Hydraulic transportation of non-spherical coarse particles in deep-sea mining: Impact of particle shape on flow dynamics

In deep-sea mining, ore is often not transported in the shape of spherical particles. This paper uses a numerical simulation combining computational fluid dynamics (CFD) and discrete element method (DEM) to study hydraulic transport of five particle shapes: Sphere, Sphero-Polygon, Polyhedron, Cylinder, and Briquette. The non- spherical drag force coefficient is applied, with sphericity and aspect ratio characterizing irregular particles. Results show that all shapes of particles tend to be transported at high speeds in the center of the pipe. Decreasing aspect ratio or increasing sphericity increases time-averaged axial solids velocity while reducing particle volume concentration in the pipe. Among the shapes, Sphere exhibits the highest transport rate, 0.4 m/s faster than Briquette particles, which have the largest localized particle volume concentration and are more likely to be retained in the pipe. Decreasing the aspect ratio of cylinder particles aids in conveying, while increasing the inlet particle concentration exacerbates volume concentration and reduces the transport rate. These findings enhance the theoretical understanding of hydraulic transport in deep-sea mining.