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Article

Comparative Life Cycle Assessment and Life Cycle Cost Analysis of Bonded Nd-Fe-B Magnets: Virgin Production versus Recycling

by
Yaxuan Yang
1,
Min Liu
1,
Peihong Zhu
1,
Ke Gao
1,
Yueheng Xuan
2,
Qingmei Lu
1,
Yue Ding
3,
Baoguo Zhang
3 and
Ming Yue
1,*
1
Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
2
School of Software, Dalian University of Foreign Languages, Dalian 116044, China
3
Hangzhou Kede Magnetic Components Co., Ltd., Hangzhou 311500, China
*
Author to whom correspondence should be addressed.
Sustainability 2024, 16(19), 8599; https://doi.org/10.3390/su16198599
Submission received: 6 August 2024 / Revised: 21 September 2024 / Accepted: 25 September 2024 / Published: 3 October 2024
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Abstract

:
Conducting a comprehensive analysis of life cycle assessment and life cycle cost is critical for quantifying environmental impacts and estimating production costs associated with new production methods. Therefore, the life cycle assessment and life cycle cost of 1 kg bonded Nd-Fe-B magnetic powder produced by different production methods from “cradle to gate” are studied in this study. The results indicate that recycling is more advantageous than direct production in both environmental and economic terms. Specifically, the endpoint impact categories for 1 kg of bonded Nd-Fe-B powder produced by various methods reveal that recycling and regeneration reduce the environmental impact by 42%, 41%, and 42% compared to direct production in the categories of Human Health, Ecosystem Diversity, and Resource Availability, respectively. Additionally, in terms of life cycle cost, recycling yields savings of 47% and 32% compared to direct production in the internal and external life cycle cost, respectively. The results demonstrate that the environmentally friendly and cost-reducing method of recycling and regeneration points out a pathway for transforming the industrial structure of bonded Nd-Fe-B magnetic powder.

1. Introduction

Nd-Fe-B rare earth permanent magnet materials are essential for applications in the energy, military, and aerospace sectors [1,2,3]. Presently, over 90% of the global production capacity for rare earth permanent magnets is concentrated in China within the domain of rare earth functional materials [4]. The bonded Nd-Fe-B permanent magnet material has gained considerable attention for its capacity to produce more intricate and precise workpieces at a relatively low cost [3,5,6,7]. However, the substantial energy consumption and environmental impact associated with the development of mineral resources for producing bonded Nd-Fe-B magnets warrant careful consideration [8]. The recycling of large quantities of used bonded Nd-Fe-B magnets at the end of their life cycle can mitigate the demand for additional mining of rare earth resources, thereby supporting global initiatives for “green production” [9,10].
Unlike sintered Nd-Fe-B recovered by hydrometallurgy or fire metallurgy, bonded Nd-Fe-B has led researchers to explore a new recovery path suitable for bonded Nd-Fe-B because of its large number of binders. The recovery process of the bonded magnet involves the study of removing the binder. Zhu et al. recovered bonded Nd-Fe-B through ethanol, but in the subsequent high-temperature operation, the ethanol volatilized due to its low boiling point, resulting in a decrease in solvent content that affected the removal of the binder [11]. Additionally, the additional substances used in some recovery processes are harmful or high-cost, which also causes the research to be limited to the laboratory. For instance, the 1,2,3,4-tetrahydronaphthalene utilized by Terada et al. can effectively degrade the binders in magnet waste, but it is classified as a potential human carcinogen. Although ionic liquids, which can greatly reduce human harm, can also participate in the recycling of bonded Nd-Fe-B magnet waste, their high price limits the factory-scale production of this method. In summary, these technologies are too immature to be applied in industry processes due to the above problems now [12,13,14,15].
The combination of life cycle assessment and life cycle cost is an effective tool for finding economic efficiency in production systems and the environment [16]. The use of LCA–LCC tools has emerged in solid waste [17], medicine [18], construction [19], transportation [20], and other fields. With the continuous upgrading of dual-carbon policy and industrialization today, the efficient use of LCA–LCC tools in rare earth production is particularly important. The life cycle assessment (LCA) method, which is based on ISO14040 [21] principles and the framework of environmental management life cycle assessment, is an effective method to quantify the environmental impact of different magnetic powder production processes [8,22,23,24,25,26,27,28,29,30]. The life cycle cost (LCC) method is based on the LCA and used to calculate internal and external costs from “cradle to gate”, which can better assess the impact of all aspects of Nd-Fe-B production, rather than the use stage [22,23,24,31]. As far as the current research is concerned, many scholars have evaluated the environmental impact or cost of producing Nd-Fe-B by the sintering method [32,33,34]. Jin et al. used LCA to evaluate Nd-Fe-B magnets produced from raw materials and magnets recycled from magnets to magnets [29]. Karal et al. performed LCA sensitivity analysis and cost analysis by comparing Nd-Fe-B magnets produced by conventional processes with Nd-Fe-B produced by the hydrometallurgical recovery of neodymium from waste electrical and electronic equipment [23]. However, at present, an LCA–LCC comprehensive assessment of recycling bonded Nd-Fe-B has not been reported due to the immaturity of the bonded Nd-Fe-B recycling techniques.
To address both large-scale application and environmental sustainability, we have developed a low-cost method for recycling and regenerating bonded Nd-Fe-B using a NaOH-ethylene glycol solution [11]. At present, the study has been piloted by us and the recovery effects show that it can be applied in large-scale industrial recycling. However, it is important to acknowledge that significant energy and chemical reagents are still required during the recycling process. Therefore, additional research is necessary to evaluate whether this method is more environmentally friendly compared to the direct production of Nd-Fe-B permanent magnet powder. A comprehensive analysis of the environmental impacts and cost implications of recycling methods is also needed.
Herein, this study proposes a method for a more comprehensive economic and ecological evaluation by integrating LCA and LCC. Specifically, it is applied to compare the environmental impact and production cost of direct production of bonded Nd-Fe-B magnetic powder with recycling and regenerated methods. Simapro 9.0.0.4.8 was used to quantitatively analyze the environmental impact of different production methods. The internal cost and external cost of bonded Nd-Fe-B magnetic powder under two different production methods were calculated using LCC. Finally, the sensitivity analysis shows that electric energy is the most sensitive material flow. These results indicate that recycling and reproduction are superior to direct production in both environmental impact and economic evaluation. This approach not only provides a theoretical foundation for the future development of magnets, but also offers guidance for optimizing recycling methods by identifying key processes involved in recycling and regeneration.

