CA2083601A1

CA2083601A1 - Process and device for utilizing organic wastes

Info

Publication number: CA2083601A1
Application number: CA002083601A
Authority: CA
Inventors: Reinhard Fischer; Volker Lackner; Georg Menges
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-05-26
Filing date: 1991-05-23
Publication date: 1991-11-27
Also published as: ATE131519T1; EP0531371A1; WO1991018960A1; JPH05507749A; DE59107086D1; EP0531371B1

Abstract

The invention relates to a process for utilizing organic wastes consisting at least predominantly of macromolecules. The aim is to be able to utilize plastic wastes in a simple, ecological manner and also to extract useful raw materials, substitute materials or energy carriers or to prepare their simple extraction. To this end, the invention proposes that the macromolecules of at least part of the wastes be decomposed by heating to more than 150 ·C to liquid and/or gaseous constituents which can therefore be reutilized.

Description

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LITERAL A~D VERIFIED TRANSLATION OF PCT-APPLICATION NO.
PCT/EP91/00959 (AS AMENDED) CARRYING OUT THE METHOD

The invention relates to a method for the utilization of organic wastes consisting predominantly of macromolecules.

German Patent Publication DE-A-3,735,061 describes a method in which partly organic wastes are burned with high percentage oxygen, instead of with combustion air. Household garbage, special wastes and the like were mentioned under the category of waste, as well as the waste of shredders, which will be further referred to separately.

The wastes are burned with oxygen in a suitable oven, the exhaust gases are cooled in a waste heat boiler and then, in a suitable gas cleaning plant, they are freed substantially from pollutants.
In this combustion process, carbon and/or carbon containi~g matter are mainly combusted to carbon dioxide and water.

Since the nitrogen, which is present as a ballast when combusting with air is lacklng here, the burning exhaust gases have only small nitrogen contents, depending on the nitrogen levels in the waste to be burned. Carbon dioxide is an unwanted combustion by-product, since it adds to the so-called "greenhouse effectN.

Further, many methods are known, in which carbon monoxide is hydrogenated to various hydrocarbon compounds of most varied . . . .

2~8361~1 1 compositions, through the use of a suitable catalyst. The Fischer-Tropsch benzine synthesis should be mentioned here:
nCO + 2nH2 ~ nCH2 + nH2O, or methanol synthesis.
CO + 2H2 ' CH3OH

Carbon monoxide and water vapor can also be transformed into various hydrocarbon compounds, with suitable mixing conditions and catalysts (H. Kloebel and Fr. Engelhardt, Applied Chemistry 64, 1952, pp. 54-5~
mCO + nH2O = oCH2 + pC2H5OH + qco2 The hydrogenization of carbon dioxide with hydrogen is also pos-sible (European Patent Publication 0,079,207):
mCO2 2 = oCH4 p 3 q While usually, so-called synthesizing gases are used for the synthesis of hydrocarbon compounds, however synthesis has also been carried out with blast furnace gas and water gas, it can be taken from the German Patent Publication DE-A-3,525,479 to convert the CO2 that is generated by combusting gases, at a high temperature with methane and water vapor into a gas made up mostly of CO and H2, which is suitdble as a synthesizing gas for various synthesis products.
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The hydrogenization of carbon containing waste is already known from ~Kunststoff Journal" 12/87, p. 3.

Tbe shredder wastes mentioned above will now be dealt with. Wastes made of synthetic material are produced in large quantities during .

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1 the shredding of used car bodies. These wastes make up about 3/4 of the so-called light fraction, which in turn make up 25% of the entire weight of the car, that is, the synthetic material wastes constitute about 12~ to 18% of the car's total weight. These wastes are decreased by the removal of reusable parts, such as large com-ponents. However, at least half of the waste still remains, because these parts are so permanently fixed to the body that their removal is not possible or would require too great an effort. These wastes in the light fraction are available as shreds of a mixture of var-ious synthetic materials, textiles, caoutchouc (rubber) and wood. There-fore, they can no longer be economically separated and they cannot be reused, for example, directly out of a melt, so that they must now be stored at a waste dump. In addition, these wastes are so contaminated with motor and hydraulic oils, that they also cannot be burned, so that they must be disposed of as special waste at a very high cost.

This mixture of organic waste materials, however, has a high heat value of about 12.5 MJ/kg, since it is made up of, for the most part, polymers produced from crude oil. Processing such mixtures by melting has not led to useful, marketable products.

Methods have been suggested, however, to crack the high molecular hydrogen ox~cunds into lower molecular gases and oils. These pro-cesses are the pyrolysis, hydrolysis, and hydrogenization. The latter process relates directly to the hydrogenization of coal.
The wastes must be cleaned and cdmminuted, in order to be mixed to form a mash with used oils, which is then hydrogenized. The hydrogenization, however, requires a costly preparation of the wastes by manual sorting and grinding to a fine powder.

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1 In pyrolysis it has been found that the by-products such as chlorine and sulfur, collect in the form of undesired, sometimes highly toxic compounds in the pyrolysis oils. Therefore, pyrolysis today is sensible only with chlorine-free wastes. Hydrolysis is only suitable for a portion of the synthetic materials, namely for those that were produced through polycondensation.

