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CONTINUOUS MICRO-SORTING OF COMPLEX WASTE PLASTICS PARTICLEMIXTURES VIA LIQUID-FLUIDIZED BED CLASSIFICATION (LFBC) FOR WASTE MINIMIZATIONAND RECYCLING
Description:
A fundamental investigation is proposed to provide a technical basis for the development of a novel, liquid-fluidized bed classification (LFBC) technology for the continuous separation of complex waste plastic mixtures for in-process recycling and waste minimization. Although a number of processes have been developed or proposed for the separation of waste plastics from manufacturing operations, none are completely satisfactory in terms of economics and performance. LFBC has a number of distinct advantages over most of these processes: (1) It can be used to separate a number of plastic particle types simultaneously in the same device. All other density-based techniques like flotation, centrifugation, air classification, hydroclones, etc., can only separate "lights" from "heavies" (i.e., two fractions), at best. (2) Only unmodified water is required for both "heavier-than-water" plastics ("upflow fluidization) and "lighter-than-water" plastics ("downflow" fluidization). Therefore, no density-modification of the fluidizing medium is necessary, which obviates the need for separation and recovery of modifying agents. Only water is needed to effect the separation of all plastic types; and water is already in ample use in chopping, grinding, and washing operations of plastic particles. (3) Due to the inherent physicochemical property differences between different plastic types, selective particle size/density modification can be performed in conjunction with LFBC to enhance separations, and/or to perform separations between different particle types with similar densities which are not possible using other conventional density-based separation processes. Finally, LFBC is completely compatible with most other separation/identification methods, such that it can be used in conjunction with other technology to improve the overall process economics.