Investigating particle transport characteristics of a deep-sea mining pump considering solid phase breakage using computational fluid dynamics and discrete element method

The deep sea multistage mining pump plays a key component of the hydraulic lifting system. Breakage of polymetallic nodule ores during transport affects the particle transport characteristics of mining pumps. The damage accumulation coefficients of the particles were fitted by combining Hertzian elastic contact theory and slow compression tests. In this study, the Tavares breakage model was applied for the first time to simulate the breakage of polymetallic nodules in deep-sea mining pump, combined with the computational fluid dynamics–discrete element method. The operating conditions with different pump rotational speeds and particle shapes were simulated. The results show that the size of polymetallic nodules is reduced with the pump stage downstream, and the first stage of the mining pump contributed the most to particle breakage. Collisions between particles, particle impacts with the blades, and shroud walls of the impellers and space guide vanes are the main factors in the breakage for polymetallic nodules. Quantitative analysis revealed that the mass fraction of fine size (1–4 mm) particles increased from 53.41% to 76.55% when the rotational speed was increased from 960 to 1740 rpm and from 70.7% to 84.25% when the shape factor (α) was increased from 1.0 to 2.0. These findings provide a reference for further exploring solid–liquid flow of mining pumps and optimizing their design and operational parameters.