4. Conclusions
A new recycling process without negative impact to the environment
for recycling WPCB was established. It was found that
the recycling process technology containing vacuum pyrolysis,
crushing, size classification and gravity separation was an efficient
method to recycle the different fractions of WPCB such as organic
resins, copper and glass fiber. The following conclusions could be
drawn from the present study.
Vacuum pyrolysis of theWPCBled to an average mass balance of
74.7 wt.% residues, 15.0 wt.% oils, and 10.3 wt.% gases. The residues
mainly consisted of copper, glass fiber and carbon. And the residues
were very friable and better laminated that could be easily liberated
for copper recovery. The oils were amixture of organic compounds,
which were mainly composed of phenol, substituted phenols, benzofuran
and substituted benzofurans as well as bromophenols. The
gases consisted mainly of carbon dioxide, carbon monoxide, C1–C4
alkanes and alkenes, as well as methyl bromide and hydrogen bromide.
The oils and gases could be used as fuels or chemical material
resources after the proper treatment.
A high-speed universal crusher equipped with cutters using
cutting stresses was effective for liberating the copper present in
vacuum pyrolysis residues of WPCB. The copper liberation degree
of 99.60% was obtained in the fractions of size 0.45mm was about 99% based
on the whole WPCB, while approximately 92% of the non-metallic
components were concentrated in the finer fractions with particle
size