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Iron ore

Iron ores are rocks and mineral Mineral

Minerals are natural compounds formed through geological [i] processes. ... 

s from which metallic iron Iron

Iron is a chemical element [i] with the symbol Fe and atomic number [i] 26. ... 

 can be economically extracted. The ores are usually rich in iron oxide Iron oxide

Altogether there are 16 known iron [i] oxide [i]s. ... 

s and vary in colour from dark grey to rusty red. The iron itself is usually found in the form of magnetite Magnetite

Magnetite is a ferrimagnetic [i] mineral [i] with IUPAC [i] name iron(II,III) oxide ... 

 , hematite Hematite

Hematite or haematite is the mineral [i] form of Iron oxide [i], , one of several iron oxide [i] ... 

 , limonite Limonite

Limonite is a hydrated iron oxide-hydroxide [i] of varying composition. ... 

 or siderite Siderite

Siderite is also the name of a type of iron [i] meteorite [i]. ... 

. Hematite is also known as "natural ore". The name refers to the early years of mining, when certain hematite ores contained 66% iron and could be fed directly into steel-making blast furnaces. Iron ore is the raw material used to make pig iron Pig iron

Pig iron is raw iron [i], the immediate product of smelting [i] iron ore [i] with coke [i] and limestone [i] ... 

, which is one of the main raw materials to make steel Steel

Steel is a metal [i] alloy [i] whose major component is iron [i], with carbon [i] content between 0.02% ... 

.

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Encyclopedia



Iron ores are rocks and mineral Mineral

Minerals are natural compounds formed through geological [i] processes. ... 

s from which metallic iron Iron

Iron is a chemical element [i] with the symbol Fe and atomic number [i] 26. ... 

 can be economically extracted. The ores are usually rich in iron oxide Iron oxide

Altogether there are 16 known iron [i] oxide [i]s.
... 

s and vary in colour from dark grey to rusty red. The iron itself is usually found in the form of magnetite Magnetite

Magnetite is a ferrimagnetic [i] mineral [i] with IUPAC [i] name iron(II,III) oxide... 

 , hematite Hematite

Hematite or haematite is the mineral [i] form of Iron oxide [i], , one of several iron oxide [i] ... 

 , limonite Limonite

Limonite is a hydrated iron oxide-hydroxide [i] of varying composition. ... 

 or siderite Siderite

Siderite is also the name of a type of iron [i] meteorite [i].
... 

. Hematite is also known as "natural ore". The name refers to the early years of mining, when certain hematite ores contained 66% iron and could be fed directly into steel-making blast furnaces. Iron ore is the raw material used to make pig iron Pig iron

Pig iron is raw iron [i], the immediate product of smelting [i] iron ore [i] with coke [i] and limestone [i] ... 

, which is one of the main raw materials to make steel Steel

Steel is a metal [i] alloy [i] whose major component is iron [i], with carbon [i] content between 0.02% ... 

. 98% of the mined iron ore is used to make steel. Iron ore cargoes may affect magnetic compasses. Normally, loading rates are very high, preplanning of ballasting operation is essential.

Mining

Iron ore types and mining methods vary geographically.

Modern mines Mining

Mining is the extraction of valuable [i] mineral [i]s or other geological [i] materials f ... 

, in Minnesota Minnesota

Minnesota is a state [i] in the Midwestern [i] region of the United States [i]... 

 and Michigan Michigan

Michigan is a Midwestern [i] state [i] of the United States [i], located in the east north central [i] ... 

 in the U.S. United States

The United States of America, also known as the United States, the U.S., the U.S.A., a... 

, and Eastern Canada Canada

Canada is the world's second-largest [i] country by total area, occupying most ... 

 mine taconite. Taconite is a term to describe magnetite ore that is very hard and fine-grained. Taconite must be first processed into iron oxide pellets by crushing and magnetic separation of the magnetite to concentrate the iron to about 66% before it can be used in steel-making.

