How does electrolytic refining produce very high-purity tin?

Electrolytic refining is a specialized process used to achieve very high-purity tin, reaching levels of up to 99.999 percent. This method is particularly effective for treating products derived from complex ores or secondary tin sources.12

The process functions through the following steps:

• Anode Preparation: Impure tin is cast into anodes, which serve as the source of the metal to be refined.1
• Electrolysis: These anodes are submerged in an acidic electrolyte alongside starting cathodes, which consist of thin sheets of high-purity tin.1
• Deposition: As the electrical current passes through the solution, the tin dissolves from the anode and deposits onto the cathode. To ensure the resulting cathode deposits are dense and compact, special agents are added to the electrolyte.1
• Recovery: After approximately one week, the high-purity tin cathodes are removed from the electrolytic cell.1

This technique is distinct from fire refining, which is typically used for general commercial-grade tin. Additionally, electrolysis is used in detinning to recover high-grade tin from tinplate scrap while simultaneously cleaning the underlying steel.132