The chemistry of smelting The processes that occur inside the blast furnace are quite complex, and different reactions happen at the top and bottom of the furnace. The objective is to ensure that the right chemical reactions occur in each part of the furnace so that controlled and continuous processing is achieved. Iron oxide sinks down the furnace where it reacts with carbon monoxide gas coming up from the bottom of the furnace. The two then react to produce carbon dioxide gas and liquid iron. Liquids descend through the mixture in the furnace.
Carbon monoxide reacts with iron ore to produce molten iron and carbon dioxide gas.
The molten iron sinks to the bottom of the furnace. The waste gases pass out through pipes at the top of the furnace. The oxygen reacts with the coke to produce carbon dioxide gas, which in turn reacts with more of the coke to produce carbon monoxide. Cold iron ore, coke and limestone are added as a charge into the top of the furnace. Oxygen gas is pumped in.