Highly efficient recovery of high-purity Cu, PVC, and phthalate plasticizer from waste wire harnesses through PVC swelling and rod milling

Abstract

Novel methods for recycling waste wire harnesses, namely, dry rod milling (which involves the swelling of the cables followed by milling) and wet rod milling (which involves the simultaneous swelling and milling of the cables), were developed for the simultaneous recovery of the Cu wires, polyvinyl chloride (PVC) coatings, and phthalate plasticizer in high purity. The swelling of the PVC coatings facilitated the separation of the coatings from the Cu wires at moderate rod milling speeds and allowed for the extraction of the plasticizer. n-Butyl acetate was used as the swelling solvent and resulted in a sufficient degree of swelling (the volume increased to ∼3.5 times that of the original cables), thus allowing for the quantitative extraction of the plasticizer, which was diisononyl phthalate (DINP). The complete stripping of the PVC coatings and Cu wires from 20 cm-long cables could be performed within 60 min by both dry and wet milling at a low rotation speed (15 rpm). Furthermore, more than 90 wt% of the Cu wires longer than 10 cm could be recovered for subsequent Cu refining. The used n-butyl acetate was regenerated by distillation and exhibited PVC swelling properties comparable with those in the fresh state. Thus, the developed methods allow for the successful quantitative recovery of high-purity Cu, PVC, and DINP without requiring any of the complex multistep physical separation processes involved in the conventional granulation technique for the recycling of waste wire harnesses.