CFD-DEM modelling of the conveying characteristics of a vertical pipeline for deep-sea mineral particles with wide particle size gradations

In this study, the Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM) are coupled to simulate the particle velocity and distribution, the conveying stability and energy efficiency of large-size and wide-gradation mineral particles in a vertical pipeline, and the accuracy of the coupled model is validated by comparing with previous experimental data. The effects of the conveying speed, the initial concentration and the Particle Size Gradations (PSGs) are investigated. The results of the particle behaviour show that small particles tend to move towards the pipeline centre, while large particles tend to accumulate around the pipeline wall during conveying. The particles are forced to disperse, leading to a more uniform distribution at a high conveying speed and low initial concentration. The conveying performance, including the particle velocities, the conveying stability and the energy efficiency can be improved by increasing the proportion of small particles.