Influence of Dysprosium Compounds on the Extraction Behavior of Dy from Nd-Dy-Fe-B Magnet Using Liquid Magnesium

During the liquid metal extraction reaction between a Nd-Dy-Fe-B magnet and liquid Mg, Nd rapidly diffuses out of the magnet, whereas Dy is not extracted due to the reaction with the matrix and the formation of Dy2Fe17 phase. In addition, theDy2O3 phase exists at the grain boundaries. Until now, only the effect of the Dy2O3 phase on the extraction of Dy has been reported. In this study, the effect of the Dy2Fe17 phase on the extraction of Dy from the Nd-Dy-Fe-B magnet was investigated in liquid Mg. The formation of the Dy2Fe17 phase during the reaction between Mg and matrix (RE2Fe14B) was first examined using a thermodynamical approach and confirmed by microstructural analysis. It was observed that Dy extraction was dominated by Dy2Fe17 phase decomposition from 3 h to 24 h, followed by Dy2O3 phase dominant reaction with Mg. Comparing the activities of the Dy2Fe17 phase and the Dy2O3 phase, the reaction of Dy2Fe17 is dominant, as compared to the Dy2O3 phase. Finally, at 48 h, the high Dy extraction percentage of 93% was achieved. As a result, in was concluded that the Dy2Fe17 phase acts as an obstacle in the extraction of Dy. In the future, if research to control the Dy2Fe17 phase proceeds, it will be of great importance to advance the recycling of Dy.

Extraction Characteristics of the Alkali and Alkaline Earth Metal Ions in the Washing Solution of Coal with Polymer Material Crown Ether

The washing solution of Zhundong coal is a multi-ions mixed system, and the extraction reactions of the alkali and alkaline earth metal ions in the water washing solution with polymer material of dicyclohexyl-18-crown-6 were investigated. The results show that the content of Na in the washing solution is highest, followed by K. Dicyclohexyl-18-crown-6 has better extraction rate of K due to the diameter of K has the same size with the hole diameter of dicyclohexyl-18-crown-6, which enables it could effectively separate Na and K, while did not cause excessive pollution of aqueous solution. Alkali and alkaline earth metal ions were extracted by dicyclohexyl-18-crown-6 in the form of 1:1. Improving the concentration of dicyclohexyl-18- crown-6 in organic phase could effectively enhance the extraction rate. It is not conducive to the extraction reaction by increasing temperature, as the extraction reaction is exothermic.