A method of the initially described type has also become known from the US-PS 3,984,288, wherein the wastes are first heated and melted, and then transferred in this state from an extruder into a special heated chamber for the decomposition. That method requires a high apparatus expenditure and is therefore not economical.
Only one extruder is used therein to facilitate the continuous, uniform delivery and to produce a molten mass from the synthetic material wastes not yet sufficiently heated for the method and to bring this into a decomposition pipe or so-called pyrolysis chamber. It is expressly pointed out that the pyrolysis reaction shall only begin in the decomposition pipe. That method, no doubt, facilitates the pyrolysis but without eliminating the disadvantages of pyrolysis.

Starting from this prior art, it is the object of the present inven-tion to suggest a method of the above mentioned type, with which synthetic waste materials can be utilized in a simple and environ-mentally safe manner, or with which it is possible to produce or to prepare for the simple production of valuable raw materials, replacement materials or energy carriers. Further, an apparatus for carrying out the method shall be suggested.

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1 With reference to the method, the object is achieved, starting from a method of the above described type, in that in a single reaction chamber the wastes are heated to more than 150C, melted and then decomposed to wax, oil, or gas by the addition of oxygen, and/or hydrogen, and/or water, and/or air, and/or water vapor and/or metals, or metal oxides. Hereby, the disadvantages and difficulties of pyrolysis, of hydrolysis and of hydrogenization processes are avoided. ~ather, the organic polymers are broken down or cracked into lower molecular polymers, oligomers, and monomers, so that liquid and/or gaseous constituents are formed, which can then be further processed simply and as desired. All this is performed in a single reaction chamber, which naturally must be constructed in a manner suitable for this purpose, as may be taken from the apparatus claims.

! The wastes can, in addition! be exposed to pressure and/or to a shearing force. Hereby also, the necessary heating is produ~ed, or at least a portion of the heat needed is generated. They are hereby easily split or cracked into lower molecular molecules and thereby liquified or gasified.

~20~ In addition to the heat supply, different reactive gases, such as oxygen, or hydrogen or water vapor can be added individually .
or together, simultaneously or in a chosen sequence for breaking - down the polymers. The break-down of the polymers is hereby ac-, celerated. Furthermore, other materials can be added to the mixture of synthetic materials and reactive gases, which catalytica~ly accelera~te the molecular break-down, and which in addition, or ~ . -alternatively, prevent the recombination of the radicals which are~produced. These catalytic materials can be metals, metal ::
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1 With the measures mentioned herein so far, the macromolecules of the synthetic materials are split apart in the melt, that is to say they are shortened and thereby are liquified at a suitable pressure and temperature, and are possibly also completely or partially gasified. As far as it is necessary, the molten mass can be dehalogenized at the same time.

With mechanically polluted synthetic materials, a sufficient separ-ation of non-liquified or non-liquifiable constituents can simul-taneously take place with the liquification of the synthetic ma-terials in a suitable apparatus. In many mixed synthetic materialwastes, non-meltable synthetic material components must also be expected. These do not disturb the process, however, if more than half are thermo-plastics. It is then necessary, however, to in-crease the shearing force and possibly the oxygen content of the gases which are added.

The above described method is based on the fact that the covalent bonds of the carbon or the heteroatoms of the main chain of the polymers become increasingly labile at about 400C. The molecular bond characteristic of the synthetic materials breaks up under such conditions, it can however, recombine if the radicals produced are not saturated. For this reason, oxygen, possibly hydrogen, and water vapor are added already as reactive gases to the molten mass that is being formed.

Thereby, the degradation of the polymer molecules by oY.ygen is the fastest working disintegration process for most polymers.

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1 Water vapor has, among others, the special purpose of breaking down the synthetic materials present, for example in the shredder wastes, which were produced through polycondensation. In addition, it also makes sense to add water to the wastes. The water can also be added as a moistening of the product being treated. This water changes to water vapor during the process, so that the extra addition of water vapor is not necessary. The break down or decom-position of the polymers can be further amplified, if metals, metal compounds, such as metal oxides, which act as catalysts, are added to the wastes, for example, by mixing them in drums before filling them into the melting cylinder or by injecting them at the entrance of the melting cylinder. Thus, for example, iron containing com-pounds work catalytically at the splitting of polyvinyl chlorides (PVC), and heavy-metal containing compounds, especially copper, act correspondingly on polypropylene and other polyolefins.

Depending on the construction of the apparatus suitable for carrying out the method, the organic wastes can be processed continuously or in batches. The use of a worm machine as a reaction chamber is especially suitable, because all of the reaction phases can be carried out in it, and during the process it can produce a shear-ing force and pressure by itself, so that separate devices for transporting or for further processing are not necessary. Hereby, it is suitable to control during processing at least the hydrogen content in the liquid and/or gaseous constituents and to influence said content in the organic wastes in a desirable way by suitable dosing. Hereby, the composition of the liquid or gaseous constituents that are being produced, can be purposefully controlled. Prior to the further processing or utilization o-f-these products, mechanical pollutants are suitably removed from the molten mass.

