Life cycle assessment of regeneration technology routes for sintered NdFeB magnets

NdFeB magnetic material constitutes an important strategic material. With the rising demand for rare earth resources, the recycling and utilization of waste NdFeB magnet resources are increasingly considered. The objective of this study was to conduct a life cycle assessment of three regeneration technology routes for sintered NdFeB magnets using actual industrial data to determine the key processes and environmental hotspots of different production processes, thereby providing data support for the clean and sustainable development of the sintered NdFeB magnet industry.

A life cycle assessment was performed according to ISO 14040 to evaluate and recognize the potential environmental impacts of the key processes. Production data for the regeneration technology routes of sintered NdFeB magnets in a typical enterprise in China were collected and investigated. The resource consumption and pollution emissions during production via three regeneration technology routes from a life cycle perspective were comprehensively evaluated using the ReCiPe 2016 method. The evaluation results were compared to those obtained with virgin materials, thereby identifying the key environmental impact categories and sub-process contributions. In addition, the effects of various input parameters on the environmental burden were specified through sensitivity analysis. Accordingly, suggestions for improving the environmental performance of NdFeB magnet production were proposed.

The LCA results confirmed that the environmental impacts of NdFeB magnets produced by regeneration technology routes (scenarios 1, 2, and 3) are lower than those of virgin sintered NdFeB magnets (baseline scenario). The damages to the three endpoint indicators (human health damage, ecosystem damage, and resource damage) in scenario 2 were the lowest, at 71.07%, 79.35%, and 84.35% lower, respectively, than those in the baseline scenario, mainly due to the minimal use of virgin rare earth elements and the selection of recovery technology. Sensitivity analysis of the input parameters revealed that the environmental impacts of NdFeB magnets were very sensitive to the raw materials (Pr-Nd alloy or iron) and electricity consumption.

The results showed that the preparation of rare earth metals and power consumption were major contributors to the observed environmental impacts during NdFeB magnet production. Therefore, improving the recovery rate of rare earth metals and using clean electricity play important roles in reducing the environmental load. The results of this study provide data support for improving clean production technologies for sintered NdFeB magnets and potentially analyzing rare earth resource supplies.