Overview of PCB recycling and recovery

Electronic waste is a growing problem, with recycling and resource recovery challenges in electronic components, especially printed circuit boards, making it difficult to manage waste at the end of a component’s life cycle. . In order to provide a comprehensive critical review of printed circuit board recycling and recovery strategies, an article has been published in Resources, conservation and recycling.

To study: A comprehensive review of recycling discarded PCBs for resource recovery. Image Credit: Jirik V / Shutterstock.com

The scale of electronic and electronic equipment waste

The scale of electronic and electronic equipment waste is staggering. Globally, 53.6 million tonnes were generated in 2019, with projections placing it at 74.7 million tonnes by 2030, with Asia producing 50% of this waste, followed by America and Europe. In India, the third national producer of electronic waste, only 1 to 2% of recycled and collected electronic waste is documented, with no separation between it and municipal waste. This leads the majority to be illegally discarded or burned.

The increase in electronic waste around the world is due to technological advancements and needs. The rapid miniaturization, shortened lifecycles, value and affordability of upgraded devices all contribute to the problem.

Landfilling is the most common method of disposing of electronic parts, resulting in environmental damage from toxic and bio-accumulative pollution. Common pollutants in electronic waste include persistent organic pollutants such as polychlorinated biphenyls, polybrominated biphenyls, and heavy metals.

The economic importance of recycling electronic waste

Electronic components contain several economically important materials. These include base metals such as zinc, lead, copper and nickel, special metals such as selenium and indium, rare earth elements such as yttrium and lanthanum, as well as precious metals such as gold and silver.

The economic importance of recycling and recovery is considerable. It is estimated that extracting these resources costs 7 times the cost of recovering printed circuit boards for the same amount of recovered resources. A ton of discarded cell phones without batteries produces significantly higher levels of important metals such as gold, nickel, lead and copper than natural ores. Estimates show that recovering gold from mobile phones can meet 10% of the total global demand for this precious metal.

Recycling of PCB waste

Printed circuit boards represent a higher percentage of electronic waste than their weight (4.7% of the mass of all waste, compared to 0.01-1% by weight) and the content of precious metals accounts for 90% of the intrinsic value of printed circuit boards. Printed circuit boards are classified into low, medium and high grades based on their gold content.

Recycling printed circuit boards reduces carbon emissions and prevents the extraction of dwindling resources, while being less damaging to the environment than traditional mining methods. Therefore, the recycling of these electronic components and the reuse of the metals they contain is of crucial importance for the sustainability of the electronics industry.

How can we solve the massive problem of electronic waste?

Video credit: CNBC / Youtube.com

Current methods of recycling printed circuit board waste include pyrometallurgical, hydrometallurgical, physical and combined techniques. Currently, pyrometallurgical processes are favored on a commercial scale. Pretreatments are used to improve the efficiency of extraction methods and recent attention has been paid to new methods of pretreatment and hybrid-thermal-chemical pathway combination to improve extraction and recovery processes.

Recently, the selective recovery of high purity contents from a multi-element leach solution has been investigated for their potential as a recycling and recovery process. These processes include ion exchange, adsorption, precipitation and solvent extraction.

Review of PCB Recycling and Resource Recovery

According to the review published in Resources, conservation and recycling, tthere have been many studies that have selectively focused on specific extraction and recovery processes, but to date there has not been a comprehensive field review. Moreover, few of them have focused on a holistic recycling process, and no studies have described the recycling of electronic components from printed circuit boards and the generation of value-added end products.

The review attempted to delineate the sequential treatment pathways as well as the dissolution and purification methods used in the recycling of electronic waste. In addition, commercial recycling processes, recent advancements and unconventional recycling methods have been studied and discussed, along with appropriate post-treatment processes. In addition, a comprehensive review of recycling methods for different components of printed circuit boards such as integrated circuits was presented.

In addition, the production of value-added end products from printed circuit boards was discussed. Finally, a schematic diagram for the recovery of printed circuit and component resources has been proposed by the research team. Therefore, a comprehensive and comprehensive critical review has been presented which provides an important knowledge base for the electronics industry.

The future

As the demand for electronics increases globally, recovering electronic components from waste to produce economically important resources and reduce carbon emissions is a priority for the electronics industry. The review in Resources, conservation and recycling will undoubtedly help inform future recycling and reuse strategies.

Using Acid Leaching to Recover Metals from PCB Waste

Reference

Mir, S & Dhawan, N (2021) A comprehensive review of recycling discarded PCBs for resource recovery [online] Resources, conservation and recycling 178A | sciencedirect.com. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0921344921006352

Disclaimer: The views expressed herein are those of the author, expressed in a private capacity and do not necessarily represent the views of AZoM.com Limited T / A AZoNetwork, the owner and operator of this website. This disclaimer is part of the terms and conditions of use of this website.


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