scholarly journals Gold recovery from waste printed circuit boards of mobile phones by using microwave pyrolysis and hydrometallurgical methods

2022 ◽  
Vol 32 (1) ◽  
Author(s):  
Yu-Fong Huang ◽  
Szu-Ling Chou ◽  
Shang-Lien Lo
Keyword(s):  
Hydrogen Peroxide ◽  
Solvent Extraction ◽  
Printed Circuit Boards ◽  
Gold Recovery ◽  
Circuit Boards ◽  
Microwave Pyrolysis ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Waste Pcbs ◽  
Oxidative Precipitation

AbstractRecycling of waste printed circuit boards (PCBs) has attracted increasing attention because of its high annually produced amount and high content of gold. In this study, gold recovery from waste PCBs was carried out by using the processes including microwave pyrolysis, acid leaching, solvent extraction and oxidative precipitation. The leaching efficiency of copper was approximately 95% when using a lixiviant composed of sulfuric acid and hydrogen peroxide, and the leaching efficiencies of gold were approximately 59, 95 and 95% by using thiourea, thiosulfate and aqua regia, respectively. The gold ions contained in the leachate previously produced by the leaching processes were not satisfactorily extracted by using organic solvents including di-(2-ethylhexyl)phosphoric acid, tributyl phosphate, dibutyl carbitol and trioctylamine, so the leachate was decided to bypass solvent extraction and directly apply to the oxidative precipitation process. By using the oxidants of hydrogen peroxide and perchloric acid, the precipitation efficiencies of gold were approximately 95 and 99%, and the final recovery rates were approximately 90 and 93%, respectively. The high recovery rates of gold can be attributable to the use of microwave pyrolysis that prevents the loss of gold caused by shredding and grinding processes. In addition, perchloric acid can provide higher selectivity for gold recovery than hydrogen peroxide. The maximum processing capacity of microwave pyrolysis of waste PCBs would be approximately 1.23 kg. The gold recovered from 1 t of waste PCBs can be sold for approximately USD 10,000, and thus the return on investment can be as high as approximately 1400%.

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%.

A Novel Flowsheet for the Recycling of Valuable Constituents from Waste Printed Circuit Boards

2011 ◽  
pp. 296-306
Author(s):  
Jingfeng He ◽  
Yaqun He ◽  
Nianxin Zhou ◽  
Chenlong Duan ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Separation Efficiency ◽  
Precious Metals ◽  
Metal Recovery ◽  
Recovery Ratio ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Waste Pcbs ◽  
Impact Crushing

Waste printed circuit boards (PCBs) contain a number of valuable constituents. It is of great significance to separate precious metals and non-metallic constituents from waste PCBs with appropriate methods for resource recycling and environment protection. A novel flowsheet for the recycling of waste PCBs using physical beneficiation methods was constructed. Waste PCBs were disassembled into substrates and slots firstly. The substrates were crushed to the size below 1mm through wet impact crushing and separated with a tapered column separation bed. The results indicated that products with integrated separation efficiency of 93.9% and metal recovery ratio of 93.7% were obtained by the primary separation with the water discharge of 5.5 m3/h, feed-rate of 250g/min and inclination angle of 35°. Waste PCBs slots components were crushed to the size of 0.5-5mm through impact crushing and separated with an active pulsing air classifier. The separation results showed that products with integration separation efficiency of 92.4% and metal recovery ratio of 96.2% were obtained with the airflow velocity of 2.90m/s and pulsing frequency of 2.33Hz. Precious metals could be obtained by further separation and purification of the metal components and the non-metal components could be used as refuse derived fuel. The flowsheet has great potential to be applied in the field of waste PCBs treatment and recycling.

Progress in the Preparation of Composites Based on the Nonmetallic Fractions Recycled from Waste Printed Circuit Boards

2010 ◽  
Vol 160-162 ◽  
pp. 518-523 ◽  
Author(s):  
Wei Qiao Liu ◽  
Xing Xing Wang ◽  
Wei Ning Lei ◽  
Tong Ming Shang ◽  
Quan Fa Zhou
Keyword(s):  
Renewable Resources ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Research Directions ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Inorganic Composites ◽  
Metals Recovery ◽  
Waste Pcbs ◽  
Properties Of Composites

From the use of renewable resources and environmental protection, recycling of waste printed circuit boards (PCBs) receives wide concerns as the amounts of scrap PCBs increases dramatically. However, the recycle technology for waste PCBs in China is still immature. Previous studies focused on metals recovery, but resource utilization for nonmetallic fractions (NMFs) is relatively fewer. In this paper, the physical properties of the recovered nonmetallic powder is briefly introduced. The preparation of composites including organic and inorganic composites through the recycling NMFs was reviewed. In addition, the research directions of preparation of composites based on recycling NMFs were put forward. Firstly, the study on the reaction mechanism of composites preparation should be strengthened to explore the reasons why the additional quantity and particle size of NMFs powder have effects on the properties of composites. Secondly, a suitable coupling agent should be chosen to improve the the interface compatibility between the NMFs and matrix.

