Design and Optimization of Processes for Recovering Rare Earth Elements from End-of-Life Hard Disk Drives

Abstract

As the United States continues efforts to decarbonize the power and transportation sectors, significant challenges associated with the reliance of clean energy technologies on rare earth elements (REEs) will have to be overcome. One potential approach for increasing the supply of these elements is to extract REEs from end-of-life (EOL) hard disk drives (HDDs). HDDs contain neodymium and praseodymium, which are among the most important REEs for the clean energy transition, as they are crucial to producing the permanent magnets needed for wind turbines and electric vehicles. Here, we propose a superstructure-based approach to find the optimal pathway for recovering REEs from EOL HDDs. The superstructure was optimized by maximizing the net present value (NPV) over 15 years. Projected prices for commercial rare earth oxides and the projected amount of EOL HDDs in the U.S. were estimated and used in the model. These projections were used to establish the base case optimal result, assuming that the plant recycles 60% of personal computers EOL HDDs in the U.S. each year. The model was then expanded to consider the recycling of EOL HDDs generated before the beginning of plant production. Next, a sensitivity analysis was conducted to evaluate the impact of different parameters on the venture's profitability and the optimal processing pathway. Combined, these results offer both valuable insights into the economic viability of REE recycling extraction and a method for performing similar analyses in the future.