In Australia Australia

Australia, officially the Commonwealth of Australia, is a country in the Southern Hemisphere [i] c ... 

 iron ore is won from three main sources: massive magnetite Magnetite

Magnetite is a ferrimagnetic [i] mineral [i] with IUPAC [i] name iron(II,III) oxide... 

 ore such as at Savage River, Tasmania Tasmania

The island [i] of Tasmania, is located 200 km south of the eastern side of the continent [i] Australia [i] ... 

; pisolite "channel-iron" ore derived by mechanical erosion of primary banded-iron formations and accumulated in alluvial channels such as at Robe River, Western Australia; and the dominant banded iron formation Banded iron formation

Banded iron formations are a distinctive type of rock often found in old sedimentary rock [i]s. ... 

 related ores such as at Newman Newman, Western Australia

Newman, located about 1120 km northeast of Perth [i] and 9km north of the Tropic of Capricorn [i]... 

, the Hamersley Range and Koolyanobbing, Western Australia Western Australia

Western Australia is Australia [i]'s largest state [i] in area, cove ... 

. Other types of ore are coming to the fore recently, such as oxidised ferruginous hardcaps, for instance iron ore deposits near Lake Argyle Lake Argyle

Lake Argyle is Australia [i]'s largest artificial lake [i], part of the Ord River [i] Scheme, near the E ... 

 in Western Australia.

World production averages one billion metric tons of raw ore annually. The world's largest producer of iron ore is the Brazilian mining corporation CVRD Companhia Vale do Rio Doce

Companhia Vale do Rio Doce is a global diversified mining [i] company and is also the largest logistics ... 

, followed by Australian company BHP Billiton BHP Billiton

BHP Billiton is the world's largest mining [i] company. ... 

 and the Anglo-Australian Rio Tinto Group Rio Tinto Group

Rio Tinto is a multinational mining [i] and resources group founded originally in 1873. ... 

. A further Australian supplier, Fortescue Metals Group Ltd, is currently entering the development stage and may eventually bring Australia's production to second in the world. China is currently the largest consumer of iron ore, which translates to be the world's largest steel producing country. Iron-rich rocks are common worldwide, but ore-grade commercial mining Mining

Mining is the extraction of valuable [i] mineral [i]s or other geological [i] materials f ... 

 operations are dominated by the countries listed below:

Estimated iron ore production in million tons for 2004, according to U.S. Geological Survey

Country Production
China China

China is a cultural region [i] and ancient civilization [i] in East Asia [i]. ... 

280
Australia Australia

Australia, officially the Commonwealth of Australia, is a country in the Southern Hemisphere [i] c ... 

 
220
Brazil Brazil

Brazil, officially the Federative Republic of Brazil , is the largest and most populous country [i] ... 

220
India India

India , officially the Republic of India, is a country in South Asia [i]. ... 

 
110
Russia Russia

Russia , also the Russian Federation , is a country [i] that stretches over a vast expanse of Eurasia [i] ... 

 
95
Ukraine Ukraine

Ukraine is a country [i] in Eastern Europe [i]. ... 

 
66
United States United States

The United States of America, also known as the United States, the U.S., the U.S.A., a... 

54
South Africa South Africa

The Republic of South Africa is a country located at the southern tip of the Africa [i]n continent [i]. ... 

 
40
Canada Canada

Canada is the world's second-largest [i] country by total area, occupying most ... 

 
31
Sweden Sweden

The Kingdom of Sweden is a Nordic country [i] in Scandinavia [i]. ... 

 
22
Venezuela Venezuela

Venezuela is a country on the northern tropical [i] Caribbean [i] coast of South America [i] ... 

 
18
Kazakhstan Kazakhstan

Kazakhstan, also spelled Kazakstan, , officially the Republic of Kazakhstan, is a country th... 

 
17
Iran Iran


Throughout history, Iran has been of great geostrategic [i] importance because of its centr ... 

 
16
Mauritania Mauritania

Mauritania , officially the Islamic Republic of Mauritania, is a country in northwest Africa [i]. ... 

