Comprehensive theoretical-numerical investigations of flow phenomena and the homogenization of miscible fluids in conventional mixing vessels have been carried out. It has been verified that more than 80% of the energy transferred to the fluid remains in the primary motion and only less than 20% is transferred onto the secondary motion. In homogenization processes it is the secondary flow only that contributes to mixing. A detailed analysis of the development Of the concentration field in the fluid revealed that the mixing process may be divided in three steps: 1) convective transport of fluid A by the jet stream resulting from centrifugal forces to the vessel wall in the plane of the stirrer, 2) convective transport of fluid A by the vortices of secondary flow, 3) molecular transport of fluid A when the field of lines of constant concentration approaches identity with the field of stream lines. From the results of this investigation conclusions have been drawn useful for improvement of technical mixing systems.