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1 The components produced by the break down of the macromolecules have a consistency, such that they can be transferred into or in-jected into,without problems by conventional devices, conventional containers, combustion chambers or reactors and the like. This can also be advantageous to replace, at least partially, the ma-terials used in conventional systems until now, for example, to produce synthesis gas or other useable gases or also as a reduction agent. According to the invention, it is also possible that syn-thetic material wastes consisting predominantly of PVC can be directly transformed into granular material using the method des-cribed above, and can thus be further utilized for metallurgic purposes. In this context, the production of titanium tetra-chloride should be mentioned, for ex~mple. Normally, TiO2 or rutile is mixed with coke and tar, gasified and calcined. Then it is chlorinated at 800C, for example, in a shaft furnace or fluidized bed. However at least a portion of the co~e and tar can be replaced, for example, by the hydrocarbons from the PVC wastes and the chlori-nation can be carried out as usual at an increased temperature, with the complete or partial elimination of the usual chlorine gas. The PVC-fraction that arises from the separation can be shredded or formed into granules or a powder, and then mixed with metal containing and/or metal compounds containing materials as a~ at least partial replacement of carbon and chlorine containing materials, and can then be converted in conventional metallurgic processes.

The feed material to be processed should be made up of substantially clean synthétic materials, whereby these materials are suitably separated substantially from all contained foreign matter and then coarsely comminuted. Herein, it is advantageous if the comminution is to less than lOOcm2.

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1 In the separation, it is especially advantageous if the fractions are separated into non-synthetic material and synthetic material with a fraction having a specific weight over approximately 1 g/cm3 and a fraction with a specific weight below approximately 1 g/cm3.
In this manner, on the one hand, non-synthetic materials are separated from the synthetic materials, and through the separation of synthetic materials by specific weight, it is possible to make a further separation of the PVC and other synthetic materials. Fractions separated in such a way can then be introduced advantageously to separate processes which are suited to the special characteristics of the separated synthetic materials. Particularly, the fraction with a specific weight under 1 g/cm3 has the special advantage, that it can easily be separated from foam material and then consists only of unfilled synthetic materials of polyolefin polymers, which have almost no toxic components, so that they can be converted into a gas or oil rich in hydrogen which can be used as reduction agent.

The processing of the synthetic materials described so far, makes it possible to have the chlorine content andtor hydroc~rbon content of the wastes available again for use, which takes place advanta-geously in that the contents mentioned are used in metallurgic reactions.

Thus, it i~ suggested on the one hand to break down said wastes again, and it is further suggested that this break down does not necessarily take place with a view to obtain raw materials for the production of synthetic material, rather to provide raw materials which can be utilized in other processes, for example, in metallurgic reactions, to produce energy, among others.

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1 It is also possible to heat a mixture of PVC wastes, metal- and/or metal compound containing materials and other desired additional materials, whereby the PVC wastes become plastified so that pellets or the like are then produced from the entire mixture for later utilization.

It is also possible to bring the PVC fraction in liquified or powder form by means of a nozzle lance into a liquid metal bath and then to use it there for the removal of contaminants. The PVC fraction is advantageously brought into a reactor under increased tempèrature for reaction with metal or metal compound containing materials.
Hereby, the PVC fraction can also be gasified first. It is also possible to bring the gasified PVC fraction into a liquid metal bath with the help of a nozzle lance.

Surprisingly, it has now been discovered, that it is also possible to dehalogenize larger portions of PVC in the synthetic material waste mixtures, in that the halogens are treated for a duration of 10 seconds to 10 minutes at a temperature of 150~C to 350C, in order to split off the chlorine or other halogens, possibly together with hydrogen. These split off halogens can be regained through condensation or by washing the gases that are produced during this heat treatment. They can also be brought directly into reactions with other materials. The toxic gases that are split off during the heat treatment, so far as any are produced, can be vacuumed off and supplied to a wet wash for separation.
In such a wet wash an aqueous solution of alkaline and/or earth alkaline compounds are preferably used.

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1 It is also especially advantageous that the liquified and/or gasified constituents can be supplied to an incineration, whereby the heat produced by the incineration can be given off into the surroundings or it can be utilized in other devices.

A further possibility according to the invention, for utilizing the organic wastes lies therein, to burn a portion of the wastes with oxygen, to liquify or gasify the other portion and to inject the liquified and/or gasified constituents of this other portion into the smoke gas stream produced by burning the first portion and thereby to form a gas suitable for synthesis or a synthesis gas itself. Especially that portion should be incinerated with oxygen, which contains toxic materials or is not of the polyolefin type. Herein, the oxygen content of the incineration medium should be greater than 50%.

Fillers and fuels gases can also be worked in.

It is also possible to transform the gas mixture produced by the injection, through the choice of a suitable catalyst and pressure and temperature, into synthesis gas, fuel gas, reduction gas, or other useful gases. This can take place advantageously, in that the gas mixture produced by the injection is brought into existing systems for producing such gases as a complete or partial replace-ment for the normally used materials or also in addition to these materials.

A system with one or more worm machines, in which the reaction chambers are formed by the worm machines themselves, is especially suited for carrying out the method of the invention. These worm .
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1 machines are constructed to be heatable, having openings for gas removal and injection, and having a device connected to the worm machine for further processing of at least a portion of the product produced by the worm machine. Naturally, several worm machines of the same or different construction can be connected to one another and/or utilized.

