Water in the spiral chute runs downward spiral movement and also flows in circulation transversely. water in the upper layer run fast, generating centrifugal force with large inertia to toss toward the outer edge of the chute. Back-flow of water in the lower layer adjacent to the chute bootom runs slowly with small centrifugal force and flows from the outer edge to the inner edge with the action of gravity, generating secondary back-flow. Particles of heavy minerals in slurry settle rapidly and gradually moves toward the inner edge along the converged helix prior to finally being produced as concentrate. Light minerals settle slowly and flow fast in the surface layer of ore flow with large centrifugal force and gradually move toward the outer edge along the expanding helix before finally being produced as tailings.