Feasibility of pyrometallurgy to recover metals from waste printed circuit boards

Due to environmental concerns, there is a need to develop a proper metal-recycling strategy for waste printed circuit boards (PCBs). The use of modified pyrometallurgy to recover metals from PCBs was discussed in this paper. Results showed that NaOH could be used as the slagformation material to ensure the effective separation of metals from slag and to help decrease the melting temperature of PCBs. Addition of NaOH by 12 wt.% of PCBs could result in more than 99% copper recovery below 1200° C. The remaining slag in the blowing step was found to favor the separation of Cu from other metals and allow noble metals to enter the metal phase to the greatest extent. When all of the slag was retained in the smelting step, 99.04% Ag recovery could be achieved. Additionally, the resulting slag was shown to be very effective in cleaning the pyrolysis gas mainly due to the deoxidization of Cu₂O and the interception of alkali materials. The mass balance calculation demonstrated that 68.4% Cu-, 92.6% Ag - and 85.5% Au - recovery could be achieved in this process. Taken together, the findings confirm preliminarily the feasibility of modified pyrometallurgy in recovering metals from waste PCBs.