Manganese nodules are very fragile and easy to be broken to small pieces even to μm or mm size. This can cause environmental problems in the process of a sea test or a commercial mining. For the efficient solid separation from the mixture of sea water and ultrafine particles, we have designed and manufactured a hydrocyclone by a CFD (Computational Fluid Dynamics) analysis and have performed a short experiment. Eulerian multi-phase method was used to describe the settling behaviors of solids in the hydrocyclone. From the CFD results, it was predicted that the solid recovery was 79%, which agreed with the preliminary experiment.
For the recovery of useful minerals and the prevention of contamination, appropriate solid/liquid separation processes are needed from the lifted slurry (Yoon et al., 2004). In a sea test in Korea scheduled in the near future, solid-liquid mixture more than 150 tons per hour should be processed continuously and also the purified seawater should be returned to the sea. Because the release of sea water even with small amount of particles can cause environmental problems, a rapid and highly efficient separation method is required to separate solid particles from the sea water. The suspended solids are separated from the liquid due to the centrifugal force induced inside the hydrocyclone (Fig. 2). The bigger and heavier particles flows out along with the hydrocyclone wall towards the underflow pipe, while the smaller and lighter ones change their directions upwards when they approach the cone apex and flow out through the vortex finder(Nowakowski et al., 2004). It has been used in many fields like dewatering of oil or gas and medicine liquid extraction from organic materials as well as liquid separation from solid materials (Cullivan etal., 2004;Yang et al., 2004).