Advantageously, a sorting apparatus and a comminuting apparatus and a filling or packing-in apparatus are arranged upstream of the worm machine or worm machines. The comminuting apparatus can reduce the size of the waste pieces to a granular size suitable for extruding. The sorting apparatus can be arranged upstream of the comminuting apparatus or else between the comminuting ap-paratus and the worm machine, depending on its purpose.

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An incinerator can also be included in the system for urther proces-sing the liquified and/or gasified wastes. ~y a suitable incinera-tion, the wastes can be disposed of in an environmentally safe way and the energy gained can be utilized for further processes.
The environmentally safe disposal lies especially therein, that with the help of the smoke or flue gases and other constituents brought into the smoke gases, further gases of a desired composition are produced by the incineration. In this manner, the gases pro- -duced by the incineration do not enter the environment, but are used to produce useable gases. As far as excess heat is produced during this incineration, it makes sense to use this heat in a thermal prime mover, which advantageously is part of the system described above for further processing. Additionally, or alterna-tive}y, this excess heat can be regained by a heat exchanger for further use. This heat exchanger is then also advantageously a component part of the system for further-processing.
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1 In order that the possible remainder gases from the incineration do not produce an environmental hazard, it is ~urther an advantage if this system for further processing also includes a suitable gas cleaning apparatus.

Due to the various processing possibilities, it is further especially advantageous if the system for the further processing comprises a mixing apparatus for admixing to the melt, organic materials such as wood, straw, textiles, or paper. In order to produce spec-' ific gases for a desired further use or for neutralizing, it is useful, if the apparatus ~ the invention comprises a separator for separating the desLred gases from the gas mixture.

In order to work with a substantial automated process, it is sug-,gested according to the invention, that the plant comprises an input feeder and sensors for ascertaining desired status data of the final and intermediate products, and that furthermore, open loop and closed loop controls are provided for the input feeder which control,the input feeder in an open or closed loop in response to the results measured by the sensors. In this way it is possible to ,monitor the composltion of the melt and/or of the produced gases, and the composition can be influenced by a respective admixing of suitable ~synthetic material wastes.

In the following reference will be made to several example possi-bilities that are opened up by the method of the invention, whereby the organic polymers are first decomposed to form low molecular hydrocarbons, which still can be polymers. These can then, for example at very high temperatures, be converted to a synthesis gas which is useful for recovering any hydrocarbons. This approach .
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1 is especially advantageous if the waste materials to be processed contain toxic ingredients such as oils containing PCBs, dioxin, and furanes, different aromatic compounds and so forth. Such hydro-carbon compounds are very stable and decompose only at temperatures well above 1200C. Further, some carbon companions are considered to be directly responsible for the formation of highly toxic dioxin, if the combustion or processing temperatures remain too low. As far as a combustion P12 is involved here, the temperatures in the reactor should be 1200C and higher.

The synthesis gases that are produced are the direct basis for the production of hydrocarbon compounds. Conventionally, these are produced almost exclusively of natural gas and crude oil. They are, however, also produced of coal or other hydrocarbon compounds.
Thus, heretofore natural gas, crude oil, and coal have been used to produce synthesi~ gas. According to the method of the invention, however, synthetic material wastes are used in place of the con-ventionally used raw materials. For this purpose, clean synthetic material wastes, for example from synthetic material production, or prepared wastes from other sources can be used. However, the use of contaminated synthetic material wastes is also possible.
-; In this way, for example, the light fraction which arises when shredding automobiles, the so-called shredder wastes can be used, whereby it is naturally useful to first screen out the nonpolymer components, mostly minerals, such as glass shards and stone. A
further difference to known processes lies therein, that the material fed into the process is melted down by a simple warming without the exclusion of air, whereby the macromolecules of the synthetic materials can be broken down and shortened by processing with reactive gases, prefera~ly with oxygen, but also with hydrogen and water , .
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1 vapor, either alone or in combination, simultaneously with or after melting, and thereby, under suitable pressure and temperature, be liquified to a point so that they can be injected by conventional nozzles or burners or the like into the reactors to produce the desired synthesis gases or gases for other applications. To achieve this, one may proceed as follows:

The synthetic material parts which come, for example, from a shredder for used cars, are comminuted to about the size of a palm and are processed in accordance with the extent to which they are intermixed with non-thermoplastic synthetic material components, in systems with higher shearing forces and simultaneously higher oxygen content.
The prepared wastes are melted down.

For this purpose, a worm extruder is used (see Fig. 2), such as a worm kneader rotating in the same direction. Thereby, the sup-plied synthetic materials shreds can be brought together very early that is, already in the feeding funnel, with the reactive materials that start the intended break down of the polymer molecules,for this the funnel is flooded with this gas or gas mixture. To make the feeding of the synthetic material shreds easier, filling devices or stuffers can be arranged.

The worms which may be provided with one or more kneading, shearing, and stowing steps, have the task of continually advancing the feed-in materials; of melting and breaking down under the supportive action of the shearing force, with the help of which the molecule chains are mechanically ripped apart, and the possibly added reactive agents; of building up a pressure great enough for the injection, in combination with the mixing-in of the reactive materials and, if applicable, the pulverizing propellant.

