Flotation separation of plastic mixtures from End-Of-Life products
RECYCLING 2015: A Challenge for Chemistry, Metz France, 16 - 18 March 2015
Among different recycling processes of plastics, density sorting and optical sorting are the most widely used. However, for mixed plastics, especially those with dark colours or closed densities, or even with both of the two characteristics, it’s difficult to separate. Other limitations of plastic recycling exist as well, for example, many plastic materials are added with flame retardant in order to delay flames production, which set difficulty to recycling process. In this case of study, we try to apply mining technology to plastics sorting problem: froth flotation, a process for separating hydrophobic from hydrophilic materials, which is widely used for separating minerals from gangue and also for selecting ores after grinding. The former laboratorial tests have been carried out and showed that this method has a potential for plastics mixtures sorting. The treatment criteria of the processes such as particle sizes, contacting time with surfactants, etc., have a crucial effect on the separation of plastic mixtures, for which there is no other sorting methods. One of the main criteria and also difficulties is the wettability of plastic materials. Therefore, we will focus on the selection of surfactants in order to control the wettability of plastics, at the same time concentrate on the connections of sorting efficiency, technological feasibility and environmental and economic performance.