Modeling Nickel Electrowinning with Electrode Diaphragms Based on Nernst-Plank Equation and a Volume Force Form of Darcy's Law

Abstract

The Ni electrowinning process with electrode diaphragms was simulated with an Electrochemical-Computational Fluid Dynamic model by considering a two-phase flow, mass transport, and electrochemical reactions. The effects of electrode diaphragms on the fluid flow, concentration, voltage drop, and current distribution were analyzed based on the simulation results. Results show that the electrode diaphragms have significant effects on the fluid flow and voltage drop in the electrolyte. The electrode diaphragms greatly reduced the strong convective flow caused by rising bubbles in the cell, and thus reduce the transport of H + (generated at the anode) to the cathode. Based on this model, the effects of different operating parameters on the electrolyte potential and cathode current distribution have been analyzed. The results show that the cell temperature of 60°C, Ni concentration of 80 g/L, and a relatively low current density are the most favorable compared with other settings in the simulation for decreasing the electrolyte voltage drop and reducing the roughness of the deposition.

Phase-Field Modeling and Simulation of Gas Bubble Coalescence and Detachment in a Gas-Liquid Two-Phase Electrochemical System

“…Gas evolution and bubble generation on the electrodes are commonly involved in many electrochemical systems, including water treatment, 1 electrolysis of water, 2 chlorine gas production, 3 and metal electrowinning. [4][5][6] The gas generated on the electrode surface forms bubbles in the electrolyte, and the behavior of these bubbles are critical to the performance of the electrochemical system. In most of these cases, the bubbles in the electrolyte can enhance the fluid flow of the electrolyte as their buoyancy force propels them upward, thereby bolstering the convective mass transport and homogenizing the temperature field in the bulk electrolyte.…”