Optimization of copper electrowinning from synthetic copper sulfate solution using a pulsed bed electrode

Abstract

This paper concludes a series of investigations concerning the use of pulsed bed electrodes (PBEs) for copper electrowinning. In previous papers, the main operational parameters affecting the current efficiency (CE), space–time yield (Y), and energy consumption (EC) were identified and their effects on the performance of the process were analyzed. In light of the results, the fluidized bed time was set at 2s and it was found that the electrode thickness should be reduced in order to achieve values of CE and EC lower than those obtained in conventional industrial processes using flat plate electrodes. In this work, the electrode thickness was reduced from 3.4 to 2.4cm and the process was optimized using factorial experimental design and the Derringer desirability method to obtain current density (i), acid concentration (Cac), and pulsed bed time (tp) values that maximized CE and Y and minimized EC. The best Cac value was 100mgL−1 (a low level), while the optimum i and tp values were 2600Am−2 and 60s, respectively (high levels). Use of these values avoided short circuit and minimized copper dissolution during fluidization. The overpotential distribution within the porous cathode was improved using the 2.4cm electrode, and values of 100% (CE), 102kgm−3h−1 (Y), and 1.7kWhkg−1 (EC) were achieved under the optimized conditions. These values are better than those found for flat plate electrodes.