Tyre-derived aggregate (TDA) and tyre-derived Fuel are the two main products derived from the tyre recycling process. We will mainly focus on tyre-derived aggregate both as marketing the rubber powder and crumb; such as for rubber surfaces such as artificial turfs or playgrounds surfaces, gym, driveways, shock-absorbent flooting, rubber mulch in the garden or processing it further such as moulding it into tiles, paving bricks, mats or rubber lumber.

Nomenclature

Tyre-derived aggregate: building material made of recycled tires, which are shredded into pieces of varying sizes.
Crumb rubber: recycled rubber produced from automotive and truck scrap tires. During the recycling process, steel and tire cord (fluff) are removed, leaving tire rubber with a granular consistency.
Rubberized asphalt: noise reducing pavement material that consists of regular asphalt concrete mixed with crumb rubber made from recycled tyres
Rubber mulch: a type of mulch used in gardens and landscaping that is made from recycled rubber, most often crumb rubber sourced from waste tyres.

Process

Overview

The shredder reduces these materials into smaller pieces (sometimes in two stages), while the granulator refines them into granules that can be used to create new plastic and rubber products.

The shredder rips the tyres into chunks, the crusher then crushes them into smaller pieces or granules. The remnants are raked over a vibrating screen while a dust extrator is working. The vibrating machines sifts the right sized smaller pieces and sends the bigger pieces through the crusher or granulator again. All the while a magnetic seperator machine pulls out remaining metal shards. The fiber is also seperated from the rubber. What is left is the granulated rubber product which is often sent through the virbrating screen again to seperate the smaller powder like with a softer feel(for surfaces) from the larger crumbs used in pavers (see below).

There is a optional starting phase of debeading a tyre to remove the wire and to remove the sidewall and to cut it into smaller pieces. There is a debate around the former based on the type of shredding machine and cutting the tyre into pieces before shredding adds another step to the process.

The full tyre recycling tyre crushing and separating line is more or less as follows:

Tyre Shredder Machine

The tyre shredding machine preprocesses the entire tire into large rubber pieces or chunks. E.g. Some shredders do 50-80mm chunks.

Steel Wire Separator Machine

The tyre chips were further processed (e.g. smaller 20mm chunks) into less than serrated knife of steel wires separator machine.

Magnetic Separator Machine
Removes the metal from the rubber using a conveyor belt with magnets

Granulator or Crusher machine
Takes the rubber chunks and granulates it into smaller particles say 2-7mm particles however this simply depends on what size screen is being used. The nylon and the fibers are also ofren removed here by a Dust Collection Machine.

Vibrating Screening Machine

Feeds the particles through a sieve to ensure its the right size. If not gets fed through granulator again.

The above is usually what a full line looks like, I will go into a smaller line soon. As with tyre retreading these can be purchased (imported) as a complete line but can also be assembled piecemeal. But what is important to note is that most of the above is not specific to tyre recycling. Only the shredder, granulator and wire remover. Magnetic seperators, virbrating machines, dust collection machines those are machines used in mining, manufacturing. So when assembling locally Techno Power can supply the magnetic seperator which they also supply to food mining etc. Same for vibrating screen machines mining suppliers like Flo-scan sell screen vibrators. Same with dust extractors.

Sourcing equipment

Firstly remember that we are dealing with intricate multi-million rand equipment that needs to be properly sourced otherwise you will have serious problems. In other words scope creep needs to be avoided and the equipment has to work.

Now there are strategies when sourcing equipment such as make sure your setup is modular, avoid combo machines if possible (slower than individual machines and if it breaks you have two problems rather than one).

When sourcing specialised equipment in South Africa you are unlikely to get a full line like you can order from China. Nor will get get a off-the-shelf machine unless they are ordering it from China.

I spoke to a local shredder manufacturer and I said I want to recycle passenger tyres and they had this to say:

All our machines are custom-built to customer requirements.
What I need to know is size and quantity of shred output so that we can determine the correct shredder.

This is the nature of a lot of local specialised machine manufacturers they only build custom.

Equipment

If you are looking for a tyre-specific local shredding or granulating equipment you can post a lead in the marketplace.

Making rubber pavers

The (around 3-5mm) rubber crumbs proved above are twirled inside heated mixers a polyurethane binder helps hold everything together. Dyes are added to change the colour, the rubber and polyurethane is added to the paver mould, put on trays and then compressed with an hydraulic press.