pig iron

noun

1. iron tapped from a blast furnace and cast into pigs in preparation for conversion into steel, cast iron, or wrought iron.
2. iron in the chemical state in which it exists when tapped from the blast furnace, without alloying or refinement.

noun

1. crude iron produced in a blast furnace and poured into moulds in preparation for making wrought iron, steels, alloys, etc

n.1660s; see pig (n.) + iron (n.).