Critical to that development was the use of natural Na-bentonite as a binding agent. In this process, the ore is first finely ground to liberate the iron oxide from the host rock. Unfortunately, the fineness of the resulting powdered iron ore concentrate creates handling problems during shipping an d during processing at the blast furnace. These problems are solved by mixing a small amount of bentonite and water with the finely ground iron ore concentrate and then passing the mixture through a pelletizer to produce spherical pellets about 1 cm in diameter .

These pellets are dried and then sintered. After cooling, the hardened pellets can withstand long-distance transport and handling without breaking. The pellets also allow gas flow through reduction furnaces in the steel-making process. In some cases, iron ore concentrates mixed with bentonite are compacted under high pressure to make briquettes. Approximately 20% of global bentonite production is consumed in iron ore pelletizing.

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