The alkaline treatment of NdFeB powders in NaOH solution at various equivalent amounts of NaOH at 100• C was performed. The resultant powders were then leached in 0.5M H 2 SO 4 solution at 25• C for 2 minutes. At 5 equivalents of NaOH, neodymium in NdFeB powders was partially transformed to neodymium hydroxide. The transformation of neodymium to neodymium hydroxide actually occurred at 10 equivalents of NaOH and was facilitated by increasing the equivalent of NaOH from 10 to 30. In addition, iron was partially transformed to magnetite during the alkaline treatment, which was also promoted at a higher equivalent of NaOH. The leaching yield of neodymium from alkaline-treated powders was increased with an increasing equivalent of NaOH up to 10; however, it slightly decreased with the equivalent NaOH of over 10. The leaching yield of iron was inversely proportional to that of rare earth elements. NdFeB powders treated at 10 equivalents of NaOH showed a maximum leaching yield of neodymium and dysprosium of 91.6% and 94.6%, respectively, and the lowest leaching yield of iron of 24.2%, resulting in the highest selective leaching efficiency of 69.4%.
The present paper deals with liquid-liquid extraction studies and the possible separation of light rare earths (LREs) from chloride solutions. Aromatic diluents such as benzene, toluene and xylene were tested for LREs extraction and possible separation from chloride solutions. Bis(2,4,4-triethylpentyl)phosphinic acid (trade name Cyanex ® 272) was used as an extractant and dissolved in the diluents. Various experimental parameters such as time effect, influence of pH, extractant concentration variation and maximum loading capacity of the target LREs to Cyanex ® 272 were examined. Finally, the separation potential of each of the other LREs was calculated, and a suitable diluent system was proposed. The highest separation factors were found using the present systems.
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