Compound Electrostatic Separation Of Multiple Mixed Granular Plastic Wastes

For those plastic wastes contain a variety of plastic components,separating those components form each other,the reproducibility and economic value of plastic wastes would highly improved.Base on that,this study proposed the application of compound electrostatic separation method to separate mixed plastic wastes.There are two method in compound electrostatic separation,cyclone electrostatic separation and corona charge-decay electrostatic separation.Charge characteristic,trajectory simulation and separation efficiency of these two methods were studied.Finally compound electrostatic separation was used to separate plastic wastes(containing ABS,PP,PVC)from refrigerator disposal remains.Cyclone charging and corona charging of plastic particles were studied.Mechanism of cyclone charging was put forward and collision model of the mechanism showed that charge Q related to friction coefficient ?,collision angle?,cross section radius R~2,collision frequency n_t~3 and charge time T.Experiment results had verified Q?n_t~3·T,providing a theoretical basis for cyclone tribocharger optimization.Cyclone tribocharging series studies showed that environmental humidity and friction medium will slightly change the sequence of tribocharging series.Corona charging studies of plastic particles showed charge quantity in aggregation state was twice the discrete state.In aggregation state,charge decay curve of different particles were measured,discovering three different kinds of decay type,maintain type,fast decay type and slightly decay type,providing basis for charge-decay electrostatics separation.MATLAB simulation was utilized to study trajectories of charged particle in separation electric field,which include the influence of different parameters.High-speed photography was introduced to verify free fall plate separation field model of cyclone charged particle.Experimental design optimized the parameters in centrifugal roll separation field model of corona charged particle.In the studies of cyclone triboelectric separation of ABS/PP plastics and charge-decay electrostatics separation of ABS/PVC or PP/PVC plastics,optimal separation conditions were identical to simulation results.Decay time t had the greatest influence to charge-decay electrostatics separation,when decay time was longer than 300 s,PVC recovery was 100%,the purity of ABS,PP also reached 100%.Composting cyclone electrostatic separation and corona charge-decay electrostatic separation,compound electrostatic separation was proposed.The ability and process of compound electrostatic separation was put forward.Then compound electrostatic separation was used to separate plastic wastes from refrigerator disposal remains,the separation results was good as that 96%purity PVC,90.1% purity ABS,91.7% purity PP were gotten.