Evaluating Upstream Processing Strategies for Rare Earth Element Recovery from NdFeB Waste Magnets: A Comparative Technoeconomic and Environmental Analysis

Abstract

The production of rare earth elements (REEs) from secondary resources such as permanent magnets is an excellent advancement of a circular economy. This study evaluates four upstream processing approaches, each addressing REE extraction and impurity removal through physical and chemical methods. A comparative study of technoeconomic analysis and life cycle assessment reveals substantial differences in both economic and environmental impacts. The hydrogen decrepitation-associated process is the least favorable due to its high electricity consumption, resulting in the highest environmental footprint and operational costs. In contrast, the hydrothermal process emerges as the most sustainable and cost-effective option, exhibiting the lowest greenhouse gas emissions (8.8 kg CO₂-eq per kg REE salt), the shortest payback period (0.8 years), and the highest return on investment (187.1%). The cash flow analysis over the plant’s lifetime confirms that, in the best-case scenario, achieving a net positive cash flow of $41 million is possible over 13 years. These results are valuable insights for upstream approaches prior to industrialization.