INTERMEDIATE product of smelting iron ore.Pig iron has a very high carbon content, typically 3.5 - 4.5%, therefore, it is an impure form of iron.In a blast furnace, coke (C) reacts with oxygen to form carbon monoxide, which then reacts with iron oxide to form carbon dioxide and pig iron.Iron oxide must be REDUCED in order to obtain iron and this can be DONE only in a blast furnace.It is the molten iron from the blast furnace, which is a large and cylinder-shaped furnace charged with iron ore, coke, and limestone.Extra facts:Wrought iron is the purest form of iron. It is an iron alloy with a very LOW carbon (less than 0.08%) content in contrast to cast iron (2.1% to 4%).