Rubber Recycling

Whole tires are first shredded into rough chips, then run through granulators and magnetic separators to strip out embedded steel belting, and finally reduced further into crumb rubber through mechanical grinding or cryogenic freezing followed by fracturing. The resulting crumb is screened by particle size for use in products like playground surfacing, asphalt rubber, or molded goods.

Whole tires are bulky, don't compact well in landfills, and can trap methane gas or become breeding sites for mosquitoes when stockpiled, which is why many jurisdictions restrict or ban landfilling whole tires outright. Rubber's vulcanized structure also doesn't break down naturally the way many other materials do, so it needs specialized shredding, devulcanization, or pyrolysis equipment rather than standard waste processing.

Shredding just reduces tire or rubber material to smaller physical pieces without changing its chemical structure, so the rubber stays cross-linked and can only be used in applications like crumb infill or mulch. Devulcanization breaks the sulfur cross-links formed during the original vulcanization process, restoring some of the rubber's elasticity and processability so it can be reintroduced as a raw material into new rubber compounds rather than just used as filler.

Crumb rubber is widely used in playground and athletic field surfacing, as an additive in asphalt rubber for road paving, and in molded products like mats, mulch, and flooring tiles. The recovered steel belting from tire shredding is sold as scrap metal, while the nylon or polyester fiber fraction is typically separated out and, depending on quality, may go to fiber recovery or be landfilled as residual.

Primary shredders and tire cutters reduce whole tires to chips, which then pass through granulators, magnetic separators for steel, and air classifiers or screens to separate out fiber and size the crumb rubber. Pyrolysis units, which thermally decompose rubber in an oxygen-free chamber, are also used to convert scrap tires into recovered carbon black, pyrolysis oil, and steel, rather than mechanically grinding them into crumb.

Pyrolysis heats shredded tire material in the absence of oxygen, breaking the rubber compound down into recovered carbon black, a hydrocarbon-rich pyrolysis oil, syngas, and residual steel. The oil can be refined further or used as a fuel substitute, while recovered carbon black can potentially be reused as a filler in new rubber or plastic compounds, though its quality varies depending on the feedstock and process control.

Not always — non-tire rubber often contains different fillers, reinforcing fabrics, or bonded metal fittings that complicate shredding and can contaminate crumb rubber streams meant for tire-derived products. Some non-tire rubber scrap is processed separately through dedicated grinding lines or diverted to pyrolysis or tire-derived fuel applications where material purity is less critical.

Many US states operate scrap tire management programs that require registered haulers and processors, track tire generation and disposition, and in some cases charge a disposal fee at the point of sale to fund recycling infrastructure. Because whole tires are widely restricted from landfill disposal, generators typically must document that tires are sent to a permitted processor, recycler, or tire-derived fuel facility.

Recycling scrap tires eliminates the fire and vector-breeding risks of large tire stockpiles and keeps bulky, slow-degrading material out of landfill airspace. Crumb rubber, tire-derived fuel, and pyrolysis products also create real revenue streams for processors, while asphalt rubber and molded rubber products reduce demand for virgin rubber and petroleum-based materials.

Demand for asphalt rubber in road construction and for crumb rubber in synthetic turf and playground surfacing continues to drive investment in higher-throughput granulation and cryogenic grinding capacity. At the same time, devulcanization and advanced pyrolysis technologies are gaining attention as ways to recover higher-value rubber and carbon black rather than settling for lower-grade crumb, though scaling these processes cost-effectively remains an active challenge for the industry.