Research on Hard Drives in the Context of the Construction of Shredding Knives in the Recovery of Rare Earth Elements

The publication presents an inventory of waste electrical and electronic equipment (WEEE) equipped with neodymium (NdFeB) magnets, which, when decommissioned, will be able to become a source of REE procurement. These magnets contain Rare Earth Elements (REEs) such as neodymium, dysprosium and praseodymium. Products equipped with NdFeB magnets have been identified: computer hardware, consumer electronics, wind power generators, and electric-powered vehicles. A prospective source of REE acquisition could be HDDs and speakers in laptops and phones, which account for about 10% of the analysed equipment containing NdFeB magnets. A study of the selected WEEE—hard disk drive in terms of material properties was carried out. The following analyses were performed: phase composition studies (XRD), microstructure studies (SEM–EDS), micro-area chemical composition studies (S/TEM) and hardness studies. Based on the studies, the material for the cutting knives of the twin-shaft shredder was selected. Three variants of cutting knives differing in the number of blades on the perimeter were developed in Autodesk Inventor 2023. Variants with three, four and five blades were considered. Strength calculations were then carried out using the Nastran plug-in. A force was applied to the cutting knife blades, from which von Mises stresses and strains were determined.