Solid film at the anode influences the process of polyvalent metal electrorefining: theoretical bifurcation analysis of the problem

Abstract

A theoretical study of polyvalent metal anodic electrorefining has been carried out, and the decisive influence of surface film on the long-term process has been shown. A mathematical model of the long-term continuous electrorefining process in the form of non-linear differential equations is proposed. The developed model was investigated by the methods of the bifurcation theory. The model predicts the following types of electrolytic system: 1. The low-valence compound of the anodic film does not form. 2. A steady-state process with a stationary thickness of the anodic deposit. 3. An unlimited accumulation of low-valence compounds at the anode. 4. An unstable steady state: a bifurcation with a transition to case 3 or to the regime of undamped oscillations. The model provides satisfactory explanations of the experimental results related to long-term continuous electrorefining processes in molten salts.