Without even thinking about it, we produce huge quantities of metal waste in our everyday lives. Drinks cans, food cans, aluminium foil – and there’s even more metal waste in old electronics and demolished buildings. Find out more about how metal is recycled and what the challenges are.
Commonly Recycled Metals
Aluminium is probably the most well-known metal. It’s the main material used in fizzy drinks cans, a familiar and common household item. Aluminium has an enormous range of uses: from aeroplanes and Formula 1 cars to bicycles and window fascias. It’s extremely lightweight and rigid, but it’s a soft material that needs to be blended into an alloy to gain strength.
When iron is combined with carbon, it becomes steel: it’s much stronger than iron and less prone to corrosion when mixed with other metals. You’ll find plenty of steel in kitchens – from cutlery to appliances. Even food cans are made of coated steel. Because of its enormous tensile strength, steel is a common construction material found in all manner of buildings.
Plumbing and electrical wiring are made of copper. It’s one of the most common metals in manufacturing and it has fantastic conductive properties, which makes it good for electrics and cooking – but it’s really expensive. The price of copper makes it an attractive recycling material.
This alloy of copper and zinc has a distinctively dull golden colour. It’s heavy and strong but malleable, and doesn’t tarnish easily. It’s also resonant, which makes it an excellent material for musical instruments like horns and cymbals. Most commonly, it’s used to make taps, door handles and keys. The presence of copper makes it valuable, so it’s frequently recycled.
Everyone knows gold is valuable, but not that it’s in just about every electronic device in the world. Gold is an excellent conductor of electricity and almost immune to corrosion, which is why it’s used for contact points in devices. Gold is rare, so even when recycled it retains a high value: but it’s very hard to separate from other components in devices, which often makes the process unprofitable without specialist equipment.
Which Metals Can’t be Recycled?
Practically every metal can be recycled, but some metals are more challenging to extract than others. Gold, for instance, is present in electronic devices but in such small quantities that its removal is often not worth the effort. Paint cans and oil cans are difficult to recycle due to contamination, where the contents have impregnated the metal.
Lead was once used for water pipes and in pubs – before it was found to be poisonous to humans. It’s still a commonly used metal in roofing, because it’s soft and resistant to corrosion. It’s valuable, so it’s usually recovered and sold on as-is. Lead in paints and older electric devices is not recyclable.
What Happens to a Fizzy Drink Can When it’s Recycled?
So, now we know more about metal recycling, how is metal recycled? There are a few different methods for different materials – but let’s look at one of the most common examples: an aluminium drinks can.
First, the can is collected – usually mixed in with other household recycling. Everything gets taken to the recycling centre for sorting, separating everything into groups. All aluminium drinks cans are grouped into the same conveyer belt. Next, they’re crushed into sheets or shredded for easier processing before heading into a furnace for melting.
Next, the aluminum goes into a furnace, specifically heated to melt aluminium. Once completely liquified, the aluminium is purified by scraping off the dross and degassing it, sometimes using chemical additives to accelerate the process. The metal is then cast into an easily transportable and stored shape, such as an ingot, before being cooled.
The purified aluminium will go on to become new cans, cars, planes – anything at all that calls for lightweight aluminium!