Recovery of Neodymium from Spent Neodymium Magnets Using “Dry Aqua Regia”

Neodymium (Nd), a rare earth element (REE), is mainly used for strong permanent magnets. These magnets are important for vehicles, computers, and other broad fields. Most REEs including Nd are mined in China and the supply is unstable. On the other hand, the recycling of REEs, especially Nd, is not conducted industrially mainly because of their low price and the cost of the recycling processes. Considering the sustainable supply and reduction of the environmental impact of REEs mining, an effective recycling procedure from spent magnets is required. The authors have developed a novel recycling process of REEs using “dry aqua regia.” This is a molten salt consisting of ferric chloride (FeCl3) and potassium chloride (KCl) and has already been applied for the recycling of platinum group metals (PGMs). In this study, the authors applied this dry aqua regia for the chlorination of REEs in magnet scraps and recovered REEs as oxalic compounds. As a result, we succeeded in the chlorination of REEs contained in spent magnets and the selective recovery of Nd by the addition of oxalic acid. The recovery ratio of Nd was up to 79.0%. These results suggest that the procedure using “dry aqua regia” can be an effective recovery process of REEs from magnet scraps.