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.