The iron is extracted by reduction in a blast furnace . The reducing agent is carbon monoxide. A charge of iron ore, coke and limestone is put in the top of the furnace.
Hot air is blown in near the bottom.
The coke burns in the air to form carbon dioxide. This is a strongly exothermic reaction As the carbon dioxide passes up through more hot coke it is reduced to carbon monoxide. This reaction is endothermic The carbon monoxide reduces the iron oxide to iron. This reaction is slightly exothermic. As the iron moves down the furnace it melts and runs down to collect in a pool at the bottom.