Copper electrowinning using a pulsed bed three-dimensional electrode

• Copper electrowinning was performed using three-dimensional electrodes.
• Pulsed bed electrode provides high surface area in a small volume reactor.
• Innovative membraneless reactor and flow rate pulse setup are presented.
• The current efficiency is highly dependent on pulse frequencies and current density.
• Low energy consumption and high space-time yield can be achieved.

This work concerns the electrowinning of copper from an acidic medium using a membraneless three-dimensional pulsed bed electrode (PBE). The effect of current density (i), packed bed time (tp), and fluidized bed time (tf) on current efficiency (CE), energy consumption (EC), and space-time yield (Y) was investigated using a fractional factorial design (FFD). The results showed that the most important variables affecting the electrodeposition process were i and tp. Experiments using i greater than 3000 A m− 2 and tf lower than 2 s revealed that the process rapidly short circuited, mainly due to a non-uniform overpotential distribution inside the porous cathode. An important improvement of the reaction kinetics and EC was achieved by increasing tp and decreasing tf. The best values of CE (76.7%) and EC (2.5 kWh kg− 1) were obtained by applying 3000 A m− 2, with tf = 2 s and tp = 60 s. Although the CE value was lower than reported elsewhere, the EC value was within the range commonly found for industrial processes. The FFD results indicated ways by which copper electrowinning using a PBE reactor could be further optimized.