How is tin recovered from used bearings and solder alloys?

When recovering tin from used bearings and solder alloys, it is often more economical to use the scrap directly to produce new alloys rather than attempting to recover high-grade tin.1

When recovery is pursued, these materials are treated similarly to tin concentrates: they are processed through smelting and refining methods. Common refining techniques include:1

• Fire refining: This includes processes such as liquation, which separates impurities based on melting points, and vacuum distillation, which uses high temperatures and reduced pressure to remove impurities.2
• Electrolytic refining: This method is frequently employed for secondary tin production to achieve high purity levels by casting the impure metal into anodes and using an acidic electrolyte to deposit pure tin onto cathodes.21

Alternatively, scrap metal is often blended and remelted to create alloys that are similar to or more complex than the original source material. In some cases, such as with tinplate, the material is specifically detinned using hot caustic soda to recover the metal via electrolysis or chemical precipitation.314