Metallurgical recovery of rare earth elements: A bibliometric analysis and systematic literature review

Metallurgical recovery of rare earth elements: A bibliometric analysis and systematic literature review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Systematic Review Metallurgical recovery of rare earth elements: A bibliometric analysis and systematic literature review Marco Antonio Cotrina-Teatino, Jairo Jhonatan Marquina-Araujo, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5868907/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This article aimed to comprehensively map research on the metallurgical recovery of rare earth elements (REEs) in the mining industry from 2010 to 2024, identifying key themes, trends, and future directions. Using a mixed-methods approach that included bibliometric analysis, text mining, and content analysis, the study pursued the following objectives: (i) to capture the scientific background of research on the metallurgical recovery of REEs, identifying key themes and trends over the past 14 years, (ii) to provide a comprehensive overview of the existing literature on the topic, and (iii) to propose future directions in this field. A total of 132 peer-reviewed articles were analyzed, sourced from the Scopus, JSTOR, and Taylor & Francis databases, and selected using the PRISMA method and ad hoc sampling. The analysis identified three primary research areas: (1) innovation in rare earth recovery, (2) environmentally friendly metallurgical methods contributing to sustainability, and (3) challenges and perspectives on recycling and reusing rare earth elements. Based on these findings, three future research lines were proposed: Optimization and Integration of Hybrid Processes for Sustainable REE Recovery, Technological Advancements in Selective Recovery and REE Processing y Closed-Loop Systems and Biotechnological Solutions for REE Recycling. These efforts aim to enhance sustainability and optimize resource utilization in the mining industry, promoting practices that contribute to a more responsible, efficient, and sustainable development model for REE recovery. Metallurgy Rare earths processing recovery bibliometrix VOSviewer Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction Rare earth elements (REEs) govern the modern lifestyle, though many people remain unaware of their significant impacts (Dushyantha et al., 2020 ). Rare earth elements are utilized across numerous fields, including chemical engineering, the nuclear industry, metallurgy, medicine, electronics, and information technology (Daulay et al., 2024 ). Over the past few decades, there has been a surge in applications of REEs and their alloys in various technological devices, such as computer memory, DVDs, rechargeable batteries, supermagnets, mobile phones, LED lighting, superconductors, glass additives, fluorescent materials, solar panels, and MRI imaging agents (Balaram, 2019 ). These elements naturally occur in around 25 minerals, primarily as metallic oxides, with the most economically viable and exploited being bastnäsite, monazite, xenotime, loparite, cerite, and gadolinite. Current methods for recovering rare earth elements involve extensive processing steps, high energy consumption, and significant carbon emissions (Li et al., 2024 ). Global demand for REEs is steadily increasing, highlighting the need for effective extraction and recovery methods (Kaim-Sevalneva et al., 2024 ). (Danouche et al., 2024 ) discuss biological strategies like biohydrometallurgy, an innovative alternative that employs microorganisms to extract REEs. (Salinas-Rodríguez et al., 2019 ) present key preliminary findings related to the adsorption of specific REEs using a natural mineral, such as bentonite. (Park et al., 2023 ) analyzes the efficiency of separating and recovering neodymium and dysprosium from Mg-REE alloys through vacuum distillation, observing a relatively rapid separation behavior for dysprosium compared to neodymium. (Jang et al., 2024 ) employs a decanter centrifuge to successfully separate phosphoric acid and REE-containing particles from phosphoric acid sludge, demonstrating a recovery rate of approximately 95% for phosphoric acid and 90% for REEs in a single pass. Recycling plays a critical role today due to its significant contributions to mitigating energy concerns and environmental challenges. By recycling rare earth resources from obsolete equipment, dependence on newly mined rare earth resources can be reduced, thereby lowering associated environmental and energy footprints and increasing supply chain stability (Zhang et al., 2024 ). (Modalavalasa & Ayyagari, 2024 ) explore applications that maximize the recycling of slag from aluminum smelting plants; unlike other recyclable materials, slag contains substantial amounts of REEs, making it a valuable product in the recycling sector. (Cesaro et al., 2024 ) describes a hydrometallurgical process to treat waste from electrical and electronic equipment, identifying potential benefits in recovering REEs. (Iacob et al., 2024 ) focus on reusing nickel-metal hydride AA batteries to recover cobalt, nickel, and rare earth elements. (Torta et al., 2024a ) investigate the recycling potential of end-of-life electric vehicles to recover REEs. Tailings bioleaching for REE recovery was also studied, demonstrating that REEs can be efficiently bioleached using a functional bacterial consortium for acid bioleaching. The recovery of low concentration REEs from wastewater using a titanium dioxide composite electrode was explored, achieving efficient recovery of rare earths such as europium, dysprosium, terbium and lanthanum. To date, no evidence has been found of previous studies combining bibliometric analysis, text mining, and content analysis to examine the metallurgical recovery of rare earth elements. Thus, this study aims to fill that gap by conducting a bibliometric analysis and systematic literature review using databases such as Scopus, Taylor & Francis, and JSTOR. The goal is to identify how research on the metallurgical recovery of rare earth elements has evolved over time, enabling the visualization of emerging trends in new metallurgical processes and the improvement of existing methods. This bibliometric review on the metallurgical recovery of rare earth elements seeks to achieve the following objectives: (i) to capture the scientific background of research on the metallurgical recovery of rare earth elements, identifying key themes and trends from the past 14 years , (ii) to present a comprehensive overview of the existing literature on the topic , and (iii) to propose future research directions for the metallurgical recovery of rare earth elements . The study addresses the following research questions: What are the most prominent methodologies and technologies in the scientific literature for the metallurgical recovery of rare earth elements, and how have they evolved over the past 14 years? What patterns and trends emerge in scientific articles on the metallurgical recovery of rare earth elements through text mining analysis, and which thematic areas hold the greatest potential for technological advancements? What emerging technologies or innovative approaches could be explored in future research to improve the efficiency and sustainability of metallurgical processes in the recovery of rare earth elements? This article is structured as follows: Section 2 presents the research methodology; Section 3 provides the results of the bibliometric analysis and its interpretation; and finally, Section 4 concludes the article. Methodology Search strategies The search string was specifically designed around the metallurgical recovery of rare earth elements, guiding the selection of keywords related to this topic. Additionally, supplementary terms commonly associated with the metallurgical recovery of rare earth elements, such as “processing” , were incorporated. The search was conducted in the title, abstract, and keywords fields across three bibliographic databases: Scopus, Taylor & Francis, and JSTOR. This initial search yielded a total of 723 documents, as illustrated in Fig. 1 . Inclusion and exclusion criteria In line with the objectives of this review, only peer-reviewed articles and literature reviews written in English were included. Books, book chapters, reports, conference proceedings, dissertations, editorials, and unpublished manuscripts were excluded. Both empirical and theoretical or conceptual studies were considered if they addressed the metallurgical recovery of rare earth elements. Articles published between 2010 and 2024 relevant to research on the metallurgical recovery of rare earth elements were included. Figure 2 provides a detailed description of the inclusion and exclusion criteria applied in this study. Selection procedure The study selection process was illustrated using the PRISMA flow diagram (Moher et al., 2009 ). In the initial stage, 723 articles were identified from database searches. Additionally, 11 publications that were not detected in the keyword search but were found in the reference lists of selected articles were included in the sample. After removing duplicates and ensuring the consistency of the search protocol (Snyder, 2019 ), 701 articles were selected, resolving any discrepancies during the evaluation process. In the final stage, 149 potentially eligible articles were fully reviewed, and 17 were excluded during the comprehensive review process, resulting in a final sample of 132 articles. Software used for bibliometric analysis R-Studio software Biblioshiny is an interactive tool integrated within the R-Studio software, specifically designed to support bibliometric research. Its intuitive interface has led to widespread adoption among researchers, as evidenced by several studies that have utilized it for academic literature analysis (Aria & Cuccurullo, 2017 ; Kristia et al., 2023 ; Linnenluecke et al., 2020 ). This software enables the extraction of bibliographic data from various sources, such as Scopus, and, through its integration with the bibliometrix R package, offers a wide range of analyses. These include evaluating annual scientific output, identifying the most-cited articles, key sources of information, prominent authors and institutions, geographic distribution of research, and generating keyword clouds. VOSviewer software VOSviewer is a widely used tool in the field of bibliometrics, enabling the creation of detailed networks of bibliographic relationships, encompassing authors, institutions, countries, and regions collaborating in research (Mejia et al., 2021 ; van Eck & Waltman, 2010 ). This software facilitates various approaches to collaborative network analysis, such as keyword co-occurrence, bibliographic coupling, co-citation, and co-authorship. In this study, keyword analysis was used to identify the relevance of research areas within the field. Text mining Text mining refers to the process of extracting relevant information and meaningful patterns from large volumes of text using statistical, linguistic, and machine learning techniques. It is a useful tool for identifying trends, research patterns, emerging technologies, and gaps in scientific literature. For this study, a text-mining analysis was conducted using a term co-occurrence algorithm applied to the titles and abstracts of publications, leveraging version 1.6.20 of VOSviewer. This approach enabled the identification of the conceptual structure and emerging themes in the literature on knowledge management in the context of research on the metallurgical recovery of rare earth elements. Content analysis In line with the methods established by (Jia & Jiang, 2018 ) and (Schöggl et al., 2020 ), a content analysis was conducted as a complementary qualitative layer to deepen the quantitative findings. Using clustering techniques, the most relevant articles within each group were subjected to qualitative content analysis to examine the dominant theoretical orientations in the field of metallurgical recovery of rare earth elements. Results To meet the proposed objectives, the results were organized into Sections 3.1, 3.2, and 3.3, corresponding to each specific research objective. Bibliometric maps of previous research This section presents indicators derived from bibliometric analysis, aimed at addressing the first research objective: capturing the scientific context of studies on the metallurgical recovery of rare earth elements by identifying relevant themes and prevailing trends over the past 14 years. Analysis of publication trends The number of published articles and received citations are valuable metrics for evaluating research development. Trends for the period between 2010 and 2024 are illustrated in Fig. 4 . Publications on the metallurgical recovery of rare earth elements began to emerge in 2013, increasing from one article that year to 16 in 2024. Over these 14 years, the trajectory of research on the metallurgical