Recovery Of Rare Earth Metals Research Articles

Recent Advances in Extraction and Separation of Rare-Earth Metals Using Ionic Liquids

In the present review article, we summarize recent advances in extraction and separation of rare-earth metals using ionic liquids. Rare-earth metals have unique electronic and magnetic properties. In Japan, increasing amounts of rare-earth metals are being used every year in industries employing cutting-edge technology. Therefore, maintaining a stable supply of rare-earth metals is important. In recent times, extensive research has been carried out on the use of ionic liquids for the extraction of rare-earth metals; this is because the extraction ability and/or selectivity for rare-earth metals have been found to increase when using hydrophobic ionic liquids, which have potential applications in liquid–liquid extraction processes. In the octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) extraction system using ionic liquids, the extraction ability was more than 103 times better than that when using n-dodecane; however, stripping of the extracted metal ions was difficult in the former case. In initial research on the extraction processes based on ionic liquids, industrial extractant PC-88A was employed as well as CMPO, but issues resulting from the low solubility of these extractants and their metal complexes remain to be addressed. To overcome this problem, a new extractant, N,N-dioctyldiglycol amic acid (DODGAA), which is highly soluble in the ionic liquids, has been synthesized. DODGAA shows better performance for the separation of rare-earth metals in ionic liquids than in n-dodecane. Furthermore, a liquid membrane system based on ionic liquids has been developed for the separation and recovery of rare-earth metals. The use of a liquid membrane system may help in reducing the amount of ionic liquids required for metal recovery.

Metal separations of interest to the Chinese metallurgical industry

IBC Advanced Technologies' Molecular Recognition Technology (MRT) SuperLig(r) products selectively and rapidly bind with target species enabling their selective removal from solutions. The MRT process can produce a high purity separation product of maximum added value at a competitive cost. SuperLig(r) products have high selectivity for many target species which can include metal ions, anions, and neutral molecules. In operation, the SuperLig(r) product is first placed in a packed column. A solution containing a mixture of the target species and other chemical species is then passed through the column. The target species is removed selectively by the SuperLig(r) product, the column is washed to remove residual feed solution, and the target species is recovered by a minimal quantity of eluent. The result is a pure and concentrated species that can be kept for its value or disposed of safely. The process is environmentally and ecologically friendly with no organic solvents being used. This paper provides a review of some examples of applications of MRT to separations of interest to the Chinese metallurgical industry. Included are several applications of MRT, including Pd separations from Pt metal refinery streams and low-grade spent catalyst wastes, Rh recovery from spent auto catalyst and other feeds, Re removal from selected impurity ions, Cd removal from Co electrolyte, Bi removal from Cu electrolyte, In and Ge separations from difficult matrices, and removal of bivalent first transition series and other metal ions from acid mine drainage (Berkeley Pit, Montana). Finally, the potential application of MRT to separations involving the recovery of rare earth metals and Li from low-level waste solutions and end-of-life products is discussed.

Separation and Recovery of Rare Earth Metals by Molten Salt Electrolysis using Alloy Diaphragm

Separation and Recovery of Rare Earth Metals by Molten Salt Electrolysis using Alloy Diaphragm