A Study of Liberation and Separation Process of Metals from Printed Circuit Boards (PCBs) Scraps

2013 ◽  
Vol 594-595 ◽  
pp. 123-127
Author(s):  
Aimi Noorliyana Hashim ◽  
Kasmuin Mohd Zaheruddin ◽  
Hussin Kamarudin
Keyword(s):  
Rare Earth ◽  
Magnetic Particles ◽  
Printed Circuit Boards ◽  
Ceramic Materials ◽  
Circuit Boards ◽  
Metallic Elements ◽  
Fundamental Study ◽  
Magnetic Separator ◽  
Printed Circuit ◽  
Pre Treatment

Since the metallic elements are covered with or encapsulated by various plastic or ceramic materials on printed circuit boards (PCBs), a pre-treatment process allowing their liberation and separation is first needed in order to facilitate proficient extraction. In this work, a fundamental study has been carried out to recover metallic concentrates from PCBs scraps. The most important step is to separate or release particles from the associated gangue minerals at the possible liberation particle size. The samples of printed circuit boards were separated into the magnetic and non-magnetic fractions by Rare-earth Roll Magnetic Separator. Then, the magnetic and non-magnetic fractions were separated to heavy fraction (metallic elements) and light fraction (plastic) by Mozley Laboratory Table Separator. Results show that the unliberated particles still remain in the comminution fines PCBs. The use of Rare-earth roll magnetic separation was clarified that the Fe, Ni and Zn element tend to be condensed in magnetic particles. Meanwhile Cu element tends to be release in non-magnetic particles. Mozley Laboratory Table Separation was capable to obtain fractions with relatively high concentrations of metallic elements. This study is expected to provide useful data for the efficient physical separation of metallic components from printed circuit boards scraps.

scholarly journals Utilising Commercially Fabricated Printed Circuit Boards as an Electrochemical Biosensing Platform

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 793
Author(s):  
Uroš Zupančič ◽  
Joshua Rainbow ◽  
Pedro Estrela ◽  
Despina Moschou
Keyword(s):  
Printed Circuit Boards ◽  
Electrochemical Sensors ◽  
Cost Effective ◽  
Electrochemical Sensing ◽  
Label Free ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Sensing Applications ◽  
Electrochemical Biosensing ◽  
Pre Treatment

Printed circuit boards (PCBs) offer a promising platform for the development of electronics-assisted biomedical diagnostic sensors and microsystems. The long-standing industrial basis offers distinctive advantages for cost-effective, reproducible, and easily integrated sample-in-answer-out diagnostic microsystems. Nonetheless, the commercial techniques used in the fabrication of PCBs produce various contaminants potentially degrading severely their stability and repeatability in electrochemical sensing applications. Herein, we analyse for the first time such critical technological considerations, allowing the exploitation of commercial PCB platforms as reliable electrochemical sensing platforms. The presented electrochemical and physical characterisation data reveal clear evidence of both organic and inorganic sensing electrode surface contaminants, which can be removed using various pre-cleaning techniques. We demonstrate that, following such pre-treatment rules, PCB-based electrodes can be reliably fabricated for sensitive electrochemical biosensors. Herein, we demonstrate the applicability of the methodology both for labelled protein (procalcitonin) and label-free nucleic acid (E. coli-specific DNA) biomarker quantification, with observed limits of detection (LoD) of 2 pM and 110 pM, respectively. The proposed optimisation of surface pre-treatment is critical in the development of robust and sensitive PCB-based electrochemical sensors for both clinical and environmental diagnostics and monitoring applications.

scholarly journals Effect of Acid Leaching Pre-Treatment on Gold Extraction from Printed Circuit Boards of Spent Mobile Phones

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 362
Author(s):  
Nicolò Maria Ippolito ◽  
Franco Medici ◽  
Loris Pietrelli ◽  
Luigi Piga
Keyword(s):  
Mobile Phones ◽  
Printed Circuit Boards ◽  
Acid Leaching ◽  
Economic Feasibility ◽  
Circuit Boards ◽  
Gold Extraction ◽  
Printed Circuit ◽  
Solid Ratio ◽  
Thiourea Complex ◽  
Pre Treatment

The effect of a preliminary acid leaching for the recovery of gold by thiourea from printed circuit boards (PCBs) of spent mobile phones, was investigated. Preliminary leaching is aimed to recover copper in the leachate that would compete with gold in the successive leaching of the residue with thiourea, thus preventing the formation of the gold-thiourea complex. Two hydrometallurgical routes were tested for the recovery of copper first, and gold after. The first one was based on a two-step leaching that utilizes sulfuric acid and hydrogen peroxide in the preliminary leaching and then thiourea for the recovery of gold in the successive leaching: A copper and gold recovery of 81% and 79% were obtained, respectively. In the second route, nitric acid was used: 100% of copper was recovered in the leachate and 85% of gold in the thiourea successive leaching. The main operative parameters, namely thiourea and ferric sulphate concentrations, leach time, liquid-solid ratio, and temperature were studied according to a factorial plan strategy. A flowsheet of the processes was proposed, and a mass balance of both routes was obtained. Finally, qualitative considerations on the technical and economic feasibility of the different routes were made.

