Optimized elemental analysis of fluorescence lamp shredder waste

Area of Science:

• Environmental Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Fluorescent lamps are rich in rare earth elements (REE), vital for many technologies.
• Current recycling rates for REE from spent lamps are below 1%, indicating a significant recovery gap.
• Accurate elemental analysis is essential for optimizing REE recovery processes.

Purpose of the Study:

• To evaluate different microwave-assisted digestion methods for analyzing REE and trace metals in fluorescent lamp waste.
• To identify the most effective digestion reagent mixture for comprehensive elemental recovery.
• To quantify REE concentrations in a representative fluorescent lamp shredder sample.

Main Methods:

• Microwave-assisted digestion of fluorescent lamp shredder using seven different reagent mixtures.
• Analysis of 25 key elements, including REE and trace metals, in the digested samples.
• Comparison of digestion efficiency based on elemental recovery rates.

Main Results:

• A digestion mixture of perchloric, nitric, and hydrofluoric acids, along with aqua regia, proved most effective for analyzing 23 out of 25 elements.
• The concentrations of key REE in the lamp shredder were determined (e.g., Yttrium: 10.2 g/kg, Lanthanum: 12.1 g/kg, Cerium: 7.77 g/kg).
• Tin (Sn) and Terbium (Tb) were exceptions, not optimally recovered by the tested acid mixtures.

Conclusions:

• Optimized acid digestion methods are critical for accurate elemental analysis in fluorescent lamp recycling.
• The developed methods facilitate improved monitoring and efficiency in REE recovery from waste.
• Further refinement may be needed for complete recovery of all elements, such as Sn and Tb.