Grey, ductile and malleable cast iron — engine blocks, brake drums, manhole covers and machinery bases (2–4% carbon). Remelted by iron foundries.

ISRI Description and Specification

Cast iron scrap consists of grey cast iron, ductile (nodular) cast iron, and malleable cast iron items from industrial, municipal, and consumer sources — including engine blocks, cylinder heads, brake drums, flywheels, manhole covers, pipe sections, boiler components, and machinery bases. Cast iron contains 2–4% carbon (compared to less than 2% for steel) and significant silicon (1–3%), manganese, and sulphur, giving it distinctive properties: high compressive strength, excellent machinability, and brittleness under impact. These compositional differences — particularly the high carbon and silicon — mean that cast iron scrap cannot be mixed with steel scrap without careful chemistry management. In an EAF, cast iron raises the melt carbon level significantly, which is sometimes desirable (as a cheap carbon source) but must be controlled to avoid carbon specification exceedances in the final product. Cast iron scrap must be free of steel attachments beyond tolerable limits, free of excessive dirt or sand cores (from the casting process), and free of non-ferrous components.

Who Uses Cast Iron Scrap

Grey and ductile iron foundries are the primary consumers of cast iron scrap — they re-melt it in cupola furnaces or electric induction furnaces to produce new iron castings for automotive (brake drums, discs, cylinder blocks, exhaust manifolds), municipal infrastructure (manhole covers, stormwater grates, pipe fittings), industrial machinery (machine tool beds, press frames), and agricultural equipment. In India, the automotive casting cluster in Rajkot (Gujarat), Coimbatore (Tamil Nadu), Pune (Maharashtra), and Ludhiana (Punjab) consumes large volumes of cast iron scrap as the primary melting feedstock for grey iron and ductile iron castings supplied to OEMs. EAF steel producers may also consume limited quantities of cast iron as a carbon-raising charge component, particularly when producing high-carbon steel grades for rails, springs, or engineering bar.