All fluorescent lights contain small amounts of mercury and rare earth metals. There is a need to safely remove and recycle mercury and rare earth elements from used fluorescent lamps in order to keep the valuable and potentially poisonous metals out of the environment and aid the domestic recovery of critical materials. Conventional processes include heating and distillation to volatilize the mercury and do not include an adequate process to refine the individual rare earth components. In order to optimize the recyclability of fluorescent lights a process is needed that doesn't incorporate the volatilization of mercury and a process to refine and separate the various rare earth elements contained within the phosphor composition.
The invention is an integrated method to more safely seperate and remove mercury and rare earth elements from fluoresecent light bulbs without the need for volatilizing the mercury.
Process steps include:
1. Separation of the phosphor powder from glass via ultrasonics;
2. Separation of mercury from phosphor powder;
3. Separation of rare earths from phosphor matrix via oxidation/reduction and acid/base mechanisms;
4. Novel on-line method to refine rare earths.
Rare earths are extracted from the phosphor matrix using a supercritical fluid extraction process with carbon dioxide, mineral acids, acid adducts and metal complexing agents. Additional refining to separate dissolved rare earths into individual fractions is used to provide rare earth products. Each step in the process is integrated and can be run in batch, semi-batch or continuous-flow mode for the recovery of mercury and rare earths.
INL Technology ID: BA-852
Patent Publications: https://patents.google.com/patent/US20180119251A1/
Applications and Industries
- Does not require volatilization of mercury
- Integrated process to remove and refine rare earths and mercury
- Can be run as on-line continuous process