It is cast into moulds called pigs , and the iron is called cast iron or pig iron . Cast iron is used for manhole covers and as engine blocks for petrol and diesel engines .
Carbon is removed from molten cast iron by bubbling oxygen through it.
The oxygen reacts with the carbon in preference to the iron because carbon is more reactive . Pure iron , which has had all the carbon removed , is called wrought iron . Iron is the catalyst in the Haber Process .