Effect of Magnet Scrap Size on the Extraction Behavior of Heavy Rare Earth Elements by Liquid Metal Extraction

Liquid metal extraction (LME) process results in 100% neodymium (Nd) extraction but the highest extraction efficiency reportedfor Dysprosium (Dy) so far is 74%. Oxidation of Dy is the major limiting factor for incomplete Dy extraction. In order to enhance the extraction efficiency and to further investigate the limiting factors for incomplete extraction, experiments were carried out on six different particle sizes of under 200 μm, 200-300 μm, 300-700 μm, 700-1000 μm, 1000-2000 μm and over 2000 μm at 900°C with magnesium-to-magnet scrap ratio of 15:1 for 6, 24 and 48 hours, respectively. This research identified Dy₂ Fe₁₇ in addition toDy₂ O₃ phase to be responsible for incomplete extraction. The relationship between Dy₂ Fe₁₇ and Dy₂O₃ phase was investigated, and the overall extraction efficiency of Dy was enhanced to 97%.