With the mandatory requirement of recycling and reuse of electronic scraps arising from printed circuit boards (PCB), the non-polluting separation methods to separate metals and plastics are of growing importance nowadays. Mechanical recycling of electronic scrap oriented towards the overall materials recovery from obsolete electronics is being implemented worldwide. Air classification is one among the clean mechanical separation methods that can achieve reasonably good separation of metals and plastics from the PCB stuff. In the present investigation, the separation of metals and plastics from the milled PCB using a column air classifier has been studied in detail. A detailed study on the separation of species in the air classification system was analysed by using the efficiency curve approach and the classifier model parameters such as the reduced efficiency curve parameter (alpha), corrected cut size (V-a/V-I)(50c) and the size selectivity increment (Delta S) with respect to the process variables. The reduced efficiency relationship for the plastics and metals for all the experimental data were analysed using one parameter (alpha). The accuracy of the developed model was checked with the predicted values with all the observed values. The results showed that the simulation model is able to predict the experimental results satisfactorily. (C) 2006 Elsevier B.V. All rights reserved.