| Abstract [eng] |
Every year, there is a significant increase in the number of tyres that are no longer fit for use. Increasingly stringent European Union legal requirements are making it necessary to ensure that this waste stream is properly and efficiently managed, thus encouraging the transition towards a circular economy. In 2019, the European Union generated over 3.55 million tonnes of waste used tyres, 55 % of which was reused to recover valuable materials. In Lithuania, the situation is somewhat different, with over 28.3 thousand tonnes of end-of-life tyres accounted for in 2019, of which around 34 % were recycled. The materials recovered during recycling (rubber, metal, textiles) can be used in a wide range of applications: rubber bases, carpets, other products, civil engineering; metal alloys; textile overlays, layering. The final Master's project analyses the recycling of end-of-life tyres and the use of recycled recycled material to produce higher value-added products while reducing the energy intensity of the processes. To this end, the following objectives were set: analysis of statistical data, analysis of the main legislative and regulatory frameworks in the field of end-of-life tyre management, search for and analysis of basic and new innovative recycling methods, assessment of the current environmental performance of the selected facility, assessment of the possibility of producing higher value-added products, proposal of ways of improving energy efficiency and reducing environmental impact, and an environmental assessment of the use of a higher value-added product in civil engineering. The object chosen for a more detailed analysis is JSC „Torgita“, a company that carries out traditional mechanical recycling of end-of-life tyres. The study was based on the analysis of statistical data, legal acts, scientific and practical literature. The main research methods of the final project were: elements of the methodology for the implementation of Cleaner Production (CP) conception in industrial enterprises, such as: analysis of material and energy flows, material balance, and feasibility analysis of proposals (technical, environmental and economic assessment); elements of the Industrial Ecology such as: dematerialization of material flows, industrial metabolism. The life cycle assessment methodology was used to determine the environmental impact of a product throughout its life cycle. Case study and/or case-control analysis methods, environmental assessment of effectiveness (EAE) were used to summarize the results obtained. The experiment showed that secondary raw materials (up to 1281 t of rubber pellets (a yield of about 56 %) and 910.56 t of metal scraps) were recovered from 2271 t of end-of-life tyres, 76 t of textile waste were generated in analyses object in 2020. The main environmental and economic problems were identified: high electricity consumption (up to 278.8 kWh) for a low value-added unit (tonne) of final output (≤30 mm fraction rubber); therefore, indirect environmental impact due to climate change – up to 117 kg CO2e / tonne of produced rubber (PR). Three alternatives were proposed to improve the current situation: (1) optimization of the operation of some of the equipment in the technological line and the introduction of an additional process for the pre-treatment of the tyres, without changing the value of the final product - PR; (2) introduction of an additional process for the reduction of rubber to a smaller fraction, and a new method of cutting the tyres to obtain products with a higher added value (≤ 8 mm rubber with less metal contamination); (3) replacement of the existing mechanical recycling technology with a completely new innovative technology for the production of products with the highest added value (e.g., 800 µm fraction ultra-high purity rubber with < 2 % of additives). Have already implemented first process optimization proposal allowed minimizing electricity consumption by 77 kWh per tonne of PR, and thus reducing indirect GHG emissions by about 32 kg CO2e /tonne of PR. The second innovation would lead to higher yields and higher value-added product. This would also lead to additional electricity savings by 9 kWh/tonne of PR and minimizing indirect GHGs by 3.9 kg CO2e /tonne of PR. The third innovation would allow producing the highest value-added product (ultra-high purity rubber), with a less electricity consumption (by 1.6 kWh/tonne of PR) and, thus, less environmental impact to GHGs (by 0.56 kg of /tonne of PR). In case of the second innovation, the produced rubber could be used in the road construction industry for the production of rubber modified bitumen asphalt, and the use of such a road could lead to a reduction of GHGs by 40% of CO2e in compared to a standard road. |
