Purity prediction of the two‐stage high voltage electrostatic separation of a mixture of three polymers

Clean and efficient separation is an important requirement for the high‐value‐added recycling of end‐of‐life automobile polymers. In this study, polymer particles for vehicles were considered as research objects, and a two‐stage electrostatic separation device was designed to separate a mixture of three polymer particles. A kinematic model of friction‐charged particles in a two‐stage free‐fall separator was established. Then, a suitable time period for triboelectrostatic charging with regard to electrostatic separation was determined, and a charge–mass ratio distribution of mixed‐polymer particles, that is, polyamide (PA), polypropylene (PP), and polyethylene (PE), was measured using a Faraday cage based on the triboelectrostatic charging experiment of three types of particles in a friction barrel‐type tribocharger. The theoretical purities of PA, PP, and PE were calculated using the motion and particle charge–mass ratio distribution models were 100.00%, 89.51%, and 92.95% respectively. The experimental purities of PA, PP, and PE were 94.68%, 80.76%, and 84.27%, respectively, which is consistent with the theoretical purity. Results of the study can provide a theoretical and experimental reference for one‐pass electrostatic separation of three kinds of plastic particles. The paper aims to separate three kinds of polymer particles by electrostatic separation technology and propose a solution to effectively predict the separation results by analyzing the motion of polymer particles in the separator. The theoretical purities of PA, PP, and PE were 100.00%, 89.51%, and 92.95%, respectively. The experimental purities of PA, PP, and PE were 94.68%, 80.76%, and 84.27%, respectively, which is consistent with the theoretical purities