Aluminum recycling – how it’s done and why it’s important
Aluminum is one of the most abundant metals found on Earth and is also widely recycled across much of the world. Alongside glass and steel, aluminum is one of the easiest materials to recycle. According to the Aluminum Association, nearly 75% of all aluminum that has ever been produced is still in use to this day; with the majority of aluminum cans that you purchase in a store having already been recycled many times over.
But, aluminum isn’t easy to produce. It’s an extremely energy-intensive process. Extracted and refined from mined bauxite ore, producing virgin aluminum takes an average of 14,000 kWh of electricity to produce just one metric tonne. Increasing aluminum recycling translates to less energy used and a lower carbon impact.
How is aluminum recycled?
Recycling aluminum is a lot more straightforward than creating new aluminum and represents the circular economy at its finest.
Aluminum scrap comes from two primary sources:
- Fresh scrap, which is the surplus metal left over from the manufacturing and fabrication of aluminum products, mostly found in manufacturing plants
- Old scrap, which is a discarded aluminum product, like a beverage can
Aluminum is recycled by being shredded into chips and fed through an infrared sorter to remove any plastic, glass or other contaminants, followed by a magnet which pulls up any scraps of steel. Did you know aluminum isn’t magnetic?
The chips are then melted down at a temperature of approximately 1,221 Fahrenheit into molten aluminum, and poured into large molds. It takes just two and a half hours for a 10m long ingot to set.
During the remelting process any paints or lacquers used are vaporized, and an aluminum oxide called dross is produced and reacts with air. To remove the dross, a furnace operator uses a large spatula to skim the dross off the top. The dross is collected, and then goes through its own recycling process to extract residual aluminum.
Dross is highly toxic and has to be buried in landfills. This dross must be tightly sealed in containers so that it doesn’t leak out and enter groundwater. Engineers at the Worcester Polytechnic Institute are trying to find ways to use the waste product to strengthen cement instead of burying it.
After an ingot has been removed from its mold, its transported to a rolling mill. The furnace is heated to 995 Fahrenheit, which is hot enough to relax the bonds between the aluminum. It’s then pressed through a series of rollers that roll the ingot thinner and thinner, until the ingot become a sheet of aluminum approximately 0.1″ thick. It’s rolled into a reel approximately 1,000 times its original length!
Before widespread commercial aluminum recycling, aluminum used to be one of the most expensive metals on the planet; more so than gold.
Advantages of recycling aluminum and reducing our carbon footprint
- Thanks to recycling aluminum, more than 90 million tons of carbon dioxide are stopped from being released into the environment each year
- Recycling aluminum saves more than 90% of the energy costs necessary for primary production
- It prevents 97% of greenhouse gas emissions than creating new aluminum
- Recycling aluminum saves 9 tonnes of CO2 emissions and 4 tonnes of bauxite
- In the US, industrial recycling saves over 90 million barrels of oil annually
While the production and recycling of aluminum isn’t a perfect process, it’s one of the best solutions we have to make manufacturing across multiple industries greener and more sustainable.