Identification of mercury species in spent fluorescent lamps and mercury recovery by distillation

Abstract

The discarding of spent fluorescent lamps, one of the most significant sources of mercury usage in industry, might cause mercury release into the environment when suffering from breakage. The reclamation disposal of fluorescent lamps for mercury recycling is essential, while how to achieve highly efficient conversion of various mercury species into elemental mercury vapor is a key challenge. Herein, the distillation method was adopted for mercury recycling from phosphor powder. The results show that the contents of elemental mercury and oxidized mercury vapor filled in the lamps were 150–3500μg and 5–20μg, respectively. The mercury release sustained for 13(±2) h, with a maximum mercury concentration of 4500μg/m3. The mercury in phosphor can be desorbed to an undetected level when distilling at 600 °C under vacuum for 30 min, while that would be achieved at 700 °C when distilling under atmospheric pressure. This suggests that the vacuum distillation was favorable for the conversion of oxidized mercury into elemental mercury. The variation of mineral phase, particle size distribution and morphology of phosphor after distillation was insignificant, which guaranteed the recycling of phosphor simultaneously accompanying with mercury recycling. This work clarified the mercury release behavior during lamps crushing and provided a feasible way for mercury recycling.