Impact Milling of Printed Circuit Board Waste for Resource Recycling and Evaluation of Liberation using Heavy Medium Separation [Translated]†

Abstract

The authors evaluated the degree of liberation of printed circuit boards ground by impact milling to recover valuable materials. Wastes of two board types were ground with a swing-hammer-type impact mill. Heavy medium separation using tetrabromoethane was employed to separate the ground materials into the sink product, containing mainly copper, and the float product, consisting mainly of epoxy resin and glass fiber. The degree of liberation was evaluated with heavy medium separation. The sink product was larger than the float product. When processing boards whose surfaces are fully plated with copper foil we attained a degree of liberation for copper in the sink of up to 95%, which was higher than the degree of printed circuit board liberation. By contrast, the copper content of the float product was quite low at less than 1%. Thus, non-copper materials are easily liberated, and non-copper materials with few impurities can be obtained from printed circuit board wastes.† This report was originally printed in J. Soc. Powder Technology, Japan. 36(6), 479-483 (1999) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.