 
10
Other countries 40
Total world 1250

Refining

Pure elemental iron is virtually unknown on the surface of the Earth except as wüstite from meteorite Meteorite

A meteorite is an extraterrestrial body that survives its impact with the Earth [i]'s surface without be ... 

s and very rare forms of deep mantle xenolith Xenolith

A xenolith is a rock [i] fragment which becomes enveloped in a larger rock during the latter's deve... 

s. Therefore, all sources of iron used by human industry exploit iron oxide minerals, the primary form which is used in industry being hematite Hematite

Hematite or haematite is the mineral [i] form of Iron oxide [i], , one of several iron oxide [i] ... 

.

However, in some situations, more inferior iron ore sources have been used by industrialized societies when access to high-grade hematite ore was not available. This has included utilisation of taconite in the United States, particularly during World War II World War II

World War II, or the Second World War, was a worldwide [i] conflict [i] fought betwe ... 

, and goethite Goethite

Goethite is an iron bearing oxide mineral found in soil and other low temperature environments.... 

 or bog ore Bog iron

Bog iron refers to impure iron [i] deposits that develop in bogs or swamps [i] by the chemical [i] ... 

 used during the Revolutionary war American Revolutionary War

The American Revolutionary War , also known as the American War of Independence, was a war between... 

 and the Napoleonic war Napoleonic Wars

The Napoleonic Wars, a series of global [i] conflicts [i] fought during Napoleon Bonaparte [i]... 

s. Magnetite Magnetite

Magnetite is a ferrimagnetic [i] mineral [i] with IUPAC [i] name iron(II,III) oxide... 

 is often used because it is magnetic Magnetism

In physics [i], magnetism is one of the phenomena [i] by which materials [i] exert an attractive or repu ... 

 and hence easily liberated from the gangue minerals.

Inferior sources of iron ore generally required beneficiation. Due to the high density of hematite relative to silicates, beneficiation usually involves a combination of crushing and milling as well as heavy liquid separation. This is achieved by passing the finely crushed ore over a bath of solution containing bentonite Bentonite

Bentonite is an absorbent aluminium [i] phyllosilicate [i] generally impure clay [i] c ... 

 or other agent which increases the density of the solution. When the density of the solution is properly calibrated, the hematite will sink and the silicate mineral fragments will float and can be removed.

Taconite mining involves moving tremendous amounts of ore and waste. The waste comes in two forms, bedrock in the mine that isn't ore, and unwanted minerals which are an intrinsic part of the ore rock itself . The mullock is mined and piled in waste dumps, and the gangue is separated during the beneficiation process and is removed as tailings. Taconite tailings are mostly the mineral quartz Quartz

Quartz is one of the most common mineral [i]s in the Earth [i]'s continental crust [i].... 

, which is chemically inert. This material is stored in large, regulated water settling ponds.

Magnetite is beneficiated by crushing and then separating the magnetite from the gangue minerals with a magnet. This is usually so efficient that lower grade ore can be treated when it is magnetite than a comparable grade of hematite ore, especially when the magnetite is quite coarse.

To convert an oxide of iron to metallic iron it must be smelted.

Smelting

Iron ore consists of oxygen Oxygen

Oxygen is a chemical element [i] with the chemical symbol O and atomic number [i] 8.... 

 and iron atoms bonded together into molecules. To create pure iron, the ore must be smelted to remove the oxygen. Oxygen-iron bonds are strong, and to remove the iron from the oxygen, a stronger elemental bond must be presented to attach to the oxygen. Carbon is used, because the strength of a carbon-oxygen bond is greater than that of the iron-oxygen bond, at high temperatures. Thus, the iron ore must be powdered and mixed with coke, to be burnt in the smelting process.

