Article

Assessment of environmental impact of rare earth metals recycling from used magnets

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Abstract

Large amount of rare earth metals is stored in the used electric products. Hitachi has started to develop the environment-friendly process for rare earth metals recovery from used magnets. We report here the environmental impact of our process, in comparison with the conventional recycle process utilizing solvent extraction. As an evaluation method, Life-cycle Impact assessment Method based on Endpoint modeling ver. 2 (LIME2) developed by the National Institute of Advanced Industrial Science and Technology (AIST) in Japan is applied. It was found that the environmental impact of the new process was more than that of the conventional process. For further reduction of its environmental impact, minimization of energy consumption to operate the equipment was most effective. Decreasing the amount of magnesium, used as an extractant, and the improvement of the extraction rate of rare earth metals were also considered as specific options for reducing energy consumption in the plant development.

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... The authors reported that the recycling of Nd from computer HDDs, particularly manually, was preferable to primary production. Akahori et al. (2014) reported that the pyrometallurgical processes have a higher environmental impact than hydrometallurgical processes because of an increase in material losses and energy demand. Schulze et al. (2018) conducted an ex-ante LCA study of REE recovery from NdFeB magnet scrap based on a molten fluoride electrolysis bath process. ...
... Overall, this analysis does point to the potential benefits and reduced environmental burdens of the use of recovered Nd in Nd-Fe-B magnet production. These results are consistent with the findings of the study of Akahori et al. (2014), who conducted an environmental assessment for the recycling of REE from used magnets. The authors also reported that pyrometallurgical processes had a higher environmental impact than those of the hydrometallurgical processes because of an increase in material losses and energy demand. ...
... Such limitations are inherent and ultimately unavoidable to the ex-ante nature of this LCA study. On the other hand, it is a fundamental step to develop an industrial scale process for recovery of REEs to decrease the related environmental impact related complementing natural ore production (Akahori et al., 2014). As the scaling up process of the hydrometallurgical route for the recycling of Nd is associated with a high level of uncertainty, sensitivity analyses were conducted for Nd-Fe-B magnet production using recovered Nd. ...
Article
Rare earth elements (REEs) are commercially used in an increasing number of critical or widely popular consumer and industrial products. Neodymium (Nd) element has emerged in recent years as one of the most critical REE, due to risks associated with its security of supply at required amounts. It has been widely reported that end of life (EoL) consumer electrical products contain significant amounts of metals and plastics. Thus, recovery of Nd from magnet scraps, EoL appliances or industrial applications is gaining even more strategic importance nowadays. In this study, an ex-ante life cycle assessment (LCA) of the hydrometallurgical recovery of Nd from waste electric and electronic equipment (WEEE) was conducted. The hydrometallurgical Nd recovery route consists of pretreatment, chemical leaching and Nd metal precipitation The feasibility and environmental performance of Nd metal recycling experiment model was investigated with an LCA scenario focusing on neodymium-iron-boron (Nd-Fe-B) magnet production. The LCA results were compared to that due to Nd-Fe-B magnet production from bastnäsite/monazite mineral ores using the traditional sintered magnet route. LCA sensitivity analysis and cost analysis were also performed. It was found out that, from both an economical and environmental point of view, magnet production from recovered Nd performed better than that of virgin magnet production. The scaled-up Nd metal recovery system reduced environmental impacts of Nd-Fe-B magnet production system by up to 65% for eight of the eleven environmental impact categories. Nd recycling reduced production cost from 8.55 to 3.98 USD/kg.
... Given the uncertainties in price, quality, quantity, and dependability of the materials, the research is increasing for REE recycling and this percentage will certainly rise. Companies such as Toyota, Honda, Hitachi, and Mitsubishi have announced REE recycling initiatives targeting as much as 10% of their REE consumption via recycled materials (Akahori et al., 2014; Golev et al., 2014 ). Further, there have been attempts to look at the recycling and remanufacturing of products incorporating REEs (Dent, 2012; Nagai and Uzawa, 2014; Tan et al., 2014). ...
... Recycling would further complicate the REE life cycle. The methods and processes for recycling would have to be evaluated, and a couple of LCA studies have been conducted on different routes of recovering Nd and Dy from magnets (Akahori et al., 2014; Sprecher et al., 2014). ...
