Tallinn University of Technology

A joint study by the Oil Shale Competence Centre of Virumaa College of Tallinn University of Technology and the company Ecometal confirmed the suitability of heavy plastic waste from lead-acid batteries for pyrolysis with oil shale without changing the quality of the oil compared to shale oil.

Due to the relatively simple and unified construction of lead-acid batteries, their recycling has reached an industrial level. Photo: Ecometal

The Estonian company Ecometal processes up to 20,000 tons of used batteries every year and thus produces lead and various lead alloys, sodium sulfate and polypropylene. In addition to products, heavy plastic waste is also generated from battery separators. There is an opportunity to crush this waste and direct it to the cement industry as an energy component. However, in terms of their composition, these wastes are not suitable for the production of energy by direct combustion in a waste incineration plant. With the wider application of circular economy principles and the growing interest in using plastic waste as a raw material, it makes sense to look for ways to recycle heavy plastic waste.

The Oil Shale Competence Centre, which has competence in the research of co-processing of plastics and oil shale and Ecometal set the goal of the cooperation project to find out the suitability of heavy plastic waste as a raw material for oil production. For this purpose, waste pretreatment and co-pyrolysis experiments were carried out with the interpretation of the results based on the previous experience of the laboratory of the Competence Centre.

Summing up the study, it can be said that plastic waste from accumulators is well suited for pyrolysis together with oil shale, because:

  • it increases the yield of the amount of oil and light fraction;
  • the resulting oil is stable;
  • sulfur content in oil fractions decreases;
  • when adding plastic waste to the co-pyrolysis mixture, the quality of the resulting oil does not change compared to shale oil.

In addition, it became clear that there was no need for prior neutralization of plastic waste.

Due to good cooperation and the involvement of Eesti Energia as an additional partner, the whole project was successful. Important knowledge was gained by both Ecometal, conducting batteries reprocessing, and the companies planning the recycling of plastic waste (Eesti Energia, Viru Keemia Grupp, Kiviõli Keemiatööstus), as well as the performer of applied research itself.

As an added value, the project is important for the Oil Shale Competence Centre, since it makes it possible to assess the suitability of specific waste as a raw material for oil production using the example of specific waste. In this way, the Center can move from basic research to the level of applied research and use the acquired experience in conducting similar research. The implementation of the project "Research on the use of lead-acid heavy plastics in the oil industry" was supported by the European Regional Development Fund of the European Union.

Additional information: Kalle Pirk, kalle.pirk@taltech.ee, tel 502 4714