Perspective—Is Sustainable Electrowinning of Neodymium Metal Achievable?

Abstract

Rare–earth metals such as neodymium are central to numerous technologically important applications such as electrified transportation, renewable energy harvesting, and magnetic data storage. Presently, neodymium metal is produced via electrolysis of Nd2O3–containing NdF3–LiF molten salts at high temperatures. However, this conventional electrolytic route has several drawbacks including emissions of greenhouse gases such as CO2 and perfluorocarbons, which are harmful to the environment. In this perspective, an alternate concept based on electrolysis of NdCl3–containing chloride–based molten salts is explored and its potential advantages are discussed. Notably, NdCl3 can be obtained via direct non–carbothermic chlorination of Nd2O3, supported by thermodynamic calculations and experimental evidence from literature. The chloride–based molten salt electrolysis route also offers the possibility of incorporating a non–consumable or dimensionally stable anode leading to reduced electrical energy consumption, stable cell operation and ease of process scalability.