In this paper, we investigate the influences of air flow and vibration on the separation of a binary mixture, when air velocity u is less than the minimums fluidized velocity u_(mf) (0＜u/u_(mf)＜1). By the layered extraction method, we obtain the particle distribution both in the vertical and radial direction in a cylindrical bed. 13X molecular sieve particles with diameter 2.00 mm and 4.00 mm are used. Vibration frequency f is 30 Hz and dimensionless vibration acceleration Γ is 1.02, 2.04 and 3.06. The results indicate that as air velocity increases, the granular particles system under air flow tends to Reversed Brazilian nut BN (RBN) in vertical direction. When u/u_(mf)=0.73 approximately, a large number of large particles begin to sink to the bottom, which is recognized as a turning point from homogeneous mixture to RBN. In the radial direction, depending on air velocity, different separation can take place. Under low air velocity, increasing u/u_(mf) leads particles from slight BN to homogeneous mixture. When air velocity is getting larger, the radial distribution is inclined to Radial Reversed BN (R-RBN), especially in the middle layers.
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