Toward a desktop attrition tester; validation with dilute phase pneumatic conveying

A new attrition tester has been developed which on a bench scale measures the attrition behavior of granules. Two different types of granules are tested viz. sodium benzoate and ammonium nitrate fertilizer granules. Attrition in the repeated impact tester is compared to attrition during dilute phase pneumatic conveying. Typical impact velocities in the new tester vary between 1 m/s and 5 m/s, during dilute phase pneumatic conveying typical air velocities are in the range of 20–40 m/s. To compensate for the velocity difference the number of collisions is increased. Experiments show an initial similarity between transferred kinetic energy and the attrition of the granules independent of the impact velocity. This is explained by the removal of surface asperities of the initial granules. The initial similarity region includes 12 bends at 40 m/s. In practice often not more than 6–10 bends are used for pneumatic conveying. The new attrition tester therefore seems a promising desktop tool for testing attrition during for example pneumatic conveying. But to be more conclusive more measurements with different types of particles are required.