Tyres are what makes the world go around. Until they develop hover vehicles, tyres will be a key component in ensuring that we have freedom of travel and transport to get goods from source to consumer. Tyres are omnipresent and they are made to take a serious level of abuse. Consequently, they are difficult to dispose of.
Globally, tyres are considered as a single waste stream. They are removed from mixed waste. They have a clearly identifiable collection network and tyre waste lends itself to single-stream treatment.
The bulk of material recovery from tyres comes by way of ambient processing – that is, shredding – or via cryogenic plants and hammer mills.
However, there are some indicators that the market is developing alternative avenues of dealing with tyre-derived materials, such as pyrolysis and devulcanisation. Both processes have been available for many decades, but it is only recently that the research projects have begun to move towards commercialisation.
Scandinavian Enviro Systems is producing recovered Carbon Black (rCB), and it has been used as a 100% substitute for Carbon Black in moulded seals and body plugs destined for
Volvo vehicles. Carbon Black Bear in the Netherlands has its first commercial pyrolysis operation in partnership with Dutch Green Carbon, a subsidiary of Kargro Recycling,
one of the largest used-tyre casing dealers in Europe.
Elsewhere, devulcanisation of rubber has been developed by a number of companies as an alternative to reclaimed rubber. One particular Canadian process has been licensed by one of the largest Chinese tyre manufacturers, and very soon trucks and cars around the world will be driving on tyres using devulcanised rubber as a component of their new compounds.
However, the materials recovery sector is under pressure from a lobby that claims tyre rubber is toxic and as such should not be used in turf infill or children’s playgrounds. There are currently studies being run in Europe and the US to assess the impact of tyre rubber in sports infill on human health. To date, no scientific survey has found a link between tyre rubber and human health issues.
Simultaneous tests in different countries in Europe – Portugal, the Netherlands and Italy – have all shown that football players training and playing on artificial sports surfaces with rubber infill, over an extended period, have suffered no ill effects, and urine tests have not shown up any increase in toxins that can be related to playing on artificial sports surfaces.
However, the lobby is an emotional one and the industry needs to argue strongly to defend its main market. The loss of sports infill would have a dramatic effect on the efficiency of the tyre recycling sector.
Fact file: Tyre recycling
- Across Europe in 2014, there were waste arisings totalling 3.2m tonnes of all types of tyre, an increase of 5% on the previous year, according to Astutus Research
- Of those tyres, some 52% are destined for energy recovery. That is, they are used as fuel in cement kilns, iron foundries and, in Sweden, in power generation. The balance is recorded as going for material recovery
- Of the tyres going to material recovery, 24% for play surfaces and sports tracks; 30% go for use as infill in synthetic turf; 24% for moulded goods; 16% to other uses and export; 5% to indeterminate use and 1% to rubberised asphalt [Source: Ecopneus]