Tin cans, steel, copper and aluminum undergo different types of recycling processes. Each require specific methods of cleaning beforehand and distinct ways of melting during breakdown.
Tin cans mostly consist of steel and aluminum, but have a thin outside layer of tin to prevent rust. Recycling centers usually receive the cans flattened, with their tops and bottoms removed. They then clean and de-tin the cans in a chemical solution, and bathe the metal in electrolysis, which separates the exterior film of tin from the aluminum and steel, then uses electricity to attract the tin to a plate. The recycling center then collects the aluminum, shreds it into small chips, melts it, and turns it into metal casts or ingots. They ship the steel remnants to a steel mill, where a furnace melts them down to a liquid. Workers pour the steel in slabs that are later used for the design of new products, such as vehicles or cans.
Copper must achieve a high grading before recycling. Recycling centers melt number 1 copper to refine the metal and increase its quality. They then deoxidize the copper, turn it into billets or ingots, and save and store the loose scraps of copper for future processing.