recovery of rare earth elements can be divided into three phases: the initial stage, the stability phase, and the growth period (Fig. 4 ). Initial stage (2010–2014) : This phase saw the publication of four articles in total. During this period, the concept of recovering rare earth elements from secondary materials began to gain visibility. Studies such as the recovery of rare earth elements from electronic waste (Lister et al., 2014 ) and fluorescent lamp waste (Mansouri et al., 2021 ) demonstrated the feasibility of recovering rare earth elements from waste materials (Góralczyk & Uzunow, 2013 ). Stability phase (2015–2017) : In this phase, the number of publications increased to 18 articles, marking significant growth compared to the initial stage. This was due to the consolidation of the concept of metallurgical recovery of rare earth elements. Research during this period focused on developing new extraction technologies using a variety of rare earth element source materials (Jin et al., 2017 ) and adopting a political industrial ecology approach (Deutz et al., 2017 ). Growth period (2018–2024) : During this phase, 110 articles were published, accounting for 83% of the total publications, with an annual average of 16 articles. This sustained growth reflects increasing interest in the application of rare earth elements for various modern technologies and industrial applications (Torta et al., 2024b ). Analysis of leading journals and authors A total of 82 journals contributed 132 articles on the metallurgical recovery of rare earth elements between 2010 and 2024. As shown in Fig. 5 , the top 10 most influential journals account for 50 of these works, equivalent to 38% of the total publications in this field. Among these, Minerals stands out with 17 studies, representing 13% of the publications, focusing primarily on the recovery of rare earth elements from mining tailings (Echeverry-Vargas & Ocampo-Carmona, 2022 ; Sedda et al., 2024 ). It is followed by the Journal of Sustainable Metallurgy with seven articles, and Metals and Minerals Engineering, both with five articles, centering their research on the recovery of rare earth elements from secondary materials and ecological policy (Deutz et al., 2017 ; Góralczyk & Uzunow, 2013 ; Jin et al., 2017 ; Mansouri et al., 2021 ). In the domain of metallurgical recovery of rare earth elements, a total of 581 authors participated, with 32 contributing two or more articles. Table 1 highlights the top 10 authors, ranked by the number of published articles and the impact of their work. The most prolific researcher was Yang X., with four publications. Other notable contributors include Alemrajabi M., Binnemans K., Jiao Y., Jin H., Parque D., and Sastre S., each with three publications. In terms of citations, authors such as Sethurajan M. (260 citations), Borra C. (143 citations), Mayes W. (133 citations), and Moldoveanu G. (113 citations) have achieved significant recognition in the literature, indicating a high level of academic influence within the research community. Table 1 Top 10 authors and cited authors by number of published articles N° Authors N° of articles Cited author N° of citations 1 Yang X 4 Sethurajan M 260 2 Alemrajabi M 3 Borra C 143 3 Binnemans K 3 Mayes W 133 4 Jiao Y 3 Moldoveanu G 113 5 Jin H 3 Firdaus M 109 6 Parque D 3 Dong Z 97 7 Sastre Soy 3 Araya N 96 8 Abaka-Wood E 2 Lister T 91 9 Addai-Mensah J 2 Pagina M 83 10 Batinica B 2 Das S 80 The number of citations an article receives is a key indicator for identifying the most influential publications in a research area. Table 2 lists the 10 most-cited articles in the dataset. These articles, published in various journals, demonstrate the significant contributions of multiple sources to the study of metallurgical recovery of rare earth elements. The most-cited article examines recent advances in the hydrometallurgical recovery of rare earth elements from end-of-life electronic waste (Sethurajan et al., 2019 ). (Borra et al., 2016 ) studied the selective recovery of iron and rare earth elements through smelting of bauxite residues. (Moldoveanu & Papangelakis, 2016 ) analyzes rare earth recovery via ion-exchange leaching of ion-adsorption clays. (Firdaus et al., 2016 ) explores the high-temperature recovery of rare earths (Nd/Dy) from magnetic residues. (Dong et al., 2021 ) presents a novel study utilizing lanmodulin protein for the recovery and separation of rare earth elements. Additionally, (Araya et al., 2020 ) investigated the techno-economic feasibility of recovering rare earth elements from mining tailings. Table 2 Top 10 most-cited articles on circular economy in the mining industry N° Article title TC(a) TC/Y(b) Author(s) 1 Recent advances on hydrometallurgical recovery of critical and precious elements from end of life electronic wastes - a review 260 43.33 Sethurajan et al., 2019 2 Smelting of Bauxite Residue (Red Mud) in View of Iron and Selective Rare Earths Recovery 143 15.89 Borra et al., 2016 3 Advances in Understanding Environmental Risks of Red Mud After the Ajka Spill, Hungary 133 14.78 Mayes et al., 2016 4 An overview of rare-earth recovery by ion-exchange leaching from ion-adsorption clays of various origins 113 12.56 Moldoveanu et al., 2016 5 Review of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste 109 12.11 Firdaus et al., 2016 6 Bridging Hydrometallurgy and Biochemistry: A Protein-Based Process for Recovery and Separation of Rare Earth Elements 97 24.25 Dong et al., 2021 7 Towards mine tailings valorization: Recovery of critical materials from Chilean mine tailings 96 19.2 Araya et al., 2020 8 Recovery of critical and value metals from mobile electronics enabled by electrochemical processing 91 8.27 Lister et al., 2014 9 Comparative study of the application of chelating resins for rare earth recovery 83 10.38 Page et al., 2017 10 Techno-economic analysis of supercritical extraction of rare earth elements from coal ash 80 11.43 Das et al., 2018 (a) Total citations; (b) total citations per year. Analysis of collaboration among institutions and countries A total of 207 institutions from various countries participated in research related to the metallurgical recovery of rare earth elements, publishing articles between 2010 and 2024. Of these institutions, 54 published more than four articles. Table 3 lists the top 10 institutions based on the number of articles published during this period. The KTH Royal Institute of Technology tops the list with 15 articles, representing 3% of the total, followed by the Universitat Politècnica de Catalunya with 11 articles. Other notable institutions include Los Alamos National Laboratory with 10 publications, as well as Polytechnica University of Timişoara, RWTH Aachen University, Universiti Kebangsaan Malaysia, and Université de Lorraine, each with 8 articles. Table 3 Top 10 institutions by number of articles published Institution Country N° of articles Kth Royal Institute of Technology USA 15 Universitat Politècnica de Catalunya United Kingdom 11 Los Alamos National Laboratory Turkey 10 Polytechnica University of Timişoara Sweden 8 Rwth Aachen University Spain 8 Universiti Kebangsaan Malaysia South Africa 8 Université de Lorraine Slovenia 8 Chemical Sciences Division Serbia 7 Curtin University Romania 7 National Research Council of Canada Portugal 7 The geographic distribution of research, encompassing 32 countries and 207 institutions, is shown in Fig. 6 . According to the data, the United States, Germany, and Australia lead in the number of publications, with 21, 8, and 7 articles, respectively, establishing themselves as the most influential countries in this field. Regarding international collaboration, as illustrated in Fig. 7 , Germany stands out with 9 international collaborations in the global research network on the metallurgical recovery of rare earth elements, followed by Turkey and the United Kingdom with 7 collaborations each. In contrast, the United States and Russia, with only 2 collaborations each, are among the countries with the least collaborations over the 14-year study period. Keyword analysis Keywords provided by authors represent a synthesis of the primary focus of their research, offering a clear view of thematic trends and priority areas within the field. Analyzing these keywords based on their co-occurrence allows visualization of connections between various topics and helps identify both prominent themes and emerging areas in scientific literature. Figure 8 presents a keyword cloud where the size of each term reflects its frequency of appearance in the analyzed articles. The most prominent terms, such as “Hydrometallurgy” , “recycling” , “critical raw materials” , and “circular economy” , reveal the central research topics in the metallurgical recovery of rare earth elements. This graphic representation provides an instant view of the most relevant topics, though it does not illustrate the temporal evolution of these concepts, but rather their cumulative presence during the studied period. Figure 9 , on the other hand, presents a co-occurrence network of keywords with a temporal dimension. The colors of the nodes, ranging from blue to yellow, represent the average publication year associated with each keyword. Dark blue keywords are linked to earlier research, while yellow-toned keywords indicate more recent topics. This visualization enables the identification of shifts and evolution in research focuses, showing how certain topics, such as “Hydrogen decrepitation” , “Mineralogical process” , and “Critical raw materials” , have gained greater relevance in recent years. This co-occurrence network not only highlights the most frequently used terms but also demonstrates how these terms interconnect and evolve, reflecting the development of new areas of interest within the metallurgical recovery of rare earth elements. Identification of key themes and trends in research This section directly addresses the second research objective, providing a broad and structured overview of the existing literature on the metallurgical recovery of rare earth elements. The results derived from text-mining analysis reveal three fundamental research themes, as presented in Fig. 10 . This section details and analyzes the dominant themes, which include: (1) sustainable extraction methods, (2) innovation in the recovery of rare earths, and (3) recycling and reuse of rare earth elements. Cluster 1: Sustainable extraction methods The studies in Cluster 1 demonstrate a concerted effort toward the development of sustainable extraction methods for rare earth elements (REEs). These methods prioritize minimizing environmental impacts, enhancing efficiency, and leveraging waste or secondary materials as alternative sources. The collected works cover a diverse range of techniques, including hydrometallurgical processes, bioleaching, advanced flotation, and resource recovery from mining residues, coal fly ash, and other industrial byproducts. The theme of sustainability is central to this cluster, as researchers emphasize the need to shift from traditional mining practices to more environmentally friendly alternatives. Studies on coal fly ash are particularly significant in this regard. For instance, (Begalinov et al., 2022 ) details leaching experiments to extract REEs from coal combustion residues, focusing on the optimization of key parameters like temperature, acid concentration, and leaching time to maximize recovery rates. Complementing this, (Cornelius et al., 2021 ) explores enrichment techniques such as magnetic separation and zeolitization, demonstrating their ability to concentrate rare earth elements effectively. Similarly, (Borra et al., 2021 ) introduces ultrasonic roasting as a promising pretreatment to improve subsequent recovery processes. The recovery of rare earths from mining tailings also features prominently. In (Echeverry-Vargas & Ocampo-Carmona, 2022 ) researchers assess the potential of tailings as a secondary source of critical materials. Their findings underscore the economic and environmental advantages of reprocessing tailings, aligning with the principles of sustainable resource management. The study (Torta et al., 2024a ) further illustrates the value of end-of-life products, such as electric vehicle components, in providing a viable alternative to primary mining for REE supply. Hydrometallurgical methods are a cornerstone of the research in this cluster. Several studies demonstrate the effectiveness of solvent extraction, ion flotation, and selective leaching in recovering REEs from various sources. For example, (Paiva et al., 2022 ) highlights the use of hydrometallurgical processes to recover both REEs and precious metals from spent catalysts. Similarly, (Islam et al., 2022 ) discusses the scalability of membrane solvent extraction, emphasizing its energy efficiency and adaptability for industrial applications. Another notable work, (Arslan & Bulut, 2022 ) explores the potential of