How Are Metal Cans Recycled?

Recycling Explained

What happens after mixed recycling gets tossed into your bin? Let’s walk through the recycling process for metal:

1. Collection

Waste Haulers collect mixed recycling materials, also known as single stream, from homes and businesses. In Sioux Falls, there are over 20 licensed waste haulers, so you have a wide selection to choose from for who picks up your trash and recycling (see a list of local haulers). After the material is picked up by your hauler, it is brought to Millennium Recycling (If you don’t have a waste hauler you can also bring it directly to the public dropoff bin).

The only types of metal accepted in the single stream include Aluminum Cans, Aluminum Trays, Aluminum Pans, Balled Aluminum Foil (No Foil Wrappers or Bags like chip bags or candy wrappers) and Steel or Tin Cans (1 Gallon or Smaller) like empty aerosol cans or soup cans. They must be clean of food waste and dry of liquids.

2. Sorting

At Millennium, the mixed recyclables are dumped into a huge pile and a team member checks to make sure no large, bulky items are in the mix that could damage the equipment or hurt employees (i.e. tree branches, car engines, bicycles, etc). If large scrap metal is found – this is where it’s pulled out so it doesn’t ruin equipment – Scrap metal is not accepted in the single stream and should be recycled separately. Any scrap metal found here is separated manually and recycled with companies like Sioux Falls based TJN.

After the large, not-accepted items have been removed, the materials are moved onto a conveyor belt where workers pull out plastic bags and other items found that are not recyclable or might jam up the equipment (i.e. clothing, wire hangers, garden hoses, etc). The cardboard and paper then get separated out using screens (learn how) and the remaining items (plastic, glass and metal) fall through and continue on.

A large spinning magnet is used to suck steel off the conveyor belt and toss it into a separate holding bin. The materials continue on and enter a machine called an eddy current, which uses a powerful magnetic field to separate and repel non-ferrous metals like aluminum cans. The remaining items (plastic and glass), continue onto the rest of the sorting process back on the conveyor belt.

Now that the steel and aluminum metal have been separated, they are baled and transported to specialized metal recyclers like  Novelis or Alcoa as examples.

3. Shredding (Aluminum only)

At the aluminum processor, cans are shredded, which helps remove any colored coatings.

4. De-Tinning (Steel only)

Steel is dipped into a chemical solution that dissolves the tin layer from the steel. It is then drained and rinsed.

5. Melting

Both shredded aluminum and steel are melted down in furnaces to create a molten, liquid metal.

6. Finishing

Aluminum molten gets poured into molds, cooled with water, and rolled into thin aluminum sheets for use in new cans, window frames, airplane parts and road signs. Steel is formed into big steel slabs to be made into new products like bikes, cars, paperclips, and train tracks!