Rare Earth Metals and Alloys by Electrolytic Methods

Abstract

Fused salt electrolysis as applied to the production of reactive refractory metals is a useful process for rare earth metals preparation also. The relatively low melting point of some of the rare earth metals and many of their alloys is an advantage here. With great ingenuity, electrolytic cells have been designed and methods developed for the preparation of high melting rare earth metals also in consolidated forms, using oxide–fluoride electrolytes. Any process of rare earth metal preparation had to contend with the great reactivity of these metals not only with the atmospheric gases but also with a great variety of crucible materials as well. The development of electrolytic processes involving both the chloride medium as well as the oxide–fluoride compositions had to be guided by this factor. The search for solutions to circumvent the numerous challenges inherent in the electrolytic extraction of rare earth metals led to some interesting process development. One of them is the preparation of rare earth metals by a method involving a consumable cathode. In this an alloy is prepared first by electrolysis and the metal is then recovered by a simple non electrolytic route from the alloy. Using one or other of these three possibilities, all the rare earth metals, and many of their alloys, could be prepared by electrolytic methods. All these issues and possibilities are highlighted in this paper.

Keywords::

• Fused salt
• Electrolysis
• Rare earths
• Metals
• Alloys