flotation methods for selectively extracting rare earths from dilute solutions. The cluster also addresses biological approaches to REE recovery. The application of microorganisms and biosorbents offers a greener alternative to traditional chemical processes. In (Ramasamy et al., 2019 ) marine algae are explored as bio-sorbents capable of selectively recovering REEs from aqueous environments. Similarly, (Monneron-Enaud et al., 2020 ) discusses the use of acidophilic bacteria to extract rare earths from electronic waste, highlighting its low environmental footprint and potential scalability. The study (Kucuker & Kuchta, 2018 ) further demonstrates the viability of bioleaching for recovering valuable elements from mining residues and other industrial wastes. Another key area of innovation involves the modification and optimization of materials for REE recovery. The paper (Barros et al., 2024 ) showcases how advanced material science and computational tools can be combined to enhance the efficiency of adsorption processes. By tailoring the chemical properties of zeolites, researchers achieved improved selectivity and capacity for REE recovery, paving the way for more effective and sustainable extraction methods. The importance of utilizing secondary resources and industrial byproducts as feedstocks is repeatedly emphasized in this cluster. Studies such as (Cavallo & Dino, 2022 ) and (Said et al., 2022 ) demonstrate the feasibility of recovering REEs and other valuable materials from industrial residues, mining waste, and liquid waste streams. These works underscore the potential of a circular economy approach, wherein waste materials are transformed into valuable resources. Throughout the studies in this cluster, there is a consistent emphasis on minimizing environmental harm while maintaining economic viability. For instance, (Borra et al., 2021 ) highlights the dual benefits of waste reduction and material recovery, integrating sustainability into the entire supply chain. Similarly, (Van Rythoven et al., 2021 ) uses advanced modeling techniques to optimize recovery strategies, demonstrating the intersection of data science and sustainable mining practices. The cluster also includes research on advanced flotation and separation technologies(Stojković et al., 2024 ) and (Arslan & Bulut, 2022 ) provide insights into enhancing selectivity and efficiency in mineral processing. These techniques not only improve recovery rates but also reduce the reliance on chemical-intensive processes. Cluster 2: Innovation in the recovery of rare earths Cluster 2 encompasses studies that focus on innovative methods and advancements in the recovery of rare earth elements (REEs), emphasizing the importance of technological breakthroughs and process optimizations to meet the growing demand for these critical resources. The studies span various methodologies, including hydrometallurgical processes, advanced recycling systems, and process innovations for extracting REEs from diverse sources such as electronic waste, mining tailings, and industrial byproducts. A significant portion of the research highlights the recovery of REEs from waste electrical and electronic equipment (WEEE). In (Sethurajan et al., 2019 ) the authors review over 150 publications detailing hydrometallurgical methods for recovering REEs from electronic waste, including solvent extraction, ionic liquids, and electrowinning techniques. This work provides a comprehensive understanding of the state-of-the-art processes and their techno-economic viability for WEEE as a secondary resource. Complementing this is (Deshmane et al., 2020 ) which demonstrates the scalability of supported membrane solvent extraction for recovering REEs from various electronic waste streams, achieving purity levels above 99.5% and recovery efficiencies greater than 95%. The innovative use of hydrometallurgical and pyrometallurgical techniques for recovering REEs is well-documented. (Kumari et al., 2015 ) details a comprehensive process involving demagnetization, leaching, and solvent extraction to recover neodymium, praseodymium, and dysprosium from discarded permanent magnets, achieving recovery rates exceeding 95%. Similarly, (Arellano Ruiz et al., 2020 ) employs organo-phosphorus derivatives to selectively extract neodymium from mixed rare earth solutions, underscoring the significance of selective separation in reducing waste and improving efficiency. Pyrometallurgical innovations are showcased in (Blenau et al., 2023 ) where a two-step process achieves selective recovery of REEs from slag while minimizing iron contamination. Research on alternative extraction techniques is also prominent. (Piotrowicz et al., 2020 ) introduces a thermal hydrogen decrepitation method for converting sintered NdFeB magnets into demagnetized powder, offering a direct reuse pathway. The study highlights the effectiveness of the method in achieving high recovery rates under controlled conditions. Additionally, (Xu et al., 2020 ) presents an electrochemical approach for recovering REEs and iron simultaneously, demonstrating the potential of integrated recycling systems. The valorization of mining and industrial tailings as sources of REEs also receives significant attention. (Araya et al., 2020 ) evaluates the techno-economic feasibility of recovering REEs and other critical materials from tailings, showing that while the process is viable, market factors like raw material prices heavily influence profitability. Similarly, (Yang et al., 2019 ) examines the distribution of REEs in beneficiation tailings and phosphogypsum, suggesting strategies for efficient recovery from these byproducts. (Sedda et al., 2024 ) explores the potential of mining waste in Sardinia, Italy, revealing significant REE concentrations that could be economically extracted using advanced processing techniques. Several studies explore innovations in material modifications and extraction agents to enhance REE recovery. For example, (Barros et al., 2024 ) uses machine learning to optimize zeolite modifications for REE adsorption and desorption, achieving recovery rates above 90%. (Pavón et al., 2018 ) leverages ionic liquids for selectively recovering yttrium and europium, showcasing the potential of tailored chemical agents in achieving high-purity extractions. Other works investigate solid-state and alternative processes. (Pavón et al., 2021a ) discusses the recovery of yttrium and europium from fluorescent lamp wastes using solid-state chlorination, which minimizes chemical consumption and operational costs. Similarly, (Le et al., 2019 ) demonstrates an innovative cementation process for ruthenium recovery, achieving a 99% recovery rate with minimal environmental impact. Cluster 3: Recycling and reuse of rare earth elements Cluster 3 centers on the recycling and reuse of rare earth elements (REEs), a vital area of research driven by the necessity to mitigate resource scarcity and environmental impact. The studies within this cluster emphasize the development of circular economy frameworks and innovative methodologies to recover REEs from waste streams, electronic waste, spent batteries, and industrial byproducts. One of the primary themes in this cluster is the recovery of REEs from industrial and mining waste, reflecting the growing emphasis on utilizing underexplored resources. For instance, (Balassone et al., 2021 ) outlines a novel process for extracting REE-bearing minerals from mining waste, leveraging alkaline leaching to achieve significant recovery rates while incorporating carbon capture as part of the circular flow. Similarly, (Yang et al., 2021 ) investigates the beneficiation of Estonian phosphorite ores, demonstrating the potential to extract REEs as a byproduct of phosphate rock processing. The recovery of REEs from coal fly ash is another prominent topic. In (Abaka-Wood et al., 2022 ) the authors detail a dual-step process involving ultrasonic roasting and acid leaching to recover REEs. This method exemplifies the shift toward greener and more efficient processing techniques. Another study, (Zheng et al., 2024 ) explores the potential of alumina-rich fly ashes as an alternative source of REEs, utilizing physical separation techniques to concentrate critical elements like lanthanides and yttrium. The use of spent batteries and electronic waste as sources of REEs is a recurring theme. (Vieceli et al., 2016 ) provides an overview of recycling methodologies for lithium-ion and nickel-metal hydride batteries, highlighting hydrometallurgical processes for recovering valuable metals, including REEs. Meanwhile, (Lister et al., 2014 ) showcases an electrorecycling approach for efficiently recovering REEs, palladium, and gold from mobile electronic devices. This study underscores the increasing focus on electronic waste as a feedstock for REE recovery. Several studies in this cluster address the recycling of fluorescent lamp waste, which contains significant concentrations of yttrium and europium. For example, (Pavón et al., 2018 ) demonstrates a process for selectively recovering high-purity REEs using ionic liquids, achieving extraction efficiencies above 99%. Similarly, "(Pavón et al., 2021b ) explores a dry chlorination process that minimizes chemical consumption and operational costs while recovering over 90% of yttrium and europium from lamp phosphors. Another noteworthy focus is on phosphoric acid sludge and its potential as a source of REEs. In (Jin et al., 2017 ) a decanter centrifuge is used to separate phosphoric acid and REE-containing solids, achieving recovery efficiencies of 90% for REEs. This study highlights the economic feasibility of scaling up REE recovery from industrial sludge and integrating it into larger production systems. Innovative methods for magnet recycling also feature prominently. (Blenau et al., 2023 ) presents a two-step process combining oxidative smelting and carbothermic reduction to recover rare earth oxides from permanent magnet waste. Similarly, (Torta et al., 2024a ) evaluates the feasibility of recycling NdFeB magnets from electric vehicle motors, emphasizing the economic potential of specific recycling techniques like demagnetization and mechanical processing. Biological processes for REE recovery are explored in (Monneron-Enaud et al., 2020 ) which demonstrates the use of bioleaching to dismantle electronic components and recover valuable metals, including REEs, with reduced environmental impact. Another study, (Dong et al., 2021 ) introduces a biobased approach using lanmodulin protein for selective REE recovery, achieving high purity and stability across multiple cycles. The cluster also investigates alternative processing techniques for specific materials. (Said et al., 2022 ) explores the crystallization of REEs from synthetic leachate solutions, optimizing reaction conditions to achieve high-purity recovery of lanthanum. Additionally, (Wang et al., 2022 ) integrates theoretical and experimental approaches to enhance REE recovery from acid mine drainage precipitates. Future directions for research in circular economy within the mining industry Based on the insights obtained from bibliometric analyses, text mining, and qualitative content analyses conducted in this study, this section outlines a series of future research directions. This aligns with the third objective of the study, which aims to suggest new areas for exploration in research on the metallurgical recovery of Rare Earth Elements (REEs). Following an exhaustive analysis, several knowledge gaps have been identified that warrant further attention. The following research priorities are proposed to address critical challenges and maximize the potential of metallurgical recovery of Rare Earth Elements. Optimization and Integration of Hybrid Processes for Sustainable REE Recovery Future research in sustainable extraction methods for rare earth elements (REEs) should focus on the integration of hybrid processes combining bioleaching, hydrometallurgical, and advanced material-based approaches. While studies like (Yang & Honaker, 2020 ) and (Yang & Honaker, 2020 ) have shown the promise of tailored chemical and computational techniques, scaling these methods to industrial levels remains a significant challenge. Emphasis should be placed on optimizing operational parameters, minimizing energy consumption, and reducing environmental impacts, as demonstrated in (Kucuker & Kuchta, 2018 ) Additionally, using machine learning for predictive modeling and process optimization could enhance efficiency. Future efforts should also investigate the economic and geographical feasibility of recovering REEs from unconventional sources like coal fly ash and mining tailings, as explored in (Echeverry-Vargas & Ocampo-Carmona, 2022 ) Technological Advancements in Selective Recovery and REE Processing Advancements in REE recovery from electronic waste and complex materials need further innovation in scalable technologies. Studies such as “(Kumari et al., 2015 )” strated the potential for hydrometallurgical methods to achieve high recovery rates. Future research should refine selective separation techniques, like those discussed in(Pavón et al., 2018 ) to imprwhile reducing chemical waste. Methods that handle mixed waste streams, such as combining mechanical processing with hydrometallurgical or pyrometallurgical steps, as highlighted in(Blenau et al., 2023 ) should also be prConducting comprehensive life cycle assessments (LCAs) of these innovative methods will help evaluate their environmental and social impacts. The exploration of advanced adsorbents or catalysts for selective REE recovery, as noted in(Barros et al., 2024 ) could open new pathways forrecovery from multi-metal systems. Closed-Loop Systems and Biotechnological Solutions for REE Recycling For recycling and reuse, future research must prioritize the development of closed-loop systems with minimal waste generation. Studies like (Vieceli et al., 2016 ) and (Lister et al., 2014 ) have underscored the importance of inteanced sorting and pre-treatment technologies to enhance separation efficiency. AI-driven systems for automated sorting of waste streams could be transformative. Additionally, the long-term economic viability of recovering REEs from spent batteries and industrial byproducts, as explored in (Jang et al., 2024 ), requires deeper analysis. Research into biotecholutions, like protein-based recovery processes described in “(Dong et al., 2021 )”, could offer sustainable alternatives. Standardizing methoross industries, especially for assessing and processing diverse waste types, is crucial to overcoming current ,technological and logistical challenges. Conclusions This study provides a comprehensive and updated perspective on the metallurgical recovery of Rare Earth Elements (REEs) over the past 14 years, fulfilling three fundamental objectives: (i) capturing the scientific background of research on the metallurgical recovery of REEs by identifying key themes and trends from the last 14 years, (ii) presenting an integrated overview of the existing literature on the topic, and (iii) proposing future directions in the field. To achieve this, a mixed-methods approach was adopted, encompassing bibliometric analysis, text mining, and content analysis applied to a rigorously selected sample of 132 peer-reviewed articles sourced from the Scopus, JSTOR, and Taylor & Francis databases, published between 2010 and 2024. To ensure the quality and relevance of the included studies, filters were applied using the PRISMA method, and additional documents were incorporated through an ad-hoc approach. The findings of this research identified three key areas in the metallurgical recovery of REEs: (1) sustainable extraction methods, (2) innovations in the recovery of REEs, and (3) recycling and reuse of REEs. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5868907","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Systematic Review","associatedPublications":[],"authors":[{"id":404795289,"identity":"20487fb9-f71c-48ea-8411-b8a1b018acc0","order_by":0,"name":"Marco Antonio Cotrina-Teatino","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYNACAyBmb2BgSEBw8QLGBpAaHp4DQC0JRGsBAh4JkHJitOi2Hz7+uKLgjry95BuzBw9/3EtsYG/eJsG4wwanFrMzaYmNZwyeGfZI55gbJCQUJzbwHCuTYDyThlvLDR7DxgaDw4xALWYSCQkJiQ0SQAZj22GCWux7JM9Atci/AWn5T1BLYo8ED8wWHpCWA3j9MhOoJbnnTFqZREJagnEbT1qxReKZZNxajh8+8LHhz2Hb9vbD2yR/2CTI9rMf3njj4w47nFowARuISGwgQQcEMJKuZRSMglEwCoYvAADBhlPJ15su3wAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-3801-0370","institution":"National University of Trujillo","correspondingAuthor":true,"prefix":"","firstName":"Marco","middleName":"Antonio","lastName":"Cotrina-Teatino","suffix":""},{"id":404795290,"identity":"325055d2-da2d-4c27-8c81-3bcffa8ae62e","order_by":1,"name":"Jairo Jhonatan Marquina-Araujo","email":"","orcid":"https://orcid.org/0000-0002-5880-8227","institution":"National University of Trujillo","correspondingAuthor":false,"prefix":"","firstName":"Jairo","middleName":"Jhonatan","lastName":"Marquina-Araujo","suffix":""},{"id":404795291,"identity":"34a36952-2570-4e01-8de8-5d5ed3bd294f","order_by":2,"name":"Wilmer Alva-Gaspar","email":"","orcid":"https://orcid.org/0009-0009-3508-480X","institution":"National University of Trujillo","correspondingAuthor":false,"prefix":"","firstName":"Wilmer","middleName":"","lastName":"Alva-Gaspar","suffix":""},{"id":404795292,"identity":"264b11e4-b948-447b-9d41-370c72e2bf2f","order_by":3,"name":"Alex Jhonatan Cruz-Ulloa","email":"","orcid":"https://orcid.org/0009-0005-1534-1718","institution":"National University of Trujillo","correspondingAuthor":false,"prefix":"","firstName":"Alex","middleName":"Jhonatan","lastName":"Cruz-Ulloa","suffix":""}],"badges":[],"createdAt":"2025-01-20 23:04:27","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-5868907/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5868907/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":74528348,"identity":"6de8beb0-6ed1-4e1b-997b-d5b924f1d517","added_by":"auto","created_at":"2025-01-23 07:16:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":128532,"visible":true,"origin":"","legend":"\u003cp\u003eSearch string for information on the metallurgical recovery of rare earth elements.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/d053021c1628ab5e69ce77b1.png"},{"id":74529309,"identity":"0d753da6-fcc1-4134-8392-4290d8fbdec2","added_by":"auto","created_at":"2025-01-23 07:24:14","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":129855,"visible":true,"origin":"","legend":"\u003cp\u003eInclusion and exclusion criteria.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/84a8f2f6bc2230842d8fb4bd.png"},{"id":74528362,"identity":"9d1dfac8-da92-423d-a7af-492440b473f6","added_by":"auto","created_at":"2025-01-23 07:16:13","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":141512,"visible":true,"origin":"","legend":"\u003cp\u003ePRISMA methodology for document selection.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/8e8a391920e96d5c94bdde53.png"},{"id":74529307,"identity":"41f316b9-d567-4da1-9743-317d9875cc82","added_by":"auto","created_at":"2025-01-23 07:24:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":105619,"visible":true,"origin":"","legend":"\u003cp\u003eAnnual number of published articles and total citations during the period 2010–2024.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/4b0bc0040607cffc2f53602b.png"},{"id":74528366,"identity":"072adebe-3d07-4fd2-b1e3-dd916a8d589e","added_by":"auto","created_at":"2025-01-23 07:16:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":65789,"visible":true,"origin":"","legend":"\u003cp\u003eMost relevant journals from 2000 to 2024.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/7fb384644d52c9c52c5f138e.png"},{"id":74528349,"identity":"824a6548-3f61-4b8c-878e-4cbf38740677","added_by":"auto","created_at":"2025-01-23 07:16:13","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":116901,"visible":true,"origin":"","legend":"\u003cp\u003eGeographic distribution of the literature on the metallurgical recovery of rare earth elements.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/fc9f9f6a9891bd836bb5844f.png"},{"id":74529311,"identity":"3d06c7bc-88a7-40ce-aa17-9675c1355cea","added_by":"auto","created_at":"2025-01-23 07:24:14","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":67635,"visible":true,"origin":"","legend":"\u003cp\u003eCollaboration among countries on the metallurgical recovery of rare earth elements.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/31a2dfb232f6ca22f2206346.png"},{"id":74528383,"identity":"b37fabc0-13a2-42a9-8622-25ac6a93456c","added_by":"auto","created_at":"2025-01-23 07:16:14","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":89138,"visible":true,"origin":"","legend":"\u003cp\u003eKeyword clouds from articles on the metallurgical recovery of rare earth elements.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/031f9c5748d409b79309cc9f.png"},{"id":74528378,"identity":"4c77d2fb-a721-42dc-b3cf-741023a6ef74","added_by":"auto","created_at":"2025-01-23 07:16:14","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":117432,"visible":true,"origin":"","legend":"\u003cp\u003eKeyword co-occurrence network on the metallurgical recovery of rare earth elements.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/b7ef731791f405b44f509362.png"},{"id":74528380,"identity":"65c32ca3-f535-450f-be5d-a3e1e286fccd","added_by":"auto","created_at":"2025-01-23 07:16:14","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":480092,"visible":true,"origin":"","legend":"\u003cp\u003eCo-occurrence map of title and abstract keywords.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/1dd9f49d1b616dd8041251f2.png"},{"id":74529688,"identity":"18629108-893f-42fe-94ab-e0a620bbb1f5","added_by":"auto","created_at":"2025-01-23 07:32:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2285774,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/7c02f27b-caa0-4982-b3f6-bb240841f148.pdf"},{"id":74528351,"identity":"17797eb6-c0bd-46f3-a193-4cbb7688c494","added_by":"auto","created_at":"2025-01-23 07:16:13","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":257543,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical abstract\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"GraphicalAbstract.png","url":"https://assets-eu.researchsquare.com/files/rs-5868907/v1/dcb0c1ee9dc642d7396f03a1.png"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eMetallurgical recovery of rare earth elements: A bibliometric analysis and systematic literature review\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eRare earth elements (REEs) govern the modern lifestyle, though many people remain unaware of their significant impacts (Dushyantha et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Rare earth elements are utilized across numerous fields, including chemical engineering, the nuclear industry, metallurgy, medicine, electronics, and information technology (Daulay et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Over the past few decades, there has been a surge in applications of REEs and their alloys in various technological devices, such as computer memory, DVDs, rechargeable batteries, supermagnets, mobile phones, LED lighting, superconductors, glass additives, fluorescent materials, solar panels, and MRI imaging agents (Balaram, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). These elements naturally occur in around 25 minerals, primarily as metallic oxides, with the most economically viable and exploited being bastn\u0026auml;site, monazite, xenotime, loparite, cerite, and gadolinite. Current methods for recovering rare earth elements involve extensive processing steps, high energy consumption, and significant carbon emissions (Li et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Global demand for REEs is steadily increasing, highlighting the need for effective extraction and recovery methods (Kaim-Sevalneva et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). (Danouche et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) discuss biological strategies like biohydrometallurgy, an innovative alternative that employs microorganisms to extract REEs. (Salinas-Rodr\u0026iacute;guez et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) present key preliminary findings related to the adsorption of specific REEs using a natural mineral, such as bentonite. (Park et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) analyzes the efficiency of separating and recovering neodymium and dysprosium from Mg-REE alloys through vacuum distillation, observing a relatively rapid separation behavior for dysprosium compared to neodymium.\u003c/p\u003e \u003cp\u003e(Jang et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) employs a decanter centrifuge to successfully separate phosphoric acid and REE-containing particles from phosphoric acid sludge, demonstrating a recovery rate of approximately 95% for phosphoric acid and 90% for REEs in a single pass. Recycling plays a critical role today due to its significant contributions to mitigating energy concerns and environmental challenges. By recycling rare earth resources from obsolete equipment, dependence on newly mined rare earth resources can be reduced, thereby lowering associated environmental and energy footprints and increasing supply chain stability (Zhang et al., \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). (Modalavalasa \u0026amp; Ayyagari, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) explore applications that maximize the recycling of slag from aluminum smelting plants; unlike other recyclable materials, slag contains substantial amounts of REEs, making it a valuable product in the recycling sector. (Cesaro et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) describes a hydrometallurgical process to treat waste from electrical and electronic equipment, identifying potential benefits in recovering REEs. (Iacob et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) focus on reusing nickel-metal hydride AA batteries to recover cobalt, nickel, and rare earth elements. (Torta et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024a\u003c/span\u003e) investigate the recycling potential of end-of-life electric vehicles to recover REEs. Tailings bioleaching for REE recovery was also studied, demonstrating that REEs can be efficiently bioleached using a functional bacterial consortium for acid bioleaching. The recovery of low concentration REEs from wastewater using a titanium dioxide composite electrode was explored, achieving efficient recovery of rare earths such as europium, dysprosium, terbium and lanthanum.