Abstract: Deep-sea polymetallic nodules predominantly exist in semi-buried states within deep-sea sediments characterized by high moisture content and low shear strength. Adhesion characteristic between sediments and nodules is a critical factor affecting collection efficiency. Based on the similarity of physical-mechanical properties in seabed surface sediments, sediment samples were developed to simulate the sedimentary substrate environment for nodule collection experiments. Systematic investigation of adhesion mechanisms was conducted through nodule-simulated sediment pull-out experiments and Coandă-effect-based hydraulic collection experiments. The results indicate that the sediment-nodule contact area and sediment shear strength are the primary factors affecting the adhesion, whereas pull-out speed and jet flow velocity show negligible effects. Moreover, an increase in contact area and higher shear strength enhance the adhesive effect of sediments on the nodules. What’s more, under constant pull-out speed and contact area, the adhesion coefficient exhibits an approximately linear relationship with shear strength. By comparing the results of the pull-out experiment and hydraulic collection experiments, it is found that the adhesion coefficient trends are similar under identical conditions, with a difference of less than 10%, validating methodological correlation. These findings provide valuable insights for the design of hydraulic collection experiments and the optimization of jet parameters in deep-sea mining operations.

Key words: deep sea mining, deep sea sediments, polymetallic nodule, adhesive interaction, Coand? effect