Leaching of Copper from Waste-Printed Circuit Boards (PCBs) in Sulfate Medium Using Cupric Ion and Oxygen

In the present paper, the leaching of copper from printed circuit boards (PCBs) using sulfuric acid with Cu2+ and O2 is proposed. The effects of various process parameters such as agitation speed, temperature, the type and the flow rate of gas, initial Cu2+ concentration, and pulp density were investigated to examine the dissolution behavior of Cu from PCBs in 1 mol/L sulfuric acid. The kinetic studies were performed using the obtained leaching data. The leaching rate of Cu from PCBs was found to be higher on addition of Cu2+ and O2 to the leachant in comparison with the addition of O2 or both Cu2+ and N2 in the leachant. The leaching efficiency of Cu was found to be increased with increasing agitation speed, temperature, O2 flow rate, and initial Cu2+ concentration and decreasing pulp density. The 96% of Cu leaching efficiency was obtained under the following conditions: sulfuric acid concentration, 1 mol/L; temperature, 90 °C; agitation speed, 600 rpm; pulp density, 1%; initial Cu2+ concentration, 10,000 mg/L; and O2 flow rate, 1000 cc/min. The leaching data and analyses indicate that the Cu leaching from PCBs followed the reaction-controlled model satisfactorily and determined that the activation energy was found to be 23.8 kJ/mol. Therefore, these results indicate that the sulfuric acid solution with Cu2+ and O2 as a mild leach medium without strong oxidants such as HNO3, H2O2, and Fe3+ is valid for Cu leaching from PCBs.

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

JOM ◽

10.1007/s11837-020-04510-z ◽

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%.

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Metal Leaching Efficiency from Waste Printed Circuit Boards by Inorganic Acid

The Journal of Solid Waste Technology and Management ◽

10.5276/jswtm/2019.355 ◽

2019 ◽

Vol 45 (3) ◽

pp. 355-362

Author(s):

Zhenfeng Xiong ◽

Ying Huang ◽

Kemei Zhou ◽

Dong Zhang ◽

Juan Bao ◽

...

Keyword(s):

Nitric Acid ◽

Printed Circuit Boards ◽

Base Metals ◽

Circuit Boards ◽

Aqua Regia ◽

Printed Circuit ◽

Waste Printed Circuit Boards ◽

Inorganic Acids ◽

Mass Fractions ◽

Leaching Efficiency

Waste printed circuit boards (WPCBs) from personal computers were ground and subjected to a two-step leaching process using two inorganic acids (nitric acid and aqua regia) to leach metals. Three kinds of samples were used: the whole WPCB, the golden finger part, and the WPCB excluding the golden finger. Leaching efficiencies of metals from these samples for different nitric acid concentrations (followed by aqua regia) were evaluated to identify the best concentration of nitric acid. The extracted Au concentration from the golden finger was 5.5 times of that from the whole WPCB board. Metals that compete with Au, such as Ni and Fe, have lower mass fractions in the whole WPCB board compared to those in the golden finger. However, Cu comprises a higher proportion in the golden finger. Au can be effectively separated from most other metals by initially leaching the ground WPCB with 5M nitric acid, followed by leaching with aqua regia. Considering the high leaching proportion of Au, it is advantageous to leach Au and base metals separately from the golden finger and from WPCB excluding the golden finger.

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Pressure leaching of metals from waste printed circuit boards using sulfuric acid

JOM ◽

10.1007/s11837-011-0133-z ◽

2011 ◽

Vol 63 (8) ◽

pp. 29-32 ◽

Cited By ~ 23

Author(s):

Manis K. Jha ◽

Jae-chun Lee ◽

Archana Kumari ◽

Pankaj K. Choubey ◽

Vinay Kumar ◽

...

Keyword(s):

Sulfuric Acid ◽

Printed Circuit Boards ◽

Pressure Leaching ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards

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A System Level Thermal Analysis of Large Telecommunication Racks

Heat Transfer, Volume 1 ◽

10.1115/imece2003-42416 ◽

2003 ◽

Author(s):

L. T. Yeh

Keyword(s):

Thermal Analysis ◽

Flow Rate ◽

Printed Circuit Boards ◽

System Level ◽

Circuit Boards ◽

Air Flow Rate ◽

Printed Circuit ◽

Computational Fluid Dynamics Cfd ◽

Cfd Method ◽

Level Analysis

A system level thermal analysis is performed by employing the computational fluid dynamics (CFD) method on a large telecommunication rack. Each rack consists of two identical shelves located on the top-to-bottom orientation. Each shelf includes one fan tray with 6 fans, 3 card cages with a total of 50 printed circuit boards (PCBs). Air enters from the front of the shelf, and then makes a 90-degree turn upwards through PCBs, and finally turns another 90-degree to exit the system from the back of the shelf. The system level analysis is performed independently on each shelf. The main purpose of the analysis is to determine the air flow rate to individual printed circuit boards as well as the air temperature distribution in the system. The computed flow rate for individual PCBs is then used for a detailed board analysis to predict the component temperatures of individual boards.

