Used tires are stored in dumps and warehouses. They are already a significant environmental hazard today. Environmental pollution by these materials can only increase if measures are not taken to dispose of them. The most ecological method of such disposal is the grinding of used car tires into rubber crumbs. Then this crumb is added to road bitumens as a modifier. But this method of bitumen modification was not widely used due to insufficiently high characteristics compared to other modifiers. In addition, as much as the tires wear out, this method will not be able to dispose of them properly. Another relatively effective ecological method is the pyrolysis of used car tires. This method is the most promising since the amount of tire recycling is limited only by the productivity of the pyrolysis plant. Unlike tire burning, pyrolysis is not such a harmful method.
During pyrolysis, pyrogas (which is used as fuel for pyrolysis plants), liquid products of used car tires pyrolysis (LPUCTP), and solid residue (possible use as low-quality carbon black or activated carbon) are formed.
LPUCTP, in terms of its physical and chemical characteristics, are similar to boiler fuel and fuel oil. But, as a rule, their quality does not meet the requirements of regulatory documents. We are developing a relatively simple method of LPUCTP usage, which consists of separating light gasoline fractions (boiling temperatures are limited up to 200 °C). The fraction obtained above 200 °С meets the requirements of regulatory documents for commercial fuel oils and boiler fuels (DSTU 4058-2001, PN-C-96024:2011, ISO 8217:2017, etc.).
Gasoline fractions contain many aromatic and sulfur-containing compounds. Unsaturated hydrocarbons are also present in the amount of at least 5% by mass. (styrene, limonene). Poor environmental properties and low stability characterize such products, so these types of compounds must be removed.
An extraction process was carried out to concentrate aromatic and unsaturated compounds. N-Methyl-2-pyrrolidone (NMP) was used as a solvent. The volume ratio of gasoline fractions and the solvent was 1:1.5. The yield of extract and raffinate is 63.25 and 36.75% by weight, respectively. The raffinate can be used as a component of gasoline, and the extract as a raw material for producing aromatic compounds or fuel in a pyrolysis plant. Therefore, pyrolysis, rectification and extraction processes can be used to dispose of used car tires.
Keywords: waste rubber; alternative fuel; pyrolysis of tires; extraction
Audience Take Away:
As a result of familiarizing the audience with the report, they will receive information about used tires recycling. The report will also help specialists to process used tires to obtain hydrocarbon fuels that comply with existing regulatory documents and to get a theoretical basis for further research.