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Pig iron is the intermediate product of smelting
Smelting

Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores....
 iron ore
Iron ore

Iron ores are Rock 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, deep purple, to rusty red....
 with coke
Coke (fuel)

Cokes are the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous....
, usually with limestone
Limestone

File:Limestone Formation In Waitomo.jpgLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geology record....
 as a flux. Pig iron has a very high carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 content, typically 3.5–4.5%, which makes it very brittle
Brittle

A material is brittle if it is liable to fracture when subjected to stress . That is, it has little tendency to deform before fracture. This fracture absorbs relatively little energy, even in materials of high Strength of materials, and usually makes a snapping sound....
 and not useful directly as a material except for limited applications.

The traditional shape of the molds used for these ingots was a branching structure formed in sand
Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters....
, with many individual ingots at right angles to a central channel or runner. Such a configuration is similar in appearance to a litter of piglet
Piglet

Piglet can refer to:*A juvenile pig*Piglet , the fictional character from A. A. Milne's Winnie-the-Pooh books and the Disney spin-offs*"Philophobia ", a song by Scottish group Arab Strap on their 1998 album, Philophobia...
s suckling on a sow
Sow

Sow may refer to an African name, frequent in Senegal.* Abdoul Salam Sow, a football player.* Abdoulaye S?kou Sow, a former Prime Minister of Mali....
.






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Pig iron is the intermediate product of smelting
Smelting

Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores....
 iron ore
Iron ore

Iron ores are Rock 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, deep purple, to rusty red....
 with coke
Coke (fuel)

Cokes are the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous....
, usually with limestone
Limestone

File:Limestone Formation In Waitomo.jpgLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geology record....
 as a flux. Pig iron has a very high carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 content, typically 3.5–4.5%, which makes it very brittle
Brittle

A material is brittle if it is liable to fracture when subjected to stress . That is, it has little tendency to deform before fracture. This fracture absorbs relatively little energy, even in materials of high Strength of materials, and usually makes a snapping sound....
 and not useful directly as a material except for limited applications.

The traditional shape of the molds used for these ingots was a branching structure formed in sand
Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters....
, with many individual ingots at right angles to a central channel or runner. Such a configuration is similar in appearance to a litter of piglet
Piglet

Piglet can refer to:*A juvenile pig*Piglet , the fictional character from A. A. Milne's Winnie-the-Pooh books and the Disney spin-offs*"Philophobia ", a song by Scottish group Arab Strap on their 1998 album, Philophobia...
s suckling on a sow
Sow

Sow may refer to an African name, frequent in Senegal.* Abdoul Salam Sow, a football player.* Abdoulaye S?kou Sow, a former Prime Minister of Mali....
. When the metal had cooled and hardened, the smaller ingots (the pigs) were simply broken from the much thinner runner (the sow), hence the name pig iron. As pig iron is intended for remelting, the uneven size of the ingots and inclusion of small amounts of sand was insignificant compared to the ease of casting and of handling.

The Chinese
China

China is a Culture of China, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
 were making pig iron by the later Zhou Dynasty
Zhou Dynasty

The Zhou Dynasty was preceded by the Shang Dynasty and followed by the Qin Dynasty in China. The Zhou dynasty lasted longer than any other dynasty in China history?though the actual political and military control of China by the dynasty only lasted during the Western Zhou....
 (1122–256 BC). In Europe
Europe

Europe is, conventionally, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural , the Caspian Sea, and by the Caucasus Mountains to the southeast....
, the process did not become common until the 14th century.

Uses


Traditionally pig iron would be worked into wrought iron
Wrought iron

Wrought iron is commercially pure iron. In contrast to steel, it has a very low carbon content. It is a fibrous material due to the slag Inclusion ....
 in finery forge
Finery forge

Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. To produce malleable wrought iron, it needs to undergo a Decarburization....
s.

Pig iron can also be used to produce cast iron
Cast iron

Cast iron usually refers to Gray iron, but also identifies a large group of ferrous alloys, which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy....
. This is achieved by remelting pig iron, often along with substantial quantities of scrap
Scrap

File:Allegheny Ludlum Steel Corp Scrap Piles.jpgScrap is a term used to describe recyclable materials left over from every manner of product consumption, such as parts of vehicles, building supplies, and surplus materials....
 iron, and removing undesirable contaminants, adding alloys, and adjusting the carbon content.

Modern uses

Today, pig iron is typically poured directly out of the bottom of the blast furnace
Blast furnace

A blast furnace is a type of metallurgy furnace used for smelting to produce metals, generally iron.In a blast furnace, fuel and ore are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions take place throughout the furnace as the material moves downward....
 through a trough
Trough

Trough may refer to:* Trough , a container for animal feed * Trough , a long depression less steep than a trench* Trough , an elongated region of low atmospheric pressure...
 into a ladle
Ladle (metallurgy)

In foundry work a ladle is a container used to transport and pour out molten metals. It needs to be:*Strong enough to contain a heavy load of metal....
 car for transfer to the steel plant in mostly liquid form, referred to as hot metal. The hot metal is then charged into a steelmaking
Steelmaking

Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the Pig iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required....
 vessel to produce steel
Steel

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight , depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten....
, typically with an electric arc furnace
Electric arc furnace

An is a furnace that heats charged material by means of an electric arc.Arc furnaces range in size from small units of approximately one ton capacity up to about 400 ton units used for secondary steelmaking....
 or basic oxygen furnace, by burning off the excess carbon in a controlled fashion and adjusting the alloy
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
 composition. Earlier processes for this included the Bessemer process
Bessemer process

The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron. The process is named after its inventor, Henry Bessemer, who took out a patent on the process in 1855....
, open hearth furnace
Open hearth furnace

Open hearth furnaces are one of a number of kinds of furnace where excess carbon and other impurities are burnt out of the pig iron to Steelmaking....
, finery forge
Finery forge

Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. To produce malleable wrought iron, it needs to undergo a Decarburization....
, and the puddling furnace.

Modern steel mill
Steel mill

A steel mill is an industrial plant for the manufacture of steel.Steel is an alloy of iron and carbon. It is produced in a two-stage process....
s and direct-reduction
Direct reduced iron

Direct-reduced iron , also called sponge iron , is produced from direct Reduction of iron ore by a reducing gas produced from natural gas or coal....
 iron plants transfer the molten iron to a ladle for immediate use in the steel making furnaces or cast it into pigs on a pig-casting machine for reuse or resale. Modern pig casting machines produce stick pigs, which break into smaller 4–10 kg pieces at discharge.

Refining

Pig iron is melted and a strong current of air is directed over it while it is being stirred or agitated. This causes the dissolved impurities (such as silicon) to be thoroughly oxidized. The metal is then cast into molds or used in other processes. This is known as refined pig iron, finers metal, or refined iron.

See also

  • Steelmaking
    Steelmaking

    Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the Pig iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required....
  • Wrought iron
    Wrought iron

    Wrought iron is commercially pure iron. In contrast to steel, it has a very low carbon content. It is a fibrous material due to the slag Inclusion ....