This study investigated whether calcium (Ca) addition improved the recovery of neodymium (Nd) and dysprosium (Dy) from Nd-Fe-B magnet scrap using magnesium (Mg)-based liquid metal extraction (LME). Traditional LME processes are limited to temperatures up to 850 °C due to oxidation issues, reducing the efficiency of rare earth element (REE) recovery, especially for Dy. By adding 10 wt.% Ca to Mg and increasing the processing temperature to 1,000 °C, we achieved nearly 100% Nd and approximately 38% Dy recovery, compared to 91% and 28%, respectively, with pure Mg at 850 °C. However, excessive Ca addition (20 wt.%) decreased the recovery efficiency due to the formation of stable intermetallic compounds. These results highlight the critical role of Ca in optimizing REE recycling from Nd-Fe-B magnet scrap.

1. Introduction 
2. Experimental Procedure 
    2.1. Materials 
    2.2. Sample Preparation 
    2.3. Liquid Metal Extraction 
    2.4. Sample Analysis 
3. Results and Discussion 
    3.1. REE Extraction with Mg and Mg-Ca Alloys 
    3.2. Effect of Temperature and Holding Time 
    3.3. Mechanism of REE Oxide Reduction by Calcium 
    3.4. Comparison with Previous Studies 
    3.5. Implications and Future Work 
4. Conclusion 
Funding
Conflict of Interest  
Data Availability Statement 
Author Information and Contribution 
Acknowledgement
References

• Hyoseop Kim(Korea Institute of Industrial Technology, 156, Gaetbeol-ro, Yeonsu-gu, Incheon, 22099, Republic of Korea) Corresponding author