\u003c/p\u003e \u003cp\u003eTo date, no evidence has been found of previous studies combining bibliometric analysis, text mining, and content analysis to examine the metallurgical recovery of rare earth elements. Thus, this study aims to fill that gap by conducting a bibliometric analysis and systematic literature review using databases such as Scopus, Taylor \u0026amp; Francis, and JSTOR. The goal is to identify how research on the metallurgical recovery of rare earth elements has evolved over time, enabling the visualization of emerging trends in new metallurgical processes and the improvement of existing methods.\u003c/p\u003e \u003cp\u003eThis bibliometric review on the metallurgical recovery of rare earth elements seeks to achieve the following objectives: (i) \u003cem\u003eto capture the scientific background of research on the metallurgical recovery of rare earth elements, identifying key themes and trends from the past 14 years\u003c/em\u003e, (ii) \u003cem\u003eto present a comprehensive overview of the existing literature on the topic\u003c/em\u003e, and (iii) \u003cem\u003eto propose future research directions for the metallurgical recovery of rare earth elements\u003c/em\u003e. The study addresses the following research questions: What are the most prominent methodologies and technologies in the scientific literature for the metallurgical recovery of rare earth elements, and how have they evolved over the past 14 years? What patterns and trends emerge in scientific articles on the metallurgical recovery of rare earth elements through text mining analysis, and which thematic areas hold the greatest potential for technological advancements? What emerging technologies or innovative approaches could be explored in future research to improve the efficiency and sustainability of metallurgical processes in the recovery of rare earth elements? This article is structured as follows: \u003cb\u003eSection 2\u003c/b\u003e presents the research methodology; \u003cb\u003eSection 3\u003c/b\u003e provides the results of the bibliometric analysis and its interpretation; and finally, \u003cb\u003eSection 4\u003c/b\u003e concludes the article.\u003c/p\u003e"},{"header":"Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eSearch strategies\u003c/h2\u003e\n \u003cp\u003eThe search string was specifically designed around the metallurgical recovery of rare earth elements, guiding the selection of keywords related to this topic. Additionally, supplementary terms commonly associated with the metallurgical recovery of rare earth elements, such as \u003cem\u003e\u0026ldquo;processing\u0026rdquo;\u003c/em\u003e, were incorporated. The search was conducted in the title, abstract, and keywords fields across three bibliographic databases: Scopus, Taylor \u0026amp; Francis, and JSTOR. This initial search yielded a total of 723 documents, as illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eInclusion and exclusion criteria\u003c/h3\u003e\n\u003cp\u003eIn line with the objectives of this review, only peer-reviewed articles and literature reviews written in English were included. Books, book chapters, reports, conference proceedings, dissertations, editorials, and unpublished manuscripts were excluded. Both empirical and theoretical or conceptual studies were considered if they addressed the metallurgical recovery of rare earth elements. Articles published between 2010 and 2024 relevant to research on the metallurgical recovery of rare earth elements were included. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e provides a detailed description of the inclusion and exclusion criteria applied in this study.\u003c/p\u003e\n\u003ch3\u003eSelection procedure\u003c/h3\u003e\n\u003cp\u003eThe study selection process was illustrated using the PRISMA flow diagram (Moher et al., \u003cspan class=\"CitationRef\"\u003e2009\u003c/span\u003e). In the initial stage, 723 articles were identified from database searches. Additionally, 11 publications that were not detected in the keyword search but were found in the reference lists of selected articles were included in the sample. After removing duplicates and ensuring the consistency of the search protocol (Snyder, \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e), 701 articles were selected, resolving any discrepancies during the evaluation process. In the final stage, 149 potentially eligible articles were fully reviewed, and 17 were excluded during the comprehensive review process, resulting in a final sample of 132 articles.\u003c/p\u003e\n\u003ch3\u003eSoftware used for bibliometric analysis\u003c/h3\u003e\n\u003cp\u003eR-Studio software\u003c/p\u003e\n\u003cp\u003eBiblioshiny is an interactive tool integrated within the R-Studio software, specifically designed to support bibliometric research. Its intuitive interface has led to widespread adoption among researchers, as evidenced by several studies that have utilized it for academic literature analysis (Aria \u0026amp; Cuccurullo, \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Kristia et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e; Linnenluecke et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). This software enables the extraction of bibliographic data from various sources, such as Scopus, and, through its integration with the bibliometrix R package, offers a wide range of analyses. These include evaluating annual scientific output, identifying the most-cited articles, key sources of information, prominent authors and institutions, geographic distribution of research, and generating keyword clouds.\u003c/p\u003e\n\u003cp\u003eVOSviewer software\u003c/p\u003e\n\u003cp\u003eVOSviewer is a widely used tool in the field of bibliometrics, enabling the creation of detailed networks of bibliographic relationships, encompassing authors, institutions, countries, and regions collaborating in research (Mejia et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; van Eck \u0026amp; Waltman, \u003cspan class=\"CitationRef\"\u003e2010\u003c/span\u003e). This software facilitates various approaches to collaborative network analysis, such as keyword co-occurrence, bibliographic coupling, co-citation, and co-authorship. In this study, keyword analysis was used to identify the relevance of research areas within the field.\u003c/p\u003e\n\u003ch3\u003eText mining\u003c/h3\u003e\n\u003cp\u003eText mining refers to the process of extracting relevant information and meaningful patterns from large volumes of text using statistical, linguistic, and machine learning techniques. It is a useful tool for identifying trends, research patterns, emerging technologies, and gaps in scientific literature. For this study, a text-mining analysis was conducted using a term co-occurrence algorithm applied to the titles and abstracts of publications, leveraging version 1.6.20 of VOSviewer. This approach enabled the identification of the conceptual structure and emerging themes in the literature on knowledge management in the context of research on the metallurgical recovery of rare earth elements.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eContent analysis\u003c/h2\u003e\n \u003cp\u003eIn line with the methods established by (Jia \u0026amp; Jiang, \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e) and (Sch\u0026ouml;ggl et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e), a content analysis was conducted as a complementary qualitative layer to deepen the quantitative findings. Using clustering techniques, the most relevant articles within each group were subjected to qualitative content analysis to examine the dominant theoretical orientations in the field of metallurgical recovery of rare earth elements.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eTo meet the proposed objectives, the results were organized into Sections 3.1, 3.2, and 3.3, corresponding to each specific research objective.\u003c/p\u003e\n\u003ch3\u003eBibliometric maps of previous research\u003c/h3\u003e\n\u003cp\u003eThis section presents indicators derived from bibliometric analysis, aimed at addressing the first research objective: capturing the scientific context of studies on the metallurgical recovery of rare earth elements by identifying relevant themes and prevailing trends over the past 14 years.\u003c/p\u003e \u003cp\u003eAnalysis of publication trends\u003c/p\u003e \u003cp\u003eThe number of published articles and received citations are valuable metrics for evaluating research development. Trends for the period between 2010 and 2024 are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Publications on the metallurgical recovery of rare earth elements began to emerge in 2013, increasing from one article that year to 16 in 2024. Over these 14 years, the trajectory of research on the metallurgical recovery of rare earth elements can be divided into three phases: the initial stage, the stability phase, and the growth period (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). \u003cb\u003eInitial stage (2010\u0026ndash;2014)\u003c/b\u003e: This phase saw the publication of four articles in total. During this period, the concept of recovering rare earth elements from secondary materials began to gain visibility. Studies such as the recovery of rare earth elements from electronic waste (Lister et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) and fluorescent lamp waste (Mansouri et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) demonstrated the feasibility of recovering rare earth elements from waste materials (G\u0026oacute;ralczyk \u0026amp; Uzunow, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). \u003cb\u003eStability phase (2015\u0026ndash;2017)\u003c/b\u003e: In this phase, the number of publications increased to 18 articles, marking significant growth compared to the initial stage. This was due to the consolidation of the concept of metallurgical recovery of rare earth elements. Research during this period focused on developing new extraction technologies using a variety of rare earth element source materials (Jin et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) and adopting a political industrial ecology approach (Deutz et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). \u003cb\u003eGrowth period (2018\u0026ndash;2024)\u003c/b\u003e: During this phase, 110 articles were published, accounting for 83% of the total publications, with an annual average of 16 articles. This sustained growth reflects increasing interest in the application of rare earth elements for various modern technologies and industrial applications (Torta et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2024b\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAnalysis of leading journals and authors\u003c/p\u003e \u003cp\u003eA total of 82 journals contributed 132 articles on the metallurgical recovery of rare earth elements between 2010 and 2024. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, the top 10 most influential journals account for 50 of these works, equivalent to 38% of the total publications in this field. Among these, Minerals stands out with 17 studies, representing 13% of the publications, focusing primarily on the recovery of rare earth elements from mining tailings (Echeverry-Vargas \u0026amp; Ocampo-Carmona, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Sedda et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). It is followed by the Journal of Sustainable Metallurgy with seven articles, and Metals and Minerals Engineering, both with five articles, centering their research on the recovery of rare earth elements from secondary materials and ecological policy (Deutz et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; G\u0026oacute;ralczyk \u0026amp; Uzunow, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Jin et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Mansouri et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In the domain of metallurgical recovery of rare earth elements, a total of 581 authors participated, with 32 contributing two or more articles. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e highlights the top 10 authors, ranked by the number of published articles and the impact of their work. The most prolific researcher was Yang X., with four publications. Other notable contributors include Alemrajabi M., Binnemans K., Jiao Y., Jin H., Parque D., and Sastre S., each with three publications. In terms of citations, authors such as Sethurajan M. (260 citations), Borra C. (143 citations), Mayes W. (133 citations), and Moldoveanu G. (113 citations) have achieved significant recognition in the literature, indicating a high level of academic influence within the research community.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTop 10 authors and cited authors by number of published articles\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN\u0026deg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAuthors\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u0026deg; of articles\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCited author\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eN\u0026deg; of citations\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYang X\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSethurajan M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e260\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAlemrajabi M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBorra C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e143\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBinnemans K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMayes W\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e133\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJiao Y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMoldoveanu G\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e113\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJin H\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFirdaus M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eParque D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDong Z\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSastre Soy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAraya N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbaka-Wood E\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLister T\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAddai-Mensah J\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePagina M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e83\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBatinica B\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDas S\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe number of citations an article receives is a key indicator for identifying the most influential publications in a research area. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e lists the 10 most-cited articles in the dataset. These articles, published in various journals, demonstrate the significant contributions of multiple sources to the study of metallurgical recovery of rare earth elements. The most-cited article examines recent advances in the hydrometallurgical recovery of rare earth elements from end-of-life electronic waste (Sethurajan et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). (Borra et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) studied the selective recovery of iron and rare earth elements through smelting of bauxite residues. (Moldoveanu \u0026amp; Papangelakis, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) analyzes rare earth recovery via ion-exchange leaching of ion-adsorption clays. (Firdaus et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) explores the high-temperature recovery of rare earths (Nd/Dy) from magnetic residues. (Dong et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) presents a novel study utilizing lanmodulin protein for the recovery and separation of rare earth elements. Additionally, (Araya et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) investigated the techno-economic feasibility of recovering rare earth elements from mining tailings.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTop 10 most-cited articles on circular economy in the mining industry\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN\u0026deg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArticle title\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTC(a)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTC/Y(b)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAuthor(s)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRecent advances on hydrometallurgical recovery of critical and precious elements from end of life electronic wastes - a review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e260\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSethurajan et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2019\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSmelting of Bauxite Residue (Red Mud) in View of Iron and Selective Rare Earths Recovery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e143\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e15.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBorra et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdvances in Understanding Environmental Risks of Red Mud After the Ajka Spill, Hungary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMayes et al., 2016\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAn overview of rare-earth recovery by ion-exchange leaching from ion-adsorption clays of various origins\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e113\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMoldoveanu et al., 2016\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFirdaus et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBridging Hydrometallurgy and Biochemistry: A Protein-Based Process for Recovery and Separation of Rare Earth Elements\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e24.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDong et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTowards mine tailings valorization: Recovery of critical materials from Chilean mine tailings\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAraya et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRecovery of critical and value metals from mobile electronics enabled by electrochemical processing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLister et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComparative study of the application of chelating resins for rare earth recovery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePage et al., 2017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTechno-economic analysis of supercritical extraction of rare earth elements from coal ash\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDas\u0026nbsp; et al., 2018\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e(a) Total citations; (b) total citations per year.\u003c/p\u003e \u003cp\u003eAnalysis of collaboration among institutions and countries\u003c/p\u003e \u003cp\u003eA total of 207 institutions from various countries participated in research related to the metallurgical recovery of rare earth elements, publishing articles between 2010 and 2024. Of these institutions, 54 published more than four articles. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e lists the top 10 institutions based on the number of articles published during this period. The KTH Royal Institute of Technology tops the list with 15 articles, representing 3% of the total, followed by the Universitat Polit\u0026egrave;cnica de Catalunya with 11 articles. Other notable institutions include Los Alamos National Laboratory with 10 publications, as well as Polytechnica University of Timişoara, RWTH Aachen University, Universiti Kebangsaan Malaysia, and Universit\u0026eacute; de Lorraine, each with 8 articles.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTop 10 institutions by number of articles published\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInstitution\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCountry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u0026deg; of articles\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKth Royal Institute of Technology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUniversitat Polit\u0026egrave;cnica de Catalunya\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnited Kingdom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLos Alamos National Laboratory\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTurkey\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePolytechnica University of Timişoara\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSweden\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRwth Aachen University\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUniversiti Kebangsaan Malaysia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSouth Africa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUniversit\u0026eacute; de Lorraine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSlovenia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChemical Sciences Division\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSerbia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCurtin University\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRomania\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNational Research Council of Canada\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePortugal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe geographic distribution of research, encompassing 32 countries and 207 institutions, is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. According to the data, the United States, Germany, and Australia lead in the number of publications, with 21, 8, and 7 articles, respectively, establishing themselves as the most influential countries in this field. Regarding international collaboration, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, Germany stands out with 9 international collaborations in the global research network on the metallurgical recovery of rare earth elements, followed by Turkey and the United Kingdom with 7 collaborations each. In contrast, the United States and Russia, with only 2 collaborations each, are among the countries with the least collaborations over the 14-year study period.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eKeyword analysis\u003c/p\u003e \u003cp\u003eKeywords provided by authors represent a synthesis of the primary focus of their research, offering a clear view of thematic trends and priority areas within the field. Analyzing these keywords based on their co-occurrence allows visualization of connections between various topics and helps identify both prominent themes and emerging areas in scientific literature. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e presents a keyword cloud where the size of each term reflects its frequency of appearance in the analyzed articles. The most prominent terms, such as \u003cem\u003e\u0026ldquo;Hydrometallurgy\u0026rdquo;\u003c/em\u003e, \u003cem\u003e\u0026ldquo;recycling\u0026rdquo;\u003c/em\u003e, \u003cem\u003e\u0026ldquo;critical raw materials\u0026rdquo;\u003c/em\u003e, and \u003cem\u003e\u0026ldquo;circular economy\u0026rdquo;\u003c/em\u003e, reveal the central research topics in the metallurgical recovery of rare earth elements. This graphic representation provides an instant view of the most relevant topics, though it does not illustrate the temporal evolution of these concepts, but rather their cumulative presence during the studied period.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, on the other hand, presents a co-occurrence network of keywords with a temporal dimension. The colors of the nodes, ranging from blue to yellow, represent the average publication year associated with each keyword. Dark blue keywords are linked to earlier research, while yellow-toned keywords indicate more recent topics. This visualization enables the identification of shifts and evolution in research focuses, showing how certain topics, such as \u003cem\u003e\u0026ldquo;Hydrogen decrepitation\u0026rdquo;\u003c/em\u003e, \u003cem\u003e\u0026ldquo;Mineralogical process\u0026rdquo;\u003c/em\u003e, and \u003cem\u003e\u0026ldquo;Critical raw materials\u0026rdquo;\u003c/em\u003e, have gained greater relevance in recent years. This co-occurrence network not only highlights the most frequently used terms but also demonstrates how these terms interconnect and evolve, reflecting the development of new areas of interest within the metallurgical recovery of rare earth elements.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIdentification of key themes and trends in research\u003c/p\u003e \u003cp\u003eThis section directly addresses the second research objective, providing a broad and structured overview of the existing literature on the metallurgical recovery of rare earth elements. The results derived from text-mining analysis reveal three fundamental research themes, as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e. This section details and analyzes the dominant themes, which include: (1) sustainable extraction methods, (2) innovation in the recovery of rare earths, and (3) recycling and reuse of rare earth elements.