Abstract
Waste printed circuit boards (WPCBs) from discarded mobile phones and smartphones are considerably heterogeneous materials with a high gold content (approx. 490 grams per ton). The aim of our chemical analysis of samples of WPCBs was to determine the amounts of gold using open acid digestion and atomic absorption spectrometry (HR CS AAS). The test samples designated for chemical analysis must genuinely represent the bulk WPCBs from which they are taken. This study aimed to develop a correct sampling procedure to analyze the heterogeneous materials from printed circuit boards; explicitly concerning the influence of particle size on the precision of chemical analysis of WPCBs from discarded mobile phones. Chemical analysis of the representative sample of WPCBs with a grain size fraction of d ≤ 200 μm determined that the gold content was 475 g∙t-1 with a low variation coefficient and low dispersion which indicates very high accuracy of the designed sampling procedure.
Highlights
According to the literature [1], waste material from mobile phones as part of electronic waste (WEEE) is classified as hazardous waste, and should, be managed following the specific legislation
The results of the chemical analysis to determine the Au content in the four grain-size fraction samples of Waste printed circuit boards (WPCBs) are shown in Table
The statistically-evaluated results of the analysis revealed that the granularity of the representative sample had the most significant impact on the accuracy of the sampling procedure in order to determine Au content in waste printed circuit boards
Summary
According to the literature [1], waste material from mobile phones as part of electronic waste (WEEE) is classified as hazardous waste, and should, be managed following the specific legislation In recycling, elements such as copper and aluminum are recovered, as well as the precious metals gold, silver, platinum, and palladium, which can be recouped profitably from electronic waste. Sampling and assaying are necessary in order to determine the composition and content of precious metals in the flow of e-waste and to ensure that the optimum process is used to recover precious metals. All electronic scrap is sampled before entering the processing line This sampling procedure is essential because the metal amounts determined in the analyzed waste material become the basis for the payment received by the supplier. An e-scrap shredder crushes the waste printed circuit boards which are delivered intact, and the material passes through the stream sampler and is delivered to a storage facility where it is mixed before smelting [8]
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