The waste tyres research group is an interdisciplinary effort between the Department of Process Engineering and the Department of Chemistry and Polymer Sciences at Stellenbosch University, sponsored by the Recycling and Economic Development Initiative of South Africa (REDISA). The research effort has a focus on the development of technological pathways for the revalorisation of waste tyres, both from an environmental and economic viewpoint.
South Africa currently has approximately 60 million waste tyres in landfills and stockpiles and annually 11 million are added to this problem. This type of disposal can result in significant environmental disturbances, such as uncontrolled fires (with accompanying pollution of the atmosphere, soil and groundwater) or by supplying breeding ground for rats, mosquitoes, etc. At its core REDISA concentrates on addressing this mounting environmental problem by finding solutions that benefit the tyre recycling industry with waste reduction and economic value adding, whilst simultaneously creating work opportunities.
In line with its mandate to develop a waste tyres collection and recycling industry, REDISA has entered into a four-year research agreement with Stellenbosch University (SU), entitled Beneficiation of Waste Tyres from Recycling. The RESIDA-SU research group supports the recycling industry by investigating several approaches for the recovery of value added chemicals/materials from waste tyres, either for re‐use in the production of tyres or other economically valuable applications.
The two main approaches currently under development are devulcanisation and thermal fractionation, followed by separations and upgrading. Both of these pathways generate a broad range of valuable products ranging from plasticisers, solubilised polymers, oils, pyrolysis-char and -gas, and numerous chemical species such as limonene, styrene, syngas, etc. Classical and novel separation processes, e.g. distillation, solvent extraction and membrane technology, are utilised. The group also investigates the production of environmental friendly tyres, using alternative, sustainable sources of raw materials. Further aspects of sustainable tyre recycling include conversion efficiency, economic viability and environmental impacts.
The REDISA-SU research group hosts ten postgraduate students and two postdoctoral researchers, supervised by Prof Johann Görgens and Drs Cara Schwarz and Percy van der Gryp from the Department of Process Engineering and Prof André de Villiers from the Department of Chemistry and Polymer Sciences.
This initiative by REDISA marks an innovative and daring research field, aiming to transform the tyre recycling industry, and making a valuable contribution to waste management in South Africa.
Photo left: Monwabisi Scott doing pyrolysis of waste tyres.
Photo right: Kirsty Henry does upgrading of pyrolytic char obtained from waste tyres.
