Multi-Layer Ceramic Capacitors in Lighting Equipment: Presence and Characterisation of Rare Earth Elements and Precious Metals

Abstract

The need to reduce energy consumption in buildings, the emergence of light-emitting diode (LED) lamps in lighting around 2010, their long lifetime, and the 2025 target to use only LED lamps are changing the existing composition of Category 3 waste electrical–electronic equipment (WEEE) and creating expectations for simple, high-concentration recycling streams. In this study, multi-layer ceramic capacitors (MLCCs) detached from the lighting sector’s WEEE were characterised for the presence of rare earth elements (REEs) and precious metals (PMs). Their digestion was carried out with HNO3 and aqua regia on a heating plate and characterised using inductively coupled plasma optical emission spectroscopy (ICP-OES) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The contents of REEs and PMs found in the MLCCs were 0.84 wt% and 0.60 wt%, respectively, and create an economic stored value that is essentially defined by PMs of 98.67% and by palladium (Pd) of 78.37%. The analysis showed that the content of the main elements was: neodymium (Nd) 0.366 wt%, yttrium (Y) 0.220 wt%, dysprosium (Dy) 0.131 wt%, silver (Ag) 0.467 wt%, and Pd 0.105 wt%. These results indicate the need for selective removal and separate recycling processes of MLCCs from WEEE drivers.

Keywords

• measurements and characterisation
• lighting equipment
• multi-layer ceramic capacitors
• rare earth elements
• precious metals
• inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis