Morphology, mineralogy and separation characteristics of nonmetallic fractions from waste printed circuit boards

Abstract

The recovery of resources from waste printed circuit boards is of growing importance in parallel with the rapid increase of waste printed circuit boards as a result of the shorter product life cycles and upgrade of electronic equipment. As a byproduct of the recycling process of waste printed circuit boards, the nonmetallic fractions have an urgent requirement for recycling from the perspective of environment protection and resource recovery. In this paper, morphology, mineralogy and separation characteristics of nonmetallic fractions collected from the recycling line of waste printed circuit boards were analyzed by application of multi-analytical techniques, which lay the foundation for the recycling of nonmetallic fractions. Analysis results demonstrate that organic materials account for 60.03 wt% in raw nonmetallic fractions while the concentration of residual metals is up to 16.68 wt%. The concentration of magnetic production is 5.92 wt% in raw nonmetallic fractions and presents increasing trend with the size decreasing. The metal components in nonmagnetic part are mainly in single substance forms, while compound forms are presented in magnetic parts. Scanning electron microscope images demonstrate that there is an adequate liberation between metals and nonmetals, but glass fibers did not liberate from epoxy resin in +0.125 mm size fraction. There is an obvious difference in the components of different size fraction; and the metals were mainly concentrated in fine size fraction. Based on the mineralogical characteristics of each size fraction of nonmetallic fractions, the optimal recycling process of nonmetallic fractions including several processing operations is proposed.