Technique for Enhanced Rare Earth Separation

Abstract

A process is demonstrated for the efficient separation of rare earth elements, using a combination of selective reduction and vacuum distillation of halides. The large differences in the redox chemistry of the rare earth elements and in the vapor pressures of rare earth di- and trihalides are exploited for separation. Experimental proof of concept is provided for the binary systems praseodymium-neodymium and neodymium-samarium. This process enhances the separation factor for the isolation of samarium and neodymium from their mixture by more than an order of magnitude.

Investigation of Sorption and Separation of Lanthanides on the Ion Exchangers of Various Types

“…Lanthanides separation and preconcentration of high purity compounds is one of the most difficult problems in inorganic chemistry as it makes use of the subtle differences between the physicochemical properties of these elements and their compounds like solubility, basicity, volatility and possibility of occurrence with different oxidation numbers Jimenez-Reyes, 1993;Uda et al 2000).…”

Review of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste

“…Extraction of REs as chlorides in the gas phase was first applied to REPM by Murase et al [29,30] based on Adachi et al [69] findings. The process was modified by Uda et al [31,32] (Route Nos. 1 and 2 in Tables 2 and 3), Mochizuki et al [55,56], and several others to increase the separation efficiency.…”

“…The extraction of RE using molten salt (Route Nos. 2, 3, and 4 in Tables 2 and 3) was first introduced by Uda et al [31,32], in combination with distillation, and then by Okabe et al [33] following their results in recycling using pure magnesium [42]. Itoh et al [34] used the same method but using a different salt.…”

“…Instead of a CVT reaction, they used distillation which utilizes the disparities in vapor pressure (Fig. 13) caused by differences in the oxidation state of the chlorides, similar to the approach of Uda et al [31,32]. As seen from Fig.…”

“…13), resulting in the simultaneous separation of REEs. Uda et al [31,32] studied such a selective chlorination flowsheet with molten FeCl 2 combined with distillation (Table 2 Route No. 2).…”