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Open AccessArticle

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

1
Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2
MINES ParisTech—PSL Research University, Rue Claude Daunesse, F-06904 Sophia Antipolis CEDEX, B.P. 207 1 Paris, France
3
School of Resources, Environment and Materials, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China, [email protected]
4
Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahang-no, Yuseong-gu, Daejeon 305-350, Korea
*
Author to whom correspondence should be addressed.
Sustainability 2019, 11(12), 3461; https://doi.org/10.3390/su11123461
Received: 8 April 2019 / Revised: 18 June 2019 / Accepted: 20 June 2019 / Published: 24 June 2019
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. View Full-Text
Keywords: bottom ash; sulfation; roasting; oxalic acid; rare earth; erbium; secondary raw material bottom ash; sulfation; roasting; oxalic acid; rare earth; erbium; secondary raw material
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Ponou, J.; Garrouste, M.; Dodbiba, G.; Fujita, T.; Ahn, J.-W. Sulfation–Roasting–Leaching–Precipitation Processes for Selective Recovery of Erbium from Bottom Ash. Sustainability 2019, 11, 3461.

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