State and prospects of development of tire recycling technologies and their environmental impact
Because of rapid increase in the number of cars, there is an actual problem of warehousing, storage, transportation and recycling of dozen million tires annually. On the one hand, scrap tire is a waste, on the other - a valuable recyclable material. In this article the most common recycling technologies for tires are investigated. There are recovery, incineration, mechanical crushing and pyrolysis. Shredding of rubber wastes is recognized as the simplest and most rational way of recycling because it allows to preserve physical, mechanical and chemical properties of the material. However, the final stage of use of the resulting crumbs is a stumbling block of costeffective solution to the problem of full recycling of rubber wastes. Incineration of tires leads to significant pollution with heavy metals (cadmium, nickel), sulfur oxides and carbon compounds. Pyrolysis of tire recycling provides the lowest level of emissions and complete recycling of tires. The study shows that typical pyrolysis plant with four wasteheat boilers does not result in the emission of heavy metals and sulfur. As a result of pyrolysis with an average load - 850-1000 tons/year of rubber wastes there are produced: the liquid fraction - 500 liters/day (500 m<sup>3</sup>/year), high-carbon residue - 1 ton/day (1,000 tons/year), metal - 0,2 tons/day (200 tons/year), gas - 200 m<sup>3</sup>/day (200,000 m<sup>3</sup>/year). Surface concentrations of pollutants is calculated using «EOL+». A map of the MPC levels of certain contaminants in nine areas is developed depending on the distance to the source of the emission. The research confirms the environmental safety tire pyrolysis recycling.