NBK Institute of Mining Engineering, University of British Columbia, Vancouver, BC, Canada.
NBK Institute of Mining Engineering, University of British Columbia, Vancouver, BC, Canada.
Waste Manag. 2018 May;75:94-102. doi: 10.1016/j.wasman.2018.02.010. Epub 2018 Feb 12.
Electronic waste is one the fastest growing waste streams in the world and waste printed circuit boards (PCB) are the most valuable part of this stream due to the presence of gold, silver, copper, and palladium. The metal present in PCBs is mostly recovered for the market value whereas the nonmetal fractions are often ignored. This research explored the characteristics of the non-metal fraction (NMF) obtained after the processing of milled waste PCBs with a focus on responsible end-of-life solutions, in the form of non-hazardous landfilling or incineration. The NMF was characterized using sizing, assaying, loss on ignition, calorific value measurement, and thermogravimetric analysis (TGA). The result showed that the metal content in the NMF increased with decrease in the particle size for most of the metals except antimony and the result from loss on ignition (LOI) also showed that over 50% of the coarser fraction represented organic matter compared to less than 30% for the finest fraction. The study also showed that after the recovery of metals from the waste PCBs, landfill leaching for most of the metal is reduced below the environmental limits, with lead being the only exception. The lead leachate concentration of 18 mg/L was observed, which requires further treatment prior to landfilling. With an energy value of 16 GJ/t, the NMF could provide high energy recovery if incinerated but 194 mg/kg of hazardous flame retardants present in the NMF might be released if the combustion process is not closely monitored.
电子废物是世界上增长最快的废物流之一，而废印刷电路板（PCB）是该废物流中最有价值的部分，因为其中含有金、银、铜和钯。PCB 中存在的金属主要是为了回收其市场价值，而非金属部分通常被忽视。本研究探索了经粉碎的废 PCB 加工后获得的非金属部分（NMF）的特性，重点是负责任的报废解决方案，以无害填埋或焚烧的形式。使用粒度、分析、灼烧损失、热值测量和热重分析（TGA）对 NMF 进行了表征。结果表明，除了锑以外，大多数金属的 NMF 金属含量随粒径减小而增加，而灼烧损失（LOI）的结果还表明，与最细部分相比，粗部分超过 50%的代表有机物，而最细部分不到 30%。该研究还表明，从废 PCB 中回收金属后，大多数金属的填埋浸出量都降低到了环境限值以下，只有铅是个例外。观察到铅浸出液浓度为 18 mg/L，这需要在填埋前进行进一步处理。NMF 的能量值为 16 GJ/t，如果焚烧，可提供高能量回收，但如果燃烧过程没有密切监测，NMF 中存在的 194 mg/kg 危险阻燃剂可能会释放出来。