However, this is not entirely as simple as that; carbon monoxide Carbon monoxide

Carbon monoxide, with the chemical formula CO, is a colourless, odourless, and tasteless gas [i]. ... 

 is the primary ingredient of chemically stripping oxygen from iron. Thus, the iron and carbon smelting must be kept at an oxygen deficient reduced state to promote burning of carbon to produce CO not CO2.
Air blast and charcoal : 2C + O2 2CO.
Carbon monoxide is the principle reduction agent.

Stage One: 3Fe2 O3 + CO 2Fe3 O4 + CO2
Stage Two: Fe3 O4 + CO 3Fe O + CO2
Stage Three: FeO + CO Fe + CO2
Limestone fluxing chemistry: CaCO3 CaO + CO2

Contaminants

Ideally iron ore contains only iron and oxygen. In nature this is rarely the case. Typically, iron ore contains a host of deleterious elements which are unwanted in modern steel.

Silica

Iron ore typically contains silicates, usually in the form of quartz Quartz

Quartz is one of the most common mineral [i]s in the Earth [i]'s continental crust [i].... 

. Silica is undesirable because silicon does not bond with carbon during the smelting process and can remain in the iron after it is refined. Historically, siliceous iron ore created wrought iron Wrought iron

Wrought iron is commercially pure iron [i], having a very small carbon [i] content, but usually contains ... 

, a malleable and strong form of iron used by blacksmiths throughout history.

Modern steelmaking techniques generally use lime and other flux Flux

In the various subfields of physics [i], there exist two common usages of the term flux, both with rigor ... 

es to help remove the silica from the molten iron ore, and form a slag Slag

Slags are the by-product [i] of smelting [i] ore [i] to purify metal [i]s. ... 

 on the surface of the molten metal. This slag can then be removed.

Phosphorus

Phosphorus Phosphorus

|-
| Critical temperature [i] || 994 K [i]
... 

 is a deleterious metal because it makes steel brittle, even at concentrations of as little as 0.5%. Phosphorus cannot be easily removed by fluxing or smelting, and so iron ores must generally be low in phosphorus to begin with. The iron pillar Delhi iron pillar

The iron pillar of Delhi [i], the capital city of India [i], is one of the world's foremost metallurgica ... 

 of India which does not rust, however, is protected by a phosphoric composition. Phosphoric acid Phosphoric acid

|-
| align="center" colspan="2" bgcolor="#ffffff" | |
... 

 is used at a rust converter because phosphoric iron is less susceptible to oxidation.

Aluminium

Aluminium Aluminium

Aluminium or aluminum is the chemical element in the periodic table that has the symbol Al ... 

 is generally present in iron ores as clay Clay

Clay is a term used to describe a group of hydrous aluminium [i] phyllosilicate [i] ... 

. This is usually removed by washing the iron ore, and by fluxing. However, again, iron oxide deposits must be relatively low in aluminium in order to be considered ore.

Sulfur

Sulfur Sulfur

Sulfur or sulphur is the chemical element [i] in the periodic table [i] that has the symbol S' ... 

 is unwanted because it produces undesirable sulfur dioxide Sulfur dioxide

Sulfur dioxide is the chemical compound [i] with the formula SO2. ... 

 gases in the flue emissions from a smelter and interferes with the smelting process.

See also

  • Extraction of iron Extraction of iron

    Iron [i] is the second-most abundant metal [i] in the Earth's crust [i] after aluminium [i]. ... 

  • Ore genesis
  • Banded iron formation Banded iron formation

    Banded iron formations are a distinctive type of rock often found in old sedimentary rock [i]s. ... 

  • Magnetite Magnetite

    Magnetite is a ferrimagnetic [i] mineral [i] with IUPAC [i] name iron(II,III) oxide... 

    , hematite Hematite

    Hematite or haematite is the mineral [i] form of Iron oxide [i], , one of several iron oxide [i] ... 

    , goethite Goethite

    Goethite is an iron bearing oxide mineral found in soil and other low temperature environments.... 

    -limonite Limonite

    Limonite is a hydrated iron oxide-hydroxide [i] of varying composition. ... 

  • Beneficiation

External links



References