The lifecycle of cardboard at the Norfolk Wave

It would be a safe assumption to make that most of us interact with cardboard daily. Whether it’s to pour out our morning cornflakes, bring home shopping from Foodies, or unpack a parcel, most of us touch, use or see cardboard every day. It’s an extremely handy and versatile material, but what actually is cardboard?

Cardboard is a heavy-duty cellulose-based product produced from wood pulp. ‘Cardboard’ is a generic term that encapsulates many physical structures, from corrugated card to stiff tubing. Although harmless in appearance, did you know that cardboard contains many harmful elements? Inks, linings, pigments, and other obscure additions make cardboard the widely used and widely loved product it is today. But this illusion of convenience hides elements like antimony, rutile, chromium, and polymers like PFAS (per-and poly-fluoroalkyl substances).

Safety Data Sheets classify cardboard as ‘hazardous’ due to the chemical components contained inside and state that it is not readily biodegradable, yet we all unknowingly use it in our gardens and to start our fires. Last year alone, Norfolk exported over 19 tonnes of cardboard to Australia for recycling and incorporated a proportion of it into the Hot Rot composter as well.

To minimise export costs and find an innovative way to use this resource responsibly, Revolve Your World has chosen to carbonise the cardboard produced on Norfolk. For those of you wanting a brief version: we will safely heat the cardboard in a way that doesn’t pollute the atmosphere to create pure carbon. We will then incorporate this carbon with lime and granulated plastic to create concrete aggregate.

For those of you that are into the nitty gritty of the inner workings, read on 😊

When cardboard and glossy paper arrive at the Norfolk Wave, it is sorted on the Recyclapod bench and moved to our cardboard bin. Cardboard and co. are then baled with our vertical cardboard baler. Using this baler, we can produce bales to the exact size and compression we want for the carboniser. Too big and they won’t fit; too compressed and the heat won’t be distributed well throughout the bale.

After baling, the cardboard materials are placed inside the carboniser. The carboniser itself is a large, double-hulled chamber, essentially an oven inside an oven. Into the inner chamber is loaded the cardboard bale. The chamber is then closed and sealed shut. After sealing the outer chamber, we fire up the carbonsier using vaporised sump oil (used engine oil). The chamber gets heated to 100°C for 4-5 hours to dry the cardboard out. Cardboard is about 30% moisture, so it takes time to dry. A valve at the top of the chamber is opened to release the steam produced during this process.

After drying is complete, we increase the temperature to about 350°C. This is where the magic happens. The gas created from the cardboard in rising temperatures is called synthesis gas, or syngas for short. The pressure that builds in the chamber due to shutting the steam valve forces the syngas through piping and into the first condensation chamber. The gas is filtered through charcoal in this first chamber to remove polyethylene. It then travels to the second chamber, where it is exposed to a metallic catalyst (in this case, we’re using rusty steel). The oxidising iron binds with and removes the SO2 (sulfur dioxide) as H2SO4 (sulfuric acid). The syngas, now free of polymers and sulfur dioxide, is put through a straw filter in the third and final chamber. The straw acts as a very fine particulate filter to remove any particles that may still be present. This pure syngas is then fed back into the chamber to prolong the heating process of the cardboard. The system is now closed loop and will produce enough energy to perpetuate the carbonisation of the entire bale of cardboard. Once the process is finished, we’re left with pure carbon. As mentioned before, cardboard is 1/3 moisture, 1/3 gas, and 1/3 carbon. Through our evaporation and filtration process, we’ve removed the first 2, which leaves only carbon.

A minimal amount of residual sediment is created. We’ll add this to the waste oils/chemicals stream for export.

The Resin8 plastics process we’re installing can operate using fly ash or the carbon we’re creating. From the carboniser, the carbon is powdered, suctioned up through pipes and deposited into a hopper for storage. Stored in other hoppers are granulated plastic and lime. Our Flexicon equipment can then mix appropriate ratios of carbon, lime, and polymer for extrusion and the creation of concrete aggregate.

And that is the destiny of a cardboard box brought to the Norfolk Wave!

With a bit more understanding of our cardboard recycling process, may I please remind yorlyi again of the importance of clean streams. Let it only be cardboard if you’re bringing us a ‘cardboard’ bin. No cigarette butts and no hidden plastic, please.

Stay tuned for more innovation that’s taking place at the Norfolk Wave!

Thaenks f aklan

Mandi, Lil, Nat and the Revolve Your World team