2. Method

2.1. LCA

Based on the LCA methodology of ISO14040 principles and the framework for environmental management life cycle assessment, LCA is mainly divided into goal and scope definition, inventory analysis, impact assessment, and interpretation of results. The Recipe 2016 method is applied in the software Simapro 9.0.0.4.8 to analyze 17 categories of environmental impact combined with the LCA framework system, efficiently obtaining data and visually analyzing the environmental impact of two kinds of bonded Nd-Fe-B magnetic powder production methods. LCC takes the “cradle to the gate” of LCA as its research scope and explores economic issues by calculating internal costs and external costs.

2.1.1. Goal and Scope Definition

In Figure 1, the goal and scope definition for the direct production of bonded Nd-Fe-B magnetic powder and the recycling and regeneration method are defined in the dashed line box. The steps involved in direct production of bonded Nd-Fe-B magnetic powder include four steps: melting, rapid quenching, crystallization, and crushing, among which melting involves transportation and mining of minerals. The recycling and regeneration method includes four steps: demagnetization, crushing, removing binder, and drying, among which demagnetization includes the collection of waste magnetic. The process data for each unit was sorted and compiled to obtain nine environmental impact characteristics and standardized values using Simapro 9.0.0.4.8 software calculation with the ReCiPe 2016 model, while the economic benefits were evaluated by LCC, based on the production of 1 kg bonded Nd-Fe-B magnetic powder as the functional unit.

2.1.2. Inventory Analysis

Whether it be direct production or recycling, the environmental impact of 1 kg Nd-Fe-B magnetic powder consists of the production of raw materials, energy consumption, and product emissions. The collected data for electrical power, ferroboron, iron, and other production data came from the Material Environmental Coordination Evaluation Basic Database of Beijing University of Technology (Sino Center), in addition to field research. The electrical power inventory is given in Table S1. The data inventories for basic substances such as sodium hydroxide, ethanol, and argon are sourced from the Ecoinvent database in Simapro software. Neodymium and transportation are also included in building life cycle inventories based on production processes as understood in the literature.
In direct production, Nd2Fe14B pre-alloy was prepared by arc melting 99.9% Nd, Fe, and FeB alloys in an argon atmosphere. The ingot was melted three times to obtain a high degree of uniformity, and the total amount of these pre-alloys was about 1 kg, which was fused from the quartz tube to the copper wheel in an argon atmosphere of 0.05 MPa. The hole diameter of the quartz tube was fixed at 1.0 mm, and the distance between the nozzle and the wheel surface was maintained at 5 mm (the surface wheel speed is 14 m/s). After melting and fast quenching, the Nd-Fe-B strip was heat treated at 700 °C for 10 min until crystallization. To improve the density and magnetic properties of the bonded Nd-Fe-B magnet, the Nd-Fe-B strip was broken into Nd-Fe-B magnetic powder with a particle size of 75~150 μm. The life cycle inventory are shown in Table S2 and midpoint characterization value for different step of the direct producing 1 kg Nd-Fe-B magnetic powders as shown in Table S3.
The recycling process remains essentially the same as described in our previously published article, with the only difference being the variation in reaction conditions [11]. Firstly, the collected bonded Nd-Fe-B magnet waste, which was still magnetic, was heated to more than 300 °C for demagnetization. Then, by applying a gradually decreasing alternating magnetic field to the bonded Nd-Fe-B magnet waste, the organic binder in the waste was melted and decomposed into hydrocarbon vapor, so that the residue of the waste was gradually reduced and finally lost its magnetism. After crushing by a jaw crusher (100X60, Hangzhou Lantian Instrument Ltd., Hangzhou, China), the binder in the magnetic powder was removed by the addition of ethylene glycol. In the process of recovery and preparation, ethylene glycol (197 °C) with a higher boiling point was used instead of ethanol, so that the solution provided a hydroxyl group, and the high-temperature resistance of the preparation experiment was improved [35]. After removing the binder, the impurities were washed away with ethanol. The ratio of waste magnetic powder to solution was 1 g:1 mL. In addition, during the reaction, the system was protected by a nitrogen atmosphere to prevent Nd-Fe-B from oxidizing at high temperatures. After drying, 1 kg Nd-Fe-B powder was prepared by a recovery method of alkali-alcohol solution. The life cycle inventory is shown in Table S4 and midpoint characterization value for different steps in the recycling of 1 kg Nd-Fe-B magnetic powders as shown in Table S5.

