The research on the motion of particles in fluid conveying is significant for the mechanism study of hydraulic collecting process in deep-ocean mining. The experiments were conducted in a water tank to measure the translational and rotational motion of spherical particles by developing a spherical detector with a built-in a nine-axis attitude sensor. The three-axis linear acceleration and angular velocity can be measured and stored by the detector. The attitude angle, defined as the spatial rotation of the detector coordinate system relative to the laboratory coordinate system and described via the Euler angle, is obtained with a Quaternion algorithm and a Kalman filter. The method is validated with a 50 mm diameter spherical object by three respective tests. Finally, the detector is tested as a tracer particle in hydraulic collecting. Findings indicate that the method is capable of tracing the detailed behaviors of particle in hydraulic collecting.
In the process of exploring and developing the ocean, human beings have found that the seabed contains extremely rich metal mineral resources, oil, natural gas hydrate, etc., which can be of many types, huge reserves and high grades, and have great prospects for development and utilization (Lusty, 2018). A deep sea mining system is an integrated unit of mining vessel-pipe-mining vehicle on seabed that picks up solid particles or alluvial forms of solids, including heavy mineral particles, from the deep seabed and transports the solid particles to the sea surface. The mineral particles are mostly spherical or ellipsoidal, with their long-axis length varying from 2 cm to 10 cm, and the hydraulic lifting process is the large particle solid-liquid two-phase flow (Li, 2003). The movement mechanism of particle-water mixture is the key to the hydraulic lifting technology.
Sup Hong et al. (1999, 2001) conducted a hydraulic collection test in a long tank using a collection head with nozzles, and found that the pressure distribution on the bottom of the tank and the shape of the collection channel had an impact on the collection efficiency of nodules. Bernd Grupe et al. (2001) obtained deep-sea sediment samples using a sampling device and measured the traction force required to lift different shaped nodules from undisturbed sediment samples under laboratory conditions to determine the nodule-sediment adhesion focus. Yang et al. (2003) qualitatively analyzed the influence of the main shape parameters of the collection head with nozzles on the hydraulic collection performance through experiments, and pointed out that the distance between the front and rear rows of nozzles, the height of the nozzle from the bottom and the diameter of the nozzle jet hole are the key shape parameters.
