Author(s)

M. Stelmachowski & K. Słowiński

Abstract

Waste rubber (particularly scrap tires) generated worldwide exerts a detrimental influence on the world economy and the environment. Their fraction in municipal wastes amounted to 2% by mass in 2000. By the end of the 20th century, rubber production was about 34 million tons in the world. It is estimated that 20% of tires have to be recycled every year. Dumping and land filling of used tires were the most popular methods of utilization of them not long ago. Other alternative methods that have been used for tire recycling such as retreating, reclaiming, incineration, grinding have also significant drawbacks and/or limitations but they influence the environment to a lesser extent than dumping. Pyrolysis or gasification of waste rubber may be the best way of its utilization. The results of the thermal degradation of waste rubber performed in a new type of the tubular reactor with molten metal are presented in the paper. The melting and degradation processes were carried out in one apparatus at the temperature 390-420°C. The problems encountered with: the disintegration of wastes, the heat transfer from the wall to the particles, cooking at the walls of the reactor, and mixing of the molten volume of wastes are significantly reduced. Two products: gaseous (below 15% weight %) and liquid (over 40 weight %) product were obtained during the degradation of waste rubber. Both streams of products were analyzed by gas chromatography. The gaseous stream contained hydrocarbons from C2 to C8 and the liquid product consisted of hydrocarbons C4 to C24. Over 80 mol % of liquid hydrocarbons mixture was the fraction C4-C10. The obtained liquid product may be used in petrochemical, refinery or may be recycled for tires manufacturing. Keywords: thermal decomposition, waste rubber, scrap tires, molten metal.

Keywords

thermal decomposition, waste rubber, scrap tires, molten metal