Abstract: Hydraulic collecting is a typical way to collect ores in deep sea mining. The study on mechanical characteristics of spherical particles in collecting flow field is the basis of collecting system design. The experiment system of hydraulic collecting is set up in the laboratory to study the impact of the ratio of bottom clearance to diameter of the particle (h/d), the angle between pipe inlet end face and the bottom of particle (θ), the towed speed of the suction pipe (vt) on vertical suction force coefficient (Cvs) and radius suction force coefficient (Crs). The results show that Cvs decreases exponentially with the increase of h/d; the vertical force predicting model of particles is established with the maximum error less than 10%; θ=20° is the point at which the fast fading of Cvs begins; the maximum of Crs and Cvs tend to increase slightly with the increase of vt, and Crs always reaches the maximum at θ=35° or θ=40°. The results of this article can provide reference for the design of hydraulic collecting system and refinement of collecting process.

Key words: deep sea mining; hydraulic collecting; spherical particles; dimensional analysis; mechanical characteristics