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1 The fed-in polymer material is heated in the worm to approximately 400C or even higher. Under the influence of high temperatures, shearing forces, oxygen, hydrogen, air, water, and possibly other additives, the molecules are broken down and neutralized, so that a thin liquid molten mass is formed due to the now short molecules.
In the last third of the worm gear, the molten mass that has been prepared in this manner, flows into a decompression stage provided on the worm gear and formed by suitable worm gear elements, into which the heated reactive gases are injected. In the last zone of the worm gear, which is formed as a mixing zone, these reactive materials are evenly distributed into the molten mass and the mixture is condensed at a pressure between 20 and 100 bar. A cascade-like arrangement of extruders or pumps around a mixing chamber is, however, also a possibility.

The molten mass can then be brought into the reaction chamber through an apertured plate or through a rotating disk or another suitable device, and can then be dispersed into fine droplets through a nozzle. The molten mass can be divided into thin strands especially through an apertured plate, so that the high pressure gases in the molten mass disperse the mass into fine droplets as soon as they enter the low pressure reactor. Other known nozzle~ or burners can, however, also be used to inject the liquified synthetic material into the reactor.

The injected molten droplets should partially be combusted, so that the necessary high temperatures of at least about 1200C are obtained. In this way a portion of the injected polymer molten mass is used as combustion fuel, the rest is transformed into the ~ desired synthesis gas.

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1 Besides the especially high temperature in the reactor, which serves to destroy all dangerous hydrocarbon compounds, it is of special importance that the polymer molecules are substantially broken down during the treatment in the extruder by the addition of oxygen, hydrogen or water vapor, said materials being added also in combi-nation, so that the molten mass, even before entering the mixing zone at the end of the worm, has a viscosity as low as possible, so that the mixing-in of the reactive materials is simplified, and so that said mass can be easily ripped into simple droplets upon exiting into the low pressure chamber provided by the reactor.
The early contact with oxygen and possibly with hydrogen, has the further important task of preventing a recombination of the polymer fractions and radicals that were formed by the saturization of the radicals and the free valences of the molecular fractions by the atoms of the reactive gases.

It can be advantageous for the continuously operating system, with reference to a uniform composition of the synthesis gases, to con-tinuously control the molten mass with regard to the relationship of carbon to hydrogen, that is the hydrogen content, and to auto-matically conform this content to the synthetic material supply.The sensor that supplies these data is advantageously mounted in a by-pass and comprises, for example, an infrared detector that detects the critical molecules. This control simultaneously provides the possibility that the addition of a determined amount of a chemical or other components to absorb undesired constituents can also be regulated by a suitable regulator.

If the synthetic material wastes to be processed contain mechanical contaminants, then the extruder is equipped with an apparatus, such 83~0~
1 as a conventionally known molten mass filter, in order to separate the liquified synthetic material from the solid materials. Further processing of the synthetlc material that has been comminuted, liquified, and injected into the reactor follows now in a known manner. Fig. 2 is a schematic drawing of the arrangement of a ~"
suitable system and the steps of the process. Fig. 2 is self-explanatory and and needs to additional comment.

Process Example Embodiment The experiment described below shows one possible sequence of the process.

The light fraction of the shredder wastes which have been coarsely cleaned of non-organic wastes through a sieve, originate from an automobile shredder system from the processing of, as already stated, 106 passenger automobiles.

The following Table 1 gives information about the origins or the shredder wastes.

T e Number Percent %
YP

VW/Audi 33 31 Opel 23 22 Daimler 9enz 11 10 Ford 9 8.5 Renault/Peugeot/Citroen 15 14 Fiat 9 8 Mazda/Honda 2 2 ~ord USA 1 --- lD6 100 - lB -2a~3~
1 Table 1 The polymer wastes were obtained by winnowing behind the hammer mill. They comprise various synthetic materials (compare Table 2).

Weight Percent of Material ~ame Abbreviation the Auto Body %
Polyurethane PUR 42 Polypropylene PP 24.5 Polyethylene PE 11.3 Acrylonitrile/Butadiene-Styrene-Copolymer ABS 11.0 Polyvinyl chloride PVC 6.0 10 Non-neutralized polyester UP-GV 2.5 Polyphenylene oxide (modif.) PPO 2.1 Polyamide PA 0.4 Polyacetal POM 0.3 Table 2: Weight percent of the synthetic materials in the autobody type PORSCHE 928 is without elastomers, textiles and paints.

Most of the polymer wastes are chip-like fragments of synthetic material components. Since the diameter of these fragments was too large for the experimental worm gear machine used in this experiment, they were additionally reduced to fragmentary granules of less than 3 mm in diameter by a granulator.

The extruder - a Werner and Pfleiderer ZSK - double worm gear laboratory ~neader ZSX 30 with a worm gear diameter of 30 mm -was equipped with a funnel from which the fragments were pu}led into the worm gear in a free-flowing manner. Manual help was not necessary. The funnel was flooded with oxygen.

