The copper in the waste printed circuit boards (WPCBs) is cleanly recycled by physical methods and presented in the form of nano copper particles by hydrometallurgical, which provides environmental approach to the advanced utilization of metal copper. Copper in WPCBs was first pre-concentrated by gradient enrichment process including gravity separation, mechanical grinding and flotation. The leaching method was then used to dissolve copper from the flotation concentrate in ammoniacal/ammonium salt solutions. Subsequently, reduction treatment was conducted to synthesize nano-copper from leaching solution. The enrichment results of the clean physical separation process show that the grade of copper increased from 16.22% to –38.05% by gravity separation, and the grade of copper further increased to 72.62 % by flotation after dissociation, which avoids overgrinding of low value components. Copper nanoparticles can be prepared effectively, and the recovery of copper in the leaching process reaches 99 %. The particle size of copper nanoparticles obtained by ascorbic acid reduction is tens of nanometers, and the surface of copper nanoparticles is smooth and nearly spherical. The present study proposes an environmentally friendly process of preparing nano-copper from the copper in WPCBs.

废印刷电路板（WPCB）中的铜通过物理方法干净地回收，并通过湿法冶金以纳米铜颗粒的形式提供，这为高级利用金属铜提供了环境途径。WPCB中的铜首先通过梯度富集工艺进行了预富集，包括重力分离，机械研磨和浮选。然后使用浸出法将浮选精矿中的铜溶解在氨/铵盐溶液中。随后，进行还原处理以从浸出溶液合成纳米铜。清洁物理分离工艺的富集结果表明，通过重力分离，铜的品位从16.22％增加到–38.05％，通过解离后的浮选，铜的品位进一步提高到72.62％，避免了低价值组件的过度磨削。可以有效地制备铜纳米颗粒，浸出过程中铜的回收率达到99％。通过抗坏血酸还原获得的铜纳米颗粒的粒径为数十纳米，并且铜纳米颗粒的表面光滑且接近球形。本研究提出了一种从WPCB中的铜制备纳米铜的环保方法。