2.1.3. Impact Assessment

Through the data selection of intermediate points in Simapro software, we mainly studied 9 categories of mid-point environmental impact categories: Global warming potential (GWP); Photochemical oxidant formation potential: humans (HOFP); Particulate matter formation potentials (PMFP); Photochemical oxidant formation potential: ecosystems (EOFP); Acidification potentials (AP); Human toxicity potential (HTPc); Human toxicity potential (HTPnc); Surplus ore potential (SOP); Fossil fuel potential (FFP). The environmental impact categories, characteristic factors, and units of intermediate points are shown in Table 1 [36,37]. All environmental impact categories were characterized by Simapro 9.0.0.4.8

2.2. LCC Analysis

The LCC method used in this study is the economic equivalent of the LCA method. The combination of LCC and LCA has well addressed the need to improve ecological quality and economic efficiency due to challenges such as climate change and resource scarcity, and a comprehensive assessment of the two methods is indispensable [38,39,40,41].
The LCC analysis in this study is primarily categorized into internal costs and external costs (Table 2). The boundary follows the same system as that of LCA, with a functional unit of 1 kg bonded Nd-Fe-B powder. Internal cost data are obtained from field research and the China Price Information Network (Tables S6 and S7), while external costs are based on LCA results. The units for external costs are derived from Özdemir [42].
The external LCC is related to the outcome of the LCA and is calculated by monetary factors and the following formula, namely:
C e x = ∑ e x   c j × e j
Cex is the sum of external costs, cj is the external monetary factor of Class J environmental impact, ej is the Class J environmental impact potential. Table 3 and Table 4 are external the LCC for direct production and recycling, respectively.

3. Results and Discussion

3.1. LCA Result Interpretation

The LCA environmental impact category characteristic value of 1 kg bonded Nd-Fe-B powder is determined using various methods calculated by Simapro with Recipe 2016, and the corresponding results are presented in Tables S8 and S9. Figure 2 and Figure 3 are obtained from the software calculation results, revealing that regardless of direct production or recycling and regeneration, the environmental impact from electric energy consumption constitutes a significant proportion of the different production methods in environmental impact categories. In the case of direct production, aside from the environmental impact of electric energy consumption, mining activities for various minerals have resulted in substantial damage to the environment. This has a much more pronounced environmental impact compared to adding glycol and ethanol for binder removal during recycling and regeneration.
In Figure 2a, smelting and binder removal account for 82% and 94% of the Global Warming Potential (GWP) in direct production and recycling, respectively. In Figure 3a, Nd mining in direct production contributes to 47% of the GWP, while electricity consumption contributes to 37%. In Figure 3b, in the case of recycling, electricity consumption provides 65% of the GWP.
In Photochemical oxidant formation in Figure 2b, the impacts on land and human health are significant. Melting and binder removal account for 76% and 92% of direct production and recycling respectively; additionally, in Figure 3a, Nd extraction in direct production accounted for 37% and 38% of the Photochemical oxidant formation potential: human health (HOFP) and Photochemical oxidant formation potential: terrestrial ecosystems (EOFP). Furthermore, electricity consumption plays a substantial role, accounting for 47% and 46% of the HOFP and the EOFP in direct production, while accounting for 81% of the HOFP and 79% of the EOFP in the recycling process in Figure 3b.
In Fine particulate matter formation in Figure 2c, both melting and binder removal accounted for 79% and 92% in direct production and recycling, respectively. In Figure 3a, Nd mining and power consumption account for 42% and 44% of Particulate matter formation potential (PMFP) in direct production, respectively. Furthermore, in Figure 3b, Electricity consumption during the recycling process contributes to 80% of the PMFP.
In Figure 2d, melting and binder removal in Terrestrial acidification account for 78% and 92% in direct production and recycling, respectively. In Figure 3a, in the case of direct production, the exploitation and power consumption of Nd account for 40% and 47% of terrestrial acidification potential (TAP), respectively. In Figure 3b, the electricity consumed in the recycling process contributes to 85% of the TAP.
In terms of Human toxicity in Figure 2e, the magnetic powder produced by both methods has a significantly greater impact on non-cancer effects compared to cancer effects as a whole. When it comes to non-cancer effects, melting and binder removal account for 70% and 91% in direct production and recycling, respectively. In the case of direct production, mining and electricity consumption of Nd contribute to 27% and 64% of the Human toxicity: non-cancer potential (HTPnc), respectively, as shown in Figure 3a. In Figure 3b, the electricity consumed during the recycling process contributes to 91% of the HTPnc.
In mineral resource scarcity in Figure 2f, melting and binder removal accounted for 100% in direct production and recycling, respectively. Specifically, in direct production, Zr, Fe, and Nd mining contributed to 30%, 27%, and 24% of the surplus ore potential (SOP), respectively, as shown in Figure 3a. Additionally, in Figure 3b, the recovery process yielded ethanol and glycol solutions which provided 42% and 53% of the SOP, respectively.
In Figure 2g, melting and binder removal both accounted for 86% and 96% of the Fossil fuel potential (FFP) in direct production and recycling, respectively. Electricity consumption accounted for 53% of the FFP in direct production and 43% of the FFP in recycling, respectively, as shown in Figure 3. In summary, direct production has a greater impact on the environment. In addition to the statistics on the intermediate points of the environmental impacts, the end environmental impacts calculated by the end conversion factor from Table S10, as shown in Figure S1, can also show that the recovery method is an environmentally friendly production method which is nearly 50% lower than the direct production method in the categories of human health (HH), ecosystem diversity (ED) and resource availability (RA), respectively. Direct production has a greater environmental impact due to the larger volume of Nd mining and electricity consumption in the melting process, as evidenced by the comparison of the two production methods. In contrast, for the recycling and regeneration method, the removal of binders is a crucial step, which involves electricity, ethylene glycol, and ethanol. Therefore, the removal of binders has the most significant environmental impact in the recycling process.