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1 The extruder was equipped with plug-in type worms having a length 36 x D. These were provided with conveying elements on the first 10 x D of their length. This conveying zone was closed by two shearing elements with a length of 2 x D, followed by two further conveying-kneading zones, each zone having a length of 2 x D for the conveying element and 1 x D for the kneading element. Down-stream of the two zones is a radial choke with a length of 1 x D.
Conveying elements 5 x D having a double gear pitch are arranged behind the radial choke. Since in this zone a low pressure pre-vails, the injection of oxygen and water vapor took place here.
The remaining 11 x D of the worm gear was provided with conveying elements with a simple gear pitch and with mixing elements, in order to be able to build up the necessary pressure and to dis-tribute the reactive gases throughout the molten mass. The cylinder of the worm gear was closed off with a perforated plate provided with bore holes 2 mm in diameter. A normal sieve plate with three fine sieve layers was superimposed, preferably to cause a pressure build-up in the molten mass. The perforated plate fed into the ' reactor chamber.

,1 The extruder cylinder was heated to have a rising temperature ` in the first half and then heated to 420C in the second half.
The throughput or mass flow was up to 60 kg/h at 500 r.p.m. Oxygen in a quantity of up to 50 kg/h preheated to 250C and hot steam were pressed into the molten mass at 20 x D in the decompression .
zone upstream of the mixing zone. The extruder was flanged onto a combustion chamber set to atmospheric pressure and serving as a reactor, so that the perforated plate extended into the reaction chamber. The reactor could be heated by electrical heating bands :

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1 for starting combustion. In addition, a gas burner was connected, which ignited the gas synthetic material droplet mixture entering from the extruder.

In order to measure the exhaust gases, these were caught in bags and analyzed by conventional methods. Depending on the tempera-ture of the reaction chamber, a gas mixture comprising low molecular hydrocarbons, CO, hydrogen and up to 10% carbon-dioxide was produced.
The gas composition could be varied substantially by varying the amounts of oxygen and water vapor fedinto the mixing chamber.
During injection of these gases, their temperature was held con-stant at 250C.

In case the gasification of certain synthetic materials was not yet sufficient downstream of the extruder, the still liquid synthe-tic materials were not injected directly into the combustion cham-ber or reactor. Rather, these liquids were injected into a super-imposed upstream arranged gasifying chamber which is heated and in which the gasification takes place.

Not only synthesis gas or fuel gas can be produced of the liquified synthetic materials, as shown thus far. Rather, also reduction gas can be produced which is suitable, for example, for the pro-duction of spongy iron.

It makes sense in all these utilizations, to use the synthetic materials that have been liquified or gasified in the manner des-cribed, not only in systems that have been built exclusively for these materials. Rather, they can be utilized in already existing 2083B~
1 systems to partially or completely replace the reactive materials usually used therein. They can also be utilized in addition to these conventional materials.

The liquified synthetic materials can also, as mentioned, be formed into granules or into powder by spraying. Such granules or powder are raw materials which are easily dosed for producing synthesis gas and/or other useable hydrocarbons and gases. They can also be used as combustibles or fuel and as a reducing agent. EspeciaIly for this purpose the characteristic of the synthetia material in question is important, namely to be able to gasiy practically without residue at an increased temperature. With a granule size of 2mm in diameter, gasification occurs in less than 0.5 second at 1000C.

If the synthetic material produced contains a PVC fraction or is made up entirely Gf PVC, special difficulties arise in the conventional technology. PVC is considered to be one of the least "friendly-to-recycling" synthetic materials. In the conventional methods of waste removal of PVC, the chlorine in the PVC and other ~toxic gaseous components that are produced, cause special diffi-culties. These difficulties are even more problematic, sincePVC is an unusually widespread mass-produced synthetic r rial, which can hardly be done without, as a result of which it occurs in all synthetic waste material mixtures. In addition, severe corrosion damage due to hydrochloric acid used to occur in the combustion plants, mainly in the waste-heat boilers.

The method according to the invention provides a possibility for the removal of chlorine containing PVC wastes, whereby our experiments -2083~
1 have shown that the content of remaining chlorine was less than 0.3~ in the produced waxes or oils. Such oils or waxes would be officially approved as a heating oil.

It is known, that PVC begins to give off chlorine and hydrogen at relatively low temperatures of about 100C, so that a hydro-chloric acid is produced in its status nascendi. Surprisingly, it has been found that, in spite of the so-called stabilization of the PVC above 200C, and especially 250C, a very rapid and complete splitting off of the chlorine takes place. This splitting off is practically completed within normal dwell times of a few minutes at 300C. Further, it appears that when this heating procedure occurs under substantially air-free conditions, only this splitting off occurs on the polymers, so that the gases pro-duced are made up almost exclusively of hydrochloric acid. In addition, above 200C the splitting off increases in speed, so that it becomes unnecessary to separate the PVC wastes. Dienes remain as remnants that can be completely decomposed and broken down at higher temperatures.

, To utilize wastes with a PVC fraction or pure PVC wastes, one ; 20 can however also proceed as follows; PVC has a relatively large specific weight for a synthetic material, and it can therefore be easily separated, for example, by floatation, from other syn-thetic material wastes, so that a waste material exclusively com-prising PVC is available for further utilization. Next, if it is needed, the product can be cleaned of possibly clinging dirt by washing. A comminution must only be undertaken, insofar as lt is necessary for the preparation for the process. The prepared PVC waste can now be further utilized in the following manner in the reactions to be carrled out:

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2o836~l 1 ~1. The PVC waste is ground down cold, or is otherwise substantially comminuted, so that a granule like product is produced. This granule like product can now be mixed alone or in combination with otherwise customary additives, with metal and/or metal com-pound containing materials, and then brought to reaction in the course of the usual processes. The chlorine that is liberated by the break down at increasing temperatures reacts in the same way as the chlorine in other chlorine containing materials or like gaseous C12. Here hydrocarbons of the PVC simultaneously serve as a reducing agent so that these hydrocarbons can either completely or partially replace the carbon which is normally added.
The addition of the granule like product is carried out by simple admixing or the mixture of PVC and metal and/or metal compound containing materials is heated, so that pellets or the like can be produced by the early softening of the PVC. As an example of the above mentioned processing, the production of titanium tetrachloride which was described above could be mentioned.

