Neodymium as the main feature of permanent magnets from hard disk drives (HDDs)

摘要

As a way to manage neodymium-iron-boron (NdFeB) magnets wasted in end-of-life hard disk drives (HDDs), a waste characterization is needed prior to a recycling process. Due to their magnetic properties, NdFeB magnets are essential in technological applications nowadays, thus causing an increase in the industrial demand for rare earth metals. However, these metals have a short supply, since they are difficult to obtain from ores, creating a critical market. In this work, a study of the characterization of sintered neodymium-iron-boron magnets was undertaken by qualitatively and quantitatively uncovering the neodymium recovery potential from this type of electronic waste. From the collection and disassembly of hard disk drives, in which the magnet represents less than 3% of the total weight, an efficient demagnetization process was proceeded at 320 ℃. Then, the magnet was ground and screened for an X-ray diffraction (XRD) analysis, which showed the Nd_2Fe_(14)B tetragonal phase as the dominant constituent of the sample. An analysis was also carried out in a scanning electron microscope (SEM) and an inductively coupled plasma optical emission spectrometer (ICP-OES), where the magnet composition showed 21.5 wt% of neodymium and 65.1 wt% of iron, among other chemicals. This Nd content is higher than the one found in Nd ores, enhancing the recyclability and the importance of waste management.