Behavior of enrichment and migration path of Cu–Ag–Pd–Bi–Pb in the recovery of waste multilayer ceramic capacitors by eutectic capture of copper

Recycling waste multilayer ceramic capacitors (MLCCs) has attracted much attention owing to its rich metal resource and environment pollution. Existing recycling processes have deficiencies in environmental protection, efficiency and metal purity. Capture technology is promising with advantages of efficient enrichment and less pollution, which was applied to recycle metals in this study. In order to study the mechanism for it, the behavior of enrichment and migration of metals in the recovery of waste MLCCs by eutectic capture of copper was discussed. The recovery rates of Ag, Pd and Bi were 87.53%, 100% and 100%, respectively. Alloy (Cu–Ag–Pd–Bi–Pb) and recyclable slag were obtained. There were three phases of Ag, Cu–Pd and Bi–Pb with the analysis of morphology and composition for the alloy. Then the capture mechanism was revealed. The slag and metal separated due to differences in chemical bonds, surface energy, density and viscosity. The interaction of metals was analyzed through phase diagrams and density functional theory. Pd tended to enter Cu phase. Ag and Cu existed as two phases. Bi and Pb neither entered Ag nor Cu phase based on phase diagrams and formation energy. This study provides a theoretical basis for the application of capture technology in metal enrichment.