Gas Evolution During Nd and DyFe Electrowinning

Rare earth electrolysis from fluoride melts has a lot in common with aluminium electrolysis; however, there are significant differences that need to be understood and investigated in order to develop efficient process control. A laboratory setup was developed to efficiently trap gases and obtain a mass balance of the components in the gas phase to understand the anode reactions. Using the described setup with a NdF₃-LiF electrolyte, it was possible to concentrate the off-gas (CO and CO₂) to approximately 10% facilitating increased sensitivity of PFC components. The laboratory cell produced metal, and the metal yield was 83% based on mass balance of CO + CO₂. The results are also discussed in context of results obtained in a small pilot cell designed and operated for metal production.