SEPARATION OF PET, PVC AND PS BY GRAVITY CONCENTRATION AND FROTH FLOTATION

摘要

In Municipal Solid Wastes (MSW) processing, mechanical separation processes like screening, magnetic, and gravity separation are already used in large scale. Nevertheless, some components of the wastes are not yet mechanically separated, due to the similarity in their physical properties. This is the case of plastics. Polyolefines like Polypropylene (PP) and Polyethylene (PE) are easily separated from heavier-than-water plastics, like Polyethylene Terephthalate (PET), Polystyrene (PS) and Polyvinyl Chloride (PVC), applying sink-float method using water as medium. PS, PET and PVC, however, have similar density being very difficult to separate one from the others. This paper describes the experimental work performed arming the separation of PET, PVC and PS from binary mixtures of the three plastics. The separation processes used were jigging, wet shaking table and froth flotation that are processes widely used in mineral processing. It was possible to achieve complete separation of PVC from PET, using jigging. A clean PET product and a product with 63% of PS, from PET+PS mixtures with 10% PS, were produced using jigging, as well. The results of wet shaking table process applied to the mixture of PVC and PS were also very promising: a clean PVC product was obtained and the PS product was 96% grade in PS.