser, commodities do not have international clearing houses and benchmark prices, with most prices negotiated between suppliers and customers one-on-one. This generally makes determining the price of ores of this nature opaque and difficult. Such metals include lithium, niobium-tantalum, bismuth, antimony and rare earths. Most of these commodities are also dominated by one or two major suppliers with >60% of the world's reserves. The London Metal Exchange aims to add uranium to its list of metals on warrant.

The World Bank reports that China was the top importer of ores and metals in 2005 followed by the US and Japan. [2] [ citation needed ]

Important ore minerals

See also

Related Research Articles

Bioleaching is the extraction of metals from their ores through the use of living organisms. This is much cleaner than the traditional heap leaching using cyanide. Bioleaching is one of several applications within biohydrometallurgy and several methods are used to recover copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.

Iron ore ore rich in iron or the element Fe

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite (Fe
3
O
4
, 72.4% Fe), hematite (Fe
2
O
3
, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).

Chalcopyrite sulfide mineral

Chalcopyrite ( KAL-ko-PY-ryt) is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical formula CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.

Chromite spinel, oxide mineral

Chromite is a mineral that is an iron chromium oxide. It has a chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite(MgCr2O4). A substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.

Copper extraction Process of extracting copper from the ground

Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper consists of a series of physical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors.

Franklinite spinel, oxide mineral

Franklinite is an oxide mineral belonging to the normal spinel subgroup's iron (Fe) series, with the formula ZnFe3+2O4.

Bushveld Igneous Complex mountain range

The Bushveld Igneous Complex (BIC) is the largest layered igneous intrusion within the Earth's crust. It has been tilted and eroded forming the outcrops around what appears to be the edge of a great geological basin: the Transvaal Basin. It is approximately 2 billion years old and is divided into four different limbs: the northern, southern, eastern, and western limbs. The Bushveld Complex comprises the Rustenburg Layered suite, the Lebowa Granites and the Rooiberg Felsics, that are overlain by the Karoo sediments. The site was first discovered around 1897 by Gustaaf Molengraaff.

In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite Cu2S, covellite CuS, digenite Cu1.8S, and djurleite Cu31S16 are deposited by the descending surface waters.

Kanichee Mine

The Kanichee Mine, also less commonly known as the Ajax Mine, is an abandoned base metal and precious metal mine, located in the Temagami region of northeastern Ontario, Canada. It is near the small unincorporated community of Temagami North, accessed by the Kanichee Mine Road from Highway 11. The Kanichee Mine zone has been explored and mined discontinuously from as early as 1910. During the 20th century, it operated and closed down at least three times, with the most recent being from 1973 to 1976. To date, the discontinuous operation of Kanichee Mine has produced 4.2 million pounds of metal.

Biomining

Biomining is a technique of extracting metals from ores and other solid materials typically using prokaryotes or fungi. These organisms secrete different organic compounds that chelate metals from the environment and bring it back to the cell where they are typically used to coordinate electrons. It was discovered in the mid 1900s that microorganisms use metals in the cell. Some microbes can use stable metals such as iron, copper, zinc, and gold as well as unstable atoms such as uranium and thorium. Companies can now grow large chemostats of microbes that are leaching metals from their media, these vats of culture can then be transformed into many marketable metal compounds. Biomining is an environmentally friendly technique compared to typical mining. Mining releases many pollutants while the only chemicals released from biomining is any metabolites or gasses that the bacteria secrete. The same concept can be used for bioremediation models. Bacteria can be inoculated into environments contaminated with metals, oils, or other toxic compounds. The bacteria can clean the environment by absorbing these toxic compounds to create energy in the cell. Microbes can achieve things at a chemical level that could never be done by humans. Bacteria can mine for metals, clean oil spills, purify gold, and use radioactive elements for energy.

Browns polymetallic ore deposit mine in Australia

The Browns polymetallic ore deposit is a large ore deposit located at Mount Fitch, near Batchelor, 64 kilometres south of Darwin, Northern Territory, Australia.

