Schulze, Rita (2018)
Reducing environmental impacts of the global rare earth production for use in Nd-Fe-B magnets - How much can recycling contribute?
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication
Abstract
Rare earth elements (REE) are classified as critical metals because of their technological importance and geo-political supply risks. They are used in a range of applications, including magnets, phosphors, battery electrodes, catalysts and polishing powders. Many of these applications are important in green technologies. Permanent magnets constitute the most important REE application in terms of market size, specifically with neodymium, praseodymium, dysprosium and terbium used in Nd-Fe-B magnets, and the demand for these magnets is increasing. To mitigate supply risks, efforts are underway to develop recycling technologies to retrieve REE from Nd-Fe-B material. Whilst the recycling of industrial Nd-Fe-B scrap is already practiced, recycling of rare earths from end-of-life products is still largely limited to laboratory and pilot projects. The question to be addressed in this dissertation is: How does the recycling of Nd-Fe-B magnet material reduce the environmental impact of the global REE production for use in Nd-Fe-B magnets? In the global production system, the extent to which environmental impacts can be reduced through the recycling of Nd-Fe-B magnet material depends on the following aspects: • the possible extent of the recycling activities, i.e. the question of how much REE material can be supplied from secondary magnet material sources • the choice of technologies applied in primary and secondary REE production • market mechanisms, which determine whether and to what extent the output of primary rare earth element production is reduced as a consequence of the recycling activities. To answer these questions, material flow analysis (MFA) and life cycle assessment (LCA) studies were utilized. The MFA study was conducted to quantify material (Nd-Fe-B) and associated substance (i.e. REE) flows for years 2020 to 2030. This was undertaken to identify the potential future size of secondary REE flows from these materials. Since recycling of REE from Nd-Fe-B magnets is at its early beginnings today, a future outlook was required. The potential role of secondary REE production from Nd-Fe-B material was compared with the expected overall size of future flows in the global Nd-Fe-B production system. The findings from the MFA study were used to model a future production system in which some of the REE demand is met through secondary production from scrap Nd-Fe-B magnets. Market effects on the jointly produced REE in the primary production system were analysed. The environmental effects of changing from the current REE production system based on primary mining to a potential future system in which some of the primary production is replaced by secondary production were analysed in a consequential life cycle assessment study (C-LCA study) – a form of LCA which focuses on changes in environmental impacts, rather than their absolute quantification. The study provides an example of how effects on an unbalanced REE market can be addressed in LCA studies. The MFA study showed that the amount of industrial Nd-Fe-B scrap available for recycling is likely to exceed achievable potentials of secondary Nd-Fe-B extractable from end-of-life (EOL) devices in years 2020–30 (by mass of Nd-Fe-B). Around 20 percent of global demand of Nd/Pr and of 22–23 percent of Dy/Tb for Nd-Fe-B production can be met from secondary sources from EOL magnets and industrial Nd-Fe-B scrap in years 2020–30. From a recycling perspective, the most promising Nd-Fe-B application groups were shown to change over the time period considered, posing a challenge to recyclers who have to handle the changing mix. To aid the C-LCA study, a life cycle inventory for in-situ leaching of REE from ion-adsorption deposits was compiled as this was not previously available in the public literature, or in publicly available data-bases. Results from the C-LCA study show that recycling of REE from Nd-Fe-B magnets would be beneficial from an environmental perspective due to the lower environmental impacts associated with the secondary recycling process compared to primary production, but also due to the possibility to avoid overproduction for joint productions in the primary production system. The avoided impact from primary production far exceeds the impact from the recycling activity for all analysed impact categories. In addition, the REE production from ion-adsorption clay deposits constitutes one of the most important REE production routes, and the most important production route for heavy rare earths such as dysprosium and terbium. Therefore, the dataset provides an important addition to the REE production datasets currently available. Furthermore, an additional life cycle assessment study was conducted to assess the potential envi-ronmental impacts of a one-step recycling process developed by researchers