Particle dynamics and wear characteristics of lining layers in curved non-metallic flexible pipes for deep-sea mining

Wear of the internal lining in the non-metallic flexible pipes (NMFPs) is a critical issue in long-distance hydraulic lifting for deep-sea mining, as it can lead to structural failure and reduced service life. The non-homogeneous, discontinuous flow of unevenly sized mineral particles, especially in the curved sections of the pipe, complicates the analysis of particle motion and wear characteristics. This research presents a numerical simulation model of particle dynamics in the internal layers of curved NMFPs, developed using the CFD−DEM coupling method, based on Hertz−Mindlin contact theory and the Archard wear model. The model captures the particle-particle and particle-wall collision behaviors, alongside energy dissipation patterns. A parametric analysis of the wear process was conducted to evaluate the service life of the bent NMFP. Results indicate that particle collision frequency and energy dissipation correlate with increased wear, while higher conveying speeds and larger particle diameters intensify wear. Under specified conditions of 6 m/s conveying speed and a maximum particle concentration of 0.15, an NMFP with a 10 mm internal layer thickness is estimated to last 3.65 years. These findings provide a technical reference for optimizing conveying parameters and minimizing internal wear in deep-sea hydraulic lifting systems at depths of 6000 meters.