Sulfation–Roasting–Leaching–Precipitation Processes for Selective Recovery of Erbium from Bottom Ash

Bottom ash (BA) is mainly composed of compounds of Al, Fe, Ca, and traces of rare earth elements (REEs). In this study, the selective recovery of erbium (Er) as REEs by means of sulfation–roasting–leaching–precipitation (SRLP) using BA was investigated. A pre-treatment process of sulfation and roast...

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Bibliographic Details
Published in:Sustainability 2019-06, Vol.11 (12), p.3461
Main Authors: Ponou, Josiane, Garrouste, Marisol, Dodbiba, Gjergj, Fujita, Toyohisa, Ahn, Ji-Whan
Format: Article
Language:English
Subjects:
Aluminum
Ammonium
Ash removal
Bottom ash
Calcium
Chromium
Coal
Copper oxides
Erbium
Food processing
Heavy metals
Iron oxides
Leaching
Lime
Metal concentrations
Metal oxides
Metals
Oxalic acid
Oxides
Researchers
Roasting
Salts
Solvent extraction processes
Sulfation
Sulfation roasting
Sustainability
Temperature
Trace elements
Waste management
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Summary:Bottom ash (BA) is mainly composed of compounds of Al, Fe, Ca, and traces of rare earth elements (REEs). In this study, the selective recovery of erbium (Er) as REEs by means of sulfation–roasting–leaching–precipitation (SRLP) using BA was investigated. A pre-treatment process of sulfation and roasting of BA was developed to selectively recover REEs using ammonium oxalate leaching (AOL) followed by precipitation. Most of the oxides were converted to their respective sulfates during sulfation. By roasting, unstable sulfates (mostly iron) decomposed into oxides, while the REE sulfates remained stable. Roasting above 600 °C induces the formation of oxy-sulfates that are almost insoluble during AOL. Dissolved REEs precipitate after 7 days at room temperature. The effects of particle size, roasting temperature, leaching time, and AOL concentration were the important parameters studied. The optimal conditions of +100–500 μm particles roasted at 500 °C were found to leach 36.15% of total REEs in 2 h 30 min and 94.24% of the leached REEs were recovered by precipitation. A total of 97.21% of Fe and 94.13% of Al could be separated from Er.
ISSN:2071-1050
2071-1050
DOI:10.3390/su11123461