Recycling Of the Epoxy Resin of the Waste Printed Circuit Boards Using Solvent Extraction

2011 ◽  
Vol 383-390 ◽  
pp. 3140-3144 ◽  
Author(s):  
Lin Zhuan Ma ◽  
Hua Wang ◽  
Shan Qing ◽  
Lin Zhuan Ma
Keyword(s):  
Solvent Extraction ◽  
Epoxy Resin ◽  
Flame Retardants ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
The Public ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Land Filling

Currently, the number of the waste printed circuit boards (WPCB) is increasing. The technologies of extracting and reclaiming of the value of the metallic fraction of WPCB have been used widely because of the major economic driving force. But the non-metallic fractions (NMFs), which take up almost 70wt% of waste WPCB, were mainly treated by combustion or land filling in the past. However, combustion of the NMFs will cause the formation of highly toxic polybrominated dibenzodioxins and dibenxofurans (PBDD/Fs). Land filling of the NMFs will lead to secondly pollution that caused by heavy meatals and brominated flame retardants (BFRs) leaching to the groundwater. Therefore, recycling of the NMFs from waste PCBs is drawing more and more attention from the public and the governments. How to recycle the NMFs environmental soundly has become a significant topic in recycling of WPCB. This paper briefly introduced that the damage of WPCB and the recycling methods of epoxy resin. The method was established for recycling of WPCB by using solvent extraction. And the optimal conditions were attained through experiments: the reaction temperature was 80°C、the reaction time was 3h、the concentration of nitrate acid was 8 mol/l, the amount of nitrate acid : the quality of WPCB was 50ml/10g.

Recycling gold and copper from waste printed circuit boards using chlorination process

RSC Advances ◽  
2015 ◽  
Vol 5 (12) ◽  
pp. 8957-8964 ◽  
Author(s):  
Yuchen He ◽  
Zhenming Xu
Keyword(s):  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Selective Recovery ◽  
Printed Circuit ◽  
Efficient Process ◽  
Chlorination Process ◽  
Waste Printed Circuit Boards ◽  
Waste Pcbs ◽  
Pretreatment Processes

This study provides a less-polluted and more efficient process for selective recovery of gold and copper from waste PCBs through pretreatment processes.

Recovery of Copper from Bio-Leaching Solutions of Waste Printed Circuit Boards Waste by Solvent Extraction Using RE609 and N902

2010 ◽  
Vol 113-116 ◽  
pp. 2228-2231 ◽  
Author(s):  
Cheng Long Zhang ◽  
Wang Dong Fang ◽  
Yu Chen ◽  
Jing Wei Wang ◽  
Jian Feng Bai
Keyword(s):  
Solvent Extraction ◽  
Printed Circuit Boards ◽  
Ph Value ◽  
Copper Extraction ◽  
Equilibration Time ◽  
Circuit Boards ◽  
Extractant Concentration ◽  
H2so4 Concentration ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

According to the properties of bioleaching solutions of printed circuit boards (PCBs), copper(Ⅱ) in the leaching solution were recovery by solvent extraction with N902 and RE609. The influence of equilibration time，extractant concentration，O/A ratios，pH value on copper(Ⅱ) extraction and sulphuric acid concentration on copper(Ⅱ) stripping had been studied. Extraction of copper increased with increasing extractant concentration with both the extractants. More than 97.45% of copper can be extracted from a typical bioleaching solution of PCBs after copper extraction was carried out using 10% N902 diluted in kerosene at O/A ratio of 1:1, while 97.14% of copper can be extracted using 20% RE609 diluted in kerosene at O/A ratio of 1:1. The stripping of copper loaded N902 and RE609 increased with increasing H2SO4 concentration, but stripping of the latter was lower than the former.More than 93.57% and 90.29%of copper can be stripped from the loaded N902 and RE609 stripped at 1:1 phase ratio with 1.8 M H2SO4 in a single stage.

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