Steam gasification assisted pyrolysis directional de bromination of waste printed circuit boards and comprehensive utilization of products

Abstract

Due to the large amount of brominated flame retardants contained in waste printed circuit boards, their incineration treatment has caused great harm to the environment. Conventional heat pyrolysis is used to treat used circuit boards, resulting in more contaminating waste due to the production of brominated gases and dioxins. In this paper, the steam atmosphere heating method is used to pyrolyze the crushed waste circuit board under optimized conditions (700 °C, 20 °C/min, 60 min, 2 mL/min). Pyrolysis residues, pyrolytic oils and pyrolysis gases were obtained, and the mass ratios were 65.47 wt%, 27.32 wt% and 7.21 wt% respectively. The bromine content in the residue is reduced to 0.005 wt%, and the content of metallic copper is 28.69 wt%, which can be used as a raw material for the collaborative smelting of copper. About 94 wt% of the bromine in the raw material is transferred to water, which can be effectively recovered as a raw material. These results result in a reduction in hazardous pollutants. Compared with conventional heating pyrolysis, steam atmosphere heating not only reduces energy consumption, but also reduces the production of brominated products and toxic substances, and promotes the subsequent utilization of pyrolysis products. This paper reports on the heating pyrolysis of steam atmospheres on waste printed circuit boards, and this study provides a new method for removing bromine from the pyrolysis process.