3.2. LCC Result

The internal and external costs of producing 1 kg bonded Nd-Fe-B magnetic powder by two production methods are depicted in Figure 4. It is evident that regardless of whether it is produced directly or recycled, the external life cycle cost (LCC) exceeds the internal LCC.
As can be seen from Figure 4a, whether it be internal LCC or external LCC, the cost of recycling is lower than that of direct production, reducing costs by 47% and 32%, respectively. In the analysis of both internal and external LCC, Figure S2 provides a clearer depiction of the proportion of each cost. Nd mining accounts for the largest proportion of internal costs at 47%, amounting to 91.08 yuan in direct production. Additionally, ethylene glycol and ethanol represent the most expensive components of recycling and regeneration, comprising about 40% and costing approximately 40 yuan. The total internal cost of direct production is 195 yuan, while the total internal cost of recycling and regeneration is 103 yuan (Figure 4b).
In the context of LCA results, the external LCC associated with LCC shows that human toxicity (both cancer and non-cancer) accounted for the largest proportion of both production methods, at 70.81% and 74.94% for direct production and recycling, respectively (Figure S2). This was followed by the environmental cost of photochemical oxide emissions. However, it is worth noting that the total external LCC of direct production is 338 yuan, while the external LCC of recycling is 229 yuan (Figure 4b).
Whether it be internal LCC or external LCC, the cost of direct production is higher than the cost of recycling and regeneration methods. In summary, whether considering the impact on the environment or cost consumption, recycling alkali alcohol solution to produce Nd-Fe-B magnetic powder is a better choice.

3.3. Sensitivity Analysis

Sensitivity analysis is a method of conducting sensitivity testing in conjunction with identified key substances. The analysis involves reducing the critical process by 10%. Figure 5 illustrates the standardization of the environmental impact of recycling and regeneration. It shows that cancerous human toxicity has the highest value among all environmental impacts, followed by non-cancerous human toxicity. Ethanol and ethylene glycol account for a large proportion of these two categories, indicating that binder removal is a crucial step in recycling and regeneration. Electricity, ethanol, and ethylene glycol are the main key processes in the recovery and reproduction process. Electricity has the most extensive impact on all stages of recovery and reproduction, while ethanol and ethylene glycol only have an impact on the removal of binder stage.
As depicted in Figure 6, a 10% reduction in electricity input leads to a decrease in all categories of environmental impacts. The most significant reductions are observed in Climate change, Photochemical oxidant formation, Fine particulate matter formation, Terrestrial acidification, Human toxicity: non-cancer, and Fossil resource scarcity. Among these categories, the reduction of electricity has the greatest impact. Additionally, the reduction of ethylene glycol also plays a crucial role in reducing Human toxicity: cancer by 4% following a 10% decrease in ethylene glycol input.

3.4. Discussion

In the traditional production process of bonded Nd-Fe-B magnetic powder, LCA analysis indicates that the main contributors to the environmental burden are electricity consumption and mineral mining. In the new preparation method, electricity consumption remains a significant factor in the environmental burden. This is largely due to China’s heavy reliance on coal-fired electricity generation for its current power production. As a result, this not only leads to increased greenhouse gas emissions and pollutants such as NOx and SO2, contributing to climate change and acidification of the ocean and terrestrial ecosystems, but also results in resource depletion, water pollution, and threats to human health during the mineral mining process. Additionally, the recovery of chemical reagents in the new preparation method also has an impact on human health. In HTPnc and HTPc, the combined impact of solvents even exceeds the environmental impact of electricity consumption in environmental impact standardized values. Therefore, even with the relatively energy-saving and environmentally friendly direct production mode, the final impact on the environment still corresponds to 60% in direct production. This shows that we still need to continue to innovate and improve methods to reduce the impact on the environment and the human body. The key processes and key substances the study previously analyzed provide directions for the optimization of future production structures. Combined with our research, measures can be taken from the following three aspects to address these issues in both factory and laboratory production of bonded Nd-Fe-B magnetic powder:
(1)
First of all, utilizing more energy-efficient equipment for energy supply, such as wind power or solar power generation.
(2)
Secondly, installing air filtration or water filtration systems around mines and laboratories to prevent contaminated gases and water from entering residential areas
(3)
Finally, providing better protection measures for workers involved in mining activities and researchers working in laboratories to mitigate potential impacts on their health from mineral operations or chemical reagents.
The LCC analysis also indicates that recycling yields higher economic benefits in terms of both internal and external LCC. In terms of direct production methods, efforts should be focused on reducing the cost of mining raw materials, such as recycling waste Nd metal to replace the high cost of mining. Additionally, for recycling, there is potential to develop more cost-effective solvents to replace current production methods. Furthermore, in consideration of external LCC, enhancing environmental detection and pollutant treatment not only improves the environment but also reduces the harm of pollutants to human health, thereby decreasing various costs associated with external LCC. Based on current evaluation results, it can be concluded that the recycling of alkali alcohol solution to produce bonded Nd-Fe-B magnetic powder remains an environmentally friendly and low-cost production method.
The comprehensive study of the combination of LCA and LCC provides a favorable multi-perspective decision theory for expanding the experimental scale to factory production. At present, the comprehensive research on LCA and LCC in combination with Nd-Fe-B is still in the initial stage, and with the transformation of enterprises to environmentally friendly practices in the future, the comprehensive analysis of LCA and LCC will become indispensable. However, in addition to the fact that the analytical studies of LCA and LCC are largely independent of each other, which may lead to repeated work (such as data collection) and inconsistency regarding basic assumptions that ultimately reduce their importance, there are also still large gaps in related inventory data. Different life cycle studies have a certain degree of bias due to data collection problems, which encourages us to strive for more universal research results and data collection [43].
LCA–LCC, as an external tool for green and efficient production, cannot be separated from the support of national and government policies. Only by vigorously strengthening the supervision of enterprises and factories, and by promoting the wide application of LCA–LCC, can LCA–LCC tools be further innovatively implemented such that green economic development can be truly implemented in practice. In terms of technology, LCA–LCC further provides a path toward promoting clean and cost-effective production, identifying key processes and key substances that will promote further improvement and innovation in related fields; on the economic side, the intervention of the state will enable some small-cost production enterprises to be supported and more confident in shifting their operations in the direction of green production.

