Li Jia, Lu Hongzhou, Guo Jie, Xu Zhenming, Zhou Yaohe
School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
Environ Sci Technol. 2007 Mar 15;41(6):1995-2000. doi: 10.1021/es0618245.
The printed circuit board (PCB) contains nearly 28% metals that are abundant non-ferrous metals such as Cu, Al, Sn, etc. The purity of precious metals in PCBs is more than 10 times higher than that of rich-content minerals. Therefore, recycling of PCBs is an important subject not only from the treatment of waste but also from the recovery of valuable materials. Chemical and mechanical methods are two traditional recycling processes for waste PCBs. However, the prospect of chemical methods will be limited since the emission of toxic liquid or gas brings secondary pollution to the environment during the process. Mechanical processes, such as shape separation, jigging, density-based separation, and electrostatic separation have been widely utilized in the recycling industry. But, recycling of waste PCBs is only beginning. In this study, a total of 400 kg of waste PCBs was processed by a recycle technology without negative impact to the environment. The technology contained mechanical two-step crushing, corona electrostatic separating, and recovery. The results indicated that (i) two-step crushing was an effect process to strip metals from base plates completely; (ii) the size of particles between 0.6 and 1.2 mm was suitable for corona electrostatic separating during industrial application; and (iii) the nonmetal of waste PCBs attained 80% weight of a kind of nonmetallic plate that expanded the applying prospect of waste nonmetallic materials.
印刷电路板（PCB）含有近28%的金属，这些金属是丰富的有色金属，如铜、铝、锡等。印刷电路板中贵金属的纯度比富矿中的纯度高出10倍以上。因此，印刷电路板的回收不仅是废物处理的重要课题，也是回收有价值材料的重要课题。化学法和机械法是两种传统的废印刷电路板回收工艺。然而，化学法的前景将受到限制，因为在该过程中有毒液体或气体的排放会给环境带来二次污染。机械工艺，如形状分离、跳汰、密度分离和静电分离，已在回收行业中广泛应用。但是，废印刷电路板的回收才刚刚起步。在本研究中，采用一种对环境无负面影响的回收技术处理了总共400千克的废印刷电路板。该技术包括机械两步破碎、电晕静电分离和回收。结果表明：（i）两步破碎是将金属从基板上完全剥离的有效过程；（ii）在工业应用中，粒径在0.6至1.2毫米之间的颗粒适合电晕静电分离；（iii）废印刷电路板的非金属部分达到了一种非金属板材重量的80%，拓宽了废非金属材料的应用前景。