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eCluster 1: Sustainable extraction methods\u003c/h2\u003e \u003cp\u003eThe studies in Cluster 1 demonstrate a concerted effort toward the development of sustainable extraction methods for rare earth elements (REEs). These methods prioritize minimizing environmental impacts, enhancing efficiency, and leveraging waste or secondary materials as alternative sources. The collected works cover a diverse range of techniques, including hydrometallurgical processes, bioleaching, advanced flotation, and resource recovery from mining residues, coal fly ash, and other industrial byproducts. The theme of sustainability is central to this cluster, as researchers emphasize the need to shift from traditional mining practices to more environmentally friendly alternatives. Studies on coal fly ash are particularly significant in this regard. For instance, (Begalinov et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) details leaching experiments to extract REEs from coal combustion residues, focusing on the optimization of key parameters like temperature, acid concentration, and leaching time to maximize recovery rates. Complementing this, (Cornelius et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) explores enrichment techniques such as magnetic separation and zeolitization, demonstrating their ability to concentrate rare earth elements effectively. Similarly, (Borra et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) introduces ultrasonic roasting as a promising pretreatment to improve subsequent recovery processes.\u003c/p\u003e \u003cp\u003eThe recovery of rare earths from mining tailings also features prominently. In (Echeverry-Vargas \u0026amp; Ocampo-Carmona, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) researchers assess the potential of tailings as a secondary source of critical materials. Their findings underscore the economic and environmental advantages of reprocessing tailings, aligning with the principles of sustainable resource management. The study (Torta et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024a\u003c/span\u003e) further illustrates the value of end-of-life products, such as electric vehicle components, in providing a viable alternative to primary mining for REE supply.\u003c/p\u003e \u003cp\u003eHydrometallurgical methods are a cornerstone of the research in this cluster. Several studies demonstrate the effectiveness of solvent extraction, ion flotation, and selective leaching in recovering REEs from various sources. For example, (Paiva et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) highlights the use of hydrometallurgical processes to recover both REEs and precious metals from spent catalysts. Similarly, (Islam et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) discusses the scalability of membrane solvent extraction, emphasizing its energy efficiency and adaptability for industrial applications. Another notable work, (Arslan \u0026amp; Bulut, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) explores the potential of flotation methods for selectively extracting rare earths from dilute solutions.\u003c/p\u003e \u003cp\u003eThe cluster also addresses biological approaches to REE recovery. The application of microorganisms and biosorbents offers a greener alternative to traditional chemical processes. In (Ramasamy et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) marine algae are explored as bio-sorbents capable of selectively recovering REEs from aqueous environments. Similarly, (Monneron-Enaud et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) discusses the use of acidophilic bacteria to extract rare earths from electronic waste, highlighting its low environmental footprint and potential scalability. The study (Kucuker \u0026amp; Kuchta, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) further demonstrates the viability of bioleaching for recovering valuable elements from mining residues and other industrial wastes.\u003c/p\u003e \u003cp\u003eAnother key area of innovation involves the modification and optimization of materials for REE recovery. The paper (Barros et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) showcases how advanced material science and computational tools can be combined to enhance the efficiency of adsorption processes. By tailoring the chemical properties of zeolites, researchers achieved improved selectivity and capacity for REE recovery, paving the way for more effective and sustainable extraction methods. The importance of utilizing secondary resources and industrial byproducts as feedstocks is repeatedly emphasized in this cluster. Studies such as (Cavallo \u0026amp; Dino, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and (Said et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) demonstrate the feasibility of recovering REEs and other valuable materials from industrial residues, mining waste, and liquid waste streams. These works underscore the potential of a circular economy approach, wherein waste materials are transformed into valuable resources.\u003c/p\u003e \u003cp\u003eThroughout the studies in this cluster, there is a consistent emphasis on minimizing environmental harm while maintaining economic viability. For instance, (Borra et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) highlights the dual benefits of waste reduction and material recovery, integrating sustainability into the entire supply chain. Similarly, (Van Rythoven et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) uses advanced modeling techniques to optimize recovery strategies, demonstrating the intersection of data science and sustainable mining practices. The cluster also includes research on advanced flotation and separation technologies(Stojković et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and (Arslan \u0026amp; Bulut, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) provide insights into enhancing selectivity and efficiency in mineral processing. These techniques not only improve recovery rates but also reduce the reliance on chemical-intensive processes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eCluster 2: Innovation in the recovery of rare earths\u003c/h2\u003e \u003cp\u003eCluster 2 encompasses studies that focus on innovative methods and advancements in the recovery of rare earth elements (REEs), emphasizing the importance of technological breakthroughs and process optimizations to meet the growing demand for these critical resources. The studies span various methodologies, including hydrometallurgical processes, advanced recycling systems, and process innovations for extracting REEs from diverse sources such as electronic waste, mining tailings, and industrial byproducts. A significant portion of the research highlights the recovery of REEs from waste electrical and electronic equipment (WEEE). In (Sethurajan et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) the authors review over 150 publications detailing hydrometallurgical methods for recovering REEs from electronic waste, including solvent extraction, ionic liquids, and electrowinning techniques. This work provides a comprehensive understanding of the state-of-the-art processes and their techno-economic viability for WEEE as a secondary resource. Complementing this is (Deshmane et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) which demonstrates the scalability of supported membrane solvent extraction for recovering REEs from various electronic waste streams, achieving purity levels above 99.5% and recovery efficiencies greater than 95%.\u003c/p\u003e \u003cp\u003eThe innovative use of hydrometallurgical and pyrometallurgical techniques for recovering REEs is well-documented. (Kumari et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) details a comprehensive process involving demagnetization, leaching, and solvent extraction to recover neodymium, praseodymium, and dysprosium from discarded permanent magnets, achieving recovery rates exceeding 95%. Similarly, (Arellano Ruiz et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) employs organo-phosphorus derivatives to selectively extract neodymium from mixed rare earth solutions, underscoring the significance of selective separation in reducing waste and improving efficiency. Pyrometallurgical innovations are showcased in (Blenau et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) where a two-step process achieves selective recovery of REEs from slag while minimizing iron contamination.\u003c/p\u003e \u003cp\u003eResearch on alternative extraction techniques is also prominent. (Piotrowicz et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) introduces a thermal hydrogen decrepitation method for converting sintered NdFeB magnets into demagnetized powder, offering a direct reuse pathway. The study highlights the effectiveness of the method in achieving high recovery rates under controlled conditions. Additionally, (Xu et al., \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) presents an electrochemical approach for recovering REEs and iron simultaneously, demonstrating the potential of integrated recycling systems. The valorization of mining and industrial tailings as sources of REEs also receives significant attention. (Araya et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) evaluates the techno-economic feasibility of recovering REEs and other critical materials from tailings, showing that while the process is viable, market factors like raw material prices heavily influence profitability. Similarly, (Yang et al., \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) examines the distribution of REEs in beneficiation tailings and phosphogypsum, suggesting strategies for efficient recovery from these byproducts. (Sedda et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) explores the potential of mining waste in Sardinia, Italy, revealing significant REE concentrations that could be economically extracted using advanced processing techniques.\u003c/p\u003e \u003cp\u003eSeveral studies explore innovations in material modifications and extraction agents to enhance REE recovery. For example, (Barros et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) uses machine learning to optimize zeolite modifications for REE adsorption and desorption, achieving recovery rates above 90%. (Pav\u0026oacute;n et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) leverages ionic liquids for selectively recovering yttrium and europium, showcasing the potential of tailored chemical agents in achieving high-purity extractions. Other works investigate solid-state and alternative processes. (Pav\u0026oacute;n et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2021a\u003c/span\u003e) discusses the recovery of yttrium and europium from fluorescent lamp wastes using solid-state chlorination, which minimizes chemical consumption and operational costs. Similarly, (Le et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) demonstrates an innovative cementation process for ruthenium recovery, achieving a 99% recovery rate with minimal environmental impact.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eCluster 3: Recycling and reuse of rare earth elements\u003c/h2\u003e \u003cp\u003eCluster 3 centers on the recycling and reuse of rare earth elements (REEs), a vital area of research driven by the necessity to mitigate resource scarcity and environmental impact. The studies within this cluster emphasize the development of circular economy frameworks and innovative methodologies to recover REEs from waste streams, electronic waste, spent batteries, and industrial byproducts. One of the primary themes in this cluster is the recovery of REEs from industrial and mining waste, reflecting the growing emphasis on utilizing underexplored resources. For instance, (Balassone et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) outlines a novel process for extracting REE-bearing minerals from mining waste, leveraging alkaline leaching to achieve significant recovery rates while incorporating carbon capture as part of the circular flow. Similarly, (Yang et al., \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) investigates the beneficiation of Estonian phosphorite ores, demonstrating the potential to extract REEs as a byproduct of phosphate rock processing. The recovery of REEs from coal fly ash is another prominent topic. In (Abaka-Wood et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) the authors detail a dual-step process involving ultrasonic roasting and acid leaching to recover REEs. This method exemplifies the shift toward greener and more efficient processing techniques. Another study, (Zheng et al., \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) explores the potential of alumina-rich fly ashes as an alternative source of REEs, utilizing physical separation techniques to concentrate critical elements like lanthanides and yttrium.