Directional concentration of bromine from nonmetallic particles of crushed waste printed circuit boards by vacuum-gasification- condensation

摘要

Nonmetallic particles of crushed waste printed circuit boards usually contain 8.0-12.3 wt% of brominated flame retardants, which are harmful to humans and environment. Some articles proposed the method of pyrolysis to treat nonmetallic particles, but the pyrolysis products were still hazardous wastes. In this study, a novel process of vacuum-gasification-condensation was proposed to directionally concentrate bromine from the nonmetallic particles. Organic components of nonmetallic particles were completely gasified at the temperature of 700 degrees C and then cooled at 200 degrees C and 50 degrees C. Oils, floc, gases and residue were obtained and the bromine were concentrated in different products. Residue contained 0.19 wt % bromine and was no longer hazardous waste. Meanwhile, another breakthrough was that bromine migrated directionally to floc (36.15% of total bromine) and gases (4637% of total bromine), which would be beneficial for the reduction of hazardous wastes. Additionally, we forecasted the future work about the treatment of the nonmetallic particles. To maximize the reuse of the nonmetallic particle, the key is to keep the bonds of other macromolecular organics stable and break C-Br bond only. This paper contributed a novel technology to collect bromine from the brominated wastes. (C) 2019 Elsevier Ltd. All rights reserved.