Advanced Topic 575 of 1102 Acids, Bases & Electrochemistry
Electrorefining
Purifying metals such as copper by anodic dissolution and cathodic deposition.
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In-depth explanation of Electrorefining
Electrorefining purifies a metal by making an impure block of it the anode of an electrolytic cell, so that the metal dissolves and passes into solution as ions. The pure metal is then deposited on a cathode of thin high-purity sheet, while less noble impurities either remain in solution or fall to the bottom as anode mud. Precious metals such as silver and gold collect in the anode mud and can be recovered as valuable by-products. The method can produce copper of 99.99 percent purity, which is needed for electrical wiring. The process is energy intensive but highly effective for metals that are easy to reduce.
Going deeper: Electrorefining
Key ideas: Impure metal is the anode and a pure thin sheet is the cathode in a solution of its salt. For copper: CuSO4 and H2SO4, about 0.2 to 0.3 V. Cu dissolves and plates out pure (99.99 percent); less active impurities (Ag, Au, Pt) fall off as anode mud, more active ones (Zn, Fe, Ni) stay dissolved.
Common mistakes and connections: Mistake: thinking a high voltage helps; it would co-deposit impurities. The cell voltage is kept low so only Cu reacts. Anode mud is a valuable by-product. Same principle refines Ag, Au, Ni, Zn and Pb. Compare with electroplating: the anode here is the crude source, not an inert supply.
Visualization of Electrorefining
In electrorefining impure copper dissolves from the anode and pure copper deposits on the cathode, while silver and gold fall away as anode mud. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Copper refined from about 99 percent purity to 99.99 percent purity in a copper sulfate electrolyte.
Frequently asked questions about Electrorefining
What is Electrorefining?
Purifying metals such as copper by anodic dissolution and cathodic deposition.
Is Electrorefining a beginner, intermediate or advanced topic?
Electrorefining is a advanced topic in Acids, Bases & Electrochemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Electrorefining?
Study these earlier topics in Acids, Bases & Electrochemistry first: Electrolysis of Molten Salts, Electrolysis of Aqueous Solutions, Electroplating.
What comes after Electrorefining?
The next topics in Acids, Bases & Electrochemistry are Hall-Heroult Process and Chlor-Alkali Process.
Can I practise Electrorefining with quizzes?
Yes. The interactive lesson includes a self-check question on Electrorefining, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Electrorefining fits in Acids, Bases & Electrochemistry
Electrorefining is topic 65 of 105 in Acids, Bases & Electrochemistry.