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

Yujin Park,Yuik Eom,Kyoungkeun Yoo,Manis Kumar Jha

doi:10.3390/met11091369

Yujin Park, Yuik Eom + Show 2 more

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https://doi.org/10.3390/met11091369

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Abstract

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.

Highlights

Printed circuit boards (PCBs) are core parts of electric and electronic equipment (EEE) [1,2,3,4,5]
Bacterial leaching processes of PCBs have been reported as environment-benign processes, where Phanerochaete chrysosporium [22], Acidithiobacillus ferrooxidans [23], Leptospirillum ferriphilum or its mixed culture with Acidithiobacillus ferrooxidans [24,25,26], and Frankia sp. [27] were used for cuprous ion (Cu) leaching
In the present study, the leaching tests of PCBs were performed in sulfuric acid solution with Cu2+ and O2 to investigate the effects of agitation speed, temperature, the type and the flow rate of gas, initial Cu2+ concentration, and pulp density for Cu leaching from PCBs in 1 mol/L sulfuric acid solution and, further, activation energy was calculated based on the leaching data and kinetic study

Summary

Introduction

Printed circuit boards (PCBs) are core parts of electric and electronic equipment (EEE) [1,2,3,4,5]. Conventional oxidants have disadvantages such as NOx gas emission due to HNO3 leaching [33,34,35,36], increase in reagent consumption due to instability of H2 O2 [37,38], and requirement of additional separation process due to the use of Fe3+ [38,39,40]. These drawbacks could increase the capital and environmental costs as mentioned above. In the present study, the leaching tests of PCBs were performed in sulfuric acid solution with Cu2+ and O2 to investigate the effects of agitation speed, temperature, the type and the flow rate of gas, initial Cu2+ concentration, and pulp density for Cu leaching from PCBs in 1 mol/L sulfuric acid solution and, further, activation energy was calculated based on the leaching data and kinetic study

Materials and Methods

Effects temperature leaching behaviors sulfuric acid solution at

Effects of pulp density onon thethe leaching behaviors of of

Plot of 1acid

Findings

Conclusions