2020 Volume 76 Issue 2 Pages I_881-I_886
To lift up coarse and heavy ores from deep seafloor, new technology by using circulating carrier materials (mixtures of viscous fluid and fine particles, CMs) in riser pipe was proposed. For effective operation, CMs must not be separated from ores during lifting. In this paper, the results of sphere falling experiments conducted to study the non-separability of ores in CMs were reported. By RFID system, falling velocities of invisible spheres, i.e. ore models (OMs), were monitored in a vertical pipe which was filled with turbid CMs. By assuming the viscous characteristics of CMs as that of Bingham fluid, the rheological properties, i.e. the plastic viscosity and the yield stress, were estimated. The obtained results demonstrated that the plastic viscosity is dependent on the mixing proportions of both thickener and fine particles while the yield stress is dependent only on the thickener. Finally, the condition of nonseparability for spherical ores of certain diameters and densities was derived based on the rheological model for CMs.
