Preparation of praseodymium metal by hydrometallurgy

Praseodymium metal was prepared by electrolytic synthesis of amalgam in aqueous solution followed by the thermal decomposition. The amalgamation yields were almost 100%. The preparation yield of praseodymium metal, however, decreased to 75-95% during thermal decomposition due to a density difference between praseodymium and mercury. In order to improve this, the resulting amalgam was concentrated by filtration under reduced pressure using a glass filter with pore size of 20-30 μm before thermal decomposition. The preparation yields of praseodymium metals improved to 93-99%. Oxygen, nitrogen and carbon contents in the prepared metal were found to be comparable with those in commercial grade metal of ca. 99.9% prepared by pyrometallurgy.