4. Conclusions

Based on the life cycle assessment method, this study conducted an analysis and comparison of the environmental and economic impacts of the direct production and recycling of bonded Nd-Fe-B powder. From Figure S1, it can be seen that in the result obtained from the environmental impact at the intermediate point, the environmental impact of recycling is reduced by 41% compared with that of direct production. In LCC, the internal cost and external cost of the recovery and reproduction method were 47% and 32% lower than those of the direct production method, respectively. The results, whether from the environmental impact assessment using Simapro software or the economic evaluation based on field investigation and LCA results, indicate that the method of recycling and regeneration is a better choice for producing bonded Nd-Fe-B powder. In the sensitivity analysis, electricity was a more sensitive material flow. Across HOFP, PMFP, EOFP, and AP, when the electric energy flow was reduced by 10%, the corresponding environmental impact value was reduced by 8%. Additionally, the integrated application of LCA and LCC in magnet production not only substantiates environmentally sustainable practices through empirical data, but also identifies strategies for enhancing production efficiency and reducing costs. This integration enriches the suite of tools available for environmental–economic assessments, offering significant potential for diverse applications of LCA and LCC in the future. In accordance with the continuous and vigorous promotion of China’s “Clear Waters and Green Mountains” policy, the comprehensive evaluation of LCA–LCC is expected to be further implemented in various production enterprises and provide data for decision-making by offering theoretical support for the efficient green development of enterprises. At the same time, it will promote the innovative reform of the LCA–LCC tool and apply it to different production processes, which is conducive to the filling of various production inventories gaps and the diversified development of assessment tools.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su16198599/s1, Figure S1: (a) The characteristic value of three characteristic values of endpoint impact categories, (b) Total environmental impacts with normalized characteristic values of endpoint impact categories, Figure S2: The proportion of each process in the internal and external LCC of different production methods: (a) and (b) are the concrete components of the internal costs of direct production and recycling, respectively. (c) and (d) are the concrete components of the external costs of direct production and recycling, respectively, Table S1: The inventories of electrical power production, Table S2: Direct production of 1 kg bonded Nd-Fe-B magnetic powder life cycle inventory, Table S3: Midpoint characterization results for different step of the producing 1 kg Nd-Fe-B magnetic powders for different energy and raw materials, Table S4: Life cycle inventory of recycling 1 kg Nd-Fe-B powders, Table S5: Midpoint characterization results for different step of the recycling 1 kg Nd-Fe-B magnetic powders for different energy and raw materials, Table S6: Internal LCC of direct production, Table S7: Internal LCC of recycling, Table S8: Directly produced of the intermediate point characteristic value of 1 kg bonded Nd-Fe-B magnetic powder, Table S9: Recycling and regenerated of the intermediate point characteristic value of 1 kg bonded Nd-Fe-B magnetic powder, Table S10: Midpoint to Endpoint Model Conversion Factor.

Author Contributions

P.Z. and K.G. observed the data, Q.L. and M.Y. supervised the recovery and regenerated process of bonded Nd-Fe-B magnetic powder, Y.Y. and M.L. analyzed the data with LCA and LCC, and interpreted the LCA and LCC results. Y.X., B.Z. and Y.D. revised the article. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Key R&D Program of China (2021YFB3500800).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data that support the finding of this study are available on request from the corresponding author.

