Why must iron ore concentrates be pelletized before they can be used in a blast furnace?

Iron ore concentrates, often referred to as "fines" (particles smaller than 7 millimetres), must be agglomerated into pellets or sinter before being charged into a blast furnace to ensure efficient and stable operation.1

Using randomly sized ore can lead to inconsistent furnace performance. By converting fines into evenly sized pellets or sinter, the furnace charge descends more regularly without sticking. This uniformity is critical because it allows for more even gas flow through the furnace, which significantly enhances the contact between the rising combustion gases and the descending iron-bearing materials. This improved gas-solid interaction is essential for the efficient reduction of iron oxides into metallic iron.23