Recycling copper (Cu⁰) from waste printed circuit boards (PCBs) is a prevalent challenge. Here, we propose a new pathway and reveal mechanisms for recovering Cu⁰ from waste PCBs via a mechanochemical approach. The successful application of mechanical force avoids using inorganic acid in the Cu⁰ recovery process. Our work demonstrates that ferric chloride (FeCl₃) was superior to ferric sulfate and ferric nitrate as a solid-phase reagent for Cu⁰ recovery due to chloride complexation. Under the induction of mechanical force, the Cu⁰ in the waste PCBs was oxidized by Fe³⁺ and complexed by Cl^¯ to form a meta-stable cuprous chloride, which was susceptible to leaching in an acidic liquid-phase system constructed by hydrolysis of ferric salt. Further mechanism analysis reveals that in the mechanochemical solid-phase reaction, Cu⁰, metallic impurities, metal oxides, and carbon materials from waste PCBs could also reduce Fe³⁺ to Fe²⁺. The optimum conditions for Cu⁰ recovery from waste PCB powder with FeCl₃ as a solid-phase reagent were: rotational speed of 500 rpm, Cu⁰:Fe³⁺ molar ratio of 1:20, and reaction time of 120 min, achieving the highest recovery of 99.6 wt%. This study presents a facile path for Cu⁰ recovery from waste PCBs for resource circulation.

从废旧印刷电路板 (PCB) 中回收铜 (Cu ⁰ ) 是一项普遍的挑战。在这里，我们提出了一种新的途径，并揭示了通过机械化学方法从废 PCB中回收 Cu ^{0的机制。}机械力的成功应用避免了在Cu ⁰回收过程中使用无机酸。我们的工作表明，由于氯化物络合，氯化铁 (FeCl _{3 ) 作为用于回收 Cu} ⁰的固相试剂优于硫酸铁和硝酸铁。在机械力的诱导下，废PCB中的Cu ^{0被Fe 3+}氧化并被Cl^络合形成亚稳定的氯化亚铜，在由铁盐水解构建的酸性液相系统中易浸出。进一步的机理分析表明，在机械化学固相反应中，废PCB中的Cu ⁰、金属杂质、金属氧化物和碳材料也可以将Fe ³⁺还原为Fe ²⁺。_{以FeCl 3}为固相试剂从废PCB粉末中回收Cu ⁰的最佳条件为：转速为500 rpm，Cu ⁰：Fe ³⁺摩尔比为1：20，反应时间为120 min。最高回收率为 99.6 wt%。本研究为 Cu ⁰从废多氯联苯中回收用于资源循环。