In iron ore smelting, haematite gets reduced at the top of the furnace, where temperature is in the range  600 – 700 °C. The Ellingham diagram indicates that in this range carbon monoxide acts as a stronger reducing agent than carbon since the process
:2 CO +  →  2 
has a more-negative free energy change than the process:
:2 C  +   →  2 CO.
In the upper part of the blast furnace, haematite is reduced by CO (produced by oxidation of coke lower down at the bottom of blast furnace, at higher temperature) even in the presence of carbon – though this is mainly because the kinetics for gaseous CO reacting with the ore are better.