Efficient bromine removal and metal recovery from waste printed circuit boards smelting flue dust by a two-stage leaching process

Debromination with Bromine Recovery from Pyrolysis of Waste Printed Circuit Boards Offers Economic and Environmental Benefits

“…Generally, bromides are fixed in the liquid phase when the reaction medium is liquid, where they migrate directly from the solid phase reactants into the liquid phase. , The hydrothermal method is an effective way to remove bromine from circuit boards by effectively destroying the physical structure of the board and the organic bromine polymer and releasing the monomer . The debromination efficiency increases with increasing temperature, and most of the bromine is retained in the water .…”

Eco-friendly and low-cost removal of bromine from waste printed circuit board smelting ash by mechano-chemical leaching

“…However, H 2 SO 4 roasting is typically performed at a high temperature (315 °C), producing harmful SO 2 /HBr/Br 2 flue gases. Lyu et al 27 developed a two-stage leaching method to remove Br from WPCB-SA. However, only 88.65% of the total CuBr and PbCl 0.6 Br 1.4 could be removed with 20 wt% alkali addition and a prolonged leaching time of 120 min.…”

“…As a pyro-metallurgical technology, collaborative smelting is widely used in the large-scale treatment of WPCBs because of its short process flow, high recovery yield of valuable metals, versatility, and economic benefits. 23 However, WPCBs contain high contents of flammable resins and plastics, and their combustion produces significant amounts of flue gases such as HBr and Br 2 , [24][25][26] which can further react with heavy metals to form bromides, such as CuBr/CuBr 2 , 25 PbBr 2 /PbCl x Br 2−x , 25,27 and ZnBr 2 . 27 These inorganic bromides together with some low saturated evaporation pressure substances finally form WPCB smelting ash (WPCB-SA), accounting for 21.4 wt% of the total Br content in WCPBs.…”

“…23 However, WPCBs contain high contents of flammable resins and plastics, and their combustion produces significant amounts of flue gases such as HBr and Br 2 , [24][25][26] which can further react with heavy metals to form bromides, such as CuBr/CuBr 2 , 25 PbBr 2 /PbCl x Br 2−x , 25,27 and ZnBr 2 . 27 These inorganic bromides together with some low saturated evaporation pressure substances finally form WPCB smelting ash (WPCB-SA), accounting for 21.4 wt% of the total Br content in WCPBs. 28 The toxic inorganic bromides in WPCB-SA are difficult to remove, and severely contaminate the environment.…”

“…However, to the best of our knowledge, studies on the removal of bromides from WPCB-SA have rarely been reported, and the strategies are limited to H 2 SO 4 roasting and alkali leaching. 25,27,29,30 Wu et al 25 developed a H 2 SO 4 roasting technology wherein 98% of CuBr and PbBr 2 in WPCB-SA were removed using a 20-30% NaOH solution. However, H 2 SO 4 roasting is typically performed at a high temperature (315 °C), producing harmful SO 2 /HBr/Br 2 flue gases.…”