in the EREAN project. In contrast to the C-LCA study, the focus of this LCA study was on the process-specific impacts associated with the technology as a function of different process parameters. Results from the analysis of the recycling process developed in EREAN show that the material recovery rate is crucial to the overall impact of the recycling process. Furthermore, the preparation of the magnet material required before the electrolysis also contributes to the overall impact. The comparison of this recycling route with primary production shows that the recycling process has the potential for much lower process-specific impacts than the current REE primary production process. To conclude, the secondary production of REE from Nd-Fe-B magnets could help reduce the environ-mental impacts associated with rare earth production. The potential environmental benefits of recycling are currently still limited by the amount of scrap becoming available each year, however, this is expected to increase in the near future. Whether rare earth production from secondary sources actually takes off will depend on the development of rare earth prices, on whether Nd-Fe-B recycling will be politically incentivized, and on geopolitical factors. In Europe, it is likely that political incentives will be necessary to kick-start recycling operations (ERECON. 2015). Further research regarding the magnitude of perfluorocarbons emissions during rare earth electrolysis, which are potent greenhouse gases, and on ionizing radiation associated with rare earth processing, which has been associated with adverse human – and environmental health effects, is recommended. Furthermore, an improvement of the environmental impact assessment methods available for life cycle assessments of REE, especially with regards to ionizing radiation and resource use, would be desirable.
Item Type: | Ph.D. Thesis | ||||
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Erschienen: | 2018 | ||||
Creators: | Schulze, Rita | ||||
Type of entry: | Primary publication | ||||
Title: | Reducing environmental impacts of the global rare earth production for use in Nd-Fe-B magnets - How much can recycling contribute? | ||||
Language: | English | ||||
Referees: | Schebek, Prof. Dr. Liselotte ; Elwert, Prof. Dr. Tobias | ||||
Date: | 2018 | ||||
Place of Publication: | Darmstadt | ||||
Refereed: | 18 April 2018 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/8301 | ||||
Abstract: | Rare earth elements (REE) are classified as critical metals because of their technological importance and geo-political supply risks. They are used in a range of applications, including magnets, phosphors, battery electrodes, catalysts and polishing powders. Many of these applications are important in green technologies. Permanent magnets constitute the most important REE application in terms of market size, specifically with neodymium, praseodymium, dysprosium and terbium used in Nd-Fe-B magnets, and the demand for these magnets is increasing. To mitigate supply risks, efforts are underway to develop recycling technologies to retrieve REE from Nd-Fe-B material. Whilst the recycling of industrial Nd-Fe-B scrap is already practiced, recycling of rare earths from end-of-life products is still largely limited to laboratory and pilot projects. The question to be addressed in this dissertation is: How does the recycling of Nd-Fe-B magnet material reduce the environmental impact of the global REE production for use in Nd-Fe-B magnets? In the global production system, the extent to which environmental impacts can be reduced through the recycling of Nd-Fe-B magnet material depends on the following aspects: • the possible extent of the recycling activities, i.e. the question of how much REE material can be supplied from secondary magnet material sources • the choice of technologies applied in primary and secondary REE production • market mechanisms, which determine whether and to what extent the output of primary rare earth element production is reduced as a consequence of the recycling activities. To answer these questions, material flow analysis (MFA) and life cycle assessment (LCA) studies were utilized. The MFA study was conducted to quantify material (Nd-Fe-B) and associated substance (i.e. REE) flows for years 2020 to 2030. This was undertaken to identify the potential future size of secondary REE flows from these materials. Since recycling of REE from Nd-Fe-B magnets is at its early beginnings today, a future outlook was required. The potential role of secondary REE production from Nd-Fe-B material was compared with the expected overall size of future flows in the global Nd-Fe-B production system. The findings from the MFA study were used to model a future production system in which some of the REE demand is met through secondary production from scrap Nd-Fe-B magnets. Market effects on the jointly produced REE in the primary production system were analysed. The environmental effects of changing from the current REE production system based on