No.4（2001）18.Stabilization of characteristics of an electrostatic separation system for PET bottle in the form of flakes

Yasuo TONOYA, Katsumi YAMAMOTO and Hiroshi SHIGEMATSU

Waste PET bottles are converted into PET flakes as recycling materials in a processing plant. Waste PVC bottle flakes are generally mixed into waste PET bottle flakes as an impure ingredient. It is indispensable for recycling PET bottles flakes to remove PVC bottle flakes from the mixed plastic waste. The authors developed an electrostatic separation system for PET bottle flakes. The electrostatic chargeability of plastics is influenced by environmental conditions, such as relative humidity. When the relative humidity in the working area of the electrostatic separation system increases to more than 60%R.H., the charge quantities of flakes decrease. As a result, the separating efficiency falls drastically. The prevention methods against the lowering of separating efficiency are discussed. We tried to dehumidify the wet atmosphere in the working area by operating dehumidifier, and as a result the separating efficiency was improved. When the relative humidity of the atmosphere is controlled to be less than 45%R.H., the extract content is more than 99.99% and the recovery is over 70%.

Keywords
Static electricity, Plastics, PET bottle, Electrostatic separation, Recycling

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