Diagramium
♻️ Narrated diagram

Where your recycling really goes

Follow one bottle from the kitchen bin through magnets, eddy currents, infrared scanners and a global commodity market — and find out why one greasy pizza box can send a whole lorry load to the incinerator.

15 steps3 min readNarrated with a studio voice
▶  Present this diagramOpen in the editor
Where your recycling really goestoo dirtycleanThe trigger that begins the processYou drop it in the binA step — work that gets doneThe lorry works the streetA step — work that gets doneTipped onto the sorting floorA step — work that gets doneA spinning drum screens out cardA step — work that gets doneMagnets lift out the steelA step — work that gets doneEddy currents fling out aluminiumA step — work that gets doneInfrared scanners read the plasticsA step — work that gets donePeople pick out what machines missA step — work that gets doneOne dirty item can spoil a baleA branch — the path splits on a conditionIs the batch clean enoughA step — work that gets doneDirty loads are burned or buriedA step — work that gets doneClean material is baledA step — work that gets doneBales are sold by the tonneA collapsed set of steps defined elsewhereWashed, shredded and meltedA stadium shape that finishes the processBack on a shelf as something new
Where your recycling really goes — the complete diagram. Press Present to watch it build itself.
Step 1 of 15

You drop it in the bin

It all begins with a two second decision at the kitchen bin. That one choice decides whether an object comes back as a new can next month or sits in the ground for four hundred years, and almost nobody ever sees what happens after the lid shuts.

Step 2 of 15

The lorry works the street

The lorry is not just a bin on wheels. Its hydraulic ram crushes the load down to roughly a quarter of its volume, and a single round can gather about twelve tonnes from a thousand or so homes before it heads for the depot.

Step 3 of 15

Tipped onto the sorting floor

At the materials recovery facility everything is tipped into one enormous heap and pushed onto a moving belt. From this moment on nothing is sorted by brand or by bin colour. Machines separate it purely by shape, weight, magnetism and the colour of reflected light.

Step 4 of 15

A spinning drum screens out card

First comes a huge rotating drum full of holes, followed by rows of spinning star shaped discs. Flat cardboard rides over the top of them while bottles and cans tumble down through the gaps. Shape alone does the entire first separation.

Step 5 of 15

Magnets lift out the steel

Then an overhead magnet does the easiest job in the building. Steel cans leap straight up out of the moving stream. Steel can be recycled endlessly without ever losing quality, and melting scrap takes only about a third of the energy needed to smelt fresh iron ore.

Step 6 of 15

Eddy currents fling out aluminium

Aluminium is not magnetic, so it takes a trick. A fast spinning magnetic rotor induces an electric current inside each aluminium can, which makes it briefly magnetic and literally flings it off the belt. Recycling aluminium uses about a twentieth of the energy of making it new.

Step 7 of 15

Infrared scanners read the plastics

Now the plastics. Infrared scanners shine light onto every item and read how it bounces back, because each type of plastic has its own fingerprint. A puff of compressed air then knocks the chosen bottles into their own bin, dozens of times a second.

Step 8 of 15

People pick out what machines miss

Machines still miss things, so people stand at the end of the line pulling out carrier bags, garden hose, nappies and the occasional bowling ball. It is loud, fast, thankless work, and it is what keeps the material clean enough to actually sell.

Step 9 of 15

One dirty item can spoil a bale

This is where good intentions do real damage. A greasy pizza box, a half empty bottle or a bag of loose paper can soak or dirty an entire bale, and one carrier bag wound around a spinning shaft can shut the whole plant down for hours.

Step 10 of 15

Is the batch clean enough

So every batch gets judged on how contaminated it is. Buyers set strict limits, often under five percent, because a mill cannot afford to melt down a load and only then discover that a good part of it was ordinary rubbish.

Step 11 of 15

Dirty loads are burned or buried

Loads that fail go to an incinerator or a landfill. That is why wish cycling, hopefully binning something when you are not sure, is worse than simply throwing it away. On average roughly one part in six of kerbside recycling never gets recycled.

Step 12 of 15

Clean material is baled

Material that passes is compressed into dense bales, each weighing around a tonne, wire tied and stacked up like giant bricks. This is the exact moment your bottle stops being rubbish and turns into a commodity with a price on it.

Step 13 of 15

Bales are sold by the tonne

Those bales are then traded on a genuine market. Prices swing with the oil price, because cheap new plastic makes recycled plastic hard to sell, and a tonne of baled aluminium is worth many times more than a tonne of mixed paper.

Step 14 of 15

Washed, shredded and melted

At the reprocessor the bale is broken open, washed, shredded into flakes and melted into pellets or ingots. Glass is crushed into cullet, which melts at a lower temperature than raw sand and saves energy on every single furnace load.

Step 15 of 15

Back on a shelf as something new

Then it comes back, usually as something completely different. Bottles become fleece jackets, cans become engine parts, and the whole loop can close in about six weeks. The bin was never the end of the journey. It was only a junction.

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