A Comparison of Methods for the Characterisation of Waste-Printed Circuit Boards

Metals

Navid R. Moheimani¹  Chris Sheedy²  Aleksandar N. Nikoloski³  Ka Yu Cheng⁴  Anna H. Kaksonen⁴  Naomi J. Boxall⁴  Jonovan Van Yken⁴ 

[1] Algae R & D Centre, Environmental and Conservation Sciences, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia;CSIRO Manufacturing, 36 Gardiner Road, Clayton, VIC 3168, Australia;College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA 6150, Australia;Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water, 147 Underwood Avenue, Floreat, WA 6014, Australia;

关键词: analytical methods;    ashing;    electronic waste;    mixed-metal standard;    acid digestion;    smelting;   

DOI  :  10.3390/met11121935

来源: DOAJ

【 摘 要 】

Electronic waste is a growing waste stream globally. With 54.6 million tons generated in 2019 worldwide and with an estimated value of USD 57 billion, it is often referred to as an urban mine. Printed circuit boards (PCBs) are a major component of electronic waste and are increasingly considered as a secondary resource for value recovery due to their high precious and base metals content. PCBs are highly heterogeneous and can vary significantly in composition depending on the original function. Currently, there are no standard methods for the characterisation of PCBs that could provide information relevant to value recovery operations. In this study, two pre-treatments, smelting and ashing of PCB samples, were investigated to determine the effect on PCB characterisation. In addition, to determine the effect of particle size and element-specific effects on the characterisation of PCBs, samples were processed using four different analytical methods. These included multi-acid digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, nitric acid digestion followed by X-ray fluorescence (XRF) analysis, multi-acid digestion followed by fusion digestion and analysis using ICP-OES, and microwave-assisted multi-acid digestion followed by ICP-OES analysis. In addition, a mixed-metal standard was created to serve as a reference material to determine the accuracy of the various analytical methods. Smelting and ashing were examined as potential pre-treatments before analytical characterisation. Smelting was found to reduce the accuracy of further analysis due to the volatilisation of some metal species at high temperatures. Ashing was found to be a viable pre-treatment. Of the four analytical methods, microwave-assisted multi-acid digestion offered the most precision and accuracy. It was found that the selection of analytical methods can significantly affect the accuracy of the observed metal content of PCBs, highlighting the need for a standardised method and the use of certified reference material.

【 授权许可】

Unknown