2. In order to refine liquid metals, PVC wastes, for example, in the form of shreds or as a granule like product are pressed into the liquid metal with the help of a suitable means, whereby certain metals are preferably bound by the freed chlorine and they can then be removed as salts from the molten metal. The removal of tin from molten lead is given as an example here.
. , 3. PVC wastes can also be gasified in a suitable apparatus, such as a rotary kiln, without first being comminuted. The gas that is produced is led into a reaction chamber, where it is brought into a reaction with the metal or metal compound containing materials.

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1 As Fig. 1 shows, th~ method of the present invention is also excel-lently suited for performance in very small systems. It is often the case that the yield of such organic wastes, preferably synthetic material wastes, is small or that its transportation to large central systems is uneconomical. With the method of the present invention, however, even small amounts of organic wastes, especially clean, mixed synthetic material wastes, can be sensibly and economi-cally utilized, whereby the wastes are comminuted to a granule size of less than 100 mm, preferably less than 50mm. Then, the wastes can be separated according to a conventional gravitational separation process into fractions of varying specific weights.
~ Depending on the composition of the wastes, several different ; fractions can be gained, for example:
a) metal, glass, stones;
b) PVC, PTFE, filled synthetic materials, as well as further synthetic materials with a specific weight of over 1 g/cm3;
c) unfilled polyolefins.
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In this presentation, the specific weight of the metals decreases toward the polyolefins. Separation of the halogen containing synthetic materials, such as PVC, from the other synthetic materials can be advantageous if a problem-free, direct burning in a combustion system or a thermal power plant, such as a combustion engine or a gas turbine, is desired.

The organic fractions are supplied to one or more extruders, which ; can be arranged in parallel to one another or in series, whereby insofar as the synthetic materials contain halogens, most commonly chlorine such as is the case in PVC, these can be split off at a rel~tively low temperatuFe of 300C in a short time duration , ~

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1 in one of the first stages of the extrusion system. The synthetic material wastes are then heated to higher temperatures of over 350C, whereby they are broken down into low molecular molecules and liquified or gasified under the influence of heat, of a possible shearing action, and the possible addition of air or water, or water vapor, and possible metal oxides that are mixed or injected, or under the influence of other catalytic materials that would accelerate the break down of the synthetic material molecules.
It is also possible, to filter the molten mass by conventional means in the extruder or extruders, in order to separate out the fine-grained mineral component or non-molten components.

Depending on the composition and consistency of the molecular fragments that finally emerge from the extruder or extruders, the fragments can now be incinerated, or if they are clean enough, they can be supplied to a thermal power plant, such as a combustion engine or a gas turbine. Insofar as they solidify at room temper-ature, they can be transported away or used directly in granulated form or foamed up in a comminuted form, alone or mixed with other materials, such as wood or straw, in loose granular or powder form or pressed into briquettes or another form.
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If the products contain toxins which are freed during incineration, then a gas purification is provided. Preferably, a gas wash which works with alkaline and/or alkaline-earth compounds would be used for this purpose. If only alkaline-earth compounds are available, then these would be added directly to the hot combustion gases, or immediately prior to the splitting off of CO2. Thereby, the system, especially the waste-heat boiler which might be present, .

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, 2~83~1 1 is protected against corrosion. The halogens that were possibly split off during the first extruder phase are suctioned off and are also added to the smoke gas purification to be neutralized.
If the waste waters containing the alkalis and earth-alkalis can be added to water without a problem, for example to brackish water or to the ocean, there is no need to further process the wash water.

Fig. 1 and Fig. 4 each show a method flow-chart from which the above described method becomes clear. The method flow-chart is self-explanatory and needs no further description.

Fig. 3 shows an alternative construction of the extruder station with reference to the system shown in Fig. 2. Fig. 3 is also self-explanatory, so that here too there is no need for further explanation. The temperatures indicated on the extruders are temperature limits. The preferred temperatures can be seen in Fig. 4.

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Claims

Claims A method for the utilization of organic wastes at least made pre-dominantly of macromolecules, characterized in that the wastes are heated to more than 150°C, then melted and broken down to low molecular waxes, oils or gases in a reaction chamber or in several reaction chambers connected in series, under the addition of reactive gases, such as oxygen and/or hydrogen and/or water and/or air and/or water vapor and/or metals or metal compounds, such as metal oxides.

The method of claim 1, characterized in that the wastes are addi-tionally subjected to pressure and/or a shearing force.

The method of claim 1 or 2, characterized in that a dehalogeniza-tion of the polymers is performed simultaneously if the polymer wastes contain halogen.

The method of one of the claims 1 to 3, characterized in that a worm machine or a combination of worm machines is used as a reaction chamber.