primary mining to a potential future system in which some of the primary production is replaced by secondary production were analysed in a consequential life cycle assessment study (C-LCA study) – a form of LCA which focuses on changes in environmental impacts, rather than their absolute quantification. The study provides an example of how effects on an unbalanced REE market can be addressed in LCA studies. The MFA study showed that the amount of industrial Nd-Fe-B scrap available for recycling is likely to exceed achievable potentials of secondary Nd-Fe-B extractable from end-of-life (EOL) devices in years 2020–30 (by mass of Nd-Fe-B). Around 20 percent of global demand of Nd/Pr and of 22–23 percent of Dy/Tb for Nd-Fe-B production can be met from secondary sources from EOL magnets and industrial Nd-Fe-B scrap in years 2020–30. From a recycling perspective, the most promising Nd-Fe-B application groups were shown to change over the time period considered, posing a challenge to recyclers who have to handle the changing mix. To aid the C-LCA study, a life cycle inventory for in-situ leaching of REE from ion-adsorption deposits was compiled as this was not previously available in the public literature, or in publicly available data-bases. Results from the C-LCA study show that recycling of REE from Nd-Fe-B magnets would be beneficial from an environmental perspective due to the lower environmental impacts associated with the secondary recycling process compared to primary production, but also due to the possibility to avoid overproduction for joint productions in the primary production system. The avoided impact from primary production far exceeds the impact from the recycling activity for all analysed impact categories. In addition, the REE production from ion-adsorption clay deposits constitutes one of the most important REE production routes, and the most important production route for heavy rare earths such as dysprosium and terbium. Therefore, the dataset provides an important addition to the REE production datasets currently available. Furthermore, an additional life cycle assessment study was conducted to assess the potential envi-ronmental impacts of a one-step recycling process developed by researchers in the EREAN project. In contrast to the C-LCA study, the focus of this LCA study was on the process-specific impacts associated with the technology as a function of different process parameters. Results from the analysis of the recycling process developed in EREAN show that the material recovery rate is crucial to the overall impact of the recycling process. Furthermore, the preparation of the magnet material required before the electrolysis also contributes to the overall impact. The comparison of this recycling route with primary production shows that the recycling process has the potential for much lower process-specific impacts than the current REE primary production process. To conclude, the secondary production of REE from Nd-Fe-B magnets could help reduce the environ-mental impacts associated with rare earth production. The potential environmental benefits of recycling are currently still limited by the amount of scrap becoming available each year, however, this is expected to increase in the near future. Whether rare earth production from secondary sources actually takes off will depend on the development of rare earth prices, on whether Nd-Fe-B recycling will be politically incentivized, and on geopolitical factors. In Europe, it is likely that political incentives will be necessary to kick-start recycling operations (ERECON. 2015). Further research regarding the magnitude of perfluorocarbons emissions during rare earth electrolysis, which are potent greenhouse gases, and on ionizing radiation associated with rare earth processing, which has been associated with adverse human – and environmental health effects, is recommended. Furthermore, an improvement of the environmental impact assessment methods available for life cycle assessments of REE, especially with regards to ionizing radiation and resource use, would be desirable. |
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URN: | urn:nbn:de:tuda-tuprints-83018 | ||||
Classification DDC: | 300 Social sciences > 330 Economics 500 Science and mathematics > 500 Science 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering |
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Divisions: | 13 Department of Civil and Environmental Engineering Sciences 13 Department of Civil and Environmental Engineering Sciences > Institute IWAR 13 Department of Civil and Environmental Engineering Sciences > Institute IWAR > Material Flow Management and Resource Economy |
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Date Deposited: | 23 Dec 2018 20:55 | ||||
Last Modified: | 23 Dec 2018 20:55 | ||||
PPN: | |||||
Referees: | Schebek, Prof. Dr. Liselotte ; Elwert, Prof. Dr. Tobias | ||||
Refereed / Verteidigung / mdl. Prüfung: | 18 April 2018 | ||||
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