Article originally published in Global Cement Magazine 2/2022
Waste processing firm FCC Ceská Republika outlines the steps involved in a recent tyre/ refuse derived fuel plant project for Lafarge in the Czech Republic.
FCC Ceská Republika was contacted by the Lafarge Cement Cízkovice cement plant in the second half of 2017. The plant wanted to know if FCC would take over the production of shredded tyres for the plant, a service that had previously been contracted to a third party. FCC was already a long-term partner of the Cízkovice plant, supplying it with high-calorie refuse derived fuel (RDF).
The existing tyre-grinding line comprised a two-shaft low-speed shredder, a star-shape screen and a set of conveyors. Theover-the-screen fraction entered again from the star-shape screen into the shredder. In fact, tyres were circulated until reaching the required size of <100m.
After some consideration, FCC decided not to purchase this technology from the previous operator. This was mainly due to its poor condition, low capacity and the need to get a building permit to be able to install the technology at a new site, a condition of the Cízkovice plant.
However, FCC did not want to lose the opportunity to supply increased volumes of alternative fuels for the cement plant. In addition to supplying shredded tyres, the company wished to use the new site, in nearby Lovosice, to produce calciner refuse derived fuel for the cement plant.
In order to be ready to supply the plant quickly, FCC opted for a mobile shredder. As mobile units, they do not require building permits, massively speeding up the project.
FCC wanted a mobile shredder that could shred waste tyres down to <100mm in a single pass. This meant a shredder equipped with a full-value output screen to guarantee the fraction size. While there are many two-shaft shredder options on the market, there are far fewer single-shaft models with an output screen. Tana is one of the suppliers of such machines, so FCC contacted its Czech representative, Komunální technika s.r.o. FCC wanted to weigh up the machine rapidly, in terms of both capability and cost. A demonstration on the new FCC site was provided, using a wide portfolio of input waste. In addition to tyres, the wastes also involved wood, car carpet, hard plastic, plastic films, hollow plastic packaging and other materials.
Representatives from the Cízkovice plant were invited to the tests to evaluate the output and to confirm that it met their requirements. Besides the size of the output fraction, the key question also involved the quality of the cut tyres. The plant had previously had a bad experience with a different supplier that provided ‘tyre spiders’ due to excessive shredding speed. Such spiders have long wires at the extremities of the rubber pieces. The wires become entangled with each other during subsequent steps, making feeding to the calciner very difficult.
This phenomenon was avoided during the TANA demonstration and the product was given the plant’s seal of approval. A similar trial with a competitor’s shredder does not achieve quite the same performance as the TANA machine. It had a lower grinding capacity and the tyres repeatedly became stuck between the rotor and the screen. The decision in favour of TANA was straightforward.
Keep the noise down!
During the tests with all of the machines, FCC was aware of the high level of noise generated by the shredders’ diesel engines. While the business premises are in an industrial area, they are also close to a river. On the opposite bank is a residential area. FCC was concerned that noise would travel easily over the water and lead to noise complaints in the future.
Quite coincidentally, Tana launched a mobile version of the machine in the market called TANA Shark, which has an electric drive. Although the need for a power supply limits its mobility, FCC does not intend to move the shredder for the forseeable future. The TANA Shark was the clear choice for FCC.
FCC ultimately ordered a TANA Shark 440EM mobile with an output screen of 76mm. After shredding tyres for the first few months of its life, FCC additionally fed it ‘blue reject’ from paper mills, the unrecyclable plastic residues from final separation of communal plastics, and other calorific wastes. The combination of these wastes allows FCC to reach the required calorific capacity of the mixture of around 15MJ/kg. Moreover, the high humidity of paper-mill reject also positively impacts the shredder’s performance. The size of the output fraction is approximately 100mm. Besides preparing RDF for the calciner, the shredder is also used for the rough shredding of tyres (without a screen).
When shredding tyres with a screen to <100mm, the capacity is around 4t/hr. Shredding tyres without a screen increases the rate to around 9t/hr. The average output achieved while shredding 60% of mixed materials (tyres + other wastes and 40% of shredding without a screen is 6.5t/hr overall.
FCC started to work intensively on the project at the start of 2018. The selection of an electrically driven shredder required the construction of a new 630kV transformer and an electric cable access line within the framework of the area. FCC concluded the purchase agreement with TANA to buy the shredder in August 2018. The construction of the transformer station and the electric cable access line were finished in December 2018. At the same time, the shredder began test operations. Fuel production began in earnest in 2019.
The main benefit of the TANA Shark 440EM is its ability to produce a well-defined, relatively fine output fraction to the client’s specification. In this respect FCC feels that it differs from the wide range of other mobile machines that are available on the market. A great benefit also consists of a high torque momentum, which allows the processing of a wide range of waste. FCC thanks the Cízkovice plant for putting its faith in the company once again and for the companies’ continued successful collaboration.