Pig Iron

Pig iron is the intermediate product of smelting iron ore; it has high carbon fuel such as coke, usually limestone with the flux. Carbon content is very high in pig iron, typically 3.5 – 4.5%. The brittleness is very high, it is not directly useful as a material excluding some limited application. Charcoal and anthracite have also been used as fuel.

The molds used for these ingots were a branching structure formed in sand, with many individual ingots at right angles to a runner. Why is called pig iron? When the metal had cooled and hardened, the smaller ingots i.e. pigs, were simply broken from the much thinner runner i.e. the sow. As pig iron is subjected  for re melting, the uneven size of the ingots and addition of small amount of sand was immaterial when compared to the ease of casting and of handling.

Pig iron uses

Usually pig iron would be worked into wrought iron in finery forges and latter into puddling furnace, and more recently into steel. During this process, the pig iron is melted and an air with strong current is rooted over it, while it is being stimulated. This causes the dissolved impurities such as silicon to be thoroughly oxidized. Refined pig iron, finers metal, or refined iron is known as an intermediate product of puddling. Pig iron is used to produce gray iron, by re melting pig iron, along with steel and iron in a considerable quantity, by removing undesirable contaminants, adding alloys, and adjusting the carbon content. Some pig iron grades are suitable for producing ductile iron, and this kind of pig iron are high purity pig iron and depends on the grade of ductile iron being produced these pig irons may be low in elements silicon, manganese, sulfur and phosphorus. These types of pig irons are useful in diluting all elements from the ductile iron charge but except carbon.

Pig iron in modern uses

Now days, pig iron is poured directly to the bottom of the blast furnace through a trough into a ladle car, for transferring to the steel mill in mostly liquid form which is referred as hot metal. Then the hot metal is then charged into a steelmaking vessel for producing steel, with electric arc furnace or basic oxygen furnace. Ancient process includes the finery forge, the puddling furnace, the Bessemer process, and open hearth furnace. NASA Boeing 747 shuttle carrier Aircraft was used Pig iron as the ballast.

Questions:

• What is pig iron?
• Which aircraft had used pig iron as a ballast?