1. Cupola principle

The cupola furnace is a vertical furnace for melting cast iron, which operates by burning coke. . The metal to be melted generally consists of new cast iron, scrap, foundry returns (etching and feeder systems, non-conforming cast iron parts). This metal is in direct contact with the fuel. This high-temperature contact results in significant carburization of the liquid metal, to levels of 2 to 3.5% carbon. The resulting cast iron is known as pig iron.