Tyre recycling is the process of recycling vehicles tyres that are no longer suitable for use on vehicles due to wear or irreparable damage (such as punctures). These tyres are among the largest and most problematic sources of waste due to the large volume produced and their durability.
Those same characteristics which make waste tyres such a problem also make them one of the most re-used waste materials, as the rubber is very resilient and can be reused in other products.
With landfills around the world minimizing their acceptance of whole tires and the health and environmental risks of stockpiling tires, many new markets have been created for scrap tires. Growing markets exist for a majority of scrap tyres produced every year, being supported by State and Local Government.
The core component of the tire recycling/granulation plant is the so-called flat die pellet mill which works according to the pan grinder roller principle. The standard system is designed for the size-reduction and separation of car and / or truck tyres at an input capacity of up to 2.5 t/h.
It consists of a pre-cutting unit for tyres as well as one granulation unit, in which the pre-cut tyre chips are gradually crushed and the rubber, steel, and textile components are separated from each other. In the downstream separation process various fractions of rubber crumb, depending on the set-up of the separation equipment can be obtained, for example (based on input):
- steel components, approx. 15 %
- rubber crumb 2 – 6 mm, up to 35 %
- rubber crumb < 2 mm, up to 25 %
- rubber / textile mixture, approx. 25 %
Depending on the condition (especially rubber content) of the input material, the yield of rubber can be up to 55 – 60 % (based on input).
The first granulation plant according to this process was set into operation in Sweden in 1999 and was modernised in 2003. Another plant has been operated since May 2001 by the company Ecomix in the Alsace, a third one with 6 flat die granulation mills since the end of 2002 in Canada. Further granulation presses have been supplied to Canada, France, Germany and Italy. In total there are currently 25 granulation lines running with this technology.
The plant consists of:
- a pre-cutting system to produce tyre-chips from complete tyres,
- a product intake unit for the pre-cut tyre chips,
- a flat die granulation mill, type 60-1250, with accessories as granulation unit,
- the FE separation for separation of the steel components from the crushed intermediate product, a mixture of rubber crumb, steel, and textile fibres,
- the separation and cleaning of the rubber crumb, classifying into fractions and separation of textile and mineral impurities, storage of rubber crumb in big bags
- the aspiration plant of the separation / classification phases consisting of aspiration filters, fans, the complete ducting, and the discharge and conveying elements for return of the separated solid matters,
- the control and switch plant for process control, complete with power circuit and cable material,
- the necessary conveying elements for transport of the product between the individual plant sections,
- the compressed air generator for supply of the compressed air required for the process.
Our size-reduction plant for waste tyres offers the following advantages compared with traditional processes:
- When using the flat die granulation mill, cooling of the input product with nitrogen necessary in case of cutting mills / hammer mills will not be required. For this reason savings of up to 80 €/t with regard to the operating costs are possible.
- Contrary to the cutting / hammer mills a size reduction to a granular size of clearly less than 4 mm with one granulator / granulation press is possible.
- Contrary to the traditional processes, the rubber crumb is not cut, but crushed between pan grinder rollers and die. Thus a much larger and more sponge-like crumb surface is produced than in case of “cut” crumb. This offers much better bonding properties, particularly when integrated in TPE.
- The grinding tools of the flat die mills have a much higher service life than the tools of the cutting mills/granulators. A service life of more than 1000 h per die plate and 2,000 h per set of rollers – without change of the product quality – is realistic. Depending on the machine size more than 2,500 to 3,000 t of product can be processed per set of tools without exchange.
- Due to the long service lives of the tools the maintenance requirements are reduced to a minimum. The tool change at the flat die granulation mill can be accomplished in about 1.5 hour, so the downtimes are reduced considerably.
- The production capacity will not be influenced by wear of the tools, the granulation plant will run at nominal capacity throughout the full service life of the granulation tools, whereas cutting granulators will loos up to 50 % of their capacity due to wear on the blades
- Due to the low wear the operating costs of the complete plant are reduced to about 40 €/t.
The plant will not emit hazardous waste. All input material will be processed to valuable products. Rubber crumb and the steel with it superb cleanliness is sold in Europe at prices listed below (based on EXW, June 2006, in France).
Steel: approx. 150 Euro/t
Rubber crumb 4 ‑ 6 mm: approx. 120 Euro/t
Rubber crumb 2 ‑ 4 mm: approx. 160 Euro/t
Rubber crumb 1 ‑ 2 mm: approx. 200 Euro/t
Rubber crumb 0.5 – 1.5 mm: approx. 220 Euro/t
Rubber crumb < 04 mm: approx. 250 Euro/t
The textile fibre can be used for energy recovery or to produce insulation material. When mixed with sand and binders it can be used as superior equestrian surface.
The plant volume can be adapted to the respective requirements. It is also possible to provide parts of the required machinery locally. The exact volume of the plant have to be discussed in a personal meeting. If you are interested in our system we would be pleased to present our system personally.
The video above show some sections of a plant in operation.
