In the second installment of this three-part feature, Geoff Courtney, chairman of the UK Can Makers, busts the myth on how complicated metals recycling really is
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Busting The Myth – Recycling One Thing Is Just The Same As The Next
Of course, all of this does not mean much if the general public does not really understand the recycling process to begin with. So how exactly do beverage cans get recycled?
For aluminium cans, the recycling process has five stages. After collection (which we have already explored), shredding is next, in which mechanical hammers shred the flattened cans into small pieces. Next comes decoating, where the decoration is removed from the can through the shreds. This is followed by melting, where the shreds are heated to 750 degrees Celsius in a furnace. The final part of the process is casting, where the hot metal flows into moulds and is cooled by jets of water, forming “ingots”. Each ingot weighs 27 tonnes and contains enough metal to make 1.5m drinks cans.
“Steel cans are recycled by being put into a converter before molten iron is added. Because the process is undertaken at high temperatures, there’s no need for further cleaning of the cans”
Steel cans are recycled by being put into a converter before molten iron is added. Because the process is undertaken at high temperatures, there’s no need for further cleaning of the cans. To make steel from molten iron, oxygen is then blasted into the converter, which heats up to around 1700 degrees Celsius. The cans in this process act as a cooling agent, meaning no additional energy is needed to turn the old cans into liquid metal. This makes it a very effective and energy efficient process. The liquid metal is subsequently processed into slabs, which are rolled into flat sheets which are then coiled and can then be used to make other steel products. This process uses only steel, so it’s referred to as a closed material loop. However, as the steel can go into any number of new products, this next stage is called an open product loop. Going back to the recycling process, in the case of steel for cans, the coils are then tin coated. From these coils new cans are made by can makers and the cycle can recommence.
A can is always a can, but aluminium and steel are very different materials, which require different processes to recycle them.
Busting The Myth – A Lot Of Packaging Just Goes To Landfill
A common concern seems to be that actively recycling does not ensure packaging is actually recycled. People are fearful that it still tends to go to landfill.
The truth is that the proportion of local authority collected waste disposed of into landfill between January and December 2011 was 39 percent, half of the 78 percent disposed of in 2001 and 2002, so a real improvement is evident. In tonnage terms, more waste was recycled, composted or reused (10.8m tonnes) than was landfilled (10.1 m tonnes). The Department of Environment, Food and Rural Affairs (Defra) took further action in 2012 to ensure these improvements continued, issuing directives to councils saying they have a key role to play in making sure recycling is increased and Britain heads towards a zero waste economy.
So what is the big deal if our refuse goes to landfill? The problems are very complex, with the time taken for many different materials to break down being a lot longer than is commonly believed. Landfill is not a solution and biodegradation will not just make rubbish disappear”
There is also a commonly held view that everything, given enough time, will eventually decompose anyway, meaning that some consumers think rubbish is only a problem as long as it persists and takes up space. So what is the big deal if our refuse goes to landfill? The problems are very complex, with the time taken for many different materials to break down being a lot longer than is commonly believed. Landfill is not a solution and biodegradation will not just make rubbish disappear.
The good news is that the metal used in a drinks can is a valuable secondary resource. High recycling rates help ensure that metal is used again and again, therefore making it an efficient material as well as economically sound. Recycling saves 70 percent of the energy required for the production of steel if new materials were being used and 95 percent of the energy required for aluminium production. Therefore, it is economically important to recycle steel and aluminium.
More waste is now being recycled than is being sent to landfill, but the challenge is to increase this number further and capture the remaining 39 percent.
Busting The Myth – Separating Metals Is Complicated
Now the recycling process is a bit clearer, the next myth that needs to be busted is that separating metals is complicated. In fact, both aluminium and steel are easy to separate and to recycle. But why are the two different metals used and what is the best process for separating them?
Some drinks cans are made with steel and some aluminium for commercial, manufacturing, filling and distribution reasons. The good news is that the separation of steel and aluminium does not need to happen at home, making recycling very simple for consumers. Drinks cans are collected in any of the ways mentioned previously and are separated from the rest of the materials. They are then crushed, baled and sent to the recycling plant where aluminium and steel cans are separated. Cans are fed along a conveyor belt, steel cans stick to a magnet, whilst aluminium cans drop off into a separate storage bay, to be recycled when ready. This is known as magnetic recovery. This is the most efficient and cost effective way of extracting steel packaging from non-sorted domestic waste.
The other technology available is Eddy Current Separation (ECS), which is used to extract aluminium typically from a mixture of aluminium and steel packaging and plastic bottles, and is often used at Materials Recycling Facilities (MRFs). ECS is based on the use of a magnetic rotor spinning rapidly inside a non-metallic drum driven by a conveyor belt. Magnetic fields create eddy currents, which repel the material away from the conveyor. While other materials drop off at the end of the conveyor, the non-ferrous metals are propelled forward for separation. This is used for aluminium, because, unlike ferrous metals, such as steel, it is not possible to extract aluminium from waste using conventional magnetic extraction.
“Separating metals is not as complex as you might think. With ECS, magnetic separation and incineration processes, separating steel and aluminium is relatively simple”
With two effective ways to separate metals already explained, an additional benefit of beverage cans is that metals can also be recovered for recycling after incineration, a process where non-separated wastes are burned. During the incineration process aluminium melts into a liquid, which, once cooled, forms drops and steel, due to its high melting point, stays solid. From here aluminium can be separated using the ECS process while steel is easily separated using magnetic extraction. As an increasing proportion of wastes are being incinerated in the UK, this recycling technique will become increasingly important.
Separating metals is not as complex as you might think. With ECS, magnetic separation and incineration processes, separating steel and aluminium is relatively simple.