Conflicts of Interest

Author Yue Ding and Baoguo Zhang were employed by the company Hangzhou Kede Magnetic Components Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Jin, H.; Afiuny, P.; Dove, S.; Furlan, G.; Zakotnik, M.; Yih, Y.; Sutherland, J.W. Life cycle assessment of neodymium-iron-boron magnet-to-magnet recycling for electric vehicle motors. Environ. Sci. Technol. 2018, 52, 3796–3802. [Google Scholar] [CrossRef] [PubMed]
  2. Luo, Y. Development of NdFeB magnet industry in new century. J. Iron Steel Res. Int. 2006, 13, 1–11. [Google Scholar] [CrossRef]
  3. Ma, B.M.; Herchenroeder, J.W.; Smith, B.; Suda, M.; Brown, D.N.; Chen, Z. Recent development in bonded NdFeB magnets. J. Magn. Magn. Mater. 2002, 239, 418–423. [Google Scholar] [CrossRef]
  4. Jaroni, M.S.; Friedrich, B.; Letmathe, P. Economical Feasibility of Rare Earth Mining outside China. Minerals 2019, 9, 576. [Google Scholar] [CrossRef]
  5. Ormerod, J.; Constantinides, S. Bonded permanent magnets: Current status and future opportunities. J. Appl. Phys. 1997, 81, 4816–4820. [Google Scholar] [CrossRef]
  6. Jiang, L.; Zhou, Q.L.; Zhang, Z.T.; Xing, J.S.; Hao, J.M. The Binder for Bonded NdFeB Magnets. In Proceedings of the 4th Pacific Rim International Conference on Advanced Materials and Processing (PRICM4), Honolulu, HI, USA, 11–15 December 2001; pp. 2811–2812. [Google Scholar]
  7. Qin, W.Z.; He, J.; Yao, L.Y. Research on the Molding Technology of Bonded NdFeB Magnets. In Proceedings of the 2nd International Conference on Advanced Design and Manufacturing Engineering (ADME 2012), Taiyuan, China, 16–18 August 2012; pp. 1815–1818. [Google Scholar]
  8. van Nielen, S.S.; Xicotencatl, B.M.; Tukker, A.; Kleijn, R. Ex-ante LCA of magnet recycling: Progressing towards sustainable industrial-scale technology. J. Clean. Prod. 2024, 458, 142453. [Google Scholar] [CrossRef]
  9. Eslamipoor, R.; Sepehriar, A. Enhancing supply chain relationships in the circular economy: Strategies for a green centralized supply chain with deteriorating products. J. Environ. Manag. 2024, 367, 121738. [Google Scholar] [CrossRef]
  10. Eslamipoor, R.; Sepehriyar, A. Promoting green supply chain under carbon tax, carbon cap and carbon trading policies. Bus. Strategy Environ. 2024, 33, 4901–4912. [Google Scholar] [CrossRef]
  11. Zhu, P.H.; Liu, M.; Yang, Y.X.; Liu, W.Q.; Lu, Q.M.; Ding, Y.; Zhang, B.G.; Meng, H.; Wei, Q.F.; Yue, M. Recycling Bonded Nd-Fe-B Magnet Wastes by Chemical Reaction and Its Mechanism. Langmuir 2023, 39, 10565–10575. [Google Scholar] [CrossRef] [PubMed]
  12. Önal, M.A.R.; Dewilde, S.; Degri, M.; Pickering, L.; Saje, B.; Riaño, S.; Walton, A.; Binnemans, K. Recycling of bonded NdFeB permanent magnets using ionic liquids. Green. Chem. 2020, 22, 2821–2830. [Google Scholar] [CrossRef]
  13. Preuss, R.; Angerer, J.; Drexler, H. Naphthalene—An environmental and occupational toxicant. Int. Arch. Occup. Environ. Health 2003, 76, 556–576. [Google Scholar] [CrossRef] [PubMed]
  14. Schubert, T.J.S. Current and Future Ionic Liquid Markets. In Proceedings of the Symposium on Ionic Liquids: Current and Future Trends/251st American-Chemical-Society National Meeting, San Diego, CA, USA, 13–17 March 2016; pp. 35–65. [Google Scholar]
  15. Terada, T.; Onishi, H.; Kawakami, T. New solvolysis and its application to epoxy resin and bonded magnets. J. Jpn. Inst. Met. 2001, 65, 627–634. [Google Scholar] [CrossRef]
  16. França, W.T.; Barros, M.V.; Salvador, R.; de Francisco, A.C.; Moreira, M.T.; Piekarski, C.M. Integrating life cycle assessment and life cycle cost: A review of environmental-economic studies. Int. J. Life Cycle Assess. 2021, 26, 244–274. [Google Scholar] [CrossRef]
  17. Sanchez, S.A.; Eckelman, M.J.; Sherman, J.D. Environmental and economic comparison of reusable and disposable blood pressure cuffs in multiple clinical settings. Resour. Conserv. Recycl. 2020, 155, 104643. [Google Scholar] [CrossRef]
  18. Wang, Z.; Lv, J.; Gu, F.; Yang, J.; Guo, J. Environmental and economic performance of an integrated municipal solid waste treatment: A Chinese case study. Sci. Total Environ. 2020, 709, 136096. [Google Scholar] [CrossRef]
  19. Balasbaneh, A.T.; Marsono, A.K.B. Applying multi-criteria decision-making on alternatives for earth-retaining walls: LCA, LCC, and S-LCA. Int. J. Life Cycle Assess. 2020, 25, 2140–2153. [Google Scholar] [CrossRef]
  20. Wang, G.; Zhao, Y.; Pan, Y.; Shi, T. Integrated Optimization Study of Electric Bus Fleet Transformation: Based on LCA, LCC and Multi-objective Planning. Acad. J. Sci. Technol. 2024, 11, 1–7. [Google Scholar] [CrossRef]
  21. ISO 14040; Environmental Management—Life-Cycle Assessment—Principles and Framework. ISO: Geneva, Switzerland, 2006.
  22. Islam, H.; Jollands, M.; Setunge, S.; Ahmed, I.; Hague, N. Life cycle assessment and life cycle cost implications of wall assemblages designs. Energy Build. 2014, 84, 33–45. [Google Scholar] [CrossRef]
  23. Karal, E.; Kucuker, M.A.; Demirel, B.; Copty, N.K.; Kuchta, K. Hydrometallurgical recovery of neodymium from spent hard disk magnets: A life cycle perspective. J. Clean. Prod. 2021, 288, 125087. [Google Scholar] [CrossRef]
  24. Rizan, C.; Brophy, T.; Lillywhite, R.; Reed, M.; Bhutta, M.F. Life cycle assessment and life cycle cost of repairing surgical scissors. Int. J. Life Cycle Assess. 2022, 27, 780–795. [Google Scholar] [CrossRef]
