Grantee Research Project Results
2017 Progress Report: Recovering Rare Earth Permanent Magnets for Reuse
EPA Grant Number: SU836785Title: Recovering Rare Earth Permanent Magnets for Reuse
Investigators: Zhao, Fu
Current Investigators: Zhao, Fu , Powers, Susan E. , Helmrich, Alysha M , Simon, Timothy , Zhu, Yongxian , Cong, Liang , Guza, Mark , Suo, Sinuo , Stahl, James , Pattison, Benjamin , Nguyen, Thanh , Feng, Yuan
Institution: Purdue University
EPA Project Officer: Page, Angela
Phase: I
Project Period: October 1, 2016 through September 30, 2017 (Extended to September 30, 2018)
Project Period Covered by this Report: October 1, 2016 through September 30,2017
Project Amount: $14,992
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Chemical Safety
Objective:
Rare earth permanent magnets (REPMs), due to their high magnetic flux density, are essential components in many electrical and electronic products, including clean energy applications such as wind turbine and hybrid electric vehicles (HEVs). Currently over 90% of the world’s rare earth elements (REEs) supply are produced in China. Citing environmental damage, in 2011 the Chinese government implemented an export quota on REEs, which led to significant price volatility. Due to REEs’ importance in high-tech applications and their supply risk, many governments have classified REEs as “critical materials”. As recommended in the DOE’s Critical Materials Strategy report, recycling is one of the approaches to address the risks associated with the supply of REEs. Unfortunately, to date, the recycling rate of REPMs has been very low and no industrial scale process has been established in the United States to recover REPMs from end of life products and reuse them in new products. As a result, REEs end up either in landfill or in smelting slag while other more “common” metals are recycled.
One explanation for why REPMs have not been retrieved from used products is that it can be time consuming and expensive if the labor cost is high. This project aims to develop an industrial scale technology for profitably recovering and reusing REPMs to maximize REEs resource efficiency. In this project, focus will be placed on recovering REPMs from motors and hard disk drives, and on exploring options of reprocessing recovered REPMs for reuse or as new bonded magnets. The application of the technology can avoid energy intensive REEs production and the associated environmental impact. During this project, we will continue our efforts to develop education materials related to a circular economy to promote sustainability on the Purdue campus. We will further our outreach efforts to communities, e.g., K-12 schools, colleges, residents, and businesses across Indiana.
Progress Summary:
In the case of motors (especially motors used in EVs and HEVs), the challenge of retrieving REPMs from the rotor comes from the strong magnetic force between the REPMs and the steel laminates, which makes it extremely time consuming to recover REPMs. To speed up the process, demagnetization is needed before REPMs recovery. This can be done via heat treatment and AC current treatment. Preliminary experiments suggest that heat treatment at mild temperature can significantly weaken the magnetic force and make the recovery of REPMs very easy. Since many e-waste recyclers are small to medium size enterprises, heat treatment might be the preferred option given its low cost and simple operation. In addition, a semi-automatic tool that can be used to extract copper windings from the stator with minimal efforts and short time duration is desired. In summary, some preliminary work has been done on dismantling motors to recover REPMs. However, our main efforts to date have been largely on recovering REPMs from HDDs. We will continue work on motors in Summer 2017.
In the case of HDDs, the REPMs and other potentially valuable components e.g., motor and storage media are “buried” deeply in the structure. Several approaches to expose these components are explored. Destructive methods were tested first, including cutting/punching/impacting. It was found that these methods are not ideal due to concerns on part damage, high cost of equipment, and worker safety. In addition, these methods could complicate further processing and sorting.
The approach selected to pursue and prototype is a non-destructive one which uses rotary tool to remove the screws securing the top cover of the HDDs. The prototype developed is a multi-head drill press, which can remove all the screws simultaneously to expose the internal components of the hard drive. Rather than building everything from scratch, an old 3D printer was taken apart and the frame and drives were used. The design is semi-automated with the drill head moving laterally and the base plate moving axially. Movement would be based on the size of the drive placed on the plate as well as the distance between screws being drilled out. For the prototype, a computer which runs MATLAB is used to control all the electronic components. A barcode scanner and an Arduino UNO with grblShield are connected to the computer. Information about hard drive model and screw layout are retrieved from a database based on barcode reading. After all the screws are removed, the top cover can be easily detached from the casing to expose the internal components, which can also be recovered easily. All these operations are done manually.
The prototype can be built using readily available tools and materials with low cost, i.e., less than $1000. It enables fully disassembling a typical HDD within two minutes. However, it should be noted that only several HDDs from a major manufacturer were tested. In addition, some manual adjustments were needed to achieve perfect alignment of the drill heads and the screws. In addition, the prototype can only handle two crews at the same time, which slows down the process significantly. Another thing that should be pointed out is that there are a large amount of “white label” HDDs being used. These HDDs are used drives that have been refurbished by the manufacturer or a third party and do not carry the same warranty. For these white label HDDs a barcode scanner will not work. All these issues will need to be addressed in Phase II. Nonetheless, communications with a couple local e-waste recyclers suggest that the approach has great potential and the recyclers welcome the opportunity to test Phase II prototype at their facilities.
For the recovered REPMs, the team will explore the opportunities for the possibility of direct reuse in other products, especially for REPMs recovered from motors given the fact that they are not coated and have regular geometry. However, the team recognizes that direct reuse of REPMs recovered from HDDs may not be possible as manufacturers may have serious concerns on the quality and reliability of the recovered magnets. To make it worse, REPMs recovered from HDDs have irregular shape and the design may change over different generations of the HDDs. In Phase I, efforts were made to reuse the REPMs from HDDs for other applications especially gadgets and toys. Using a commercially available stripper (a combination of benzenesulfonic acid 3- nitro-sodium salt and carbonic acid disodium salt) the nickel coating of the magnets can be removed in less than one hour. After heating the magnets to 325 C for one hour, the magnets can be pulverized to size of 50-200 microns. The powder can be sent to magnets manufacturers or used to make bonded magnets.
Using the tools developed the team was able to limit the total disassembling time to less than 2 minutes, the breakeven time suggested by e-waste recyclers. All the tools can be readily built using low-cost tools and materials available on the market. The disassembling time can be shortened further after optimization. Therefore, the Phase I project was successful overall since the key objective was achieved. Enabling cost effective recycling of HDDs in the United States will contribute to all three pillars of sustainability, e.g., people, prosperity, and the planet. Diverting used REPMS from the landfill and incinerator increases resource efficiency and minimizes toxic releases, while creating job opportunities in the United States. In addition, profitable recycling of HDDs in the United States eliminates the export to developing countries. This improves environmental quality in these countries, thus enhances environmental justice. This also reduces health risks to workers and communities that used to be exposed to toxic chemicals from e-waste handling, thereby contributing to improving the quality of life.
Journal Articles:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
Waste to value, electronic waste recycling, resource recovery, industrial ecology, life cycle analysis, cost benefit analysis, rare earth elements.Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.