Tire recycling (worn-out tires) is a solution for a problem that is common to the developed countries of the world. The implementation of the technology of tire recycling is of great economic and ecological importance.
According to various data, more than two tens of millions of tons of tires that have worked their time are formed annually, of which more than 60% fall on landfills.
Utilization of tires is of great importance in solving environmental problems.
At the same time in Europe more than 2 million tons of tires are being decommissioned, with the level of processing reaching 90%, with a significant part, about 40%, being burned for energy, and about 30% being processed into rubber chips. It should be noted that the European market is actively increasing the share of mechanical processing of tires.
In Russia, more than 1.1 million tons of tires are annually recycled, and the processing volume is only slightly more than 10%.
Processing of tires is carried out, as a rule, using methods of pyrolysis and crushing. At the beginning of the XXI century, the combustion method prevailed, but gradually it yields to the method of crushing. It should be noted that in some countries of Europe the technology of incineration of waste is prohibited due to environmental hazards.
At present, electromechanical grinding of worn out tires is used to a greater degree. The grinding process is based on the use of a cutting tool, while the recyclable materials can be cooled or processed in an elastic state. With this method of processing tires, a commodity product is produced - rubber crumb of various fractions widely used in various industries :
- A fraction of rubber crumb up to 1 mm is used in the manufacture of floor rubber coatings, roofing mastics, as well as high-quality asphalt pavement;
- crumb with a particle size of 1 to 3 mm is widely used in the construction of football fields and rubber coatings sports and children's playgrounds;
- a large crumb with a particle size of 5 to 8 mm is used in the oil industry and the production of some sports simulators.
The technological process of mechanical grinding is characterized, as a rule, by a large number of downtime associated with the time required to replace the cutting elements of equipment, as well as to unscheduled repairs. Low productivity, energy intensity lead to high cost of rubber chips.
In addition to these methods of recycling worn tires, there are other ways of recycling. This is, first of all, grinding tires with an "ozone knife", in which mechanical grinding is subjected to tires pre-treated with ozone in a closed chamber. The crumb obtained by this method does not preserve the properties of the original rubber, therefore it is not in demand.
One can also mention the baro-structuring method, in which large fragments of tires are subjected to high pressure with destruction of the rubber structure. In this case, the properties of the original rubber are also not preserved, so this method has also not found wide application.