Article
Full-text available
Rare earth elements (REEs) are a group of seventeen elements with similar chemical properties, including fifteen in the lanthanide group, yttrium, and scandium. Due to their unique physical and chemical properties REEs gain increasing importance in many new energy technologies and systems that contribute to reduce greenhouse gas emissions and fossil fuel depletion (e.g., wind turbine, electric vehicles, high efficiency lighting, batteries, and hydrogen storage). However, it is well known that production of REEs is far from environmentally sustainable as it requires significant material and energy consumption while generating large amounts of air/water emissions and solid waste. Although life cycle assessment (LCA) has been accepted as the most comprehensive approach to quantify the environmental sustainability of a product or process, to date, there have been only very limited LCA studies on the production of REEs. With the continual growth of renewable energy and energy efficient technologies, global production of REEs will increase. Therefore reducing environmental footprints of REE production becomes critical and identifying environmental hotspots based on a holistic and comprehensive assessment on environmental impacts serves as an important starting point. After providing an overview of LCA methodology and a high-level description of the major REE production routes used from 1990s to today, this paper reviews the published LCA studies on the production of REEs. To date, almost all the LCA studies are based on process information collected from the operation of Mountain Pass facility in U.S. in 1990s and the operation of facilities in Bayan Obo, China. Knowledge gaps are identified and future research efforts are suggested to advance understanding on environmental impacts of REE production from the life cycle perspective.
... [8,10] Some sources even introduce MREEs (medium rare earth elements), incorporating Samarium, Europium and Gadolinium. [13][14][15][16][17] According to the findings of Herrmann et al. 2016, Lanthanides can be detected in nearly all biota, usually following the Oddo-Harkins rule. [18][19][20] Although they were thought to be inert to biological life, several studies since have found that REEs influence the enzymatic activity of certain proteins and can even make up the active site of some enzymes like alcohol dehydrogenases. ...
Conference Paper
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The ERDF funded Interreg project REEgain focuses on developing new eco-friendly methods to recycle and recover REEs from Waste from Electric and Electronic Equipment (WEEEs) with the help of microorganisms. The project partners aim to develop a practicable recycling technology in collaboration with regional industry, making the technology available to businesses. The preliminary results indicate that bio-accumulation is dependent on the incubation time of the cells as well as the atomic weight of the elements in question, showing a direct influence on separation. The overall retrieval rate was determined to be 83.5% for this experiment. Further research needs to be directed, to distinguishing the correlations between separation, pH, growth, and atomic parameters.
... These processes consume chemical acids and solvents and generate hazardous waste. 8−13 Akahori et al. (2014) 14 performed LCA on NdFeB magnet recycling, but their system boundary was confined to REE extraction. Sprecher et al. (2014) 15 performed an LCA for NdFeB magnet recycling, but their work was based on a "hypothetical" lab scale recycling process. ...
Article
Neodymium-iron-boron (NdFeB) magnets offer the strongest magnetic field per unit volume, and thus, are widely used in clean energy applications such as electric vehicle motors. However, rare earth elements (REEs), which are the key materials for creating NdFeB magnets, have been subject to significant supply uncertainty in the past decade. NdFeB magnet-to-magnet recycling has recently emerged as a promising strategy to mitigate this supply risk. This paper assesses the environmental footprint of NdFeB magnet-to-magnet recycling by directly measuring the environmental inputs and outputs from relevant industries and compares the results with production from ‘virgin’ materials, using life cycle assessments. It was found that magnet-to-magnet recycling lowers environmental impacts by 64-96%, depending on the specific impact categories under investigation. With magnet-to-magnet recycling, key processes that contribute 77-95% of the total impacts were identified to be 1) hydrogen mixing & milling (13-52%), 2) sintering & annealing (6-24%), and 3) electroplating (6-75%). The inputs from industrial sphere that play key roles in creating these impacts were electricity (24-93% of the total impact) and nickel (5-75%) for coating. Therefore, alternative energy sources such as wind and hydroelectric power are suggested to further reduce the overall environmental footprint of NdFeB magnet-to-magnet recycling.
... Production knowledge is limited outside of China, and the production cost is often lower in China than other countries, which represents a barrier to new competitors entering the market [12]. The environmental consequences of REE production are significant: greenhouse gas emissions, water contamination, and resource depletion [13,14]. When REEs are extracted, by-products such as thorium or uranium are often produced. ...
Article
Rare earth permanent magnets (REPMs) play an essential role in various applications such as renewable energy production, and aerospace and defense related products. Rare earth elements (REEs) such as neodymium and dysprosium are used in REPMs, and the supply of these REEs has experienced volatility. To mitigate this risk, REEs may be recovered from end-of-life (EOL) products such as computer hard disk drives (HDDs). To facilitate REE/REPM recycling, this paper develops an operation and inventory management strategy to explore the profitability 1) under uncertain market supply and 2) with varying component/material values whose demand also faces significant uncertainties. The resulting strategy provides recommendations for the ordering and processing quantities associated with REPM containing products. An upper bound solution on the recovery profit was proposed to assess the performance of the developed strategy. We found that the proposed strategy helps increase the overall profit, and its performance is close to the upper bound. Finally, several scenarios were evaluated to examine how market conditions affect profit. To the best of authors’ knowledge, this research is the first study on REPM recycling that provides a promising strategy to the relevant industry.
