Breakage simulations and experiments of granular fertilisers for optimizing a device of side-deep fertilisation by using the discrete element method.

The investigation of the fragmentation law of granular fertilisers in side-deep fertilisation devices is crucial for optimizing machinery. In this paper, Hertz-Mindlin with Bonding was used to establish a granular fertiliser model with breakage properties. The single-factor and central composite tests were carried out with the screw pitch, screw speed, and Y-shaped mouth angle selected as the test factors, and the broken bond rate as the evaluation index to indicate the fragmentation rate of the granular fertilisers. The result indicated a positive correlation between broken bond rate and screw speed in the range of 100–300 rpm, as well as a negative correlation between broken bond rate and screw pitch in the range of 18–38 mm and the Y-shaped mouth angle in the range of 25–45°. Moreover, during the reduction in screw pitch from 33 to 23 mm, the increment of broken bond rate caused by screw pitch was increased due to the higher screw speed and decreased due to the larger Y-shaped mouth angle. The key factors, in order of importance, are the screw pitch, screw speed, and Y-shaped mouth angle. In addition, the verification test was carried out in the range of 100–300 rpm and the test results showed a similar response trend to the simulation results, indicating that the fragmentation law obtained by the simulation is reliable. These research findings can provide a reference for the optimization of the side-deep fertilisation devices. • The fragmentation rate is researched based on the side-deep fertilization device. • The Hertz-Mindlin with Bonding contact model of granular fertilizer is established. • Single-factor and central composite tests and physical experiments are conducted. • The influence law of key parameters on granular fertilizer crushing are revealed. [ABSTRACT FROM AUTHOR]