Offering Consultancy for Pig Iron Plants. 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.”