Crack Genesis in Iron Ore Pellets and Evaluation of Methods for Increasing Their Strength

The origin of cracks in pellets is primarily determined by their properties during raw pelletizing. The number and type of cracks (radial, concentric) can be used for initial diagnostics of raw pelletizing. The influence of bentonite quality (effective viscosity and swelling index) on the formation of cracks in pellets is related to the decrease in stress relaxation time as the viscosity of the bentonite suspension increases. The use of bentonites with a high swelling index (and effective viscosity) reduces the risk of crack formation and increases pellet strength. Reducing the number and height of pellet handling during transportation is a way to reduce pellet fracturing. The use of bentonite-polymer binders increases the viscosity of the aqueous suspension and reduces the number of cracks in pellets. Reducing the bentonite dosage negatively impacts the strength of dry pellets. To maintain pellet quality, the swelling index of the bentonite should not decrease.