Abstract: Process for separating fine particles (fines) from a slurry of such fine particles in a liquid by a combination of centrifugal or other separative force and axial or longitudinal flow imparted to the slurry producing secondary flows of the slurry, and apparatus for utilization of the process, including a conduit (11) having a helical or curved portion (12) through which the slurry passes, rotating means (14) for spinning the helical portion, pumping means (15) for imparting an axial flow to the slurry, and control means (16) for controlling to obtain alternate direction of the axial flow towards the opposite ends of the helical portion.