  25. Chau, C.K.; Leung, T.M.; Ng, W.Y. A review on Life Cycle Assessment, Life Cycle Energy Assessment and Life Cycle Carbon Emissions Assessment on buildings. Appl. Energy 2015, 143, 395–413. [Google Scholar] [CrossRef]
  26. Blok, R.; Bikad, D.; Kontoleon, K.; Giarma, C.; Gervasio, H. Sustainability of Constructions—Integrated Approach to Life-time Structural Engineering; Bragança, L., Koukkari, H., Blok, R., Gervásio, H., Veljkovic, M., Plewako, Z., Landolfo, R., Ungureanu, V., Silva, L.S., Eds.; Multicomp, Lda: Lisbon, Portugal, 2007; p. 63. [Google Scholar]
  27. Ma, X.; Ye, L.; Qi, C.; Yang, D.; Shen, X.; Hong, J. Life cycle assessment and water footprint evaluation of crude steel production: A case study in China. J. Environ. Manag. 2018, 224, 10–18. [Google Scholar] [CrossRef]
  28. Chowdhury, N.A.; Deng, S.D.; Jin, H.Y.; Prodius, D.; Sutherland, J.W.; Nlebedim, I.C. Sustainable Recycling of Rare-Earth Elements from NdFeB Magnet Swarf: Techno-Economic and Environmental Perspectives. ACS Sustain. Chem. Eng. 2021, 9, 15915–15924. [Google Scholar] [CrossRef]
  29. Jin, H.Y.; Afiuny, P.; McIntyre, T.; Yih, Y.; Sutherland, J.W. Comparative Life Cycle Assessment of NdFeB Magnets: Virgin Production versus Magnet-to-Magnet Recycling. In Proceedings of the 23rd CIRP Conference on Life Cycle Engineering, Berlin, Germany, 22–24 May 2016; pp. 45–50. [Google Scholar]
  30. Wang, Y.; Sun, B.X.; Gao, F.; Chen, W.J.; Nie, Z.R. Life cycle assessment of regeneration technology routes for sintered NdFeB magnets. Int. J. Life Cycle Assess. 2022, 27, 1044–1057. [Google Scholar] [CrossRef]
  31. Özkan, A.; Günkaya, Z.; Tok, G.; Karacasulu, L.; Metesoy, M.; Banar, M.; Kara, A. Life cycle assessment and life cycle cost analysis of magnesia spinel brick production. Sustainability 2016, 8, 662. [Google Scholar] [CrossRef]
  32. Nakamoto, M.; Kubo, K.; Katayama, Y.; Tanaka, T.; Yamamoto, T. Extraction of Rare Earth Elements as Oxides from a Neodymium Magnetic Sludge. Metall. Mater. Trans. B 2012, 43, 468–476. [Google Scholar] [CrossRef]
  33. Zhang, X.F.; Liu, F.; Liu, Y.L.; Ma, Q.; Li, Y.F.; Zhao, Q.; Wang, G.F.; Li, Z.B. Recycling of Sintered Nd-Fe-B Magnets Doped with PrNd Nanoparticles. J. Magn. 2015, 20, 97–102. [Google Scholar] [CrossRef]
  34. Ma, Y.; Yue, Z.; Wang, L. Life cycle assessment of sintered NdFeb magnetic materials. Rare Earth 2019, 40, 60–70. [Google Scholar] [CrossRef]
  35. Fowles, J.; Banton, M.; Klapacz, J.; Shen, H. A toxicological review of the ethylene glycol series: Commonalities and differences in toxicity and modes of action. Toxicol. Lett. 2017, 278, 66–83. [Google Scholar] [CrossRef]
  36. Huijbregts, M.A.J.; Steinmann, Z.J.N.; Elshout, P.M.F.; Stam, G.; Verones, F.; Vieira, M.; Zijp, M.; Hollander, A.; van Zelm, R. ReCiPe2016: A harmonised life cycle impact assessment method at midpoint and endpoint level. Int. J. Life Cycle Assess. 2017, 22, 138–147. [Google Scholar] [CrossRef]
  37. Hunkeler, D. LCA Compendium—The Complete World of Life Cycle Assessment. Int. J. Life Cycle Assess. 2020, 25, 1168–1170. [Google Scholar] [CrossRef]
  38. Meynerts, L.; Götze, U.; Claus, S.; Peças, P.; Ribeiro, I. Concept of Integrated Life Cycle Assessment and Costing—Application to the Case of Designing a Hybrid Train. In Proceedings of the 24th CIRP Conference on Life Cycle Engineering (CIRP LCE), Kamakura, Japan, 8–10 March 2017; pp. 744–749. [Google Scholar]
  39. Arulnathan, V.; Heidari, M.D.; Doyon, M.; Li, E.P.H.; Pelletier, N. Economic Indicators for Life Cycle Sustainability Assessment: Going beyond Life Cycle Costing. Sustainability 2023, 15, 13. [Google Scholar] [CrossRef]
  40. Islam, H.; Jollands, M.; Setunge, S. Life cycle assessment and life cycle cost implication of residential buildings-A review. Renew. Sustain. Energy Rev. 2015, 42, 129–140. [Google Scholar] [CrossRef]
  41. Miah, J.H.; Koh, S.C.L.; Stone, D. A hybridised framework combining integrated methods for environmental Life Cycle Assessment and Life Cycle Costing. J. Clean. Prod. 2017, 168, 846–866. [Google Scholar] [CrossRef]
  42. Banar, M.; Özdemir, A. An evaluation of railway passenger transport in Turkey using life cycle assessment and life cycle cost methods. Transp. Res. Part. D-Transp. Environ. 2015, 41, 88–105. [Google Scholar] [CrossRef]
  43. Bierer, A.; Götze, U.; Meynerts, L.; Sygulla, R. Integrating life cycle costing and life cycle assessment using extended material flow cost accounting. J. Clean. Prod. 2015, 108, 1289–1301. [Google Scholar] [CrossRef]
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Figure 1. The production process of direct production and recycling to produce bonded Nd-Fe-B magnetic powder.
Figure 1. The production process of direct production and recycling to produce bonded Nd-Fe-B magnetic powder.
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Figure 2. Comparison of the same environmental impact for different production methods. Characteristic values of the different production steps involved in direct production and recycling for (a) Climate change; (b) Photochemical oxidation; (c) Fine particulate matter formation; (d) Terrestrial acidification; (e) Human toxicity; (f) Mineral resource scarcity; (g) Fossil resource scarcity.
