In essence, any magnetic separator operates on the basis of imparting a preferential magnetic force on particles of higher magnetic susceptibility which are to be separated from particles of lower magnetic susceptibility. A certain amount of directional deviation to the particles takes place thus allowing for collecting each category of particles separately.
In a separator operating on the principle of a vertically fed gap, those particles that pass through the central plane, or for that matter, the central zone, of the gap are subjected to zero or effectively near zero force of attraction all along their downward vertical path. Whereas, in case of a spheroidal medium, such zones, though of course do exist, are by no means continuous along the whole passage of the particle. They exist between each cluster of neighboring spheroids only.