Deep-sea mining lifting pump differs from conventional solid–liquid two-phase flow pump, due to the complex and ever-changing operating environment. It is more likely to experience emergency shutdowns and particle reflux, leading to pump blockage and ultimately causing damage to the lifting system. Research on the influence of particle characteristic parameters on pump reflux performance can provide theoretical support for the design of high-performance deep-sea mining lifting pumps. The impact of particle size on the reflux performance of a mining lifting pump during shutdown was investigated in this study. The coupling method of CFD–DEM (computational fluid dynamics–discrete element method) was employed to simulate the reflux of spherical particles with different sizes (5 mm, 6 mm, 7 mm), and comparative analysis was conducted to the reflux performance of particles with varying sizes in the lifting pump. The results indicate that particles tend to accumulate at the junction between the impeller and guide vane when reflux occurs in the lifting pump. As the particle size increases, the distribution of particles in the first and second-stage pump becomes denser, resulting in less smooth reflux inside the pump and noticeable clogging. Moreover, particle accumulation gradually extends into the flow channel of the impeller and guide vane. The average velocity of particles gradually decreases with larger particle sizes; this leads to an increase in the time it takes for particles to pass through the pump and a gradual deterioration in the reflux performance of the lifting pump. Further analysis indicates that the ratio of collision number between particles to the total number of collisions increases continuously with the increase in particle size. Additionally, as the particle size increases, the proportion of collisions between the particles and the second guide vane significantly increases.

深海矿用提升泵不同于传统的固液两相流泵，作业环境复杂多变。它更有可能经历紧急停机和颗粒回流，导致泵堵塞并最终对提升系统造成损坏。研究颗粒特征参数对泵回流性能的影响可为高性能深海采矿提升泵的设计提供理论支撑。本研究研究了粒度对矿用提升泵停机期间回流性能的影响。采用CFD-DEM（计算流体力学-离散元法）耦合方法模拟不同尺寸（5 mm、6 mm、7 mm）球形颗粒的回流，并对颗粒的回流性能进行对比分析提升泵的尺寸不同。结果表明，当提升泵发生回流时，颗粒容易在叶轮与导叶的连接处积聚。随着颗粒尺寸的增大，颗粒在第一级和第二级泵中的分布变得更密集，导致泵内回流不太顺畅，并且出现明显的堵塞。而且，颗粒堆积逐渐延伸到叶轮和导叶的流道中。随着粒径变大，颗粒的平均速度逐渐减小；这导致颗粒通过泵的时间增加，提升泵的回流性能逐渐恶化。进一步分析表明，随着颗粒尺寸的增大，颗粒间的碰撞次数占总碰撞次数的比例不断增加。另外，随着颗粒尺寸的增加，颗粒与第二导流叶片之间的碰撞比例显着增加。