Motion Behavior Model and Multistage Magnetic Separation Method for the Removal of Impurities from Recycled Waste Plastics
Yufei Qin, Zichun Yao, Jujun Ruan, Zhenming Xu
Abstract
Plastics account for a large proportion of municipal solid waste as an important raw material for packaging and casing. Closed-loop recycling of plastics can maximize the recovery of materials, but measures are needed to ensure the good performance of recycled plastic products. We found that there would be iron fragments on the micron scale in the recycled plastic particles. This study combined the magnetic field simulation method and trajectory calculation to build a prediction model of the motion behavior of weakly magnetic particles in the process of magnetic separation. The simulation results show that the motion behavior of weakly magnetic particles is close to that of nonmagnetic particles when the separation speed is about 134 rpm (higher speed) under the set simulation conditions, which is different from the normal understanding. The model verification results show that the deviation between the predicted departure and the actual angle is less than 3°. Multistage magnetic separation equipment was designed for weakly magnetic particles based on the results of trajectory simulation. It could achieve the removal of more than 82% iron-containing particles with the process parameters of high magnetic field intensity and low separation speed (1 T, 40 rpm).