Figure 2. Comparison of the same environmental impact for different production methods. Characteristic values of the different production steps involved in direct production and recycling for (a) Climate change; (b) Photochemical oxidation; (c) Fine particulate matter formation; (d) Terrestrial acidification; (e) Human toxicity; (f) Mineral resource scarcity; (g) Fossil resource scarcity.
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Figure 3. The proportion of mineral extraction and energy consumption to the different environmental impacts of (a) direct production and reagent consumption and energy consumption to the different environmental impacts of (b) recycling and regeneration.
Figure 3. The proportion of mineral extraction and energy consumption to the different environmental impacts of (a) direct production and reagent consumption and energy consumption to the different environmental impacts of (b) recycling and regeneration.
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Figure 4. Comparison of internal and external LCC for different production methods: (a,b) show the percentage and direct data of internal and external costs, respectively, under different production methods. (c,d) are statistical charts of the proportion of internal and external costs for direct production and recycling, respectively.
Figure 4. Comparison of internal and external LCC for different production methods: (a,b) show the percentage and direct data of internal and external costs, respectively, under different production methods. (c,d) are statistical charts of the proportion of internal and external costs for direct production and recycling, respectively.
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Figure 5. Sensitivity analysis of different environmental impacts. (SOP is not displayed because it is too small after standardization, or is original; Ry is Reduce Ethylene glycol; Ra is Reduce Ethanol; Re is Reduce electricity).
Figure 5. Sensitivity analysis of different environmental impacts. (SOP is not displayed because it is too small after standardization, or is original; Ry is Reduce Ethylene glycol; Ra is Reduce Ethanol; Re is Reduce electricity).
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Figure 6. Sensitivity analysis percentage.
Figure 6. Sensitivity analysis percentage.
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Table 1. Environmental Midpoint impact category, characteristic factors, and units.
Table 1. Environmental Midpoint impact category, characteristic factors, and units.
Midpoint Impact CategoryCFmUnit
Climate changeGlobal warming potential (GWP)kg CO2 eq
Photochemical oxidant formation: human healthPhotochemical oxidant
formation potential: humans (HOFP)		kg NOx eq
Fine particulate matter formationParticulate matter formation potential (PMFP)kg PM2.5 eq
Photochemical oxidant formation: terrestrial ecosystemsPhotochemical oxidant formation potential:
ecosystems (EOFP)		kg NOx eq
Terrestrial acidificationTerrestrial acidification potential (TAP)kg SO2 eq
Human toxicity: cancerHuman toxicity potential cancer (HTPc) kg 1,4-DCB
Human toxicity: non-cancerHuman toxicity potential non-cancer (HTPnc)kg 1,4-DCB
Mineral resource scarcitySurplus ore potential (SOP)kg Cu eq
Fossil resource scarcityFossil fuel potential (FFP)kg oil eq
Table 2. Internal LCC and external LCC classification.
Table 2. Internal LCC and external LCC classification.
LCC CostLCC ComponentLCC Subcomponent
Internalproducttransportation cost
Raw materials
energy cost
ExternalPollutant costsGlobal warming
Photochemical oxidation
Toxicity (Human toxicity)
Acidification
Particulate matter formation
Table 3. External LCC of direct production.
Table 3. External LCC of direct production.
Category of Environmental ImpactUnitAmountUnit CostELCCTotal
Global warmingkg CO2 eq2.21 × 1012.20 × 10−14.853.38 × 102
Photochemical oxidationkg NOx eq1.61×10−13.88 × 1026.25 × 101
Toxicity (Human toxicity)kg1,4-DCB3.427.00 × 1012.39 × 102
Acidificationkg SO2 eq1.46 × 10−16.329.21 × 10−1
Particulate matter formationkg PM2.5 eq5.22 × 10−25.81 × 1023.03 × 101
Table 4. External LCC of recycling and regeneration.
Table 4. External LCC of recycling and regeneration.
Category of Environmental ImpactUnitAmountUnit CostELCCTotal
Global warmingkg CO2 eq1.27 × 1012.20 × 10−12.802.29 × 102
Photochemical oxidationkg NOx eq9.54 × 10−23.88 × 1023.70 × 101
Toxicity (Human toxicity)kg 1,4-DCB2.457.00 × 1011.71 × 102
Acidificationkg SO2 eq8.18 × 10−26.325.17 × 10−1
Particulate matter formationkg PM2.5 eq2.92 × 10−25.81 × 1021.70 × 101
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Yang, Y.; Liu, M.; Zhu, P.; Gao, K.; Xuan, Y.; Lu, Q.; Ding, Y.; Zhang, B.; Yue, M. Comparative Life Cycle Assessment and Life Cycle Cost Analysis of Bonded Nd-Fe-B Magnets: Virgin Production versus Recycling. Sustainability 2024, 16, 8599. https://doi.org/10.3390/su16198599

AMA Style

Yang Y, Liu M, Zhu P, Gao K, Xuan Y, Lu Q, Ding Y, Zhang B, Yue M. Comparative Life Cycle Assessment and Life Cycle Cost Analysis of Bonded Nd-Fe-B Magnets: Virgin Production versus Recycling. Sustainability. 2024; 16(19):8599. https://doi.org/10.3390/su16198599

Chicago/Turabian Style

Yang, Yaxuan, Min Liu, Peihong Zhu, Ke Gao, Yueheng Xuan, Qingmei Lu, Yue Ding, Baoguo Zhang, and Ming Yue. 2024. "Comparative Life Cycle Assessment and Life Cycle Cost Analysis of Bonded Nd-Fe-B Magnets: Virgin Production versus Recycling" Sustainability 16, no. 19: 8599. https://doi.org/10.3390/su16198599

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