One of the options for dealing with End of Life Tyres is to shred them into chips. Tyre Derived Fuel is a recognizedand approved use to processEnd of Life Tyres. The cement industry relies heavily on coal and coke to fire their kilns, requiring approximately 30 million tonnes of fuel equivalent per annum, worldwide. Fossil fuel prices continue to rise and despite reductions in Natural Gas prices in the US, there is little sign of fuel cost relief in the foreseeable future in Europe or elsewhere.
Unlike coal and pet coke, used tyres, when burned, produce carbon-neutral CO2 emissions due to the natural rubber contained therein. Used passenger car tyres, according to studies, have biomass fractions between 17% to 20%, while used truck tyres are 29% to 30% biomass and are eligible for Carbon Credits, depending on the location of the cement kilns.
Combustion of End of Life Tyres, instead of coal, has a strongly beneficial impact on heavy metals emission from kilns. This has important implications for the respiratory health of the population near the cement factories. Tyre Derived Fuel is an environmentally important and financially attractive solution to the problem of End of Life Tyre production worldwide.
Tyre chips can be completely combusted in a cement kiln or other industrial boiler that uses coal: the combination of high temperatures (1450°C to 1500°C), a positive oxygen atmosphere and a long gas residence time (4 to 12 seconds at the elevated temperatures) assures complete combustion. A cement kiln operator can reduce coal consumption by 1.25 Tonnes for every tonne of tyre chips used. Petroleum Coke (pet coke) delivered to cement kilns in North Africa is currently costing €88/Tonne. A tonne of Tyre Derived Fuel can be delivered to the same location, for €37 or less/Tonne. There is a compelling financial incentive for cement kilns to combust all available End of Life Tyres at this price.Last year in the EU, about 4 million tonnes of End of Life Tyres were produced.
Before they can be combusted in a cement kiln, tyres must be size reduced to 5-10cm chips. This is to ensure an even combustion when co-fired with coal. Whole tyres would burn “hotter” than the surrounding coal, and disrupt the process parameters of the cement manufacturing process. Safe tyre shredding requires industrial grade cutting equipment consuming large quantities of tyres and requires 30,000-40,000 tonnes of throughput annually to operate efficiently.