1. Casting: The impure copper is melted and cast into anodes (positively charged electrodes).
2. Preparation of the electrolyte: An electrolytic solution is prepared using copper sulfate (CuSO4) and sulfuric acid (H2SO4) as the electrolyte.
3. Electrolysis: The anodes made of impure copper and thin sheets of pure copper are placed in the electrolytic solution. An external voltage is applied to the electrodes, making the anode positive and the cathode (pure copper) negative.
When the circuit is completed, the following reactions occur:
- At the anode (impure copper): Cu → Cu^2+ + 2e-
- At the cathode (pure copper): Cu^2+ + 2e- → Cu
4. Purification: During electrolysis, copper ions (Cu^2+) from the impure copper anode dissolve in the electrolyte, while impurities like iron, zinc, nickel, and sulfur remain in the anode as a sludge or fall to the bottom of the cell. The dissolved copper ions are then deposited as pure copper on the cathode.
5. Removal of impurities: The anode slimes or mud containing impurities are regularly removed from the electrolytic cell to ensure efficient purification.
6. Casting and rolling: After the purification process is complete, the pure copper deposited on the cathode is melted and cast into desired shapes or rolled into sheets or wires.
Electrorefining is a widely used method for purifying copper, as it allows for the removal of a variety of impurities and produces high-purity copper. The resulting pure copper has excellent electrical and thermal properties, making it suitable for various industrial and electrical applications.
