Investigation on the status of rare earth elements contained in the powder of spent fluorescent lamps

• Most of rare earth elements are contained in particles of size finer than 7 μm.
• Most of Si, K and Na are contained in the coarser size-fractions.
• The phases in the size-fractions of the fluorescent powder have been determined.
• Europium is contained in yttrium oxide and in vanadium–yttrium oxides.
• The crystallo–chemical composition of all the phases has been determined.

The aim of this study is to examine the status of rare earth elements (REE) contained in the chemical compounds that make up the powder of spent fluorescent lamps, with a view of their recovery.The status of REE in the as-received powder, as well as in a few size-class fractions of it, has been established. This way, only those size-class fractions containing high REE concentrations can be considered in a recovery process. The investigation has been carried out using particle-size, chemical, TGA/DTA, XRPD, SEM-EDS and EMPA analyses. The last technique enabled to establish the status of REE within the lattice of the chemical compounds present in the powder. The fineness of the as-received powder and the higher REE concentration in the finest size-classes suggest that physical methods of separation should not be used to separate the REE-containing chemical compounds from each other. Leaching methods seem more suitable with a material of such size.