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Pig iron

Pig iron is raw iron in an ingot form. It is the immediate product of smelting iron ore with coke and limestone in a blast furnace - a hard but brittle mix of iron (90% or more) and carbon (typically 4-5%), manganese, sulfur, phosphorus, and silicon (roughly 3% in total). It requires further treatment in a bessemer converter or basic oxygen furnace to produce steel or wrought iron. Cast iron is made by remelting pig iron, often along with substantial quantities of scrap iron, and taking various steps to remove undesirable contaminants and adjust the carbon content.

The name is derived from the time when the iron ran into molds in sand beds fed from a common runner. The row of molds was said to resemble a litter of suckling pigs, hence the individual ingots were referred to as pigs and the runner was called the sow.

The Chinese were making pig iron by the later Zhou Dynasty (1122 BC - 256 BC). In Europe, the process did not become common until the 14th century.