GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
Special Issue: Front Edge of Submarine Mineral Resources Research in Japan
Chemical leaching of rare earth elements from highly REY-rich mud
Yutaro TakayaKoichiro FujinagaNaoya YamagataSyuhei ArakiRyota MakiKentaro NakamuraKoichi IijimaYasuhiro Kato
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2015 Volume 49 Issue 6 Pages 637-652

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Abstract

Seafloor sediment rich in rare earth elements and Y (REY-rich mud) has received attention as a new resource for REY. During research cruise KR13-02 of R/V Kairei, mud containing more than 5,000 ppm total REY was collected near Minamitorishima Island, northwestern Pacific Ocean. We conducted a series of chemical leaching experiments on this material, varying the acid concentrations, leaching times, and temperature to determine the optimum conditions of REY leaching from REY-rich mud. The highest extraction efficiency of REY other than Ce was 95.1% using hydrochloric acid and 81.3% using sulfuric acid. Extraction efficiency of REY was highest under conditions of relatively low acid concentrations (0.25–0.5 mol/L), short leaching times (2–5 min), and room temperature (25°C). REY extraction amount decreased with increasing acid concentration, leaching time (only in the case of sulfuric acid), and temperature, apparently because of precipitation of calcium sulfate, rare earth phosphate, and rare earth-Na double sulfate. Although further research is needed, the leaching properties we determined are generally favorable for industrial exploitation of REY-rich mud.

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© 2015 by The Geochemical Society of Japan
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