The present invention relates to a process for the production of liquid hydrocarbons from old tires, cable wastes, polyethylene wastes and/or polypropylene wastes. Among the liquid hydrocarbons, which are produced according to this process, are alkanes, cycloalkanes and aromatic substances, which have a boiling point from 20.degree. to about 350.degree. C. and whose molecules contain 5 to about 30 carbon atoms. The liquid hydrocarbons produced according to the invention can contain organic sulfur- and chlorine-compounds, depending on the sulfur and chlorine content of the old tires. The liquid hydrocarbons can be used as heating oil or for the mixing of heating oil, respectively, or for chemical raw materials.
Old tires are part of the waste products of the motor vehicle industry and comprise one or more rubber mixtures, a bead ring and woven material. The rubber mixture generally comprises rubber, carbon black, oils and resins, zinc oxide, a vulcanization accelerator, preservatives and sulfur. The rubber generally comprises chain-form macromolecules, which entwine among each other and in addition are linked through sulfur atoms. Tire production is carried out by using natural rubber and synthetic rubber, wherein the synthetic rubber types are developed through polymerisation of isoprene, butadiene, chlorobutadiene and copolymerisation of butadiene with styrene or isobutene with isoprene. The carbon black serves as a filler and for the improvement of the rubber characteristics, because it forms a very close bond with the rubber during the production of the tire. The oils and resins function as a plasticizer and improve the working property of the rubber mixture. The zinc oxide serves as a filler and as an activating agent for the vulcanization accelerator. The bead ring stabilizes the tires against radial forces and consists of steel wire or steel cord. The woven material present in the tire comprises synthetic fibers or steel wires. The weight percentage of the rubber mixture in old tires usually is between 75 and 80%.
Cable wastes are developed by the fabrication and repair of cables which comprises a metallic electric conductor and a synthetic insulation as well as a synthetic sheath and are used for the transmittal of news or electric energy.
Polyethylene- and polypropylene- wastes are developed by the production of synthetics and the processing of synthetics and are obtained in those cases in a relatively pure form. Polyethylene and polypropylene are produced by polymerisation of ethylene or propylene, respectively, and contain, along with the polymers, additional fillers.
The harmless disposal of old tires is difficult and expensive. Old tires today are usually disposed of by burning, which occurs either in especially constructed ovens or in waste burning facilities. The waste gases of the waste burning facilities, in which old tires are burned, must be dedusted and desulfurated, especially because of the high ZnO-- and SO.sub.2 content. Moreover, it is known that old tires can be disposed of through a pyrolysis process and processed to reusable products. Through the pyrolysis of old tires are produced a pyrolysis coke, a burnable pyrolysis gas, that mostly serves to provide the intrinsic energy requirement of the pyrolysis process, and a pyrolysis oil, that is used as heating oil. The polyethylene- and polypropylene wastes are usually burned. The cable wastes are ususally dumped in a waste deposit.
The burning processes have the disadvantage that they are difficult to carry out because of the natures of old tires and synthetic wastes and that the burning waste gases must be purified with expensive processes. The disadvantage of the pyrolysis process is that a very large part of the organic compounds, valuable in themselves, carbonizes and is thereby transformed into a less valuable form.