Aluminum and plastic recovery from aluminum laminates using electrical pulsed discharge

Aluminum laminates, widely used in food packaging, are difficult to recycle because of their complex multilayer structures, leading to disposal primarily through landfilling or incineration. In this study, we propose a method for separating aluminum foil and plastic layers from aluminum laminates using electrical pulsed discharge (EPD). Since EPD can selectively heat the aluminum foil, its energy consumption is expected to be lower than that of conventional thermal processes. However, the applicability of EPD to various aluminum laminates and its separation mechanism have not yet been fully elucidated; thus, this study aimed to investigate these aspects. EPD was applied to four aluminum laminates with varying layer thicknesses to investigate their separation behaviors. Successful separation was achieved for all samples except the thinnest one, with high aluminum recovery rates (93.6-98.7 wt%) and purity (96.6-99.7 wt%). Also, the chemical analysis of the recovered resins showed almost no change before and after the pulsed discharge. To elucidate the separation mechanism, high-speed camera imaging, heat transfer and thermal stress simulations were conducted. The results revealed that successful delamination requires both sufficient energy to decompose the interfacial resin and adequate thermal stress to propagate the delamination. To evaluate the environmental impact of the EPD method, its energy consumption and greenhouse gas (GHG) emission were compared with those of other separation methods. EPD-based recycling process demonstrated superior energy efficiency and GHG emission reduction compared to conventional processes.