Selective recovery of neodymium from oxides by direct extraction method with supercritical CO sub 2 containing TBP-HNO sub 3 complex

• Published in: Separation science and technology Vol. 37; no. 5; pp. 1153 - 1162
• Main Authors: Tomioka, O, Enokida, Y, Yamamoto, I
• Format: Journal Article
• Language: English
• Published: 01.03.2002
• ISSN: 0149-6395

A method for the direct extraction of a metal utilizing supercritical CO sub 2 containing tri-n-butylphosphate (TBP)-HNO sub 3 (TBP), which is the TBP solution of TBP-HNO sub 3 complex, has been developed for the recovery of Nd from its oxide. This method was applied using a flow reactor to several oxides (Nd sub 2 O sub 3 , ZrO sub 2 , MoO sub 3 , and RuO sub 2 ), and binary mixtures of the oxides (Nd sub 2 O sub 3 -ZrO sub 2 , Nd sub 2 O sub 3 -MoO sub 3 , and Nd sub 2 O sub 3 -RuO sub 2 ). Neodymium (Nd) was extracted almost quantitatively from 0.01 mol Nd sub 2 O sub 3 powder with supercritical CO sub 2 containing TBP-HNO sub 3 (TBP) at 313K and 12 MPa, while Zr, Mo, and Ru were hardly extracted from their oxides and remained in the reactor. Nd was extracted quantitatively and selectively also from the binary mixtures of the oxides. From these results, it is found that the supercritical CO sub 2 extraction process using TBP-HNO sub 3 (TBP) as reactant is feasible for the selective recovery of lanthanides directly from the various oxide mixtures.