TY - JOUR
T1 - Mechanism and kinetics of enhancement of cerium dissolution from weathered residual rare earth ore by planetary ball milling
AU - Kato, Tatsuya
AU - Granata, Giuseppe
AU - Tsunazawa, Yuki
AU - Takagi, Tetsuichi
AU - Tokoro, Chiharu
N1 - Funding Information:
The synchrotron radiation experiments were performed using a BL5S1 beamline courtesy of the Aichi Synchrotron Radiation Center, Aichi Science & Technology Foundation, Aichi, Japan (Proposal No. 201801021), and a BL14B2 beamline of SPring-8, with the approval of the Japan Synchrotron Radiation Research Institute (Proposal No. 2018A1696 & No. 2018A1798). Part of this work was performed as a component of the activities of the Research Institute of the Sustainable Future Society, Waseda Research Institute for Science and Engineering, Waseda University. We thank Kathryn Sole, PhD, from Edanz Group (www.edanzediting.com/ac) for English editing a draft of this manuscript.
Publisher Copyright:
© 2019
PY - 2019/4
Y1 - 2019/4
N2 - This study addressed the enhancement of cerium dissolution from weathered residual rare earth ore by mechanochemical activation by planetary ball milling. The activation mechanism was elucidated using cerium L III -edge x-ray absorption fine structure (XAFS) analysis to evaluate the effect of planetary ball milling on the crystal structure of the cerium minerals and phase composition of the ore. Leaching experiments were performed to investigate the influence of mechanochemical activation on leaching kinetics and extent of cerium dissolution. The leaching kinetics were performed using the shrinking core model in conjunction with an innovative approach based on cerium L III -edge XAFS analysis to resolve the independent leaching curves of tri- and tetravalent cerium. Planetary ball milling induced reduction of tetra- to trivalent cerium and resulted in increased cerium dissolution from weathered residual rare earth ore. Leaching results and specific surface area measurements highlighted that cerium dissolution was enhanced not only by the increase in surface area of the ore, but also by mechanochemical reaction. When the ore was grinding by planetary ball mill, the rate-determining process of leaching changed from chemical reaction to diffusion control and the leaching rate constants decreased, indicating the main mechanism of enhancement of cerium dissolution was reduction of tetravalent cerium.
AB - This study addressed the enhancement of cerium dissolution from weathered residual rare earth ore by mechanochemical activation by planetary ball milling. The activation mechanism was elucidated using cerium L III -edge x-ray absorption fine structure (XAFS) analysis to evaluate the effect of planetary ball milling on the crystal structure of the cerium minerals and phase composition of the ore. Leaching experiments were performed to investigate the influence of mechanochemical activation on leaching kinetics and extent of cerium dissolution. The leaching kinetics were performed using the shrinking core model in conjunction with an innovative approach based on cerium L III -edge XAFS analysis to resolve the independent leaching curves of tri- and tetravalent cerium. Planetary ball milling induced reduction of tetra- to trivalent cerium and resulted in increased cerium dissolution from weathered residual rare earth ore. Leaching results and specific surface area measurements highlighted that cerium dissolution was enhanced not only by the increase in surface area of the ore, but also by mechanochemical reaction. When the ore was grinding by planetary ball mill, the rate-determining process of leaching changed from chemical reaction to diffusion control and the leaching rate constants decreased, indicating the main mechanism of enhancement of cerium dissolution was reduction of tetravalent cerium.
KW - Cerium
KW - Mechanochemical reaction
KW - Rate-determining process
KW - Shrinking core model
KW - Weathered residual rare earth ore
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U2 - 10.1016/j.mineng.2019.02.017
DO - 10.1016/j.mineng.2019.02.017
M3 - Article
AN - SCOPUS:85061618690
SN - 0892-6875
VL - 134
SP - 365
EP - 371
JO - Minerals Engineering
JF - Minerals Engineering
ER -