CHARACTERISATION OF PERMANENT MAGNETS FROM WEEE

Nour-Eddine Menad (1) , Alain Seron (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

The increasing use of rare earths elements in a number of recent technological innovations led to a rapid increase in (plus 50% in the last decade) of their applications. Europe is one of the most important regions of consumption of these substances. In this context, Europe in its 'Raw materials' strategy puts the recycling at the center of its concerns to provide a part of securing its supplies in rare earth elements. Recycling of these substances, on an industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources. This paper will present some results obtained from characterization study of permanent magnets present in wastes of electric and electronic equipment. Three different electronic components containing magnets are identified: hard dick drives, small electric motors and speakers. Several kilograms of theses wastes have been sampled at recycling plant. The representative sample has been dismantled manually to recover the magnets contained to quantify the amount of magnets in the investigated components. Thorough characterization results show that the weight percentage of magnets varies in the three investigated electronic components: 4 6% in the speakers, 2.5-2.8% in the hard disks, and between 0.8 and 2% in some electric motors. The results of the thermal treatments of the magnets of the investigated samples show that the majority of these magnets lose their magnetic property upon reaching Curie temperature (300-400° C) in 15-20 minutes. Scanning Electronic Microscopy (SEM) reveals the morphological aspects of these magnets which consist in crystals shaped tetrahedral phase Nd 2 Fe 14 B sintered in the presence of the interphase rich in rare earths elements (Nd, Dy and Pr). The magnetsare layer coated with 20 µm thick. This layer consists in Ni, Zn or metals alloys. The chemical composition of some magnets obtained from EDS is close to theoretical composition of the standard magnet.

Keywords: Waste of electric and electronic equipments; magnets; thermal treatment; characterization

Domains: Chemical and Process Engineering

Nour-Eddine Menad, Alain Seron. CHARACTERISATION OF PERMANENT MAGNETS FROM WEEE. 6th International Conference on Engineering for Waste and Biomass Valorisation , May 2016, Albi, France. ⟨hal-01298267⟩