Effect of Scrap Size on Extraction of Neodymium from Nd-Fe-B Magnet Scrap by Liquid Metal Extraction

Abstract: The effects of Nd-Fe-B magnet scrap size on extraction behavior were investigated by liquid metal extraction using molten Mg. The magnet scraps with Mg were placed into a stainless steel crucible and then heated to 1,073K for 10 to 50min. The amount of ex-tracted Nd after liquid metal extraction process was increased with an increasing with holding time and scrap size, and the maximum con-tents of Nd in Mg were observed to be about 24.2 wt.% in the conditions of the 5mm sized scrap heated for 50min. It was revealed that Nd oxides existing in the magnet scraps prevent the dissolution of Nd into Mg. Keywords: Extrusion rate, liquid metal extraction, magnesium, Nd-Fe-B magnet, neodymium,. INTRODUCTION Neodymium (Nd)-based magnet materials have emerged as leaders in high-field permanent magnet applications. Since the de-velopment of the iron–neodymium–boron (Nd-Fe-B) permanent magnet in 1980, the production volume of Nd metal has increased dramatically. On the other hand, large amounts of scrap from the Nd-Fe-B magnets are being stockpiled due to the lack of a cost-effective recycling process. Thus, it is crucial to develop a recycling process for the Nd-Fe-B magnets [1-4]. Among the reported, the best separation of rare-earths from the Nd-Fe-B magnets is obtained by sulfuric acid dissolution followed by precipitation of recyclable rare-earth salts [5-7]. However, this process produces large amounts of wastewater including dangerous solutions. Recently, Xu