Batch separation of shredded bulky waste by gas–solid fluidized bed at laboratory scale

A gas–solid fluidized bed separator using various bed materials was used to separate shredded municipal bulky waste (SBW). Using 290 μm glass beads as the bed material, the apparent density of the fluidized bed was 1.5 g/cm3 and the SBW could be separated into combustibles such as wood, paper and plastics and incombustibles such as metals and glass. The overall efficiency (Newton’s efficiency) of the separation was calculated to be 0.93. In order to obtain high efficiency, the superficial velocity must be adjusted so that the fluidized bed is agitated moderately and at the same time there is no weak fluidized region. Using a mixture of particles of nylon shot and 68 μm glass beads, the apparent density of the fluidized mixture bed could be varied between 0.63 and 0.99 g/cm3 by changing the mixing ratio of the two materials. In the case of a mixing ratio of 20% for glass beads, an apparent density of 0.65 g/cm3 was produced, in which wood and paper components were recovered while plastics remained in the bed to give a final overall efficiency of 0.88.