Mapping Rare Earth Element Distribution in MSWI Ash Using Physical Separation and Sequential Extraction

Area of Science:

• Environmental Science
• Geochemistry
• Materials Science

Background:

• Growing global demand for rare earth elements (REEs) necessitates exploring secondary resources.
• Anthropogenic waste streams, like municipal solid waste incineration (MSWI) ash, are potential sources of REEs.

Purpose of the Study:

• To characterize the distribution and speciation of REEs in Korean MSWI bottom ash (BA) and fly ash (FA).
• To investigate REE behavior across different particle sizes and magnetic fractions.
• To assess REE leachability and chemical associations within the ash matrix.

Main Methods:

• Particle size fractionation and magnetic separation of BA and FA.
• Sequential extraction analysis to determine REE speciation and leachability.
• Inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD) for elemental and mineralogical analysis.

Main Results:

• REEs are concentrated in magnetic fractions and coarser particle sizes of both BA and FA.
• Light rare earth elements (LREEs) are dominant across all fractions.
• REES are primarily associated with stable mineral phases, with limited labile fractions.

Conclusions:

• MSWI ash contains REEs, predominantly in stable mineral forms within specific fractions.
• Understanding REE distribution and speciation is crucial for assessing their recovery potential.
• Further research is needed on REE mobilization from MSWI ash.