For the magnetized fluidized bed (MFB) with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles

the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities (H)

leading to the deterioration of the fluidization quality. The critical intensity (H

ms

) above which such segregation commences varies with the gas velocity (U

g

). This work focuses on establishing a segregation model to theoretically derive the H

ms-

U

g

relationship. In a magnetic field

the magnetizable particles form agglomerates. The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles. Consequently

the segregation model was established in two steps:first

the size of agglomerates (d

A

) was calculated by the force balance model; then

the H

ms-

U

g

relationship was obtained by substituting the expression of d

A

into the basic size segregation model for binary mixtures. As per the force balance model

the cohesive and collision forces were 1-2 orders of magnitude greater than the other forces e

xerted on the agglomerates. Therefore

the balance between these two forces largely determined d

A

. The calculated d

A

increased with increasing H and decreasing U

g

agreeing qualitatively with the experimental observation. The calculated H

ms-

U

g

relationship agreed reasonably with the experimental data

indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.