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Tyre recycling

ELT cannot be considered as a simple waste to be disposed of and they are, in fact, a resource of renewable materials and energy.

Surfing on the trend of Circular Economy and faced with scarcity of resources, in particular in Europe, recycling and re-use have a double role:  it benefits both the environment and the economy.

 

Recycling of ELT-derived Rubber granules and powder

After shredding and removal of the steel and fabric components, the remaining rubber is reduced to rubber granules. Applications of ELT rubber granules include moulded rubber products such as wheels for caddies, dustbins, wheelbarrows and lawnmowers, urban furniture and sign posts.

Video : Recycling of ELTs into rubber wheels (Aliapur©)

Rubber granules and powder are also to be found as flooring for playgrounds, as athletic tracks, as shock absorbing mats for schools and stables, as paving blocks or tiles for patios and swimming pool surrounds as well as roofing materials.

Video : Recycling of ELTs into moulded rubber products (Aliapur©)
Video : Recycling of ELTs in athletic tracks (Aliapur©)

One of the main uses of ELT granules is rubber infill of artificial turf for example in football fields.

Rubber granules

Rubber infill, rubber granules or crumb rubber: the elastomeric material that is most commonly used worldwide as infill material in synthetic turf systems comes mainly from recycled End of Life Tyres (ELTs).

Tyre rubber gets a second life after high-quality recycling as infill in artificial turf pitches. In this way characteristics such as elasticity, weather resistance and extremely good aging properties are maintained.

By EU regulation, rubber infill supplied to the market is not to be considered a waste, but falling under REACH and here the granules in artificial turf systems are a mixture and shall comply with relevant REACH obligation. This has been confirmed by the EU Commission following a meeting of the competent authorites (CARACAL) – see letter.

Further to this ETRMA has published a statement on “Safety of recycled rubber infill material” which summarizes the current state of play.

 

ELT-derived rubber powder is used in Rubber modified asphalt, which takes advantage of the elasticity and noise absorbing characteristics of the rubber. Although this increases the life span of the road surface, reduces the noise pollution and increases safety in wet road conditions, it is still relatively underutilised (a few hundred kilometres of roads in total) despite its many advantages.

Use of ELTs in steel mills

Shredded tyres can be used in steelworks equipped with electric arc furnaces as a substitute for anthracite and scrap metal. This application has been validated for industrial use in Belgium and in France.  About 4,000 tonnes of end of life tyres are consistently used in that application. This is encouraging as the application uses both the carbon and steel content of the tyres. Such use is already under development in the US and will most certainly follow a similar trend in Europe in the years to come.

Video : Recycling of End-of-life tyres in steelworks (Aliapur©)

The use of ELT derived products in steel plants confirmed that carbon and iron contained in tyres may be used partly or entirely to substitute the use of anthracite during the manufacturing of steel at 1,650 degrees. Indeed 1.7 kg of ELTs is equivalent to 1 kg of anthracite. The environmental impacts are positive regarding dust and gaseous effluents. Overall there are no significant differences in the total environmental impact due to the use of tyres or anthracite. The capacity is nearly unlimited.

Emerging recovery routes: Pyrolysis/Thermolysis

Thermal treatment technologies – pyrolysis, thermolysis and gasification – are some of the emerging solutions for recovering value from end of life tyres.

Tyre pyrolysis involves the thermal decomposition of end of life tyres into intermediate substances such as gas, oil and char. The economic viability of this alternative route for high temperature resource recovery from tyres is hampered by the fact that the prices obtained for the by-products often fail to justify the process costs.

Under current market conditions, the economic viability of these options has yet to be proved (there are few or no large-scale plants currently in operation) but they have the merit to offer scope for increasing recycling rates.

 

Recycling of ELTs in civil engineering applications

Whole tyres

Whole tyres are predominantly used in civil engineering applications. Those applications vary from coastal protection, erosion barriers, artificial reefs, breakwaters, avalanche shelters, slope stabilisation, road embankments and landfill construction operations, sound barriers, insulation. This market is for the moment confined to single projects and therefore fairly small scale.

Shredded tyres

ELTs that are mechanically sheared into shreds ranging in size from 25-300 mm and intended for use in civil engineering applications are called "Tyre Derived Aggregate" (TDA).  TDA is used as foundation for roads and railways, as a draining material replacement for sand and gravels, landfill construction, subgrade fill and embankments; backfill for walls and bridges and subgrade insulation for roads. TDA is lighter by 30-50%; drains 10 times better than well graded soil and provides 8 times better insulation than gravel.