electrowinning is the process of using electrical energy to drive a reaction forward leading to the deposition of metal cations in solution onto the cathode as a high purity, solid metal.

for copper electrowinning, typically a lead anode and a stainless steel cathode are used. the lead anode holds up to the production of oxygen gas for years at a time, and the stainless steel anode allows for the copper cathode to be stripped off of the metal as a pure sheet.

theoretically, a copper electrowinning cell could be setup similarly to sreetips use of electrolytic silver cells to refine silver doré. a stainless steel bowl would serve as the cathode, filled with the copper electrolyte solution (the solute from the alkaline glycine process for example¹), and lead anodes submerged in the solution. an anode bag could be used for the lead anodes to prevent particulate from falling into the forming copper cathodes, though there are no anode slimes involved that would need collecting.

while the above speculation is somewhat sensible, there are a number of issues with the practical application, which i went over in my blog post here. to avoid repeating myself i'll keep this page to prospective ideas/plans/information. after reviewing some literature², perhaps it is possible to keep the electrical potentials in the cell low enough to avoid this oxidation of glycine, and keep the ligand changing state as a zwitterion. if that's the case, it's a matter of cell geometry, electrolyte formulation, and cell potential being configured to allow for the desirable reduction of Cu²⁺ to Cu(s) and have the oxidation taking place at the anode only be that of converting the glycinate ion to its Gly-OH form (solid form is H-Gly-OH zwitterion). This would likely mean needing to adjust the pH of the solution after regenerating the solution, but if the carbonate electrolyte solution[^2] is viable, that would be relatively cost effective.

alternately, a carbon anode could allow for the oxidation of carbon to produce carbon dioxide gas, protecting the glycine in solution. again, this introduces another consumable resource in the process, and possibly will acidify the electrolyte with dissolved CO₂ as carbonic acid, requiring the pH to be balanced, as with the scenario mentioned above. these are all factors worth exploring before ruling out a closed loop alkaline glycine copper leach system.