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Recovery of Ag, Au, and Pt from Printed Circuit Boards by Pressure Leaching

Recycling ◽

10.3390/recycling6040067 ◽

2021 ◽

Vol 6 (4) ◽

pp. 67

Author(s):

Guadalupe Martinez-Ballesteros ◽

Jesus Leobardo Valenzuela-García ◽

Agustin Gómez-Alvarez ◽

Martin Antonio Encinas-Romero ◽

Flerida Adriana Mejía-Zamudio ◽

...

Keyword(s):

Sulfuric Acid ◽

Renewable Resources ◽

Printed Circuit Boards ◽

Precious Metals ◽

Pressure Leaching ◽

Circuit Boards ◽

Green Method ◽

Printed Circuit ◽

Second Stage ◽

Metals Extraction

Reclamation of printed circuit boards (PCBs) to recover metals is gaining growing attention due to minerals being non-renewable resources. Currently, metals extraction from PCBs through an efficient and green method is still under investigation. The present investigation concerns the recycling of printed circuit boards using hydrometallurgical processes. First, the basic metals (Cu, Ni, Zn and Fe) were separated using a sulfuric acid solution at moderate temperatures. The remaining solids were characterized by SEM-EDS, whereby a high content of precious metals (Au, Ag and Pt) was observed. In the second stage, solids were leached with a solution of HCl and NaClO in a 1-L titanium reactor with varied oxygen pressure (0.2, 0.34 and 0.55 MPa), temperature (40, 50 and 80 °C) and concentration of HCl (2 and 4 M), obtaining extractions above 95% at [HCl] = 4 M, P = 0.34 MPa and T = 40 °C. The extraction increased depending on the concentration of HCl. Eh–pH diagrams for Ag–Cl–H2O, Au–Cl–H2O and Pt–Cl–H2O were constructed to know the possible species in the solution.

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Simulation and economic analysis of a hydrometallurgical approach developed for the treatment of waste printed circuit boards (WPCB)

Global NEST Journal ◽

10.30955/gnj.002545 ◽

2018 ◽

Vol 20 (4) ◽

pp. 695-699

Keyword(s):

Sulfuric Acid ◽

Printed Circuit Boards ◽

Material Balance ◽

Precious Metals ◽

Industrial Plant ◽

Circuit Boards ◽

Metal Powders ◽

Printed Circuit ◽

Leaching Process ◽

Waste Printed Circuit Boards

<p>This paper presents the main achievements of a hydrometallurgical process to recover base and precious metals from waste printed circuit boards (WPCB). The technology comprises a first leaching process performed in a two-step counter current way with sulfuric acid and hydrogen peroxide for base metals solubilization and a consecutive cross leaching process with thiourea, ferric sulfate and sulfuric acid to extract precious metals. Furthermore, the reach solutions are subjected to cementation procedure with zinc powder to recover the elements of interests as metal powders. The spent solution achieved after cementation of precious metals is partially recycled within the process and the other part is treated by Fenton process and then neutralized with lime. Considering the achieved results at the laboratory level, the entire procedure was simulated using SuperPro Designer software to determine the process economy for an industrial plant. Besides this, the use of this software allows achieving the material balance of a process and the design of the plant. As a result, the process implementation at a larger scale is simulated and the main issues that can result in such a case can be determined and solved.</p>

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High-Pressure Oxidative Leaching and Iodide Leaching Followed by Selective Precipitation for Recovery of Base and Precious Metals from Waste Printed Circuit Boards Ash

Metals ◽

10.3390/met9030363 ◽

2019 ◽

Vol 9 (3) ◽

pp. 363

Author(s):

Altansukh Batnasan ◽

Kazutoshi Haga ◽

Hsin-Hsiung Huang ◽

Atsushi Shibayama

Keyword(s):

High Pressure ◽

Sulfuric Acid ◽

Printed Circuit Boards ◽

Pure Gold ◽

Circuit Boards ◽

Gold Extraction ◽

Selective Precipitation ◽

Printed Circuit ◽

Waste Printed Circuit Boards ◽

Oxidative Leaching

: This paper deals with the recovery of gold from waste printed circuit boards (WPCBs) ash by high-pressure oxidative leaching (HPOL) pre-treatment and iodide leaching followed by reduction precipitation. Base metals present in WPCB ash were removed via HPOL using a diluted sulfuric acid solution at elevated temperatures. Effects of potassium iodide concentration, hydrogen peroxide concentration, sulfuric acid concentration, leaching temperature, and leaching time on gold extraction from pure gold chips with KI–H2O2–H2SO4 were investigated. The applicability of the optimized iodide leaching process for the extraction of gold from the leach residue obtained after HPOL were examined at different pulp densities ranging from 50 g/t to 200 g/t. Results show that the removal efficiency was 99% for Cu, 95.7% for Zn, 91% for Ni, 87.3% for Al, 82% for Co, and 70% for Fe under defined conditions. Under the optimal conditions, the percentage of gold extraction from the gold chips and the residue of WPCBs was 99% and 95%, respectively. About 99% of the gold was selectively precipitated from the pregnant leach solution by sequential precipitation with sodium hydroxide and L-ascorbic acid. Finally, more than 93% of gold recovery was achieved from WPCB ash by overall combined processes.

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