Concentration of rare earth elements during high temperature pyrolysis of waste printed circuit boards

2018 ◽  
Vol 78 ◽  
pp. 602-610 ◽  
Author(s):  
R. Khanna ◽  
G. Ellamparuthy ◽  
R. Cayumil ◽  
S.K. Mishra ◽  
P.S. Mukherjee
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Rare Earth Elements ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

Printed Circuit Boards Recycling: Characterization of Granulometric Fractions from Shredding Process

2010 ◽  
Vol 636-637 ◽  
pp. 1434-1439 ◽  
Author(s):  
Paula C. Oliveira ◽  
Marta Cabral ◽  
Carlos A. Nogueira ◽  
Fernanda Margarido
Keyword(s):  
Printed Circuit Boards ◽  
Precious Metals ◽  
Chemical Characterization ◽  
Average Diameter ◽  
Ceramic Materials ◽  
Size Reduction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Minor Elements

In electronic appliances, printed circuit boards (PCB) represent an important component, containing high grade of valuable metals, besides organic resins and some ceramic materials. Copper is the major metal in PBC’s composition (normally higher than 20% w/w) but many other secondary and minor metal elements, including precious metals, are found in PCB’s. Recycling of PCB´s involves firstly the shredding operation, which is crucial in order to liberate particles from different materials, allowing its further processing by other mechanical, physical and chemical technologies. An efficient shredding operation is difficult to achieve due to the high heterogeneity of these wastes involving materials with different mechanical properties and complex assemblies. This paper presents results from laboratorial studies of shredding of PCB’s and the evaluation of size reduction efficiency as well as the chemical characterization of the obtained shredded fractions. Results showed that an efficient size reduction (characteristic average diameter d50=1.0mm) is obtained using two shredding stages of PCB’s, the first one with a grab shredder and the second one with a cutting mill. Chemical analysis of shredded PCB’s indicated that copper is the principal metal present (28%) followed by Sn, Zn, Pb and Al (3-5%) and many other minor elements. The fine fractions were rich in plastic materials while the metals were essentially present in the intermediate fractions (0.3-1.5 mm). These results can lead to guidelines regarding further design of the physical separation steps in the recycling processes.

scholarly journals Fundamental Study of Parts Detachment Mechanism from Wasted Printed Circuit Boards in Agitation Mill

2012 ◽  
Vol 59 (1) ◽  
pp. 27-32
Author(s):  
Chiharu TOKORO ◽  
Yuki TSUNAZAWA ◽  
Nozomi TSUSAKA ◽  
Kazuki TAHARA ◽  
Shuji OWADA
Keyword(s):  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Fundamental Study ◽  
Printed Circuit

scholarly journals Recovery of Metals from Heat-Treated Printed Circuit Boards via an Enhanced Gravity Concentrator and High-Gradient Magnetic Separator

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4566
Author(s):  
Yushuai Xian ◽  
Youjun Tao ◽  
Fangyuan Ma ◽  
You Zhou
Keyword(s):  
Heat Treatment ◽  
Printed Circuit Boards ◽  
Gravity Separation ◽  
Circuit Boards ◽  
Magnetic Separator ◽  
High Gradient Magnetic Separation ◽  
High Gradient ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Enhanced Gravity Separation

The recovery and reuse of waste printed circuit boards (PCBs) has attracted more and more attention from global researchers, as recycling of waste PCB metals is of great significance to the rational utilization of metal material resources. This study puts forward a clean and economical method in which enhanced gravity separation and wet high-gradient magnetic separation were combined to recover waste PCBs with heat treatment at a temperature of 240 °C. The heat treatment could improve the metal liberation effect of the PCBs, and the thermal behavior was measured by thermogravimetric analysis (TGA). The pyrolysis of the non-metal fraction (NMF) began around 300 °C, and the glass transition temperature of epoxy resin was 135.17 °C. The enhanced gravity separation technique was used for the separation of metals and NMF under the compound force field. The metals grade of the gravity concentrates fraction (GRF) was 82.97% under the optimal conditions, and the metals recovery reached 90.55%. A wet high-gradient magnetic separator was applied to classify the GRF into magnetic (MA) and non-magnetic (NMA) fractions, which could achieve iron and copper enrichment. After the three stages combined process, the copper and iron grades of the NMA and MA fractions were 70.17% and 73.42%, and the recovery reached 74.02% and 78.11%, respectively.

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