PROBLEM: More than 13.5m tonnes (~1bn tyres) of End of Life Tyres (ELT) are discarded annually throughout the world , of which Europe contributes 24% . By the year 2030, this number is forecast to reach up to ~5bn tyres (including stock piled) to be discarded globally on a regular basis . Disposal of these ELTs presents serious environmental and commercial challenges. Europe produces 3.3m tonnes of ELT every year and spends €600m annually on its management. In 2014, 37% of the collected ELTs were used in the energy recovery, 35% used in for granulation and 27% utilised for re-treading & reuse .
Several ELT management routes have been tried in the past such as;
• Land Filling- used prior to 2006. Due to heavy metals and other pollutants found in tyres there is a potential for leaching of toxins in to the water table. This is dangerous to human health and other organisms. Since 2006, ELT, Landfill is no longer an option as EU legislations (1999/31/EC) and (2000/53/EC) prohibit the disposal to landfill of the whole or partly shredded tyres
• Shredding- The rubber (SBR/NR) can be used to make floor surfaces, such as children’s playgrounds or carpet underlay. Very niche market with low margins and not big enough market to consume the tyres waste generated globally. UK alone generates 480,000t tyres per annum.
• Burning Tyres as fuel- At least two-thirds of tyres collected today are incinerated to produce energy in cement kilns and paper factories etc. due to their high calorific value (CV). Along with having a negative effect on the ‘circular economy’ and EU’s Waste Hierarchy by losing valuable materials, this causes emissions of harmful pollutants such as carbon and sulphur compound.
The only method to drive ELT management towards the Circular Economy & EU’s Waste Hierarchy is ‘Pyrolysis’ which has the potential to convert tyres into its constituent fractions which can then be recycled. Pyrolysis is thermal decomposition of the ELT in the absence of oxygen to produce steel, char, liquid oil and gas . Pyrolytic oils (mixture of paraffins, olefins & aromatic compounds) have a high heat value (CV~44MJ/kg), can be combusted directly or with petroleum products . The gas fraction contains CH4, CO, CO2, N2, H2 & O2 and is usually burnt to fuel the pyrolysis process. However, at present pyrolytic char is too contaminated and non-functional to have much commercial value. Pyrolytic char consists of carbon black(CB) and a mixture of carbonised rubber polymer, non-volatile hydrocarbons and ash containing tyre rubber additives such as ZnO, Sulphur compounds, Clays, and Silica . Although char makes up to 40%wt of the output in a pyrolysis process, there is a very limited market for the char due to these ash contaminants and its low surface area which has a range of 40-60 m2/g. Therefore, pyrolytic char obtained from conventional pyrolysis cannot be reused in high end applications such as road tyres and conveyor belt manufacturing, therefore limiting its market to low grade applications eg manufacturing of cheap thermoplastics and low cost absorbents for the treatment of industrial effluents.
Our market research suggests that while there are over 20 R&D pyrolysis plants in the EU, most are university based) and there are no commercially successful ones. One of the major factors of the commercial non-viability of these plants and the pyrolysis process is their inability to fully extract the carbon char produced Its inferior quality to virgin Carbon Black (CB), due to the impurities present and loss of functional groups due to the pyrolysis, gives it limited end use applications. It is widely believed that reprocessing of waste tyres into value-added products would improve the economic leverage of ELT pyrolysis. Recovered CB (rCB) is under constant review by tyre manufacturers (an industry which uses about 75% of all carbon black produced worldwide) however there has been little success to date. Our initial market research concludes that the major barrier to producing high quality rCB from pyrolytic char is the lack of technology to separate CB from the ash and produce a ‘functional’ rCB with a surface area in the range of 80-100m2/g. There is no existing technology which can separate CB from ash and provide the ability to modify its surface properties by adding bespoke functional groups to make it suitable for a range of applications.
IMPORTANCE FOR THE SOCIETY: Currently across Europe, there are no fully operating, commercialised pyrolysis plants which are treating ELT . A pyrolysis plant equipped with our ReTyre solution to produce ultrapure and high surface area rCB, will be the first in Europe to be truly financially viable. We aim to license our technology IP and process know-how to current and new pyrolysis plants, which have proven their capability to operate a zero-waste treatment plant but are not commercially viable. Our technology will not only make tyre pyrolysis truly a zero-waste solution for ELT, but will also produce a higher quality carbon black output with fewer ash impurities, with the potential to have even higher value than virgin CB when combined during manufacture with an advanced, functional coating. Our technology is in coherence with the EU waste hierarchy which focuses on recycling raw materials to boost the circular economy. The EU wide environmental benefits of our technology in comparison to the traditional furnace CB includes reduction of ~5,223 tpa CO2 emissions, reduction in particulate matters by ~30%, SOx by ~ 68%, NOx by ~57% and volatile organic compounds by ~42%- per plant processing 8705tons/year of char.
OVERALL OBJECTIVE: Our overall objective in the Phase 2 project is to develop the technology to TRL9 and, for the first time, separate carbon black from pyrolytic ash at a commercial scale and convert it into an ultrafine functional filler with up to 33% (60m2/g to 100m2/g) increased Specific Surface Area (SSA). We aim to develop a demonstration plant ourselves and then license the technology to the ELT handlers throughout the EU.