\u003c/p\u003e \u003cp\u003eThe use of spent batteries and electronic waste as sources of REEs is a recurring theme. (Vieceli et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) provides an overview of recycling methodologies for lithium-ion and nickel-metal hydride batteries, highlighting hydrometallurgical processes for recovering valuable metals, including REEs. Meanwhile, (Lister et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) showcases an electrorecycling approach for efficiently recovering REEs, palladium, and gold from mobile electronic devices. This study underscores the increasing focus on electronic waste as a feedstock for REE recovery. Several studies in this cluster address the recycling of fluorescent lamp waste, which contains significant concentrations of yttrium and europium. For example, (Pav\u0026oacute;n et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) demonstrates a process for selectively recovering high-purity REEs using ionic liquids, achieving extraction efficiencies above 99%. Similarly, \"(Pav\u0026oacute;n et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021b\u003c/span\u003e) explores a dry chlorination process that minimizes chemical consumption and operational costs while recovering over 90% of yttrium and europium from lamp phosphors.\u003c/p\u003e \u003cp\u003eAnother noteworthy focus is on phosphoric acid sludge and its potential as a source of REEs. In (Jin et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) a decanter centrifuge is used to separate phosphoric acid and REE-containing solids, achieving recovery efficiencies of 90% for REEs. This study highlights the economic feasibility of scaling up REE recovery from industrial sludge and integrating it into larger production systems. Innovative methods for magnet recycling also feature prominently. (Blenau et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) presents a two-step process combining oxidative smelting and carbothermic reduction to recover rare earth oxides from permanent magnet waste. Similarly, (Torta et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024a\u003c/span\u003e) evaluates the feasibility of recycling NdFeB magnets from electric vehicle motors, emphasizing the economic potential of specific recycling techniques like demagnetization and mechanical processing. Biological processes for REE recovery are explored in (Monneron-Enaud et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) which demonstrates the use of bioleaching to dismantle electronic components and recover valuable metals, including REEs, with reduced environmental impact. Another study, (Dong et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) introduces a biobased approach using lanmodulin protein for selective REE recovery, achieving high purity and stability across multiple cycles. The cluster also investigates alternative processing techniques for specific materials. (Said et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) explores the crystallization of REEs from synthetic leachate solutions, optimizing reaction conditions to achieve high-purity recovery of lanthanum. Additionally, (Wang et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) integrates theoretical and experimental approaches to enhance REE recovery from acid mine drainage precipitates.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eFuture directions for research in circular economy within the mining industry\u003c/h2\u003e \u003cp\u003eBased on the insights obtained from bibliometric analyses, text mining, and qualitative content analyses conducted in this study, this section outlines a series of future research directions. This aligns with the third objective of the study, which aims to suggest new areas for exploration in research on the metallurgical recovery of Rare Earth Elements (REEs). Following an exhaustive analysis, several knowledge gaps have been identified that warrant further attention. The following research priorities are proposed to address critical challenges and maximize the potential of metallurgical recovery of Rare Earth Elements.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eOptimization and Integration of Hybrid Processes for Sustainable REE Recovery\u003c/strong\u003e \u003cp\u003eFuture research in sustainable extraction methods for rare earth elements (REEs) should focus on the integration of hybrid processes combining bioleaching, hydrometallurgical, and advanced material-based approaches. While studies like (Yang \u0026amp; Honaker, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) and (Yang \u0026amp; Honaker, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) have shown the promise of tailored chemical and computational techniques, scaling these methods to industrial levels remains a significant challenge. Emphasis should be placed on optimizing operational parameters, minimizing energy consumption, and reducing environmental impacts, as demonstrated in (Kucuker \u0026amp; Kuchta, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) Additionally, using machine learning for predictive modeling and process optimization could enhance efficiency. Future efforts should also investigate the economic and geographical feasibility of recovering REEs from unconventional sources like coal fly ash and mining tailings, as explored in (Echeverry-Vargas \u0026amp; Ocampo-Carmona, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTechnological Advancements in Selective Recovery and REE Processing\u003c/strong\u003e \u003cp\u003eAdvancements in REE recovery from electronic waste and complex materials need further innovation in scalable technologies. Studies such as \u0026ldquo;(Kumari et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2015\u003c/span\u003e)\u0026rdquo; strated the potential for hydrometallurgical methods to achieve high recovery rates. Future research should refine selective separation techniques, like those discussed in(Pav\u0026oacute;n et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) to imprwhile reducing chemical waste. Methods that handle mixed waste streams, such as combining mechanical processing with hydrometallurgical or pyrometallurgical steps, as highlighted in(Blenau et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) should also be prConducting comprehensive life cycle assessments (LCAs) of these innovative methods will help evaluate their environmental and social impacts. The exploration of advanced adsorbents or catalysts for selective REE recovery, as noted in(Barros et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) could open new pathways forrecovery from multi-metal systems.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eClosed-Loop Systems and Biotechnological Solutions for REE Recycling\u003c/strong\u003e \u003cp\u003eFor recycling and reuse, future research must prioritize the development of closed-loop systems with minimal waste generation. Studies like (Vieceli et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) and (Lister et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) have underscored the importance of inteanced sorting and pre-treatment technologies to enhance separation efficiency. AI-driven systems for automated sorting of waste streams could be transformative. Additionally, the long-term economic viability of recovering REEs from spent batteries and industrial byproducts, as explored in (Jang et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), requires deeper analysis. Research into biotecholutions, like protein-based recovery processes described in \u0026ldquo;(Dong et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u0026rdquo;, could offer sustainable alternatives. Standardizing methoross industries, especially for assessing and processing diverse waste types, is crucial to overcoming current ,technological and logistical challenges.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study provides a comprehensive and updated perspective on the metallurgical recovery of Rare Earth Elements (REEs) over the past 14 years, fulfilling three fundamental objectives: (i) capturing the scientific background of research on the metallurgical recovery of REEs by identifying key themes and trends from the last 14 years, (ii) presenting an integrated overview of the existing literature on the topic, and (iii) proposing future directions in the field. To achieve this, a mixed-methods approach was adopted, encompassing bibliometric analysis, text mining, and content analysis applied to a rigorously selected sample of 132 peer-reviewed articles sourced from the Scopus, JSTOR, and Taylor \u0026amp; Francis databases, published between 2010 and 2024. To ensure the quality and relevance of the included studies, filters were applied using the PRISMA method, and additional documents were incorporated through an ad-hoc approach. The findings of this research identified three key areas in the metallurgical recovery of REEs: (1) sustainable extraction methods, (2) innovations in the recovery of REEs, and (3) recycling and reuse of REEs. Regarding future research directions, the study proposes the following lines of investigation to enhance the metallurgical recovery of REEs: Optimization and Integration of Hybrid Processes for Sustainable REE Recovery, Technological Advancements in Selective Recovery and REE Processing y Closed-Loop Systems and Biotechnological Solutions for REE Recycling.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAbaka-Wood, G. B., Johnson, B., Addai-Mensah, J., \u0026amp; Skinner, W. (2022). 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Revisiting sustainable resources in the combustion products of alumina-rich coal: Critical metal (Li, Ga, Nb, and REY) potential of ash from the Togtoh Power Plant, Inner Mongolia, China. \u003cem\u003eScience of The Total Environment\u003c/em\u003e, \u003cem\u003e950\u003c/em\u003e, 175056. https://doi.org/10.1016/j.scitotenv.2024.175056\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"National University of Trujillo","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Rare earths, processing, recovery, bibliometrix, VOSviewer","lastPublishedDoi":"10.21203/rs.3.rs-5868907/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5868907/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis article aimed to comprehensively map research on the metallurgical recovery of rare earth elements (REEs) in the mining industry from 2010 to 2024, identifying key themes, trends, and future directions. Using a mixed-methods approach that included bibliometric analysis, text mining, and content analysis, the study pursued the following objectives: (i) to capture the scientific background of research on the metallurgical recovery of REEs, identifying key themes and trends over the past 14 years, (ii) to provide a comprehensive overview of the existing literature on the topic, and (iii) to propose future directions in this field. A total of 132 peer-reviewed articles were analyzed, sourced from the Scopus, JSTOR, and Taylor \u0026amp; Francis databases, and selected using the PRISMA method and ad hoc sampling. The analysis identified three primary research areas: (1) innovation in rare earth recovery, (2) environmentally friendly metallurgical methods contributing to sustainability, and (3) challenges and perspectives on recycling and reusing rare earth elements. Based on these findings, three future research lines were proposed: Optimization and Integration of Hybrid Processes for Sustainable REE Recovery, Technological Advancements in Selective Recovery and REE Processing y Closed-Loop Systems and Biotechnological Solutions for REE Recycling. These efforts aim to enhance sustainability and optimize resource utilization in the mining industry, promoting practices that contribute to a more responsible, efficient, and sustainable development model for REE recovery.\u003c/p\u003e","manuscriptTitle":"Metallurgical recovery of rare earth elements: A bibliometric analysis and systematic literature review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-23 07:16:08","doi":"10.21203/rs.3.rs-5868907/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cca839db-91f2-4e7b-8a99-d31aec394a53","owner":[],"postedDate":"January 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":43154734,"name":"Metallurgy"}],"tags":[],"updatedAt":"2025-01-23T07:16:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-23 07:16:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5868907","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5868907","identity":"rs-5868907","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}