Admiralty mining district Alaska Mining District in the United States

The Admiralty mining district is a mining area in the U.S. state of Alaska which consists of Admiralty Island. Most of the gold recovered from the Admiralty district is a by-product of silver and base metal mining.

The mineral industry of Kazakhstan is one of the most competitive and fastest growing sectors of the country. Kazakhstan ranks second to Russia among the countries of the CIS in its quantity of mineral production. It is endowed with large reserves of a wide range of metallic ores, industrial minerals, and fuels, and its metallurgical sector is a major producer of a large number of metals from domestic and imported raw materials. In 2005, its metal mining sector produced bauxite, chromite, copper, iron, lead, manganese, and zinc ores, and its metallurgical sector produced such metals as beryllium, bismuth, cadmium, copper, ferroalloys, lead, magnesium, rhenium, steel, titanium, and zinc. The country produced significant amounts of other nonferrous and industrial mineral products, such as alumina, arsenic, barite, gold, molybdenum, phosphate rock, and tungsten. The country was a large producer of mineral fuels, including coal, natural gas, oil, and uranium. The country's economy is heavily dependent on the production of minerals. Output from Kazakhstan's mineral and natural resources sector for 2004 accounted for 74.1% of the value of industrial production, of which 43.1% came from the oil and gas condensate extraction. In 2004, the mineral extraction sector accounted for 32% of the GDP, employed 191,000 employees, and accounted for 33.1% of capital investment and 64.5% of direct foreign investment, of which 63.5% was in the oil sector. Kazakhstan's mining industry is estimated at US$29.5 billion by 2017.

Iron oxide copper gold ore deposits (IOCG) are important and highly valuable concentrations of copper, gold and uranium ores hosted within iron oxide dominant gangue assemblages which share a common genetic origin.

Carl Michael Lesher is an American geologist. He is an authority on the geology and origin of nickel-copper-platinum group element deposits, especially those associated with komatiites, their physical volcanology and localization, the geochemistry and petrology of associated rocks, and controls on their composition.

Mining in North Korea is important to the country's economy. North Korea is naturally abundant in metals such as magnesite, zinc, tungsten, and iron; with magnesite resources of 6 billion tonnes, particularly in the Hamgyeong-do and Jagang-do provinces. However, often these cannot be mined due to the acute shortage of electricity in the country, as well as the lack of proper tools to mine these materials and an antiquated industrial base. Coal, iron ore, limestone, and magnesite deposits are larger than other mineral commodities. Mining joint ventures with other countries include China, Canada, Egypt, and South Korea.

Mining industry of Sudan

The mining industry of Sudan was mostly driven by extraction fuel minerals, with petroleum accounting for a substantial contribution to the country's economy, until the autonomous region of Southern Sudan became an independent country in July 2011. Gold, iron ore, and base metals are mined in the Hassai Gold Mine. Chromite is another important mineral extracted from the Ingessana Hills. Other minerals extracted are gypsum, salt, and cement. Phosphate is found in Mount Kuoun and Mount Lauro in eastern Nuba. Reserves of zinc, lead, aluminium, cobalt, nickel in the form of block sulfides, and uranium are also established. Large reserves of iron ore have been established.

Field (mineral deposit) natural concentration of raw materials in the earths crust, the mining of which is economically worthwhile

A field is a mineral deposit containing a metal or other valuable resources in a cost-competitive concentration. It is usually used in the context of a mineral deposit from which it is convenient to extract its metallic component. The deposits are exploited by mining in the case of solid mineral deposits and extraction wells in case of fluids.

References

  1. Guilbert, John M. and Charles F. Park, Jr. (1986) The Geology of Ore Deposits, W. H. Freeman, p. 1. ISBN   0-7167-1456-6
  2. "Background Paper - The Outlook for Metals Markets Prepared for G20 Deputies Meeting Sydney 2006" (PDF). The China Growth Story. WorldBank.org. Washington. September 2006. p. 4. Retrieved 2019-07-19.

Further reading

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