| Description |
Electrorefining is widely utilized to refine nonferrous metals such as copper, zinc, and nickel as a final step to meet purity requirements. Thus, it is critical to control impurities and maintain high cathode purity in electrorefining. In copper electrorefining, slime particles are responsible for most cathode contamination. As a result, the adhesion, mobility, and transport of anode slime particles in flowing electrolyte are of significance and worth comprehensive studies. A 3-factor 2-level designed set of experiments was performed to determine the effects of inlet flow rate, temperature, and current density on impurity particle behavior in electrolyte and the associated distribution on the cathode in copper electrorefining. A model based in COMSOL Multiphysics® consisting of an electrorefining cell was utilized to simulate copper electrorefining. The model data for impurity particle distribution were compared with measured impurity particle contamination at the cathode surface, and the results show a very good correlation. Four series of copper electrorefining tests were performed using four different types of anodes. Test results show that the high impurity anodes and the scrap cycle anodes have more inclusions associated with the Pb-Bi-S compounds that show evidence of sintering at 50 ℃, whereas the low impurity anodes and the strip cycle anodes have more inclusions related with the Pb-Bi-S-As compounds that demonstrate evidence of sintering above 65 ℃. Arsenic content in copper anode and cell temperature are major factors affecting slime sintering and coalescence, which can improve anode slime adhesion and reduce the amount of suspended slimes. Copper electrorefining tests were conducted in a pilot scale cell made of transparent cell walls. Fluid flow velocities in the gaps between adjacent electrodes were measured. Modeling and simulation of copper electrorefining in this cell were performed. The flow velocity field results from modeling agree reasonably well with the measured electrolyte velocities. The effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity were studied by performing copper electrorefining tests in the pilot scale cell under commercial tankhouse environment. |
