The current worldwide expansion of waste PCB (WPCB) deposits represents both a pressing environmental issue and an economic opportunity, fostering the development of numerous recycling processes across the world. An important input for designing such processes is the metallic content of WPCBs, which is assayed by grinding and leaching samples taken from the stack of WPCBs to be recycled. The content values come with substantial uncertainties, arising mainly from the uneven distribution of the metals within the structure of WPCBs.

This study aims to quantify the effects on these uncertainties of the particle size, the mass of the sample digested and the number of digestion replicates. It focused on the abundance of six metals in WPCBs: Cu, Fe, Zn, Pb and Ni, and also Co, which is a critical element for the EU. A batch of 485 kg of WPCBs was put through several shredding and splitting steps to produce three fractions: one shredded to 2 mm, and two ground to 750 μm and 200 μm. From each sample, 16 samples of 0.5 g, 2 g or 5 g were digested in hot aqua regia. Bootstrapping of the results allowed the error around the mean content to be estimated, for each metal and for all the experimental conditions. Considering the largest sample masses and three replicated digestions, the uncertainties for Zn (resp. Ni) were reduced from 35% to 10% (resp. from 70% to 10%) when the particle size was reduced from 2 mm to 200 μm.

当前废PCB（WPCB）沉积物在全球范围内的扩张既代表着紧迫的环境问题，又代表着经济机遇，促进了全球众多回收工艺的发展。设计此类工艺的重要输入是WPCB的金属含量，可通过研磨和浸提从WPCB堆叠中回收的样品进行分析。含量值具有很大的不确定性，主要是由于WPCB结构中金属的不均匀分布所致。

这项研究旨在量化这些不确定性对颗粒大小，消化样品质量和消化重复次数的影响。它着重研究了WPCB中六种金属的丰富度：Cu，Fe，Zn，Pb和Ni，以及Co，这对欧盟来说是至关重要的元素。一批485千克的WPCB经过几个切碎和分裂步骤，产生了三个部分：一个切成2 mm，两个切成750μm和200μm。从每个样品中，在热王水中消化16个0.5 g，2 g或5 g样品。结果的自举使每种金属和所有实验条件的平均含量误差都得以估算。考虑到最大的样品质量和三个重复的消解，Zn（res.Ni）的不确定度从35％降低到10％（resp。Ni）。