... Akahori et al. [7] investigated the environmental impacts of recycling REEs from NdFeB magnets using pyrometallurgical and hydrometallurgical processes. The results revealed that hydrometallurgical processes have a lower environmental impact than pyrometallurgical processes due to a decrease in material losses and electricity consumption. ...
Article
Full-text available
Rare earth elements such as neodymium and dysprosium have a substantial supply risk. Yet these elements are needed for NdFeB magnets that are indispensable for clean energy applications such as hybrid/electric vehicles and wind turbines. In order to attenuate the supply risk, recycling of NdFeB magnets from end-of-life (EOL) products is a promising alternative. Life Cycle Assessments (LCAs) have been performed for NdFeB magnets produced from newly mined (“virgin”) material and for magnets produced using a magnet-to-magnet recycling process. A comparison of the results shows that the value recovery system has significantly less environmental impact than virgin production.
... The low grade of many deposits of these materials is one factor in this, as is the difficulty of separating chemically and physically similar components, particularly in the case of REEs and PGMs [65]. The high environmental impacts of sourcing rare earths from conventional mining and processing [66] provide an incentive to seek unconventional sources. However, current recycling techniques do not always improve the environmental impacts of production, and the system of waste collection, separation and disassembly requires infrastructural, institutional and behavioral adjustments. ...
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The nexus of minerals and energy becomes ever more important as the economic growth and development of countries in the global South accelerates and the needs of new energy technologies expand, while at the same time various important minerals are declining in grade and available reserves from conventional mining. Unconventional resources in the form of deep ocean deposits and urban ores are being widely examined, although exploitation is still limited. This paper examines some of the implications of the transition towards cleaner energy futures in parallel with the shifts through conventional ore decline and the uptake of unconventional mineral resources. Three energy scenarios, each with three levels of uptake of renewable energy, are assessed for the potential of critical minerals to restrict growth under 12 alternative mineral supply patterns. Under steady material intensities per unit of capacity, the study indicates that selenium, indium and tellurium could be barriers in the expansion of thin-film photovoltaics, while neodymium and dysprosium may delay the propagation of wind power. For fuel cells, no restrictions are observed.
... In the same vein, SimaPro ® does not support analysis for Neodymium magnets which are an essential part of the rotary motor of the HFD. Neodymium has a lifecycle impact of 75 kg of CO 2 equivalent per kg and an associated energy consumption of 173 MJ/kg [18]. The HFD uses only about 71 grams of additional Neodymium over the LMD. ...
Article
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Linear motor drives (LMDs) are well known to provide significant advantages in terms of positioning speed and accuracy over traditional screw drives (SDs), making them better suited for high-speed high-precision machine tools. However, their use in such machine tools is severely limited by their tendency to consume a lot of electrical energy and cause thermal issues, particularly under high cutting loads. A hybrid feed drive (HFD) has recently been proposed as a possible solution to this dilemma. The HFD switches between LMD and SD actuation depending on the mode of the manufacturing operation, thus achieving speeds and accuracies similar to LMDs while consuming much less energy. This paper presents a comparative life cycle analysis (LCA) of the proposed HFD with an LMD as the baseline for the comparison. The functional unit is taken as the production of parts that involve heavy cutting by a small-sized 3-axis precision milling machine for 250 8-hour work days per year over a 12-year first-use life span. Energy savings provided by the HFD during its use phase vis-a-vis the additional energy investments into the HFD at various phases in its life cycle are compared. The analysis predicts a net positive impact, in terms of energy and the environment, for the HFD compared to the LMD under high cutting loads.
... Likewise, each deposit is unique in its specific balance of RE, making the allocation to each element additionally challenging. The review identified one lifecycle assessment of RE, which concluded that mining and beneficiation have much lower energy and material consumption compared to the other downstream stagesseparation of rare earth oxides and reduction to rare earth elements [9]. Furthermore, the life cycle assessment results showed that the high environmental impact of rare earth elements (on a per kg basis) coupled with low yield and low abundance provided a sound incentive to investigate recycling and recovery of rare earths or minerals that contain rare earths. ...
Article
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... In comparison, a preliminary GHG emission-focused life cycle impact assessment study by Tharumarajah and Koltun (2011;Fig . 3) focused on the Bayan Obo deposit, and considered the GHG emission implications of the production and processing of a bastnä site ore with a grade of y6% REOs using indicative information on material and energy inputs, emissions and land use from public sources (e.g. ...
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