TECHNOLOGY
Composite Recycling Ltd has developed a patent pending tyre recycling process, which uses molten zinc at temperatures of 450 – 500 °C. Uniquely the technology uses whole tyres, which significantly reduces both capital and operational costs compared to rotary kiln processes. Moreover testing has demonstrated that it takes just 30 minutes to decompose a whole tyre. This is significantly better than the processes of our competitors requiring residence times of 2-4 hours for shredded or granulated tyres utilising rotary kilns. Placing a tyre onto molten zinc – a liquid – represents direct heat transfer. Direct heat transfer is the theoretically fastest heat transfer condition possible. Hence the speed of tyre decomposition of Composite Recycling’s technology cannot be exceeded by any other technology.
Another advantage of our technology being a direct heat transfer process is that scale-up difficulties commonly associated with the processes of our competitors who utilise rotary kilns do not occur. Doubling the surface area of the molten zinc, doubles the throughput of the process.
The chemical process underpinning Composite Recycling’s tyre recycling process is pyrolysis. Pyrolysis is a process executed under the exclusion of oxygen (no flame). The main advantage of pyrolysis is that it is self-sustaining i.e. the non-condensables (methane, propane) are used to maintain the operating temperature. Numerous scientific studies have established the chemistry of the process. As a result the amount of oil, gas, steel and carbon black generated by a tyre pyrolysis process is well known.
Concept layout of a tyre recycling plant
The molten zinc provides the heat and separates the steel and carbon black in a sink-float separation. As a result the process is very compact.
The Composite Recycling process adapts existing technologies reducing technological risk. The most capital intensive part of the process is the pyrolysis chamber, which has been adapted from the hot dip galvanizing industry a low margin, mature industry. As a result the capital cost of a plant is relatively low.
The process developed by Composite Recycling delivers the following benefits relative to its competitors:
- Economically viable
- Whole tyres can be processed – no shredding / granulation / steel removal required
- Direct heat contact with molten zinc – no scale up difficulties, doubling the surface area of the molten zinc doubles throughput
- Direct heat contact with molten zinc – fastest possible heat transfer conditions
- Simple reactor, containing no moving parts
- No requirement to dry the tyres
