Static and dynamic compressive loading of fired iron ore pellets

Slow compression tests are routinely used both in quality control of fired iron ore pellets during production and in negotiating commercial contracts. In spite of their widespread use, such tests represent stressing conditions consistent with those experienced by pellets during transportation in ships, wagons and conveyor belts, as well as when they are stored in silos and hoppers. However, operations that are most likely to damage pellets occur during transfers in chutes, screening, ship and wagon loading, stockpiling and reclaiming, where they are subjected to rapid loading. The present work compares the mechanical behavior of individual pellets subjected to slow compression and rapid loading, this later in an impact load cell device. Besides pellet strength, fracture energy and also stiffness of the pellets are analyzed, demonstrating that pellets present significantly higher stiffness when subjected to impact, with only marginally higher pellet strengths and no clear trend regarding fracture energy. These strain rates differences are then discussed and their potential effect on deformation behavior and wave propagation in the pellets are analyzed. [Display omitted] •Strength, fracture energy and stiffness reduced with increase in pellet size.•The same general trend was found for (double) impact and slow compression.•A ratio of 104 in strain rates was used in the experiments.•Significant differences between impact and slow compression for stiffness.•Marginally higher strengths for impact in comparison to slow compression.