Mass transfer structure effect on separation results in flotation has been considered, abstracting from all other factors. Four ideal mass transfer structures are introduced, differing in movement direction and agitation degree of liquid transport phases and air bubbles. Two non-dimensional parameters are proposed — directivity K and effective process time М, which totally determine separation in flotation zones with ideal mass transfer structures. Separation characteristics (SC) were constructed for small, medium and large effective time, with process directivity parameter assumed as particles' property. Flotation zones SC identity with all mass transfer types with small effective time is shown. With regard to large effective time, flotation zones SC with all ideal mass transfer structures, except countercurrent in ideal displacement, are same. In recovery and concentration zones with countercurrent with ideal displacement and large effective process time, nonlinear effect of increasing probability of repeated attachment in recovery zone for particles with K > 1 and repeated break-off after attachment in concentration zone for particles with K < 1 is observed. With that, total recovery of particles with K > 1 in recovery zone and zero recovery of particles with K < 1 in concentration zone are provided.