Numerical Simulation of Ascending Motion of Polymetallic Nodules for Hydraulic Lifting of Vertical Pipes

Deep-sea polymetallic nodule hydraulic lifting program belongs to the particle fluid complex system of solid-liquid two-phase flow problems, most of the previous research for low-density, small-sized particles, for high-density, large-sized particles of the research is mostly carried out in the net water free-fall problem .In this paper, the solid-liquid two-phase flow of seawater with polymetallic nodules was numerically calculated using the CFD-DEM semi-analytical method in the context of deep-sea mining polymetallic combined with hydraulic lifting. The effect on the particle rise process was investigated for several cases, such as the particle fluid density ratio of 1:2, different pipe diameters with particle size ratios of (2∼10), different pipe Reynolds numbers (400∼2000; lifting velocities of 2∼10m/s), and different initial positions of the particles. The accuracy of the computational model is also verified by comparing the infinite-boundary free-fall experiments with the results of the literature by Lei Liu and Horowitz M. The results are summarized as follows. Through numerical simulation, five subdivided types of particle ascent trajectories were obtained; Different Reynolds numbers and particle size ratios also have an impact on the upward trend of particles, while changes in initial position have little effect on the upward velocity of particles.