Model and Mechanism of Anode Effect of an Electrochemical Cell for Nd or (Nd, Pr) Reduction

Author(s)

Nunis da Silva, Andre Luiz ; Lino dos Santos, Celia Aparecida ; Riberio de Araujo, Rogerio de Melo ; Feldhaus, Dominic ; Friedrich, Bernd ; Gomes Landgraf, Fernando Jose ; Guardani, Roberto

• Document type: Journal article
• Source: METALS; v. 12, n. 3, p. 15-pg., 2022-03-01.

Abstract

The anode effect can occur during neodymium and didymium oxide electrowinning, causing a surge in the electrochemical cell voltage, interrupting the process, and increasing the greenhouse gas emissions. In this work, we develop a mathematical model, based on the mass balance of gas bubbles evolving from the anode, to understand the influence of some process parameters on the anode effect. The anode effect occurs due to bubble coverage and limitations on the mass transfer of the oxide species. Variables such as current density, oxide content, viscosity, and electrolyte composition play an important role in the anodic process. Finally, we propose a mechanism for the occurrence of the anode effect during Nd or Di (Nd-Pr) oxide electrolytic reduction based on models used in aluminum electrolysis. (AU)

• FAPESP's process: 14/50887-4 - INCT 2014: Rare-Earth Magnets Processing and Application for High-tech Industry
• Grantee: Fernando Jose Gomes Landgraf
• Support Opportunities: Research Projects - Thematic Grants