The method of one of the claims 1 to 4, characterized in that the organic wastes are processed continually or in batches, whereby at least the hydrogen component of the liquid and/or gaseous components is controlled and influenced by doses of suitable organic wastes.

The method of one of the claims 1 to 5, characterized in that prior to treatment the wastes are divided into fractions of non-synthetic materials, synthetic materials with a specific weight over 1 g/cm3 and such with a specific weight under 1 g/cm3.

The method of claim 6, characterized in that the fractions are supplied to separate processings whereby the fractions with a specific weight under 1 g/cm3 are transformed according to the methods described in claims 1 to 5, into a hydrogen-rich gas or oil that can be used as a reduction agent.

The method of one of the claims 1 to 7, characterized in that mechanical pollutants are removed from the molten mass.

The method of one of the claims 1 to 8, characterized in that at least one of the fractions produced is brought into conventional plants as at least a partial replacement of the materials heretofore used therein or in addition for producing synthesis gas or other useable gases and/or hydrocarbons, or as a reduction agent.

The method of one of the claims 1 to 8, characterized in that after breaking down and liquifying, the wastes are granulated or made into a powder by spraying or another conventional method, and are brought at least additionally as raw materials or reaction materials into existing plants.

The method of claim 1, characterized in that a chlorine content and/or the hydrocarbon content of the wastes is used in metallurgic reactions.

The method of claim 6, characterized in that a PVC fraction pro-duced by the separation is at least partially shredded or made into granules or powder, and is mixed with metal containing and/or metal compound containing materials, for at least partly replacing carbon and chlorine containing materials, and is then converted into conventional metallurgic processes.

The method of claim 6, characterized in that a mixture of PVC
wastes, metal and/or metal compound containing materials and other desired further additives, is heated, whereupon due to the plasti-fication of the PVC wastes due to the heating from this total mixture pellets or the like are formed.

The method of claim 12, characterized in that the PVC fraction or the chlorine containing gases arising from said fraction are brought into a liquid metal bath by means of nozzles or lances, and are used there for the removal of pollutants.

The method of claim 10, characterized in that the PVC fraction is brought into reaction chambers at an increased temperature, in order to react there with metal or metal compound containing materials.

The method of claim 15, characterized in that the PVC fraction is first gasified.

The method of claim 1, characterized in that the PVC wastes or other halogen containing synthetic material wastes are heated in air or an inert atmosphere or in the absence of air and are processed for a time duration of 10 seconds to 10 minutes at a temperature of 150°C to 350°C, preferably between 250°C to 350°C, in order to split off the halogens, especially chloride.

The method of claim 17, characterized in that the split off halo-gens are regained by condensation or washing out of the gases produced by the heating treatment or they are brought into reac-tion with other materials.

The method of claim 1 , characterized in that at least the toxic gases split off during the heating process, are suctioned off and led to a wet wash for separation.

The method of claim 19, characterized in that an aqueous solution of alkaline and/or earth alkaline compounds is used for the gas purification taking place in the wet wash.

The method of one of the claims 1 to 20, characterized in that filler materials and/or fuel gases are worked into the waxes or oils produced of the broken-down polymer materials.

The method of claim 1, characterized in that the liquified and/or gasified components are led to an incineration, wherein the heat produced by the incineration is given off into the environment or used in further devices.

The method of claims 1 to 20, characterized in that a portion of the wastes are incinerated with oxygen, whereby the components of the other portion which are liquified and/or gasified according to the method of claim 1, are injected into the flue gas stream of the incineration of the first portion, and thereby a gas suitable for synthesis or a synthesis gas is produced.

The method of claim 23, characterized in that a portion that contains toxic materials and/or a non-polyolefin portion is incinerated with oxygen.

The method of claim 23, characterized in that the incineration medium has an oxygen content of over 50%.

The method of claims 23 to 25, characterized in that the gas mixture produced by the injection is transformed, by the choice of suitable catalysts, pressure and temperature, into synthesis gas, fuel gas, reduction gas or other useable gases.

The method of claims 23 to 25, characterized in that the gas mixture produced by the injection, is introduced into existing systems to produce synthesis gas, fuel gas, reduction gas or other useable gases as a complete or partial replacement for the materials heretofor?
used therein, or in addition to these materials.

A system for carrying out the method of claims 1 to 27, having a worm machine and a reaction chamber, characterized in that the reaction chamber is formed by one or more worm machines, which are constructed to be heatable and have openings for gas removal and injection openings, and with a device connected to the worm machines for further processing at least a portion of the products produced in the worm machines.

The system of claim 28, characterized in that the system comprises a packing-in worm feeder.

The system of claims 28 and 29, characterized in that at least one filter is provided for the molten mass to filter out fine-grained mineral additives or to separate out non-molten components.

The system of claim 28, characterized in that the system comprises for further processing a thermal combustion engine.

The system of one of the claims 28 to 31, characterized in that the system has a separator for separating desired gases from the gas mixture.

The system of claim 28, characterized in that the system comprises a delivery unit and sensors for providing desired data about the conditions of the end and intermediate products, and that further open or closed loop control units are provided for the delivery unit, which control said delivery unit in open or closed loop manner in response to the measurements of said sensors.