Tyre Recycling

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Commercial tyre processing plant

An early variant of the technology has been implemented in a tyre-processing plant in Slovakia since 2001. The technology was developed and improved in cooperation with the commercial plant. The plant is using pyrolysis without catalyst and not the thermo-catalytic cracking method developed and perfected later.

Basic facts:

  • Yearly processing capacity: 15 000 tonnes of rubber tyres
  • Average yearly output:
    • Synthetic oil: 6 000 tonnes
    • Synthetic gas: 2 000 tonnes
    • Coke: 4 500 tonnes
    • Steel wires: 2 500 tonnes

Output shares from mixed plastic waste and used tyres

Plant design examples

The system design is very flexible and can be adopted to deliver processing capacities from 2 000 tonnes/year and upwards by increasing the screw reactor diameter and length and by adding more reactors in parallel.

Thermo-Catalytic cracking principles

Catalytic cracking – thermal decomposition in the presence of a catalyst – is more frequently used than pyrolysis.  Catalytic cracking takes place at a lower working temperature than pyrolysis, with the temperature lowered up to 150 – 450 °C in comparison. One method of catalytic cracking of plastics and wastes is to use zeolites as the catalysts. Zeolite catalysts are crystalline aluminasilicate materials based on a three-dimensional network of AlO4 and SiO4 tetrahedrally linked through oxygen atoms. Zeolites are porous and contain dimensionally defined pores with regions of high electrostatic field associated with the presence of cations. These regions are catalytically highly reactive. Pore size can be altered according the requirements on the product.  Synthetic zeolite catalysts ZSM-5 or HZSM-5 or catalysts MCM type (X and Y) can crack long-chain hydrocarbons. The drawback of this group of processes is high price of zeolite catalysts and their limited recyclability as well as the problems of the treatment with used catalyst.   On the other hand, natural zeolites are cheap, and it is not necessary to recycle them. FTS technology uses natural zeolites

The surface of a Zeolite-corn corresponds to that of a sponge with regular pores. The pore opening and the structure of the pores are characteristic for the respective zeolite type.

Through this configuration has a Zeolite a form of selectivity, which can be used as a molecular sieve and/or cracking catalyst.

Every Zeolite has characteristic pores and channels, together with the possibilities of surface modification the Zeolites become an excellent heterogeneous catalyst. The cracking occurs at the acidic centres which are located in the channels and the surface of the zeolite corn.

Utilization of plastic and Rubber waste

The disposal of rubber and plastic should be achieved by burning. The many harmful effects of the free carbon particles (strong smoke), include substantial damage to the environment and the poisonous substances attached to them are significant.

The production of rubber is based on a polymerization chemical technology. Reversing and executing the process, with external energy, the substance having a great molecule falls apart into substances with smaller molecules. The shortly described depolymerization process, if it is maintained by heat energy then it is considered pyrolysis, supposing that the reaction space is kept hermetic.

Some plastic waste is renewable, but there is a significant part which cannot be reused. However, since plastics are fundamentally crude oil derivatives, with less carbon type filler they can be converted into fuel using the thermo-catalytic cracking process.

The FTS plant works according to the principle of thermo catalytic cracking. The essence of the device is that organic waste feedstock (rubber, plastic etc) is ground (particle size 20-25 mm measure), heated with external cape heating in a partial vacuum. The waste then progresses to the steam- and gas phase, and at the end of the process char is produced.

The developing steam phase exiting from the device goes through a multi circle condensation system, through which the appropriate liquid phases are developed (similarly to the fractioned distillation process, however compared to the traditional distillation methods, under simpler and cheaper implementation circumstances).

Throughout the procedure synthetic diesel, gasoline, gas and char (so-called cracking products) are produced. The catalytic cracking system has a block system, meaning that it can be built modularly with smaller and greater performance.