Extraction of rare earth elements from their oxides using organophosphorus reagent complexes with HNO₃ and H₂O in supercritical CO₂

段五华，曹丕佳，朱永(贝睿)

Institute of Nuclear and New Energy Technology,Tsinghua University

摘 要：Direct extraction of metals from solids with complexing agents in supercritical CO2（SC-CO2） has recently attracted interests in separation,purification,recovery,and analysis of metals.In the present study,the static/dynamic extraction of rare earth elements（Nd,Ce） from their oxides（Nd2O3,CeO2） with organophosphorus complexes with HNO3 and H2O in SC-CO2 was investigated.The static extraction efficiency of Nd from Nd2O3 with the tri-n-butylphosphate（TBP）-HNO3 complex could reach 95% under optimized experimental conditions.However,the static extraction efficiency of Nd from Nd2O3 with the trilkyl phosphine oxide（TRPO）-HNO3 complex was less than 10%,and the static extraction efficiency of Ce from CeO2 with the TBP-HNO3 complex was less than 1%.The dynamic extraction efficiency of Nd from Nd2O3 with the TBP-HNO3 complex could reach more than 97%.Effects of parameters were evaluated on the extraction efficiency to ascertain the optimum conditions.This study illustrated the extraction process using the TBP-HNO3 complex in SC-CO2 would be feasible for separation,purification,recovery,and analysis of some rare earth elements from various oxide mixtures.

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