Chapter 15 - Rare earth metal recovery from typical e-waste

Abstract

Rare earth elements (REEs) are used in a wide range of products. The global demand for REEs is growing at a rate of 3.7–8.6% annually. Yttrium (Y), europium (Eu), cerium (Ce), lanthanum (La), and terbium (Tb) are used in the phosphors for fluorescent lamps (FLs). The authors review the challenges and techniques associated with the recycling and recovery of REEs in phosphors from waste FLs. The recovery rate and grade of resultant products and the processing costs are the primary factors to be considered regarding trichromatic phosphors enrichment and monochrome phosphor separation. Currently, most researchers have focused on the recovery of Y and Eu from red phosphor using hydrometallurgy methods, and on the difficulties of leaching Ce, La, Tb, and Eu in green and blue phosphors. The final recovery rate of Y and Eu can reach more than 80%, but a higher rate is desirable, considering the total value of the REEs in FLs. Studies on improving the leaching behavior of phosphors have been conducted; however, they present problems such as energy and agents consumption, and generation of viscous solution of silicate. Some pyrometallurgy and electrometallurgy approaches are also discussed.