TY - JOUR
T1 - An environmentally friendly electro-oxidative approach to recover valuable elements from NdFeB magnet waste
AU - Venkatesan, Prakash
AU - Sun, Z.H.I.
AU - Sietsma, Jilt
AU - Yang, Yongxiang
N1 - Accepted Author Manuscript
PY - 2018
Y1 - 2018
N2 - In this manuscript, we demonstrate a room temperature electrochemical process for efficiently recycling NdFeB magnet waste. First, the magnet waste was completely leached with HCl and then, in-situ electrochemical oxidation was performed to selectively oxidize Fe(II) in the leachate to Fe(III). Finally, oxalic acid was added directly to the electro-oxidized leachate which selectively precipitated more than 98% of rare earth elements as rare-earth oxalates. The calcination of rare-earth oxalates produced mixed rare-earth oxides of 99.2% purity and a marketable Fe(III) solution as by-product. The electro-oxidized leachate was also subjected to an alternative neutralization route in which ammonium hydroxide was added to remove iron as ferric hydroxide. The iron free leachate with rare earth elements and cobalt was then subjected to oxalic acid precipitation treatment, which finally produced rare-earth oxides of 99.7% purity. Furthermore, a cobalt-rich solution was obtained in the end and electrowinning studies performed on the solution showed the feasibility of recovering pure metallic cobalt.
AB - In this manuscript, we demonstrate a room temperature electrochemical process for efficiently recycling NdFeB magnet waste. First, the magnet waste was completely leached with HCl and then, in-situ electrochemical oxidation was performed to selectively oxidize Fe(II) in the leachate to Fe(III). Finally, oxalic acid was added directly to the electro-oxidized leachate which selectively precipitated more than 98% of rare earth elements as rare-earth oxalates. The calcination of rare-earth oxalates produced mixed rare-earth oxides of 99.2% purity and a marketable Fe(III) solution as by-product. The electro-oxidized leachate was also subjected to an alternative neutralization route in which ammonium hydroxide was added to remove iron as ferric hydroxide. The iron free leachate with rare earth elements and cobalt was then subjected to oxalic acid precipitation treatment, which finally produced rare-earth oxides of 99.7% purity. Furthermore, a cobalt-rich solution was obtained in the end and electrowinning studies performed on the solution showed the feasibility of recovering pure metallic cobalt.
UR - http://resolver.tudelft.nl/uuid:7950fa2e-2144-4287-9f43-7146e1675c60
UR - http://www.scopus.com/inward/record.url?scp=85030558111&partnerID=8YFLogxK
U2 - 10.1016/j.seppur.2017.09.053
DO - 10.1016/j.seppur.2017.09.053
M3 - Article
AN - SCOPUS:85030558111
SN - 1383-5866
VL - 191
SP - 384
EP - 391
JO - Separation and Purification Technology
JF - Separation and Purification Technology
ER -