scholarly journals Assessment of sampling and chemical analysis of waste printed circuit boards from WEEE: gold content determination

10.30544/427 ◽  
2019 ◽  
Vol 25 (2) ◽  
pp. 171-182
Author(s):  
Martina Laubertova ◽  
Marcela Malindzakova ◽  
Jarmila Trpcevska ◽  
Natasa Gajic
Keyword(s):  
Chemical Analysis ◽  
Mobile Phones ◽  
Printed Circuit Boards ◽  
Size Fraction ◽  
Heterogeneous Materials ◽  
Sampling Procedure ◽  
Gold Content ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

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.

scholarly journals Selective leaching of copper from waste printed circuit boards (PCBs) using glycine as a complexing agent

2021 ◽  
Keyword(s):  
Printed Circuit Boards ◽  
Size Fraction ◽  
Complexing Agent ◽  
Copper Extraction ◽  
Circuit Boards ◽  
Selective Leaching ◽  
Ambient Conditions ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Copper Leaching

<p>In this research, the selective leaching of copper from waste printed circuit boards (PCBs) using glycine as a complexing agent was investigated. PCBs were pulverized and sieved, which allowed obtaining a PCBs powder of particle size fraction ≤ 1mm. The PCBs powder has been characterized by several techniques before and after leaching. In order to understand the copper extraction process, the reaction mechanisms, and to determine the optimal leaching parameters, the effects of a range of parameters during copper leaching were investigated, including leaching time, solid-to-liquid ratio, mechanical stirring rate, leaching temperature and glycine concentration. Copper leaching from PCBs waste powder was identified as a complex four-stage gas-liquid-solid process that is carried out slowly under ambient conditions. Glycine shows a very significant selectivity for copper during leaching process allowing dissolving copper from PCBs waste with a percentage of 92.8% under ambient conditions.</p>

LEACHING OF METALS FROM WASTE PRINTED CIRCUIT BOARDS (WPCBs) USING SULFURIC AND NITRIC ACIDS

2014 ◽  
Vol 13 (10) ◽  
pp. 2601-2607 ◽  
Author(s):  
Jae-chun Lee ◽  
Manoj Kumar ◽  
Min-Seuk Kim ◽  
Jinki Jeong ◽  
Kyoungkeun Yoo
Keyword(s):  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

scholarly journals Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate

JOM ◽  
2020 ◽  
Author(s):  
Joona Rajahalme ◽  
Siiri Perämäki ◽  
Roshan Budhathoki ◽  
Ari Väisänen
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Printed Circuit Boards ◽  
Sulfuric Acid Concentration ◽  
Recovery Process ◽  
Copper Recovery ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Acid Consumption

AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen peroxide during leaching, while changes in sulfuric acid concentration were minor. During recirculation of the leachate with up to 5 cycles, copper recovery and product purity remained at high levels while acid consumption was reduced by 60%.

scholarly journals Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

2021 ◽  
Vol 9 (5) ◽  
pp. 895
Author(s):  
Carlotta Alias ◽  
Daniela Bulgari ◽  
Fabjola Bilo ◽  
Laura Borgese ◽  
Alessandra Gianoncelli ◽  
...  
Keyword(s):  
Solid State ◽  
Aspergillus Niger ◽  
Food Waste ◽  
Solid State Fermentation ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Metal Extraction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

A low-energy paradigm was adopted for sustainable, affordable, and effective urban waste valorization. Here a new, eco-designed, solid-state fermentation process is presented to obtain some useful bio-products by recycling of different wastes. Urban food waste and scraps from trimmings were used as a substrate for the production of citric acid (CA) by solid state fermentation of Aspergillus niger NRRL 334, with a yield of 20.50 mg of CA per gram of substrate. The acid solution was used to extract metals from waste printed circuit boards (WPCBs), one of the most common electronic waste. The leaching activity of the biological solution is comparable to a commercial CA one. Sn and Fe were the most leached metals (404.09 and 67.99 mg/L, respectively), followed by Ni and Zn (4.55 and 1.92 mg/L) without any pre-treatments as usually performed. Commercial CA extracted Fe more efficiently than the organic one (123.46 vs. 67.99 mg/L); vice versa, biological organic CA recovered Ni better than commercial CA (4.55 vs. 1.54 mg/L). This is the first approach that allows the extraction of metals from WPCBs through CA produced by A. niger directly grown on waste material without any sugar supplement. This “green” process could be an alternative for the recovery of valuable metals such as Fe, Pb, and Ni from electronic waste.

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