Journal of Applied Fluid Mechanics (Jan 2021)
Hydrodynamic Simulation of Two-Phase Flow in an Industrial Electrowinning Cell with New Scheme
Abstract
Electrowinning is the process of depositing copper of the electrolyte solution inside the cell to the cathode. In the present study, the hydrodynamic simulation of the electrowinning cell of Miduk Copper Complex is studied using computational fluid dynamics. The software used is Ansys CFX. The Navier-Stokes and continuity equations are considered in the form of two phases of fluid and gas, turbulent, incompressible and steady state, and the equation for copper concentration in the electrolyte is solved with consideration of its specific boundary condition. The flow turbulence is modeled using K-ω relationships. Due to large variations in the properties near cathode and anode, and also the large size of the electrowinning cell, to create a good grid, and increase the speed and accuracy of the results, global and local simulations are used together. First, in global simulation, the entire geometry of the cell is modeled by creating an appropriate grid, then, in the local simulation, the volume between two cathodes of the cell only is considered and modeled with a much smaller mesh. Data on boundary conditions of the common border plates in the local simulation are obtained from global simulation data, which increases the accuracy of modeling. The results of this simulation are the velocity vectors, the concentrations of acid and copper, turbulence Intensity, the amount of pressure, and the volume ratio of the oxygen phase in the entire electrowinning cell domain. Finally, for model validation, the model is compared with experiments conducted on actual cells in the industry. Results show high accuracy with less than 2.5% deviation of this modeling technique. Then, the mass transfer coefficient values for the different electrode intervals are obtained by this modeling and the results are validated using the results of the experimental relations, indicating a deviation of only 0.5%. In the next step, the electrolyte mixture containing different mass fractions of oxygen is sprayed into the electrowinning cell from the inlet of the simulated cell. The results demonstrate that spraying 16 liters per second of oxygen at the inlet can increase the overall mass transfer coefficient of the electrode plates up to 7%. The effect of changing inlet temperature and flow rate of the electrolyte on the mass transfer coefficient is also investigated by the obtained model.
