Pig Iron Information
WHAT IS PIG IRON?*
The vast majority of PIG IRON is produced and consumed within integrated steel mill complexes.
In this context the term “pig iron” is something of a misnomer: within integrated steel mills, blast furnace iron - hot metal - is transferred directly to the steel plant in liquid form.
The term “pig iron” arose from the old method of casting blast furnace iron into moulds arranged in sand beds such that they could be fed from a common runner.
The group of moulds resembled a litter of sucking pigs, the ingots being called “pigs” and the runner the “sow.”
MERCHANT PIG IRON is cold iron, cast into ingots and sold as ferrous feedstock for the steel and metal casting industries.
It falls into the category of ferrous metallics, of which iron and steel scrap comprises by far the largest volume, others being direct reduced iron [DRI], hot briquetted iron [HBI] and various other “alternative iron” materials.
Merchant pig iron is, by definition, produced by dedicated merchant plants all of whose production is sold to external customers. Some integrated steel mills produce blast furnace iron that is surplus to their internal requirements and this is also cast into ingots and sold as merchant pig iron.
Merchant pig iron comprises three main types: BASIC PIG IRON, used mainly in electric arc steelmaking, HAEMATITE PIG IRON [also known as FOUNDRY PIG IRON], used in mainly in the manufacture of grey iron castings in cupola furnaces, and NODULAR PIG IRON, used in the manufacture of ductile [also known as nodular or spheroidal graphite - SG] iron castings.
Pig iron contains at least 92% Fe.
Other constituents are typically:
BASIC PIG IRON:- 3.5-4.5% carbon, <1.5% silicon, 0.5-1.0% manganese, <0.05% sulphur, <0.12% phosphorus - HAEMATITE PIG IRON:- 3.5-4.5% carbon, 1.5-3.5% silicon, 0.5-1.0% manganese, <0.05% sulphur, <0.12% phosphorus - NODULAR PIG IRON:- 3.5-4.5% carbon, <0.05% manganese, <0.05% sulphur, <0.05% phosphorus -
Most merchant pig iron is produced through the reduction of iron ore in blast furnaces, using either coke or charcoal as reductant and energy source.
Pig iron, principally nodular pig iron, is also produced through the smelting of ilmenite in electric furnaces, as a by-product of titanium dioxide slag production.
With its defined and closely controlled specification and the absence of metallic impurities, pig iron is a reliable and consistent charge material for both electric steelmaking and ferrous castings production. It also contains valuable alloying elements and reduces the energy consumption of a melt.