The virgin acrylonitrile butadiene styrene -ABS-, polycarbonate -PC- and polyoxy methylene -POM- available in a plastic mix were separated from each other by a floatation technique with the aid of several depressants. Also, a Design-Expert® statistical software was used to predict plastic floatation value using plastic conditioning time with depressant , flotation tank temperature and pH and depressants concentration as input data. It revealed that the floatation technique was effective for separation of studied plastics by selected depressants. Understanding the adsorption-desorption phenomena and effective parameters on this process was crucial to explain the activity and selectivity of a depressant on a plastic surface. The increasing conditioning time up to 15 minutes had adverse effect on the floatability of the all studied plastics conditioned with tannic acid -TA-. TA and methyl isobutyl carbinol -MIBC- had not any effect on floatability of PC and POM in all studied depressant concentrations. The floatation of ABS reached to 85% for floatation tank pH of 6.5 with 15 minutes depressant conditioning at floatation tank temperature of 35℃. A complicate phenomenon involved and predominated in floatation of studied plastics. Proposed equations by Design-Expert® predicted close plastic floatation values when compared with corresponding experimental values.

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