Highlights
- Recycling e-waste could be a sustainable alternative to limited natural rare earth element resources, with potential economic and environmental benefits.
- The study examines various techniques for REE recovery from e-waste, including pyrometallurgy and hydrometallurgy, discussing their pros and cons.
- Developing efficient REE recycling methods is crucial for achieving a circular economy and addressing national security concerns in countries like the United States.
Researchers affiliated with Monash University (Department of Chemical and Biological Engineering) and RMIT University’s School of Engineering, both in Australia and Wuhan, China-based Huazhong University of Science and Technology (HUST), School of Environmental Science and Engineering raise fundamental questions about the prospects of recycling and supplies of rare earth elements, plus offering potential disruptive pathways toward new more sustainable sources. This review highlights the potential of recycling e-waste, including outlining the current unutilized potential of REE recycling from different e-waste components. Based on the Rare Earth Exchanges view on the unfolding rare earth materials supply chain ecosystem, this topic of REE recycling breakthroughs becomes of paramount importance for the West, especially the United States given the trajectory of China and its 2049 imperative.
The authors, represented by corresponding author Sankar Bhattacharya at Monash University point out in this piece published in the peer-reviewed journal Science of the Total Environment (opens in a new tab) that recycling e-waste is in fact considered a possible sustainable alternative to compensate for the limited natural rare earth elements (opens in a new tab) (REEs) resources and the difficulty of accessing these resources. Of course all of this falls under the context of Chinese dominance, especially over the processing parts of the value chain.
USA and West MUST move to innovative recycling of rare earth materials—disrupt markets
Source: Science of the Total Environment
Facilitating the recovery of valuable products while potentially minimizing emissions during their transportation, why wouldn’t this approach be more embraced?
For example, the authors in this important paper point to numerous studies offering some levels of evidence on the benefits of e-waste recycling via several techniques, including thermo-, hydro- and biometallurgical approaches.
But challenges ensue with each approach. The authors introduce the technical, economic, social, or environmental limitations with each method.
The Upside
Offering an in-depth analysis of e-waste generation on a global scale plus an Australian scenario, along with various hazardous impacts on ecosystem and human health, the authors also provide a comprehensive summary of various metal recovery processes, the pros, and the cons with selected approaches.
Conducting a “lifecycle analysis (opens in a new tab)” associated with the recovery of REEs derived from e-waste point to, according to the paper’s authors, “a positive environmental impact when compared to REEs produced from virgin sources.”
What are the sources? Electronic devices can be counted as a secondary resource for REEs in view of their concentrations. Of course, REEs are vital and critical contributors to electronic devices’ performance.
Source: Science of the Total Environment
In addition, recovering REEs form secondary sources eliminated ca. 1.5 times radioactive waste (opens in a new tab), as seen in production from primary sources scenario.
“The review outcome demonstrates the increasing potential of REE recycling to overcome critical challenges, including issues over supply security and localized dependency.” Rare Earth Exchanges has raised the imminent importance of the West, led by the USA, to innovate in this area, the type of innovation causing disruptive forces across the markets.
The Sources: In Fig. 2. (a) Global e-waste generation from 2014, projected till 2030, (b) amount of e-waste generated and per capita by region in 2019.
Source: Science of the Total Environment
The authors break down the hazards of recycling, including a section on the hazardous content in e-waste and their impacts.
Source: Science of the Total Environment
On to recover, how will a fully disruptive recycling industry grow and prosper? First, we need to understand what’s possible and that’s the authors goal in this next section of the paper.
Source: Science of the Total Environment
Thereafter the authors delve into each one of these methods, the feasibility, pros and cons, costs, and the lie. We provide an example of Pyrometallurgy below:
Source: Science of the Total Environment
Also, the authors investigate Hydrometallurgy.
Source: Science of the Total Environment
What are some Gaps and Recommendations?
First and foremost, the authors raise important questions guiding future disruptive innovation in this field.
What is the primary challenge in the recovery of REEs from e-waste?
The application of existing processes, which are designed for the recovery of base and precious metals, for the recovery of REEs.
What research pathways are critical to include a robust e-waste REE program?
Investigations into integrating REEs recovery with the recovery of base and precious metals, vital for the commercial-scale application.
What are some important themes for better understanding based on this review?
Bhattacharya and colleagues report that the need to “understand the techno-economic and environmental viability of previously validated lab-scale processes at a large scale” remain front and central.
What are some examples of the viabilities, and limitations?
While the “pyrometallurgical approach is beneficial in recovering some metals, it cannot recover the REEs lost in slag” for example.
Plus “pyrometallurgical processes, despite being straightforward, emit toxic gases during the thermal degradation (opens in a new tab) of organic compounds.”
Also, this is a costly process due to the high energy demand and corrosion problems. While pyrometallurgical processes offer excellent recovery rates for feedstock (opens in a new tab) with high REE concentrations its likely not the right choice for low-grade e-waste. Harmful emissions may be a real problem.
Concluding on the pyro-processing routes the authors declare this pathway “cannot be considered as effective stand-alone recovery pathways.”
What about hydrometallurgy?
While representative of a promising approach for the recovery of REEs from e-waste, several challenges However, several issues are to be addressed on upstream (leachate) and downstream (solvent extraction) stages of operation report the Australia and China-based authors.
What other challenges?
The authors note “the unavailability of stringent norms for recycling e-waste, which are not in consistency with time or are not properly enforced.”
While “recycling REEs from secondary sources can help avoid 1.5 times radioactive waste (opens in a new tab) per ton of REEs. However, current REE recovery processes are difficult and costly.”
They offer the reader an example: “neodymium rubidium (opens in a new tab) iron boron products often contain a metal layer coated on the surface to avoid oxidation (opens in a new tab), therefore, making the extraction of neodymium a difficult and costly task.”
The potential combining of pyrometallurgy, and hydrometallurgy may lead to value-added disruption, but this is not a mature concept yet.
Targeted research targeting such questions would certainly lead to the development of minimal chemical and energy intensive ideas in the future.
Summary
Not only is the development of appropriate scientific techniques for e-waste is essential to achieve what the authors refer to as a circular economy (opens in a new tab) to help protect both human health and the ecosystem, but also Rare Earth Exchanges suggests represents a pathway of research that is a matter of national security interest for countries like the United States.
Reviewing the most widely used technologies– pyrometallurgy and hydrometallurgy used to recover REEs from e-waste—the authors educate that the “hydrometallurgy approach is generally highlighted as an efficientand mature technology.” Yet environmental issues linked tothe by-products of this approach must be addressed. Positive impacts can be had via the use of organic acids for example. Yet their efficiency remains debatable. Also, effective strategies, to enhance the leaching efficiency of inorganic acids to a level comparable to organic acids, need to be developed.
Conducting a lifecycle analysis the authors report “contradicting results for recovering REEs from secondary sources.”
Importantly there may need to be some environmental impacts but breakthroughs in the recycling of secondary sources can “levy the burden on primary sources.”
Professor Sankar Bhattacharya (opens in a new tab) heads the Monash University Department of Chemical and Biological Engineering.
Daniel
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