Experimental Investigation on Vertical Hydraulic Transport of Ores in Deepsea Mining

Deepsea mining has been proposed since the 1960s to alleviate the lack of resources on land.Vertical hydraulic transport of collected ores from the seabed to the sea surface is considered the most promising method for industrial applications.In the present study,an indoor model test of the vertical hydraulic transport of particles was conducted.A noncontact optical method has been proposed to measure the local characteristics of the particles inside a vertical pipe,including the local concentration and particle velocity.The hydraulic gradient of ore transport was evaluated with various particle size distributions,particle densities,feeding concentrations and mixture flow velocities.During transport,the local concentration is larger than the feeding concentration,whereas the particle velocity is less than the mixture velocity.The qualitative effects of the local concentration and local fluid velocity on the particle velocity and slip velocity were investigated.The local fluid velocity contributes significantly to particle velocity and slip velocity,whereas the effect of the local concentration is marginal.A higher feeding concentration and mixture flow velocity result in an increased hydraulic gradient.The effect of the particle size gradation is slight,whereas the particle density plays a crucial role in the transport.

Numerical Investigation on Inclined Hydraulic Transport of Large Particles for Deepsea Mining

Hydraulic transport in pipelines is the most promising conveying method for large ore particles in deepsea mining.The dynamic performances of particles during transportation in vertical,inclined and horizontal pipelines are significant for the design of hydraulic transport systems.In the present study,we focus on the statistical characteristics and flow regimes of the mixture composed of ore particles and seawater in the pipelines.Numerical simulations are conducted by using Computational Fluid Dynamics(CFD)and Discrete Element Method(DEM).The influences of inclination angle and particle diameter are evaluated through two sets of numerical tests.The regulation of the inclined transport is totally different from that of the vertical transport,whereas the dynamics of the mixtures in inclined and horizontal pipes are similar.A number of particles accumulate on the pipe wall even with a small inclination angle.Large hydraulic gradient and local concentration would occur when the inclination angle of the pipe is in the range of30°-60°.With the decrease of particle diameter,the particle flow becomes uniform,reflected by the almost uniform particle distribution in the vertical pipe and the clear interface between the suspended load and the bed-load in the inclined pipe.However,small particles will introduce larger local concentrations and hydraulic gradients in the inclined pipe,which is not conducive to particle transport.

Experimental study on reinforcement of bionic grouser of deep-sea mining vehicle

To fulfill the operational demands of deep-sea tracked mining vehicles traversing soft seabed substrates,an evaluation of the characteristics of these substrates was conducted,drawing a comparison with the land swamp black soil found in the buffalo's habitat.Employing the principles of biomimicry,two distinct types of bionic grouser were devised,replicating the configuration of the buffalo's hooves in both the horizontal and vertical planes.Utilizing self-constructed testing platforms,exhaustive examinations of the reinforcement efficacy of these bionic track grousers were undertaken,spanning from single-grouser to multi-grouser configurations and encompassing the entire track assembly.The findings unequivocally demonstrate a pronounced and consistent enhancement in traction force for both types of bionic grousers.Notably,the W-shaped bionic grouser,mimicking the horizontal contour of the buffalo's hoof,exhibits the most substantial increase in traction force.The maximum enhancement in traction force for individual bionic grouser exceeds 30%,while the overall track achieves an increase of over 19%.This research provides a valuable reference and establishes a foundational framework for the design of equipment tailored for the locomotion of deep-sea tracked mining vehicles across soft substrates.