Discovery of ion-adsorption type deposits of rare earth elements (REE) in Southwest Japan with speciation of REE by extended X-ray absorption fine structure spectroscopy

• Yamaguchi Akiko

  Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

• Honda Tasuku

  Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

• Tanaka Masato

  Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

• Tanaka Kazuya

  Advanced Science Research Center, Japan Atomic Energy Agency

• Takahashi Yoshio

  Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

Abstract

Ion-adsorption type rare earth elements (REE) deposit in weathered granite is the main source of REE essential for high-technology industries. However, this type deposit has not been well surveyed in Japan. In this study, Bulk REE abundances (=REE_TOT), ion-exchangeable REE (=REE_EX) by ammonium chloride solution, and percentage of REE_EX relative to REE_TOT (=REE_PER) in fresh and weathered granite samples in Southwest Japan (i.e., Hiroshima and Shimane Prefectures) were determined. The REE_TOT and REE_PER were comparable to those of ion-adsorption type REE deposits in China. This finding indicates that ion-adsorption type REE deposits can also be found in Japan. Furthermore, extended X-ray adsorption fine structure (EXAFS) spectra of yttrium in original samples and samples after the extraction of ion-exchangeable REE showed that (i) REE in samples with high REE_PER mainly forms outer-sphere (OS) complexes and (ii) the remaining REE in the rocks after the extraction forms inter-sphere complexes. These findings suggest that ion-exchangeable REE forms OS complexes, which causes the high extraction rate by the ion-exchange reaction.

Journal

• GEOCHEMICAL JOURNAL

  GEOCHEMICAL JOURNAL 52 (5), 415-425, 2018-09-28

  GEOCHEMICAL SOCIETY OF JAPAN

Keywords

• REE
• EXAFS
• surface complex
• weathered granite
• ion-adsorption type deposit

Details

• CRID: 1390001288076421504
• NII Article ID: 130007495990
• NII Book ID: AA00654975
• DOI: 10.2343/geochemj.2.0531
• ISSN: 18805973
• ISSN: 00167002
• NDL BIB ID: 029401187
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I029401187
• Web Site: https://www.jstage.jst.go.jp/article/geochemj/52/5/52_2.0531/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed