Material Flow Analysis based Multidimensional Sustainability Assessment for Resources Circularity: Case of Neodymium

Material Flow Analysis (MFA), as a robust systematic assessment tool, is crucial for understanding the sustainability of critical materials. As an emerging critical material, neodymium (Nd) becomes increasingly significant, especially for vehicle electrification and clean energy transition. Despite Nd being identified the criticality by many countries and organizations, the recycling rate of this element remains alarmingly low. MFA offers valuable insights into material cycles but predominantly focuses on the resource aspect. Achieving complete circularity, especially for critical materials like Nd, demands a comprehensive understanding of the entire value chain evolution rather than only from the resource aspect. To address this challenge, this study focuses on achieving Nd circularity through multidimensional sustainability assessments.

The study was initiated by establishing a general framework for multidimensional sustainability assessments based on the principles of material cycles. Building upon the system definition of MFA, the framework integrates technological, economic, and engineering performances along the Nd value chain. This systematic MFA-based framework is applied to assess Nd in the resource, technological, economic, and recycling engineering dimensions by integrating methods like dynamic MFA models, text-mining patent analysis and bibliometric analysis.

The resource assessment mapped the global Nd cycles from 1990 to 2020, unveiling essential patterns and challenges in the Nd industry. China’s dominance in Nd production, coupled with challenges in end-of-life product recovery, highlights the complexities and disparities in the global Nd industry. The huge recycling potentials of Nd were also identified. These findings emphasize the need for strategic interventions to ensure sustainable Nd management and circularity through large-scale recycling.

 Moving to technological and economic assessments, the study unveils the dominance of material flows, monetary values, and technological innovation throughout the Nd value chain. Notably, the integration of Material-Value-Technology (MVT) aspects highlights the potential influence of technology on value and materials. The study showcases the correlation between technological innovation and material production or consumption across regions, emphasizing China’s robust synergy and unique dynamics in Japan, the US, Europe, and the Rest of the World. These insights are critical for understanding the global Nd industry’s evolution, driving technological advancements, and optimizing economic value.

In the recycling engineering assessment, the study identifies key barriers hindering Nd and NdFeB magnet recycling. Challenges are comprehensively categorized into resource, product, technological, economic, environmental, and social aspects. Technological innovation emerges as a pivotal solution, prompting the proposal of comprehensive countermeasures. These strategies include promoting technological advancements, enforcing regulations and policies, facilitating the transition to high-value-added product production, standardizing product design for sustainability, and fostering global collaboration. These measures collectively strive to advance NdFeB magnet recycling sustainably, significantly contributing to Nd circularity efforts.

The findings provide crucial insights into the global Nd industry evolution, offering practical implications for achieving Nd circularity. The general MFA-based multidimensional assessment framework can be also expanded to assess diverse dimensions (e.g., environmental or social) and industries for sustainable resource management. Achieving material circularity remains multidimension significant challenges. The study appeals to the crucial need for collaboration among diverse stakeholders, including policymakers, industry players, and academia, spanning various regions and countries. Only through enhanced cooperation can the complete circulation of critical materials be realized.